ES2412960A1 - Equipment and procedure with amperometric detection for water quality control applications applicable to the measure of detergents (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

The equipment (100) and procedure with amperometric detection for water quality control applications applicable to the measurement of detergents is useful for determining the physical and chemical characteristics of a water sample, especially in a washing machine. The method comprises the steps of housing a water sample (1) in a chamber (2); applying an electrical activation signal (s1) to a counter electrode (6) arranged in said chamber (2). The method further comprises the steps of detecting the electric current (I) generated in an electrode (3); sample said electric current generated in respective instants (t1 ... Tn) to determine a set of instantaneous values (i1 .. .in) of said electric current; to weight each instantaneous value of said current with a respective weight value (β1 ... βn) previously determined in a statistical way; and obtain by means of a formula a prediction of the value of the parameter (y) to be quantified in the water sample. (Machine-translation by Google Translate, not legally binding)

Description

EQUIPMENT AND PROCEDURE WITH AMPEROMETRIC DETECTION FOR WATER QUALITY CONTROL APPLICATIONS APPLICABLE TO THE MEASURE OF 5 DETERGENTS

Technical sector of the invention The equipment and method with amperometric detection for water quality control applications applicable to detergent measurement is useful for determining the

10 physical and chemical characteristics of a water sample, especially in a clothes washer.

BACKGROUND OF THE INVENTION Washing and sanitizing fabrics in a laundry machine consumes large

15 amounts of energy, water and chemicals that are necessary for the performance of sanitation and cleaning processes. At this time the world population already exceeds 8600 million inhabitants. The average water consumption per person for domestic needs is around 160 liters / day. In a typical family, the washing machine usually works 2-3 times per week, and depending on the domestic machine model, for each wash

20 with a typical cotton program at 60ºC, approximately 100 liters of water are consumed, and between 1-2 KWh of energy (a good part of the energy is used to heat the water and not in the rotation of the drum). This average water and energy consumption varies greatly from one program to another, resulting in a 20-50 liter water consumption difference between a cotton program at 90 ° C and a synthetic one at 40 ° C, with an exponential increase in

25 power consumption of up to 6 times more kWh when using one program in front of another.

The situation of scarcity of resources that is happening at this time makes it necessary that all social and individual actions minimize the energy and ecological impact on the environment around us.

30 It is therefore necessary to have equipment to measure the characteristics of the water used by washing machines in order to determine the degree of dirtiness of the clothes, the hardness of the water or the concentration of detergent to control the detergent dosage or even to be able to take advantage of the water between the last phases of a wash -

35 cleared - and the first of the next - prewash -.

To solve this need, equipment such as the one described in the ES2166358T3 patent is known which measures the charging time of a condenser through the water of the washing chamber to determine its characteristics. However, this solution only allows the evaluation of water resistivity, without being able to discern between the different components in solution.

It is therefore an objective of the present invention to disclose a device and method that allows to discern the different components in dissolution of a water sample and measure, at the same time, different parameters of interest of the water sample.

Explanation of the invention The process with amperometric detection for water quality control applications applicable to the detergent measurement of the present invention is one of the steps comprising housing a water sample with compounds dissolved in a chamber and applying a signal electrical activation to a counter electrode arranged in said chamber in contact with the water sample.

In essence, the process is characterized in that it further comprises the step of detecting the electric current generated in an electrode provided with a noble metal, also disposed in said chamber and in contact with the water sample as the compounds dissolved in the sample of oxidized or reduced water in said electrode; sampling said electric current generated in respective instants to determine a set of instantaneous values of said electric current; weight each instantaneous value of said current with a respective weighting value previously determined statistically; and obtain a prediction of the value of the parameter to be quantified in the water sample using the formula

N

Y = ∑ βi ⋅ Ii

i = 1

advantageously allowing to obtain the value of the parameter without having to add reagents or other components to the water sample. Of course it is possible to obtain the value of several parameters by simultaneously applying the same formula with different weighting values.

In another variant embodiment, the method comprises the previous step of statistically predetermining the weighting values (β1… βn) by means of a PLS (Partial Least Square) regression algorithm for parameter measurements.

5 It is also known that the electrical activation signal that is applied to the counter electrode is a pulse train, alternatively performing the oxidation and reduction of the compounds dissolved in the water sample in the electrode, with adaptable amplitudes depending on the type and electrode size within the range + 2V and -2V, this voltage being sufficient to cause oxidation and reduction of dissolved compounds in the sample

10 of water in the electrode.

It is also known that after detecting the electric current generated in the electrode to determine the value of the parameter to be quantified and before performing the detection again a regeneration stage of the electrode and the counter electrode is performed to eliminate products that would have chemisorbed or fisisorbed remains on its surface comprising the steps of replacing the water sample with clean water in the chamber; Apply an electrical cleaning signal between the counter electrode and the electrode eliminating products that would have remained chemisorbed or fisisorbed on its surface, in this way it is possible to regenerate the electrode and return it to its initial state to be able to

20 make subsequent measurements without these being affected by the measurements taken so far.

In a variant of interest, the electrical cleaning signal comprises a positive voltage pulse and a negative voltage pulse that preferably have an amplitude greater than the voltage applied in the counter electrode above to detect the electric current generated in the electrode, said electrical cleaning signal comprising, in a variant embodiment, at least a first pulse of 1.6V of duration between 2 and 3 seconds followed by a second pulse inverted to the first pulse that allows the products that had been chemisorbed or fisisorbed on its surface after detection separate from

30 electrode, being suspended or dissolved in the water sample that will be subsequently changed.

The process of the present invention is especially useful for obtaining predictions of parameters related to a physical parameter of the compounds dissolved in the water sample to be quantified such as the chemical oxygen demand, the

conductivity, turbidity, pH, hardness, total nitrogen concentration or dissolved detergent concentration. Naturally, the process could also be used to predict other parameters related to one or more physical parameters of the compounds dissolved in the water sample.

5 The equipment for carrying out the process with amperometric detection for water quality control applications applicable to the detergent measurement of the present invention is one comprising a chamber arranged inside electrical screening means to house a water sample; a means of

10 filling and means for emptying the water sample in said chamber; a counter electrode disposed in said chamber and connected to electric generating means, in contact with the water sample when the chamber houses a water sample; and an electrode also disposed in said chamber and connected to means for detecting an electric current generated in said electrode and adapted to be in

15 contact with the water sample when the camera houses a water sample.

In essence the equipment is characterized in that the electrode comprises a noble metal in which an electric current is generated due to the presence of dissolved compounds in the water sample that oxidize or reduce said noble metal when a signal is applied

20 electric activation on the counter electrode.

