EP3938770A1 - Nanostructured sensor printed on paper - Google Patents
Nanostructured sensor printed on paperInfo
- Publication number
- EP3938770A1 EP3938770A1 EP20714842.0A EP20714842A EP3938770A1 EP 3938770 A1 EP3938770 A1 EP 3938770A1 EP 20714842 A EP20714842 A EP 20714842A EP 3938770 A1 EP3938770 A1 EP 3938770A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- electrode
- paper
- printed
- working electrode
- gold nanoparticles
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims abstract description 27
- 239000000460 chlorine Substances 0.000 claims abstract description 25
- 229910052801 chlorine Inorganic materials 0.000 claims abstract description 25
- 229910052737 gold Inorganic materials 0.000 claims abstract description 25
- 239000010931 gold Substances 0.000 claims abstract description 23
- 239000002105 nanoparticle Substances 0.000 claims abstract description 23
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims abstract description 22
- 238000000034 method Methods 0.000 claims abstract description 18
- 238000005259 measurement Methods 0.000 claims description 13
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 12
- 239000010439 graphite Substances 0.000 claims description 11
- 229910002804 graphite Inorganic materials 0.000 claims description 11
- 238000007639 printing Methods 0.000 claims description 11
- 239000000872 buffer Substances 0.000 claims description 9
- 239000011859 microparticle Substances 0.000 claims description 9
- 229910052709 silver Inorganic materials 0.000 claims description 9
- 239000004332 silver Substances 0.000 claims description 9
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 8
- KRKNYBCHXYNGOX-UHFFFAOYSA-K Citrate Chemical compound [O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O KRKNYBCHXYNGOX-UHFFFAOYSA-K 0.000 claims description 6
- 230000008021 deposition Effects 0.000 claims description 6
- 239000007979 citrate buffer Substances 0.000 claims description 5
- 238000007306 functionalization reaction Methods 0.000 claims description 5
- 230000002209 hydrophobic effect Effects 0.000 claims description 5
- 239000002245 particle Substances 0.000 claims description 5
- 239000000725 suspension Substances 0.000 claims description 5
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 claims description 2
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 claims description 2
- 229910019142 PO4 Inorganic materials 0.000 claims description 2
- 239000008151 electrolyte solution Substances 0.000 claims description 2
- 239000012530 fluid Substances 0.000 claims description 2
- 239000000203 mixture Substances 0.000 claims description 2
- 239000010452 phosphate Substances 0.000 claims description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims description 2
- 239000008363 phosphate buffer Substances 0.000 claims description 2
- 238000012360 testing method Methods 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims 1
- 230000009182 swimming Effects 0.000 abstract description 5
- 238000012544 monitoring process Methods 0.000 abstract description 4
- 238000002360 preparation method Methods 0.000 abstract description 4
- 239000003643 water by type Substances 0.000 abstract description 3
- 238000003911 water pollution Methods 0.000 abstract 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 11
- 238000000151 deposition Methods 0.000 description 8
- 239000000523 sample Substances 0.000 description 8
- 239000000645 desinfectant Substances 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 4
- 238000000275 quality assurance Methods 0.000 description 4
- 230000035945 sensitivity Effects 0.000 description 4
- 238000012549 training Methods 0.000 description 4
- 239000007853 buffer solution Substances 0.000 description 3
- LOKCTEFSRHRXRJ-UHFFFAOYSA-I dipotassium trisodium dihydrogen phosphate hydrogen phosphate dichloride Chemical compound P(=O)(O)(O)[O-].[K+].P(=O)(O)([O-])[O-].[Na+].[Na+].[Cl-].[K+].[Cl-].[Na+] LOKCTEFSRHRXRJ-UHFFFAOYSA-I 0.000 description 3
- 239000002953 phosphate buffered saline Substances 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- QWPPOHNGKGFGJK-UHFFFAOYSA-N hypochlorous acid Chemical compound ClO QWPPOHNGKGFGJK-UHFFFAOYSA-N 0.000 description 2
- 238000005304 joining Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910052697 platinum Inorganic materials 0.000 description 2
- 239000012086 standard solution Substances 0.000 description 2
- 238000004659 sterilization and disinfection Methods 0.000 description 2
- ZKQDCIXGCQPQNV-UHFFFAOYSA-N Calcium hypochlorite Chemical compound [Ca+2].Cl[O-].Cl[O-] ZKQDCIXGCQPQNV-UHFFFAOYSA-N 0.000 description 1
- 208000035473 Communicable disease Diseases 0.000 description 1
- 239000005708 Sodium hypochlorite Substances 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000012491 analyte Substances 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 150000007973 cyanuric acids Chemical class 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 125000003963 dichloro group Chemical group Cl* 0.000 description 1
- 239000012470 diluted sample Substances 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 230000035622 drinking Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- XMBWDFGMSWQBCA-UHFFFAOYSA-N hydrogen iodide Chemical compound I XMBWDFGMSWQBCA-UHFFFAOYSA-N 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- WQYVRQLZKVEZGA-UHFFFAOYSA-N hypochlorite Chemical compound Cl[O-] WQYVRQLZKVEZGA-UHFFFAOYSA-N 0.000 description 1
- 208000015181 infectious disease Diseases 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000006193 liquid solution Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000002086 nanomaterial Substances 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000007650 screen-printing Methods 0.000 description 1
- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 description 1
- 238000002798 spectrophotometry method Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/28—Electrolytic cell components
- G01N27/30—Electrodes, e.g. test electrodes; Half-cells
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/18—Water
- G01N33/182—Specific anions in water
Definitions
- the present invention relates to nanostructured electrodes printed on paper; electrochemical sensors comprising at least a nanostructured electrode printed on paper; an integrated system (hereinafter also identified with the term “kit” or “device”) for the management of the sensors according to the invention; and a method for their preparation.
- the electrodes (and the sensors) in accordance with the present invention are useful for the determination of free chlorine in industrial plants, in laboratory, in water of swimming pools, in water for domestic use and for the monitoring of pollution of the waters.
- the electrodes in accordance with the present invention are printed on paper by means of a screen printing process; around said electrodes an hydrophobic area is provided by using a ink printer based on wax,; said electrodes have contours in wax that delimit an area, in which the sample to be analyzed is placed; and said electrodes are functionalised with nanomaterials.
- hypochlorite ion and hypochlorous acid the sum of the concentrations of hypochlorite ion and hypochlorous acid, produced from the hydrolysis reaction not only of sodium hypochlorite but also of gaseous chlorine, of calcium hypochlorite and derivatives of isocyanuric acid (dichloro and trichloro).
- the predominant form between acid and ion in solution, as well as the disinfectant power, is pH-dependent, and hypochlorous acid has the maximum disinfectant power.
- number (7) represents the back of a sheet of paper (6), on which nothing was printed.
- Figure 4 shows the front part of the sheet, where the printing with ink was effected, in which the numbers have the following meanings:
- nanostructured electrode printed on paper for the measurement of free chlorine in fluids, characterized in that said electrode is functionalized with gold nanoparticles;
- -the paper is selected from the group comprising filter paper or office paper;
- the functionalization is done by depositing on the working electrode 0. 1-50 gL, preferably 1-20 pi; most preferably 6 gL of a stabilized suspension of gold nanoparticles in phosphate buffer, having an average diameter of about 5 nm (nanometres); and the deposition is carried out by applying 2 m ⁇ each consecutive.
- electrochemical sensor comprising at least one electrode as defined above.
- an electrochemical sensor comprising:
- said electrode group comprises at least a working electrode; at least a reference electrode and/or at least one auxiliary electrode;
- the working electrode is functionalized using gold nanoparticles having an average diameter of about 5 nm, in which the amount of gold nanoparticles deposited on the electrode is 0. 1-50 m ⁇ , preferably 1-20 m ⁇ ; most preferably 6 m ⁇ ; in which the deposition (on working electrode) is carried out, as not limiting example, by applying 2 m ⁇ each consecutive (three applications) ;
- the reference electrode is prepared/ printed during the printing process using an ink containing particles of a metal selected from the group comprising gold, silver, platinum, copper or combinations thereof or their alloys, preferably silver, having an average diameter of 20-0.05 mih; preferably 10-0.3 pm; most preferably 1 pm;
- a metal selected from the group comprising gold, silver, platinum, copper or combinations thereof or their alloys, preferably silver, having an average diameter of 20-0.05 mih; preferably 10-0.3 pm; most preferably 1 pm;
- the auxiliary electrode is prepared during the printing process using an ink containing carbon particles, preferably graphite microparticles.