According to another variant embodiment, the counter electrode also comprises a noble metal, which allows the electrode to be regenerated by means of the electrical cleaning signal, that is, to eliminate the products that would have remained chemisorbed or fisisorbed on its

25 surface, without the need to remove them mechanically. It has been found that when said noble metal is Gold, Rhodium, Iridium or Platinum the regeneration of the electrode is optimal.

In a variant of interest, the chamber is metallic and acts as a counter electrode, avoiding having to place a dedicated counter electrode. In this case, the metal chamber, which will act at

30 counter electrode mode, will be connected to the electric generating means.

In another variant of the invention, the counter electrode and electrode are cylindrical in shape, one of them being hollow and the other being arranged in its interior concentrically; and the gap between the electrode and the counter electrode being in the hollow filled with a dielectric material, said counter electrode and electrode being integrated

forming a single package that can be handled more easily.

In a variant embodiment, the electrical generation means for applying the electrical activation signal to the counter electrode is formed by a processor connected to a

5 amplifier, in which the output of the amplifier is fed back into the processor to be able to verify that the level of electrical voltage of the generated electrical activation signal is adequate. If the level of electrical voltage generated is not adequate, the level of electrical voltage generated should be calibrated, for example, increasing it until it reaches the appropriate level.

In another variant of interest, the means for detecting an electric current are formed by means of current-voltage conversion connected to a processor, advantageously allowing the processor to be able to provide a potential value that is proportional to the intensity generated at the electrode, being able to perform this conversion of

15 independently and avoiding distortions. Naturally, if the processor were equipped with an analog current input that allowed to measure without distortion the current generated in the electrode, the electrode could even be connected directly to the processor.

In another variant embodiment, the equipment further comprises a temperature probe connected to the processor to correct errors due to thermal drift. This prevents changes in the temperature of the equipment to influence the results obtained.

In a variant of interest the connections with the processor are provided with means

25 of electrical separation that allow electrically separating the means for detecting an electrical current from the processor, preventing the value of said electrical current from being affected by the processor and also avoiding providing excessive values. In a variant of interest, the electrical separation means can be voltage followers, which allow the processor to be electrically separated.

A washing machine is also disclosed which comprises a device for measuring detergents according to the present invention in which the filling means of the chamber are adapted to fill said chamber with a sample of water from the washing drum of the washing machine and so you can perform the procedure with amperometric detection

35 for water quality control applications applicable to the detergent measurement of the present invention, the drainage means being adapted to empty the water sample from the chamber and return it to the drum or dispose of it as determined in the procedure.

5 Brief description of the drawings To complement the description that is being made and in order to facilitate the understanding of the features of the invention, a set of drawings is attached to the present specification in which, for illustrative and non-limiting purposes, The following has been represented:

Fig. 1 shows the equipment of the present invention provided with an electrode and a counter electrode; Fig. 2 shows the equipment of the present invention installed in a washing machine; Fig. 3 shows the equipment of the present invention during the detection stage; Fig. 4 shows an example of the electrical activation signal and the electric current

15 detected; Fig. 5 shows a detail of the connection of the electrode and counter electrode of Fig. 3; Fig. 6 shows a scheme of the detection method of the present invention; Fig. 7 shows the equipment of the present invention during the cleaning stage; Fig. 8 shows an example of the electrical cleaning signal;

Fig. 9 shows an example of the electrical activation signal suitable for determining the detergent concentration; Fig. 10 shows an electrical activation signal alternative to that of Fig. 9; Fig. 11 shows an electrical activation signal suitable for the determination of the Chemical Oxygen Demand, Total Nitrogen Concentration and Conductivity;

Fig. 12 shows a graph with estimated values versus actual detergent content values measured with the equipment of the present invention; Fig. 13 shows an example of estimated values versus actual values of Chemical Oxygen Demand; Fig. 14 shows an example of estimated values versus real Concentration values

30 Total Nitrogen; Fig. 15 shows an example of estimated values versus real values of Conductivity.

Detailed description of the drawings 35 As can be seen in Fig. 1, the equipment 100 for the measurement of detergents based

in the amperometric detection for water quality control applications applicable to the detergent measurement of the present invention it comprises a chamber 2 for collecting a water sample 1; filling means 7 of said chamber 2 which in the variant shown in Fig. 1 are formed by a booster pump 12 to introduce the water sample 5 into the chamber 2, after passing through a thickness filter 13 to eliminate solid parts that the water sample 1 could contain, through a first valve 14 by means of a first conduit 15. The water sample can, for example, come from the drum of a washing machine that will be analyzed in the chamber 2 as will be explained later.

10 As can be seen in Fig. 1, the equipment 100 also comprises water filling means of the network 16 comprising a second valve 17 that communicates a water intake of the network 18 with a second conduit 19 to fill the Network water chamber 2 when appropriate. The equipment 100 also comprises means for emptying 8 of said chamber 2, to allow the drain of the chamber 2 through a third conduit 20

15 provided with a third valve 21. Said third valve 21 allows the water sample 1 of the chamber 2, after use in the chamber 2, to be recycled, for example by returning it to the drum of the washing machine or, if necessary discarding it , directing it to a drain.

Inside the chamber 2 shown in Fig. 1 an electrode 3 can be observed that

20 comprises a noble metal 5, such as Gold, Platinum, Rhodium or Iridium connected to amperometric detection means 4 to detect the electric current I generated in the noble metal 5 of said electrode 3 when applying an electrical activation signal S1, is that is, an electrical voltage, to a counter electrode 6 disposed in said chamber 2 in contact with the water sample 1, the same walls acting on the variant shown in Fig. 1

25 of the counter-electrode chamber 2 6. The value of said electric current I shall be due to the presence of polarization voltage of a detergent or other components dissolved in the water sample due to the oxidation or reduction of dissolved ions of said detergent in the noble metal 5 of the electrode 3. In other variants of the invention the electrode 3 could simply be metallic, of a non-noble metal, although in this case it

30 should take into account the drawbacks that will be described later in relation to their use in subsequent measures.

Because the electric current I of the electrode 3 can be very weak and easily distorted by external signals, it is convenient that the chamber 2 is arranged in about 35 electrical shielding means 9, for example an insulating resin or plastic forming

a grounded surface or shielding chamber, to electrically isolate the electrode 3 and the chamber 2 from the outside, avoiding distortions in the measurement of the electric current I. In this variant of the invention, the chamber 2, which is metallic, can be used as a counter electrode 6.

5 Fig. 2 shows a washing machine 200 comprising a device 100 for the measurement of detergents as described above in Fig. 1. It can be seen in this case that the filling means 7 of the chamber 2, inside the shielding means 9 used of counter electrode 6, allow said chamber 2 to be filled with a water sample 1

10 from the drum 201 of the washing machine and the emptying means 8 allow the water sample to be emptied from the chamber 2 and returned to the drum 201 after its analysis, from the electric current I generated in the electrode 3 as will be detailed below. .