- an electrochemical sensor comprising at least an electrode group printed on paper, wherein said electrode group printed on paper comprises at least a working electrode; at least a reference electrode and at least one auxiliary electrode;
- the reference electrode and the auxiliary electrode are on the same side of the paper of the working electrode.
- an electrochemical sensor comprising at least an electrode group printed of on paper, wherein said electrode group printed on paper comprises at least a working electrode; at least a reference electrode and at least one auxiliary electrode;
- a potential of 0 to 0.6 V is applied to the electrodes; preferably from 0.2 to 0.5 V; more preferably 0.4 V vs Ag.
- kit/device for the monitoring of the free chlorine in industrial plants, in water for domestic use or for swimming pools comprising:
- the output signal may be a voltage, current, digital, LAN and/or radio frequency connection signal.
- a "light” layer of wax (according to the design used) is deposited using a printer to wax such as "office wax printer ColorQube", and a software for drawing, such as for example "Adobe Illustrator”;
- the "waxed" sheet thus obtained is placed in a stove at about 100 degrees, for two minutes, to create the hydrophobic region, which surrounds the hydrophilic portion, as shown in Figure 3;
- - a line connects the working electrode (not yet functionalized) printed using an ink containing graphite microparticles; - a line connects the reference electrode (printed during the printing process using an ink containing microparticles of a metal selected from the group comprising gold, silver, platinum, copper or combinations thereof or their alloys, preferably silver, having an average diameter from 20-0.05 pm; more preferably 10- 0.3 pm; most preferably 1 pm);
- auxiliary electrode printed during the printing process using an ink containing microparticles of graphite.
- the working electrode not functionalized of the second step is functionalized using gold nanoparticles (Strem Chemicals, INC, gold nanoparticles 5 nm, 1 OD, stabilised suspension in phosphate buffered saline, 515-520 nm abs max);in which the quantity of gold nanoparticles deposited on the electrode and 0. 1-50 pi, preferably 1-20 pi; most preferably 6 pi; and wherein the deposition (on the working electrode) is carried out by applying consecutively 2 pi each (three applications) using the method described in Talanta 189 (2016) 262-267;
- citrate + KI buffer at pH from 3 to 8; preferred pH from 4 to 7; particularly preferred pH 4.5 ; wherein said buffer has a concentration of KI between 1-6% (w/v), preferred is a concentration of 1.5 - 4; particularly preferred is a concentration of the KI of 2 %.
- the working electrode (still not functionalized) is printed using an ink containing microparticles of graphite (ink graphite Electrodag 421 SS) .
- the reference electrode is printed using an ink containing silver particles having a diameter of about 1 pm (silver ink Electrodag PF 410);
- the auxiliary electrode is printed using an ink containing microparticles of graphite (ink graphite Electrodag 421 SS) .
- Example 1 The working electrode not functionalized of Example 1 was functionalized using gold nanoparticles (Strem Chemicals, Inc. 1 OD, stabilised gold nanoparticles 5 nm, suspension in phosphate buffered saline, 515-520 nm abs max, Cod. Strem Chemicals, INC 2018: 79-0180),
- Table 1 are reported the analytical characteristics detected during the measurement of the quantity of free chlorine present in a sample of water of the pool using the electrode of Example 2.
- Table 2 are reported the readings (average of 3 readings) in a sample of water, to which amounts of free chlorine (ppm) known were added, both by using the electrode of Example 2 (and following the procedure reported in example 4), and by using the spectrophotometric reading carried out by the method described in“UNI EN ISO 7393-1 Qualitci dell’acqua, determinazione del cloro libero e del cloro totale, metodo titrimetrico alia N,N-dietil-l,4, fenilendiammina, plausible 2002’ .
Landscapes
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Pathology (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Physics & Mathematics (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Molecular Biology (AREA)
- Engineering & Computer Science (AREA)
- Food Science & Technology (AREA)
- Medicinal Chemistry (AREA)
- Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)
- Paper (AREA)
- Inspection Of Paper Currency And Valuable Securities (AREA)
Abstract
The present invention relates to new electrodes printed on paper and functionalized with gold nanoparticles; electrochemical sensors comprising at least a nanostructured electrode printed on paper; an integrated system for the management of said sensors and a method for their preparation. The sensor of the invention are useful for monitoring free chlorine in industrial plants, laboratory, swimming pools and domestic waters, and for monitoring water pollution.