Fig. 3 shows the detail of the chamber 2 of another variant of the equipment 100 in which it can be seen that it also comprises a counter electrode 6 disposed within the chamber

2. In the variant shown said counter electrode 6 also comprises a noble metal 5, although it could be simply metallic, and is connected to electric generating means 10. Said electric generating means 10 will generate an electric activation signal S1 that will be transmitted from the counter electrode 6 to electrode 3. In this way,

20 by means of said electrical signal S1 it is possible to create alternatively in the electrode 3 and in the counter electrode 6 oxidation and reduction reactions, which will create an electric current I in the characteristic electrode 3 according to the components dissolved in the water sample 1.

Advantageously, when the counter electrode 6 and / or the electrode 3 comprises a noble metal 5, for example when the counter electrode 6 and / or the electrode 3 is formed of said noble metal 5 or coated with said noble metal 5 totally or partially at least in its active parts between which the electrical activation signal S1 is transmitted, it is possible to perform an electrochemical polishing of said noble metal 5 to eliminate substances that may have

30 remains fisisorbidas or chemisorbed on its surface during oxidation and reduction reactions, allowing to restore the counter electrode 6 or electrode 3 when they comprise a noble metal 5 to the state prior to the measurement and therefore allowing subsequent measurements without the need to manipulate them mechanically.

35 In cases where electrode 3 or counter electrode 6 is not formed by a metal

noble 5, it is not possible to perform said electrochemical polishing, so a mechanical polishing of the substances that have been fisisorbed or chemisorbed on its surface must necessarily be performed, so that they can be reused for later measurement. Naturally, as in the electrode 3 is where the measurements of the electric current I will be carried out, it is recommended that this be formed by a noble metal 5, thus it is possible to perform the electrochemical polishing, being able to regenerate its surface with ease. Although it is also recommended that the counter electrode 6 is also of a noble metal 5, for reasons of cost, a metal counter electrode 6 can be used, although it should be verified that, in the absence of mechanical polishing, the electrical signal S1 10 can be transferred correctly from the counter electrode 6 to the electrode 3. In the case where the counter electrode 6 is the metal walls of the chamber 2, the surface of the counter electrode 6 will be much larger than the electrode 3, so that chemisorbed or fisisorbed elements remain in the walls The electrical activation signal S1 may be correctly transferred to the electrode 3, chamber even being able to be the useful time 15 of the equipment 100 much longer than the life of the washing machine in which it may be

installed said equipment 100.

As can also be seen in Fig. 3, the electric generating means 10 is

implemented by a processor 22 with an analog output connected to a voltage follower 20, to electrically separate the analog output of processor 22 from the rest

of the circuit, which in turn is connected to amplification means 24 to generate the

electrical activation signal S1 that is transmitted to counter electrode 6. To verify the level

of said electrical activation signal S1, the device 100 has means of

detection of the signal generated 27 by the electric generation means 10 in the counter electrode 6, also implemented in the processor 22 with an analog input

to receive the signal level of the counter electrode 6 through a voltage follower 23. From

In this way, it is possible to verify that the actual electrical activation signal S1 corresponds to

The desired. If the electrical activation signal S1 is not the desired one, it is

it would activate an alert to try to correct said electric activation signal S1, for example 30 by increasing the level provided by the electric generating means 10 until

detect the desired level in the detection means of the generated signal 27.

When applying the electrical activation signal S1, which for example comprises a pulse train

with varying amplitudes between + 2V and -2V through counter electrode 6, the creation of reduction and oxidation reactions in electrode 3 that lead to the

generation of a characteristic electric current I according to the components dissolved in the water sample 1. To measure said electric current I the electrode 3 is connected to amperometric detection means 4, formed by an analog current-voltage converter 25 to transfer, through a voltage follower 23, a value of 5 voltage obtained in the conversion that will be proportional to the electric current I to means for detecting the generated current 27, which in the described variant are an analog input of the processor 22, in which the value of the electric current I generated in respective moments t1 ... tn will be sampled to determine a set of instantaneous values I1 ... In of said electric current I. To correct errors due to drift

10 thermally, the processor 22 also comprises a temperature probe 26 in contact with the water sample 1.

Although in the variant of the equipment 100 shown in Fig. 3 the counter electrode 6 and electrode 3 are laminar in shape and are far apart from each other, it is possible that the counter electrode

15 6 and the electrode 3 are presented in a more compact form, for example forming a package in which the counter electrode 6 and the electrode 3 are cylindrical in shape, one of them being hollow and the other being arranged therein concentrically, being the gap between electrode 3 and counter electrode 6 filled with a dielectric material.

20 An example of the electrical activation signal S1 applied to the counter electrode 6 is shown in Fig. 4, and the corresponding characteristic electrical current I generated in the electrode 3, it is noted that said electrical currents will be of the order of microamps. After receiving the processor 22 the value of the electric current I, this will be conveniently

25 sampled in respective moments t1 ... tn and converted to digital values, obtaining a set of instantaneous values I1 ... In digital of said electric current value I, shown schematically in the detail of Fig. 4, for moments t1 to t5 in that a relative set of instantaneous values I1 to I5 are obtained that will be processed in the processor 22 to obtain the parameter Y that is to be quantified in the water sample

30 1 as will be described later. This sampling is explained schematically with a short series, since the number of instants t1 ... tn and instantaneous values I1 ... In to be processed will be much greater, as will be described later.

Fig. 5 shows the detail of an embodiment of the electrical circuit of Fig. 3. To simplify the circuit, the power supply means of the amplifiers have been omitted.

AO operational, which will be apparent to an expert. As can be seen, the electric generation means 10, means for detecting the generated signal 27 and means for detecting generated electric current 11 are implemented in a processor 22, the analog inputs and outputs of which are connected to voltage followers 23 5 formed by AO operational amplifiers in voltage follower configuration to separate the inputs / outputs of processor 22 from the rest of the circuit. The amplification means 24 are formed by an operational amplifier AO in inverter configuration with a gain of 1, in which the resistors R1 and R2 are equal. If necessary, to increase the stability of the system, the values of resistors R1 and R2 could be reduced. A capacitor C1 is placed in the feedback loop, which in the represented variant is 22pF, which gives stability to the system when the electrochemical cell has capacitive components. The amperometric detection means 4 are formed by an analog current-voltage converter 25 also based on an operational amplifier AO and a resistor R3. Said resistance R3 sets the current scale that it can accept

15 the converter to give an output in the range between -2V and + 2V, which is adequate to be provided in this case to the input of the processor 22 being in this case the range of currents that can be received between -2 / R3 A and + 2 / R3 A, which are expected to provide electrode 3 during oxidation and reduction reactions.