Description
NANOSTRUCTURED SENSOR PRINTED ON PAPER
FIELD OF THE INVENTION
The present invention relates to nanostructured electrodes printed on paper; electrochemical sensors comprising at least a nanostructured electrode printed on paper; an integrated system (hereinafter also identified with the term "kit" or "device") for the management of the sensors according to the invention; and a method for their preparation.
The electrodes (and the sensors) in accordance with the present invention are useful for the determination of free chlorine in industrial plants, in laboratory, in water of swimming pools, in water for domestic use and for the monitoring of pollution of the waters.
The electrodes in accordance with the present invention are printed on paper by means of a screen printing process; around said electrodes an hydrophobic area is provided by using a ink printer based on wax,; said electrodes have contours in wax that delimit an area, in which the sample to be analyzed is placed; and said electrodes are functionalised with nanomaterials.
BACKGROUND OF THE INVENTION
Pollutants of biological origin or deriving from disinfectants used to "sanitize" drinking and/or swimming pools water are still today responsible for infectious diseases and disorders of the eyes or the skin. Therefore, it is necessary to carry out a treatment of disinfection of the water intended for human consumption or in swimming pools.
It is however necessary to monitor the concentration of such disinfectants in waters "treated", in order to evaluate whether the concentration of the disinfectants is sufficient enough to guarantee adequate sterilisation, but at the same time not excessively high to produce reaction by-products harmful to man.
We define "free chlorine" the sum of the concentrations of hypochlorite ion and hypochlorous acid, produced from the hydrolysis reaction not only of sodium hypochlorite but also of gaseous chlorine, of calcium hypochlorite and derivatives of isocyanuric acid (dichloro and trichloro). The predominant form between acid and ion in solution, as well as the disinfectant power, is pH-dependent, and hypochlorous acid has the maximum disinfectant power.
DESCRIPTION OF THE FIGURES
In Figure 1 the device according to the present invention for a single detection of the analyte in question is shown, in which the reference numbers have the following meanings:
- electrode printed on the paper ( 1) ;
- sample to be analyzed (2) ;
- display of reading of the measurement (3) ;
- central body of the device (4) .
In Figure 2 a wax screen printer provided with a computer is shown.
In Figure 3 on the left, the printing with wax on the front side of the paper sheet (6) is shown, wherein the number (8) represents the waxed hydrophobic zone; while number (9) represents the not hydrophilic waxed area;
on the right, number (7) represents the back of a sheet of paper (6), on which nothing was printed.
Figure 4 shows the front part of the sheet, where the printing with ink was effected, in which the numbers have the following meanings:
- reference electrode ( 12) prepared using an ink containing silver particles;
- working electrode ( 10) not yet functionalized;
- auxiliary electrode ( 1 1) prepared using an ink containing microparticles of graphite.
In Figure 5 the bar graphs summarizing the amperometric responses obtained during the choice of the operating parameters of sensor are shown, produced according to the present invention, useful for the measurement of free chlorine in solution; the bar corresponding to the value selected for the given analyzed parameter is highlighted:
- 3A) average current (n = 3) recorded, and relative standard deviation, as a function of the amount of gold nanoparticles (0, 2, 4 ,6, 8, 10 gL) deposited on the surface of the working electrode for its functionalization by drop-casting (2 gL at a time), potential applied = 0,5 V vs Ag, citrate buffer + 2% KI, pH = 4.5, concentration free chlorine 1 ppm;
- 3B) average current (n = 3) recorded and relative standard deviation, as a function of the applied potential vs Ag in a range between 0.2 and 0,6 V vs Ag, using printed electrodes on paper and depositing on the working electrode 6 gL of gold nanoparticles, citrate buffer + 2% KI, pH = 4.5, concentration free chlorine 1 ppm;
- 3C) average current (n = 3) recorded and relative standard deviation, as a function of the pH of the buffer solution used, using printed electrodes on paper and depositing on the working electrode 6 gL of gold nanoparticles, applied potential = 0.4 V vs Ag, concentration free chlorine 2 ppm;
- 3D) average current (n = 3) recorded and relative standard deviation, as a function of the concentration of iodide in the buffer solution, using electrodes printed on paper and depositing on the working electrode 6 gL of gold nanoparticles, potential applied = 0.4 V vs Ag, citrate buffer, pH = 4.5, concentration free chlorine 2 ppm.