20 Although in the described variant the electronic circuit is formed by separate electronic modules, the electronic circuit could be implemented in a single integrated circuit that could be connected directly to electrode 3 and counter electrode 6.

Fig. 6 shows a scheme of operation of the procedure with detection

25 amperometric for water quality control applications applicable to detergent measurement, in which it is observed that after collecting a water sample in a chamber 2 and contacting said water sample 1 an electrode 3 connected to means of amperometric detection 4, the method comprises the step of detecting by means of said amperometric detection means 4 an electric current I generated in said

30 electrode 3 due to the presence of a detergent or other components dissolved in the water sample by oxidizing or reducing a noble metal 5 in said electrode 3. It is emphasized that it is both faradic and non-faradic processes that contribute to the generation of the electric current I generated at electrode 3 when applying the different pulses of the electric activation signal S1 on the counter electrode 6. As can be seen, for each pulse

35 a characteristic response is obtained in the generated electric current I which will depend

of the components dissolved in the water sample 1 that will determine the faradic and non-faradic processes that will have an exponential decrease over time. Specifically, non-faradic processes are understood as the restructuring processes of the double electrical layer in which there is no transfer of charges between the electrode and the dissolution, and whose contribution is significant only during the first moments of application of the pulse, while that faradic are processes with redox transfer whose duration remains higher and decreases more smoothly over time. Non-faradic processes respond more to properties such as water hardness or to compounds present in detergents as dissolved surfactants, while faradic agents

10 respond more to cations such as iron or manganese, anions and other compounds present in detergents such as peroxides and bleach.

To activate the electric current I that is generated in the electrode 3 due to the presence of a detergent or other substance that reacts dissolved in the water sample 1, which oxidizes or reduces the noble metal 5 of said electrode 3, a electrical activation signal S1 through the counter electrode 6, which in a variant of interest can also comprise a noble metal 5. After detecting the electric current I generated in the electrode 3, the electrode 3 is connected to amperometric detection means 4, formed in this case by an analog current-voltage converter 25, to detect and transfer a voltage value 20 obtained in the conversion and which will be proportional to the electric current I to the processor 22 through a voltage follower 23. They are stored in said processor 22 a set of values I1 ... In of said electric current I, to which weights respectively β1 ... βn of a statistical model are applied default to obtain the value of a Y parameter that you want to quantify. Naturally, it is also possible to apply the weighting values β1 ... βn corresponding to each set of values I1 ... In of electric current I as they are sampled and accumulate the result of their sum. It is also possible to apply several electrical activation signals S1 in a row, for example five times, and to average the set of values I1 ... In of each electrical current I generated at electrode 3 by applying each activation signal S1 to eliminate

30 noise

This average can also be subtracted from a set of electrical current values obtained from a base trace, which is that of the mains water at the same temperature.

35 It has been observed that said parameter Y of the water sample that can be quantified

This procedure can include, among others, conductivity, turbidity, pH, hardness, total organic carbon content (TOC), total nitrogen concentration (NT), chemical oxygen demand (COD) or dissolved detergent concentration.

To determine the weighting values β1… βn for the calculation of a parameter Y of the water sample, weights must initially be obtained in the laboratory corresponding to the statistical model of each parameter in order to apply them to the set of values I1… In of the electric current I in order to obtain the value of the Y parameter of interest of the water sample, according to an equation that for a linear regression model that is as follows:

N

Y = ∑ βi ⋅ Ii

i = 1

The determination of the parameters Y of interest can be carried out periodically in order to be able to monitor said parameters Y of interest over time, for example to monitor the quality of the washing water of the drum 201 of a washing machine 200, as previously shown in Fig. 2, during the washing cycle, and thus controlling the washing process and thus being able to carry out the controlled addition of detergent, softener, disinfectant or bleach required, also taking into account the characteristics of the fabric and the amount of clothing wash. This control means a significant saving in the consumption of chemical products that must subsequently be eliminated by treatment in wastewater treatment stations, since the state of the water sample can be monitored by determining the Y parameters of interest in the different samples of water Water.

The determination of the parameters Y of interest also serves to assess, for example, if the rinse water of the washing machine 200, which is normally of the order of 20 to 40 liters, can be used to prewash the next batch of clothes if the chemical requirements They are suitable.

By being able to reuse water between washes while controlling the amount of washing detergents, softeners, disinfectants or bleaches required depending on the characteristics of the fabric and the amount of clothing treated, a significant saving in chemical consumption is achieved which must subsequently be eliminated by treatment in wastewater treatment stations. This rationalization therefore supposes a double saving, that of the treatment of the excess of added product to carry out the washing and that of the manufacturing costs thereof.

5 Between cycle and cycle of determination of parameters Y it is necessary that electrode 3 and counter electrode 6 be cleaned and regenerated in order to be able to use them again. This stage is carried out after the step of detecting the electric current I generated in the electrode 3, performing a regeneration stage of the electrode 3 and optionally of the counter electrode 6 to eliminate the products that would have remained chemisorbed or fisisorbed on their

10 surface as discussed above. Although this step can be performed by mechanical polishing of said electrode 3 and counter electrode 6, it is more advisable and simple that the regeneration stage of electrode 3 and counter electrode 6 be performed electrochemically, said regeneration step comprising the steps of replacing the sample of water by clean water through the water filling means of

15 the network 16, circulating clean water for some time through the chamber 2 to remove the water from the water sample 1 that was previously used. The water used for cleaning the chamber 2 can be reused, for example, being directed to the washing drum 201 of the washing machine 200. After replacing the water in the water sample 1 with mains water, in the event that the electrode 3 comprise a noble metal 5, a

20 electrochemical cleaning of electrode 3, shown in Fig. 7, whose purpose is to enhance the elimination of products that have remained physisorbed or chemisorbed in the previous stage of measurement on their surface. Electrochemical cleaning, which can be considered electrochemical polishing, is carried out through a series of sequential oxidation and reduction processes at moderate or high potentials where it oxidizes if

25 the adsorbed matter is possible and that it is released thanks to the formation of nascent gas, oxygen and hydrogen, on the surface of the electrode 3. It is emphasized that unlike mechanical polishing this electrochemical cleaning requires only the use of mains water, free of detergents, so the water can be reused later. During the electrochemical cleaning an electrical cleaning signal S2 will be applied to the

30 counter electrode 6 which will generate an electric cleaning current S3 at electrode 3. In the variant shown in Fig. 8 it is observed that said electric cleaning signal S2 comprises a positive voltage pulse and a negative voltage pulse to alternatively cause both oxidation and reduction, the first pulse of 1.6V lasting between 2 to 3 seconds followed by a second pulse inverted to the first pulse, is

35 say -1.6V, and of the same duration as the first pulse that generates an electric current of

cleaning S3 at electrode 3. Preferably the absolute voltage values of said electric cleaning signal S2 will be higher than the absolute voltage values of the electric activation signal S1 to generate more aggressive oxidation and reduction processes, ie the signal Electrical cleaning S2 will be greater than the electrical signal of 5 activation S1. It is also expected that the duration of the pulses of the electrical cleaning signal S2 will last significantly longer than the pulses of the electrical activation signal S1, for example between 2 and 3 seconds, since it is desired that in addition to the aggressive processes of oxidation and reduction, which go beyond the duration of the faradic and non-faradic processes, a hydrolysis process is carried out that allows

10 detach the matter adsorbed on the electrode 3 mechanically by generating nascent gas, hydrogen and oxygen.