In Figure 6 the amperograms are shown obtained using the sensor according to the present invention, functionalized with 6 gL of gold nanoparticles, potential applied = 0.4 V vs Ag, buffer citrate + 2% KI, pH = 4.5, at different concentrations
of free chlorine (0; 0.25; 0.5; 1; 2; 5; 10; 20 and 50 ppm), and the respective calibration straight line which shows the current as a function of ppm.
DESCRIPTION OF THE INVENTION
It is therefore an object of the present invention a nanostructured electrode printed on paper, for the measurement of free chlorine in fluids, characterized in that said electrode is functionalized with gold nanoparticles;
wherein:
-the paper is selected from the group comprising filter paper or office paper;
-the functionalization is done by depositing on the working electrode 0. 1-50 gL, preferably 1-20 pi; most preferably 6 gL of a stabilized suspension of gold nanoparticles in phosphate buffer, having an average diameter of about 5 nm (nanometres); and the deposition is carried out by applying 2 mΐ each consecutive.
It is a further object of the present invention an electrochemical sensor comprising at least one electrode as defined above.
It is a further object of the present invention an electrochemical sensor comprising:
- at least an electrode group printed on paper, wherein said electrode group comprises at least a working electrode; at least a reference electrode and/or at least one auxiliary electrode;
characterized in that:
- the working electrode is functionalized using gold nanoparticles having an average diameter of about 5 nm, in which the amount of gold nanoparticles deposited on the electrode is 0. 1-50 mΐ, preferably 1-20 mΐ; most preferably 6 mΐ; in which the deposition (on working electrode) is carried out, as not limiting example, by applying 2 mΐ each consecutive (three applications) ;
- the reference electrode is prepared/ printed during the printing process using an ink containing particles of a metal selected from the group comprising gold, silver, platinum, copper or combinations thereof or their alloys, preferably
silver, having an average diameter of 20-0.05 mih; preferably 10-0.3 pm; most preferably 1 pm;
and
- the auxiliary electrode is prepared during the printing process using an ink containing carbon particles, preferably graphite microparticles.
It is a further object of the present invention an electrochemical sensor comprising at least an electrode group printed on paper, wherein said electrode group printed on paper comprises at least a working electrode; at least a reference electrode and at least one auxiliary electrode;
characterized in that that:
the reference electrode and the auxiliary electrode are on the same side of the paper of the working electrode.
It is a further object of the present invention an electrochemical sensor comprising at least an electrode group printed of on paper, wherein said electrode group printed on paper comprises at least a working electrode; at least a reference electrode and at least one auxiliary electrode;
characterized in that:
- for the measurement of free chlorine a potential of 0 to 0.6 V is applied to the electrodes; preferably from 0.2 to 0.5 V; more preferably 0.4 V vs Ag.
It is a further object of the present invention a kit/device for the monitoring of the free chlorine in industrial plants, in water for domestic use or for swimming pools, comprising:
- at least an electrochemical sensor according to the present invention;
- at least an electrolytic solution;
- at least a potentiostat;
- at least one electronic device for collecting, transferring and processing data;
wherein the output signal may be a voltage, current, digital, LAN and/or radio frequency connection signal.