After cleaning, a new water sample 1 is placed in chamber 2 and the equipment 100 is again able to perform a new measurement. This

The operation can be automated so that every few minutes we have information about the water sample 1 by the processor 22, for example the useful surfactant load and the contaminant load extracted by the wash water by determining one or more parameters Y of interest of the water sample 1.

20 For the correct operational operation of the equipment 100, it is necessary to configure a series of parameters such as the measurement intervals that allow setting the times between measurement and measurement, the pulse pattern that determines the electrical activation signal S1, the current scale, and the number of successive repetitions of application of the electrical activation signal S1. It is also possible to configure the data processing, it is

25 to say, if the evaluation of the state of the system is evaluated by one of two different data processing techniques: if the current traces obtained by repetition of the electrical activation signal S1 at a given time of the washing can be averaged for elimination of noise and subsequently subtracted from the intensity obtained from a base trace that is that of mains water at the same temperature (measured or

30 estimated by a suitable algorithm) or if a subsequent trace is subtracted from the first current trace to estimate the composition of the system based on the differences found, using a suitable mathematical algorithm.

They are presented in Figs. 9 to 11 examples of different electrical signals of activation S1 comprising pulse trains designed to measure for each parameter of interest Y, and in Figs. 12 to 15 examples of the determination of the respective parameters Y of interest using said electrical activation signals S1.

It is noted that the values of each parameter Y of interest were obtained through a linear regression model obtained by PLS, after applying one of the two different data processing techniques.

As an example, the procedure for obtaining the weighting values β1 ... βn for the determination of the parameters of interest "Detergent concentration" and "Hardness" is described below. An analogous procedure would be applicable to obtain the weighting values β1… βn of other parameters of interest, such as “pH”, “Chemical Oxygen Demand” (COD), “Total Nitrogen Concentration” (NT) and “Conductivity "

An example of the electrical activation signal S1 for the determination of parameters Y of interest such as Hardness or Detergent Concentration is shown in Fig. 9. It is a train of 25 pulses of 20ms duration each and variable amplitude between ± 1.2V, for a total duration of 500ms.

An alternative example of the electrical activation signal S1 for the determination of parameters Y of interest such as Hardness or Detergent Concentration is shown in Fig. 10. It is a train of 25 pulses of tension of 200ms of duration each pulse and amplitude variable between ± 1.2V, for a total duration of 5s.

An example of the electrical activation signal S1 for the determination of Y parameters of interest such as Chemical Oxygen Demand (COD), Total Nitrogen Concentration (NT) or Conductivity is shown in Fig. 11. It is a train of 10 pulses of tension of 20ms of duration of each pulse and variable amplitude between ± 750mV, for a total duration of 200ms.

Estimated values are shown in Fig. 12 versus actual values of the detergent content in medium hard water. 25 water samples were prepared with liquid detergent added at 5 different concentrations between 5 and 90ml per 20L of water, plus 5 samples of the same water without detergent.

To each water sample the electric activation signal S1 of Fig. 10 was applied five times in succession, to generate an electric current I at electrode 3, averaging the five current traces thus obtained to reduce the variability of the measurements. With a sampling time of 5ms, corresponding to the space between the moments t1 ... tn in which the value of the electric current I generated at electrode 3 is sampled, 40 measurement points per pulse are obtained, for a total of 1000 points of measurement for each current trace. The matrix X of averaged data therefore has dimensions of 40x1000 and contains a lot of redundant information, lending itself to statistical techniques of reduction and compression of the information among which is PLS, which is characterized by performing a simultaneous decomposition of X and And in terms of a small number of main components or latent variables that explain as much as possible the covariance between X and Y, followed by a linear regression that uses these latent variables to obtain 1000 regression coefficients β1 ... β1000 that minimize the error between values real and estimated Y and that will be the weighting coefficients β1… βn that

15 will be used to measure the parameter Y that you want to quantify.

Surprisingly, the high correlation between real and estimated values has been observed, which is demonstrated as can be seen in Fig. 12 by the almost-superposition of the line of best fit L1 to the line representing the real values, than by the high value of

20 coefficient of determination (R2) which is 0.924. The weighting values β1 ... β1000, which will be the weighting coefficients β1 ... βn, are not detailed, due to the length of the series, however, a person skilled in the art could obtain them following the procedure described above.

25 It should be borne in mind that said weighting coefficients β1… βn will depend on the values of the same parameter Y of interest to be measured, the type of metal for electrode 3 and counter electrode 6, the shape and amplitude of the electrical activation signal S1, the sampling interval - which directly affects the total number of weights - the number of latent variables chosen for the PLS model, as well as the shape, size and

30 relative arrangement of electrode 3 and counter electrode 6, the volume of the chamber 2, the volume of the water sample 1 in the chamber 2, the immersion depth of the electrode 3 and counter electrode 6 etc., factors that can be termed globally under the term 'measurement cell geometry' and which directly affect the electric field lines generated during the detection phase and therefore on the current in

35 the electrode 3 and of consequence on the data matrix X. Therefore, the weighting coefficients β1… βn required for the measurement of a parameter Y of interest must be obtained for each of the configurations of the equipment 100.

The results obtained after applying an analogous procedure are described below.

5 to obtain the weighting coefficients β1… βn applicable when the parameter of interest to be measured is Chemical Oxygen Demand (COD), Total Nitrogen Concentration (NT) or Conductivity.

For these parameter of interest the electric activation signal S1 has been used, both

10 for obtaining the weighting coefficients β1… βn as for the measurements, shown in Fig. 11. It is a train with 10 voltage pulses of 20ms duration each and variable amplitude between ± 750mV, for a duration total of 200ms.

Figs. 13 to 15 show estimated values versus experimental values measured in

15 laboratory of parameters Y COD, NT, and Conductivity, respectively, in 19 water samples collected during different washing phases performed in a domestic washing machine with a standard load of 7Kg of clothes, at different levels of dirt and detergent content. To each water sample, the electrical activation signal S1 of Fig. 11 was applied five times in succession, subtracting the last current trace from the first

20 to estimate the accumulation of compounds of interest on the surface of the electrode 3. With a sampling time of 200μs, 100 measuring points per pulse are obtained, for a total of 1000 measuring points for each current trace. The X matrix of averaged data has dimensions of 19x1000.