It is a further object of the present invention a process for the preparation of an electrochemical sensor comprising at least a working electrode, at least a reference electrode and at least one auxiliary electrode, in which said process is characterized by the following steps:
FIRST STEP
preparing the test area on paper:
on only one side of a sheet of the filter paper or office paper a "light" layer of wax (according to the design used) is deposited using a printer to wax such as "office wax printer ColorQube", and a software for drawing, such as for example "Adobe Illustrator";
the "waxed" sheet thus obtained is placed in a stove at about 100 degrees, for two minutes, to create the hydrophobic region, which surrounds the hydrophilic portion, as shown in Figure 3;
SECOND STEP
printing and preparing an electrode on paper , in which the working electrode is not yet functionalized:
in the hydrophilic area of the "waxed" sheet of the first step, three electrodes are printed using the method described in Anal. Chim. Acta 919 (2016) 78-84, and as shown in Figure 4;
at the end of the printing process, on the electrode printed three lines appear, which represent the conductive tracks useful for joining the connector of the instrument useful for measurement and the electrodes printed on paper;
wherein:
- a line connects the working electrode (not yet functionalized) printed using an ink containing graphite microparticles;
- a line connects the reference electrode (printed during the printing process using an ink containing microparticles of a metal selected from the group comprising gold, silver, platinum, copper or combinations thereof or their alloys, preferably silver, having an average diameter from 20-0.05 pm; more preferably 10- 0.3 pm; most preferably 1 pm);
and
- a line connects the auxiliary electrode (printed during the printing process using an ink containing microparticles of graphite).
THIRD STEP
functionalizing the working electrode
the working electrode not functionalized of the second step is functionalized using gold nanoparticles (Strem Chemicals, INC, gold nanoparticles 5 nm, 1 OD, stabilised suspension in phosphate buffered saline, 515-520 nm abs max);in which the quantity of gold nanoparticles deposited on the electrode and 0. 1-50 pi, preferably 1-20 pi; most preferably 6 pi; and wherein the deposition (on the working electrode) is carried out by applying consecutively 2 pi each (three applications) using the method described in Talanta 189 (2018) 262-267;
obtaining an electrode functionalized printed on paper, useful for the determination of free chlorine in standard solution, having the following technical characteristics:
- a sensitivity of 0. 165 ± 0.001 pA/ppm;
- an RSD inter-electrode 1 %;
- a detectability limit (LOD) calculated as S/N = 0.01 ppm;
- a LOQ of 0.03 ppm obtained from S/N = 10 (Quality Assurance in Analytical Chemistry: Training and Teaching by Bernd W. Wenclawiak, Michael Koch, Evsevios);
in which the sample to be analyzed with the electrode according to the invention before the analysis is diluted in a buffer selected from the group comprising:
Britton-Robinson , phosphate, acetate, citrate and borate buffer, or their mixtures, preferred is citrate + KI buffer, at pH from 3 to 8; preferred pH from 4 to 7; particularly preferred pH 4.5 ; wherein said buffer has a concentration of KI between 1-6% (w/v), preferred is a concentration of 1.5 - 4; particularly preferred is a concentration of the KI of 2 %.
The following examples illustrate the invention without limiting it.
EXAMPLES
Materials and Methods
Instruments
- pH meter digital 334-B, Amel Instrument
- analytical Balance, Sartorius
- screen printer multipurpose High performance precision screen printer Dek
245 DEK, Weymouth's medium, UK
- tiostat/galvanostat PalmSens portable Instrument, Echo Chemie, Utrecht, the Netherlands with software PSTrace 4.4 ;
- ColorQube 8580, Xerox, (office wax printer reagents
Reagents
- ink graphite Electrodag 421 SS
- silver ink Electrodag 410 PF
- gold nanoparticles (Strem Chemical, INC, gold nanoparticles 5nm, 10D, stabilised suspension in phosphate buffered saline, 515-520 nm abs max, Cod. Strem Chemical, INC2018: 79-0180).
- Filter Paper 67 g/m2, Cordenons.
EXAMPLE 1
Preparation of printing of an electrode not functionalized
With a wax printer, on only one side of a sheet of filter paper (67 g/m2, Cordenons) a "light" layer of wax was deposited, thereby creating a hydrophobic region which surrounds a hydrophilic portion. This "waxed" sheet was placed in an oven at 100°C for two minutes. In the hydrophilic zone of this sheet the electrode was printed using the method described in Anal. Chim. Acta 919 (2016) 78-84 (Figure 2). After this printing on the sheet three lines appeared, which represent the conductive tracks useful for joining the connector of the instrument useful for the measurement and the electrodes printed on paper:
in which:
- the working electrode (still not functionalized) is printed using an ink containing microparticles of graphite (ink graphite Electrodag 421 SS) .
- the reference electrode is printed using an ink containing silver particles having a diameter of about 1 pm (silver ink Electrodag PF 410);
and
- the auxiliary electrode is printed using an ink containing microparticles of graphite (ink graphite Electrodag 421 SS) .
EXAMPLE 2
Functionalization of the working electrode
The working electrode not functionalized of Example 1 was functionalized using gold nanoparticles (Strem Chemicals, Inc. 1 OD, stabilised gold nanoparticles 5 nm, suspension in phosphate buffered saline, 515-520 nm abs max, Cod. Strem Chemicals, INC 2018: 79-0180),
having an average diameter of 5 nm, in which the quantity of gold nanoparticles deposited on the electrode were 6 pi, in which the deposition was carried out by means of three consecutive applications of 2 pi each using the method described in Anal. Chim. Acta 919 (2016) 78-84.
At the end of this treatment it is obtained an electrode printed on paper, functionalized, useful for the determination of free chlorine, having the following technical characteristics:
- a sensitivity of 0. 160 ± 0.004 mA/ppm;
- a RSD inter electrode of the 3 %;
- a detectability limit (LOD) calculated as S/N = 0.01 ppm;
- a LOQ of 0.03 ppm obtained from S/N = 0.01 (Quality Assurance in Analytical Chemistry: training and teaching to treatment of Bernd W. Wenclawiak, Michael Koch,Evsevios).
The sample to be analyzed with the electrode according to the invention before analysis was diluted l :2(v/v) in a citrate buffer solution pH = 4.5 + KI 2 %. It is evident that the dilution carried out depends on the sample analyzed.
EXAMPLE 3
Evaluation of the Quantity of free chlorine present in a standard solution
Standard liquid solutions, prepared in buffer citrate + 2 KI, pH = 4.5 containing 0.25; 0,5; 1; 2; 5; 10; 20 and 50 ppm of chlorine, were tested using the electrode of Example 2.
By a mean of 3 readings the following results were obtained:
- sensitivity of 0. 165 ± 0.001 mA/ppm;
- RSD inter-electrode 1 %;
- detectability limit (LOD) calculated as S/N = 0.01 ppm;
- LOQ of 0.03 ppm obtained from S/N = 10 (Quality Assurance in Analytical Chemistry: Training and Teaching by Bernd W. Wenclawiak, Michael Koch, Evsevios);
EXAMPLE 4
Evaluation of the quantity of free chlorine present in a sample of water of a pool, using the electrode of Example 2.
1 mL of pool water was diluted 1 :2 (v/v) in a buffer solution of citrate + KI 2 %, pH = 4.5.
This diluted sample was tested using the electrode of Example 2.
By a mean of 3 readings the following results were obtained:
- sensitivity of 0. 160 ± 0.004 mA/ppm;
- RSD inter-electrode of 3 %;
- detectability limit (LOD) calculated as S/N = 0.01 ppm;
- LOQ of 0.03 ppm obtained from S/N = 10 (Quality Assurance in Analytical Chemistry: training and teaching by Bernd W. Wenclawiak, Michael Koch, Evsevios);
In Table 1 are reported the analytical characteristics detected during the measurement of the quantity of free chlorine present in a sample of water of the pool using the electrode of Example 2.
Table 1
EXAMPLE 5
Measurements of the free chlorine in water using the electrode according to the invention , with respect to the reference spectrophotometric method
In Table 2 are reported the readings (average of 3 readings) in a sample of water, to which amounts of free chlorine (ppm) known were added, both by using the electrode of Example 2 (and following the procedure reported in example 4), and by using the spectrophotometric reading carried out by the method described
in“UNI EN ISO 7393-1 Qualitci dell’acqua, determinazione del cloro libero e del cloro totale, metodo titrimetrico alia N,N-dietil-l,4, fenilendiammina, novembre 2002’ .
Table 2
Claims
1. Paper-based screen- printed electrode, for the measurement of free chlorine, characterized by the fact that said screen-printed electrode comprises at least a working electrode, in which said working electrode is functionalized with gold nanoparticles.
2. Paper-based screen-printed electrode of claim 1, in which the functionalization is made by deposing on the working electrode 0. 1-50 mΐ, preferably 1-20 mΐ; most preferably 6 mΐ of gold nanoparticles stabilized suspension in phosphate buffer.
3. Paper-based screen-printed electrode of claims 1-2, in which the gold nanoparticles have an average diameter of about 5 nm.