25 In all cases, a high correlation between experimental and estimated values is observed, as can be seen from their respective regression lines L2, L3, L4.

Given the measuring principle of the equipment 100, which comprises the generation of an electrical activation signal S1 on the counter electrode 6 and measurement of the electric current intensity 30 on the electrode 3, it is necessary to properly calibrate the electronic measuring equipment 100 . Both in the digital-analog conversion process and in the subsequent treatment of the generated signal until it is applied to the potentiostat of the electronic measuring equipment 100 certain inaccuracies in the analog value occur. This is due to the error made by having to approximate the resistance values. Said 35 inaccuracies can be accentuated by the tolerances of the resistors used

(1%) and for the offset of the operational amplifiers. In order to compensate for the effect of these deviations on the value of the signal applied to the working electrode, a calibration process of the digital-analog conversion process is necessary.

5 In the same way and for similar reasons, in the processing of the analog signals from the voltage control and current measurement circuits of the potentiostat and in the subsequent digital-analog conversion of the signals, deviations can occur. As a consequence, the digital values corresponding to the samples of the voltage and current signals in the working electrode may present

10 errors or deviations. Therefore, the implementation of a calibration system for the digital-analog conversion process is also necessary.

Claims (21)

1.- Procedure with amperometric detection for water quality control applications applicable to detergent measurement comprising the steps of:

-

housing a water sample (1) with compounds dissolved in a chamber (2);

-

applying an electrical activation signal (S1) to a counter electrode (6) arranged in said

chamber in contact with the water sample; characterized in that it also includes the steps of:

-

detecting an electric current (I) generated in an electrode (3) comprising a noble metal (5) by oxidizing or reducing the compounds dissolved in the water sample in said electrode, said electrode being also arranged in said chamber and in contact with the water sample;

-

sampling the electric current generated in respective instants (t1… tn) to determine a set of instantaneous values (I1… In) of said electric current;

-

weighting each instantaneous value of said current with a respective weighting value (β1… βn) previously determined statistically from reference samples; Y

-

Obtain a prediction of the value of a parameter (Y) related to a physical parameter of the compounds dissolved in the water sample that you want to quantify using the formula:

N Y = βi ⋅ I ∑ i i = 1 2. Method according to the preceding claim, characterized in that it comprises the previous step of statistically predetermining the weighting values (β1… βn) for measurements of the parameter (Y). 3. Method according to the preceding claim, characterized in that the weighting values (β1… βn) are determined by a PLS regression algorithm. 4. Method according to any one of the preceding claims, characterized in that the electrical activation signal (S1) that is applied to the counter electrode (6) is a pulse train, alternatively performing oxidation and reduction of the compounds dissolved in the sample of water in the electrode (3). 5. Method according to the preceding claim, characterized in that the pulse train It has amplitudes between + 2V and -2V. 6. Method according to any one of the preceding claims, characterized in that after detecting the electric current (I) generated in the electrode (3) to determine the value of the parameter (Y) and before performing a new detection, performs an electrode regeneration operation (3) comprising the steps of:

-

 replace the water sample (1) with clean water in the chamber (2); Y

-

 apply an electrical cleaning signal (S2) between the electrode (3) and the counter electrode (6)

to eliminate products that would have remained chemisorbed or fisisorbed on its surface. 7. Method according to the preceding claim, characterized in that the electrical cleaning signal (S2) comprises a positive voltage pulse and a negative voltage pulse. Method according to the preceding claim, characterized in that the electrical cleaning signal (S2) comprises a first pulse of 1.6V duration between 2 and 3 seconds, followed by a second pulse inverted to the first pulse and duration between 2 and 3 seconds 9. Method according to any one of claims 1 to 8, characterized in that the parameter (Y) is the chemical oxygen demand. 10. Method according to any one of claims 1 to 8, characterized in that the parameter (Y) is the conductivity. Method according to any one of claims 1 to 8, characterized in that the parameter (Y) is turbidity. 12. Method according to any one of claims 1 to 8, characterized in that the parameter (Y) is the pH. 13. Method according to any one of claims 1 to 8, characterized in that the parameter (Y) is the hardness. 14. Method according to any one of claims 1 to 8, characterized in that the parameter (Y) is the total nitrogen concentration. 15. Method according to any one of claims 1 to 8, characterized in that the parameter (Y) is the concentration of the dissolved detergent. 16. Equipment (100) for carrying out the method for measuring detergents based on the amperometric detection for water quality control applications according to any one of the preceding claims comprising:

-

 a chamber (2) arranged inside electrical shielding means (9) to house a water sample (1);

-

 filling means (7) and emptying means (8) of the water sample in said chamber;

-

 a counter electrode (6) disposed in said chamber and connected to electric generating means (10), in contact with the water sample when the chamber houses a water sample;

-

 an electrode (3) also arranged in said chamber and connected to means for

15 detecting an electric current generated (11) on said electrode in respective moments (t1… tn) and adapted to be in contact with the water sample when the chamber houses a water sample; characterized in that the electrode comprises a noble metal (5) in which an electric current (I) is generated 20 due to the presence of dissolved compounds in the water sample that oxidize or reduce said noble metal when an electrical activation signal (S1) is applied to the counter electrode. 17. Equipment (100) according to the preceding claim, characterized in that the counter electrode 25 (6) also comprises a noble metal (5). 18. Equipment (100) according to any one of claims 16 to 17, characterized in that the noble metal (5) is Gold, Rhodium, Iridium or Platinum 30 - Equipment (100) according to any one of claims 16 to 18, characterized in that the chamber (2) is metallic and acts as a counter electrode (6). 20. Equipment (100) according to any one of claims 16 to 19, characterized in that the counter electrode (6) and electrode (3) have a cylindrical shape, one of them being hollow and the other being arranged inside so concentric; and being the space of separation between said electrode and counter electrode in the hollow filled with a dielectric material. 21. Equipment (100) according to any one of claims 16 to 20, characterized in that the electrical generation means (10) for applying activation signal (S1) to the counter electrode (6) are formed by a processor (22) connected to an amplifier (24). 22. Equipment (100) according to the preceding claim, characterized in that the output of the amplifier (24) is fed back into the processor (22). 23. Equipment (100) according to any one of claims 21 to 22, characterized in that it further comprises a temperature probe (26) connected to the processor (22). 24. Equipment (100) according to any one of claims 21 to 23, characterized 15 because the connections with the processor (22) are provided with electrical isolation means (23). 25. Equipment (100) according to the preceding claim, characterized in that the electrical isolation means (23) are voltage followers. 20. A washing machine (200) comprising equipment (100) for measuring detergents according to any one of claims 16 to 25, characterized in that the filling means (7) of the chamber (2) are adapted to fill said chamber with a sample of water (1) coming from the washing drum (201) of the washing machine to perform the procedure according to Any one of claims 1 to 15, and in that the emptying means (8) are adapted to empty the water sample from the chamber and return it to the drum or dispose of it as determined in the procedure. 8 fifteen 13 12  Fig. 1 Fig 2 100  Fig. 3 Current (mA) Fig. 5 3 22 Fig. 6 100 Fig. 7 Fig. 8 Fig. 11 Samples / Scores Plot And CV Predicted 1