4. Paper-based screen-printed electrode of claims 1-3, in which the deposition is casted onto the working electrode in three steps of 2 mΐ each.
5. Paper-based screen-printed electrode of claims 1-4, comprising at least a working electrode, at least a reference electrode, and/or at least a counter-electrode, characterized by the fact that the reference electrode and the counter-electrode are printed in the same side of the working electrode.
6. Paper-based screen-printed electrode of claim 1, in which the paper is selected from the group comprising filter paper or office paper.
7. Electrochemical sensor comprising at least a paper-based screen- printed electrode of claims 1-6.
8. Electrochemical sensor of claim 7, characterized by the fact that for the measurement of the free chlorine a potential of from 0 to 0.6 V, preferably of from 0.2 to 0.5 V, most preferably 0.4 V is applied to the electrodes.
9. Process for preparing an electrochemical sensor of claim 7-8, in which said sensor comprises at least a working electrode, at least a reference electrode,
and/or at least a counter-electrode, in which said process in characterized by the following steps:
FIRST STEP realizing a testing area on the paper support: on a paper sheet an hydrophobic area (8) is printed, inside to which an hydrophilic area (9) is present, using a wax printer; the waxed sheet so obtained is put in an oven at about 100°C, for about two minutes;
SECOND STEP printing and preparing paper-based electrodes , in which the working electrode is not yet functionalised: on the hydrophilic zone (9) of the waxed sheet of the first step, are printed: at least a working electrode ( 10), using an ink containing graphite microparticles, in which said working electrode is not yet functionalised; at least a reference electrode ( 12) , using an ink containing silver particles; and / or
- at least a counter electrode ( 1 1), using an ink containing graphite microparticles;
THIRD STEP functionalizing the working electrode functionalization: the working electrode ( 10) of the second step is functionalized using gold nanoparticles having an average diameter of about 5 nm,
in which the amount of gold nanoparticles casted onto the working electrode is 0. 1-50 mΐ, preferably 1-20 mΐ; most preferably 6 mΐ; in which the deposition is casted onto the working electrode in three steps of 2 mΐ each; obtaining a paper-based functionalised printed electrode, useful for the free chlorine measurement, in which, before the measurement, the sample to be analysed is diluted in a buffer selected from the group comprising Britton- Robinson, phosphate, acetate, citrate and borate buffer, or mixture thereof; preferred is the citrate buffer + KI, pH from 3 to 8, more preferred is from 4 to 7, most preferred is pH 4.5; in which said buffer has a concentration of KI comprised from 1 to 6% (w/v); preferred is a concentration of from 1.5 to 4% (w/v); particularly preferred is a concentration of 2% (w/v).
10. A device for free chlorine measurement in a fluid, comprising: - at least an electrochemical sensor of claims 7-8, and further comprising
- at least an electronic device for the data acquisition, transfer and elaboration, in which the output signal may be an in tension signal and/or current and / or digital and / or LAN connection and / or radiofrequency;
- at least an electrolytic solution;
- at least a potenziostat.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IT102019000003447A IT201900003447A1 (en) | 2019-03-11 | 2019-03-11 | New sensors printed on nanostructured paper. |
| PCT/EP2020/056384 WO2020182830A1 (en) | 2019-03-11 | 2020-03-10 | Nanostructured sensor printed on paper |
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| Publication Number | Publication Date |
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| EP3938770A1 true EP3938770A1 (en) | 2022-01-19 |
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| EP (1) | EP3938770A1 (en) |
| IT (1) | IT201900003447A1 (en) |
| WO (1) | WO2020182830A1 (en) |
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| CN1715899A (en) * | 2004-07-02 | 2006-01-04 | 中国科学院福建物质结构研究所 | A kind of preparation method of novel residual chlorine detecting electrode |
| US10466287B2 (en) * | 2016-05-13 | 2019-11-05 | The Board Of Trustees Of Western Michigan University | Printed wireless inductive-capacitive (LC) sensor for heavy metal detection |
| CN109061190B (en) * | 2018-08-22 | 2021-12-07 | 苏州微湃医疗科技有限公司 | Preparation of multi-channel biosensor array based on paper chip and application of multi-channel biosensor array in immunodetection |
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