-

twenty

And Measured 1  Fig. 12 4000 3500 3000 2500 2000 1500 1000 500 0 Real concentration mg O2 / ml) Fig. 13 Predicted concentration (mg O2 / ml) 0 102030 40506070 Real concentration (mg / ml) Fig. 14 Fig. 15 SPANISH OFFICE OF THE PATENTS AND BRAND Application no .: 201231986 SPAIN Date of submission of the application: 21.12.2012 Priority Date: REPORT ON THE STATE OF THE TECHNIQUE 51 Int. Cl.: G01N27 / 49 (2006.01) RELEVANT DOCUMENTS

Category

56 Documents cited Claims Affected

X

WO 0244460 A1 (ASKO CYLINDA AB) 06.06.2002, summary; page 4, line 3 - page 8, line 17; page 10, line 9 - page 11, line 31; figures 1-2. 1-5.9-26

Y

6-8

TO

IVARSSON, P. et al. Supervision of rinses in a washing machine by a voltammetric electronic tongue. Sensors and Actuators B. 22.07.2005 Vol. 108, No. 1-2, pages 851-857 <DOI: 10.1016 / j.snb.2004.12.088> 1,4,5

Y

ES 2305594 T3 (Dr-A. KUNTZE GmbH) 01.11.2008, column 1, line 6 - column 2, line 66; Figure 1. 6-8

TO

CAMPOS, I et al. A voltammetric electronic tongue as tool for water quality monitoring in wastewater treatment plants. Water Research, 11.02.2012, Vol. 46, No. 8, pages 2605-2614, <DOI: 10.1016 / j.watres.2012.02.029> 9

Category of the documents cited X: of particular relevance Y: of particular relevance combined with other / s of the same category A: reflects the state of the art O: refers to unwritten disclosure P: published between the priority date and the date of priority submission of the application E: previous document, but published after the date of submission of the application

This report has been prepared • for all claims • for claims no:

Date of realization of the report 28.06.2013

Examiner A. Figuera González Page 1/6

REPORT OF THE STATE OF THE TECHNIQUE Application number: 201231986 Minimum documentation sought (classification system followed by classification symbols) G01N, D06F Electronic databases consulted during the search (name of the database and, if possible, terms of search used) INVENES, EPODOC, WPI, TXTE, COMPENDEX, INSPEC, XPESP, XPESP2, Internet State of the Art Report Page 2/6  WRITTEN OPINION Application number: 201231986 Date of Completion of Written Opinion: 06.28.2013 Statement

Novelty (Art. 6.1 LP 11/1986)

Claims Claims 4-12, 14, 16-26 1-3, 13, 15 IF NOT

Inventive activity (Art. 8.1 LP11 / 1986)

Claims Claims 1-26 IF NOT

The application is considered to comply with the industrial application requirement. This requirement was evaluated during the formal and technical examination phase of the application (Article 31.2 Law 11/1986).  Opinion Base.- This opinion has been made on the basis of the patent application as published. State of the Art Report Page 3/6  WRITTEN OPINION Application number: 201231986 1. Documents considered.- The documents belonging to the state of the art taken into consideration for the realization of this opinion are listed below.

Document

Publication or Identification Number publication date

D01

WO 0244460 A1 (ASKO CYLINDA AB) 06.06.2002

D02

IVARSSON, P. et al. Supervision of rinses in a washing machine by a voltammetric electronic tongue. Sensors and Actuators B. 07/22/2005

D03

ES 2305594 T3 (Dr-A. KUNTZE GmbH) 01.11.2008

D04

CAMPOS, I et al. A voltammetric electronic tongue as tool for water quality monitoring in wastewater treatment plants. Water Research 11.02.2012

2. Statement motivated according to articles 29.6 and 29.7 of the Regulations for the execution of Law 11/1986, of March 20, on Patents on novelty and inventive activity; quotes and explanations in support of this statement  CLAIMS 1 to 3 Document D01 describes a method for washing items in a washing machine or a dishwasher based on electrochemical measurements of the voltammetric type. Electrodes that work together with a counter electrode in contact with a fluid are used, in this case the wash water, which is water with different soluble substances or non-soluble such as minerals and other impurities or detergent. Voltammetry is based on the variation of the potential applied to the electrodes and the measurement of the response current, including the transients, providing information on the content and nature of the fluid. See D01, page 4, lines 1 to 26. In document D01, the washing machine or the dishwasher is equipped with an electrode unit 2 with one or more working electrodes 3.4 consisting of a stable metal such as platinum or rhodium with a surface in contact with the water of the washing machine or the dishwasher Both the working electrode 3 (if there is only one) and the counter electrode 5 can be placed in a special container in communication with the washing space of the washing machine or the dishwasher, for example by means of a circulation pump. The electrochemical sensor unit 1 comprises a control unit 6 that applies a variable potential, for example the curve E (t) to a working electrode 3 or 4 at each moment and to the counter electrode 5. See D01, page 5, line 12 to page 6, line 2 and figure 1. The measurement of the current at different potentials and potential changes at certain points of time using a particular working electrode during the washing process provides a large amount of information that must be reduced and ordered before its evaluation to control the washing process. For this, a stage of analysis of all this information based on multivariate data analysis (MVDA -Multivariate Data Analysis) is introduced. See D01, page 6, lines 20 to 30. An example of MVDA contemplated is the regression by partial least squares (PLS -Partial Least Square). A model is created that relates a matrix X of measurement data with a matrix Y consisting, for example, of concentrations or biological activity according to the following steps:

-

Find a relationship between X and Y

-

Predict a new Y

-

Create a model for one or more variables

Thus, document D01 discloses all the technical characteristics object of claims 1 to 3. Therefore claims 1 to 3 are not new as set forth in article 6 of Patent Law 11/1986. CLAIMS 4 and 5 An example of a variable potential curve E (t) applied between working electrode 3 or 4 and counter electrode 5 is shown in Figure D01. It is a pulse train, but it is not appreciated if values alternate positive and negative nor what are the specific values of the pulse amplitudes. However, it would have been obvious to the person skilled in the art that a possible form of the E (t) curve is a pulse train in which positive and negative values are alternated so that oxidation and reduction in the electrode alternately occur of work. State of the Art Report Page 4/6  WRITTEN OPINION Application number: 201231986 Furthermore, this possibility is already described in the state of the art as illustrated for example in Figure 3 of document D02 in which a train of pulses with values between 0.6V and -0.4V is used. This pulse train is a particular case of pulse train that has amplitudes between -2V and 2V. Thus, the range of amplitudes selected in claim 5 is apparently an arbitrary example of the state of the art that does not seem to imply any technical effect other than expected and whose values appear to be determined routinely to adapt to different design options of the electrodes so that the voltage is sufficient to cause oxidation and reduction of the compounds dissolved in the water (see description of the application page 4, lines 5 to 10). Therefore, it is considered that for the person skilled in the art the selection of a pulse train with the characteristics considered in claims 4 and 5 would have been a mere obvious design option. In conclusion, claims 4 and 5 have no inventive activity in accordance with the provisions of article 8 of Patent Law 11/1986. CLAIMS 6 to 8 Document D01 does not mention the cleaning of the electrodes. However, it is a known technical problem as disclosed for example in document D03 in which a procedure for cleaning the surface of electrodes in an installation for determining materials contained in an electrolyte which comprises electrodes arranged in a device is described. measuring cell intended to receive the electrolyte (see D03, column 1, lines 6 to 12). The solution proposed in document D03 consists in sending a preset regulated current with a certain polarity for a certain time and then reversing the polarity for another time. Thus hydrogen and oxygen are alternatively generated on the electrode surfaces by the effect of the defined current flow whose current direction is changed. Due to the switching of the current direction, depositions of materials on the electrode surfaces are prevented. It is also considered advantageous for the measuring cell to be traversed by the electrolyte during the cleaning procedure since the sediments detached from the electrode surfaces are then removed immediately from the measurement cell. See D03, column 2, lines 14 to 66). Thus, in the procedure of document D03, in the same manner as in the method of claim 6, an electrical cleaning signal is applied between the electrodes. However, in the procedure of D03 the electrolyte is not replaced by clean water during cleaning. However, for the person skilled in the art, faced with the problem that the presence of substances in the electrolyte prevents the correct cleaning of the electrodes, it would have been clear that a solution is to replace the electrolyte during cleaning with clean water. As for claim 7, from a technical point of view it is equivalent for cleaning purposes that the electrical cleaning signal comprises a positive and a negative voltage pulse and that the cleaning signal comprises a current pulse in a direction and a current pulse with the opposite polarity. With regard to claim 8, the time mentioned in document D03 is in the range of 1 to 120s and the voltage is not mentioned. However, apparently the values of times and tensions of claim 8 are values that produce no surprising effect and that appear to have been determined by applying routine experimental laboratory methods. On the other hand, claims 6 to 8 depend on the preceding claims whose object is related to an amperometric detection method. However, claims 6 to 8 are considered to refer to a cleaning problem that is independent of the problem of the amperometric detection itself. Thus, the person skilled in the art, faced with the problem of fouling the electrodes used in the process of claims 1 to 5, would have obviously resorted to the teachings of document D03 as it is a mere superposition of independent solutions. In conclusion it is considered that claims 6 to 8 in turn lack inventive activity. CLAIMS 13 and 15 Document D01 indicates that hardness is an important parameter and that it can be used for example to monitor the softener supply. See D01, page 10, lines 14 to 23. A specific example of graphic representation is also presented in document D01 in Figure 2, showing points that refer to different types of water before and after adding detergent. See D01, page 11, lines 15 to 31 and figure 2). State of the Art Report Page 5/6  WRITTEN OPINION Application number: 201231986 In short, claims 13 and 15 do not add any additional technical characteristic that has not already been contemplated in document D01. Therefore, claims 13 and 15 which depend, inter alia, on claim 1 which is not new, in turn lack novelty. CLAIMS 9 to 12 and 14 It is considered that the application of the same method to various parameters would have been obvious to the person skilled in the art since apparently it is proceeding in all cases in a manner analogous to that indicated in document D01 for the detergent without apparently presenting any Additional technical problem that needs to be resolved. In conclusion it is considered that claims 9 to 12 and 14, dependent among others, of claim 1 which is not new, have no inventive activity. Furthermore, in the case of claim 9 in the state of the art there are documents, such as D04, which illustrate that a voltammetric sensor with a partial least squares analysis can be used for the determination of the chemical oxygen demand for the Water quality measure.  CLAIMS 16 TO 18 Document D01 is considered to be the closest state of the art document to the object of claim 16. The following correspondence can be established between the elements object of claim 16 and the device described in document D01:

-

Chamber (2) housing water sample with filling means (7) and emptying means (8)

<-> special container that communicates with the cleaning space of the machine by means of a circulation pump (see D01, page 5, lines 24 to 28).

-

A counter electrode (6) and an electrode (3) arranged in said chamber (2) and connected respectively with electric generating means (10) and with means to detect the generated electric current (11)

<-> working electrodes 3,4 consisting of a stable metal such as platinum, rhodium or stainless steel, a counter electrode 5, and control unit 6 (see D01, page 5, line 12 to page 6, line 25 and figure 1) Thus, the difference between the equipment object of claim 16 and the device described in document D01 is that the use of electric shielding means is not explicitly mentioned in document D01. However, for the person skilled in the art it would have been obvious to resort, as is customary in these situations in the state of the art, to screening means in case of detecting interference with the electrical measurements carried out. In the case of counter electrode 5 of document D01 it is constructed of stainless steel. But for the person skilled in the art, it would have been obvious that the same materials as for the working electrode can be used for the counter electrode, being a simple design option, being technically equivalent materials that are chosen based on their known properties . In conclusion, claims 16 to 18 are considered to have no inventive activity. CLAIMS 19 and 20 Claims 19 and 20 refer to two alternative configurations of the equipment that are considered mere design options. In fact, the option of claim 20 is that contemplated in document D02 (see D02, page 852, first paragraph of section 2.1. Equipment and figure 1) Thus, claims 19 and 20, depending on claims 18 to 18 that do not have inventive activity, in turn lack inventive activity. CLAIMS 21 to 25 Claims 21 to 25 refer to design and configuration options customary in the state of the art and known to the person skilled in the art, for which reason these claims, depending on previous claims that do not have inventive activity, are also considered to have no activity inventiveness.  CLAIM 26 Both the equipment (100) for the measurement of detergents of claims 16 to 25, and the method with amperometric detection applicable to the measurement of detergents of claims 1 to 15 lack inventive activity. On the other hand, its application to a washing machine has already been described in document D01 and in document D02 it is shown in figure 1 how the water is taken from the drum and returned to it. Thus, it is considered that claim 26 also has no inventive activity. State of the Art Report Page 6/6