CN105203476A - Phthalic dicarboxaldehyde-NH3-Na2SO3 reaction-based flow injection spectrophotometry method for measuring Ammonia-N in water sample - Google Patents
Phthalic dicarboxaldehyde-NH3-Na2SO3 reaction-based flow injection spectrophotometry method for measuring Ammonia-N in water sample Download PDFInfo
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Abstract
The invention discloses a phthalic dicarboxaldehyde-NH3-Na2SO3 reaction-based flow injection spectrophotometry method for measuring Ammonia-N in a water sample. The method specifically comprises the step of adopting a flow injection analyzer and an ultraviolet-visible spectrophotometer to jointly measure Ammonia-N content in a water sample. An amaranth complex is generated based on an OPA(O phthalic aldehyde)-NH3-Na2SO3 reaction; the complex realizes strong absorption at a 550nm position, and has an absorbance value in direct proportion to Ammonia-N concentration in the water sample, thus creating the flow injection spectrophotometry method for measuring Ammonia-N in the water sample. The detection limit of the method can be as low as 0.007mmol/L, and measuring on Ammonia-N concentrations in various surface water can be realized; average substrate adding standard recovery rates of lake water, river water and groundwater are respectively 100.4 percent, 95.2 percent and 101.7 percent; besides, the analysis speed is high, and a result is not remarkably different from that of a indophenol blue spectrophotometry method.
Description
Technical field
The present invention relates to the assay method of ammonium nitrogen content in water sample, be specifically related to a kind of based on o-phthalaldehyde(OPA)-NH
3-Na
2sO
3the method of ammonium nitrogen in the flow injection spectral photometry water sample of reaction.
Background technology
Ammonium nitrogen (also referred to as ammonia nitrogen) refers in water with free ammonia (NH
3) and ammonium ion (NH
4 +) form exist nitrogen, its ratio of components depends on pH value and the water temperature of water.It is the most important inorganic N forms that in water body, phytoplankton can directly utilize, and due to the impact by mankind's activity, the ammonium nitrogen content of some water bodys is higher, even reaches the degree of poisoning hydrobiont and destroying water ecology balance.Therefore, ammonium nitrogen is that water quality must survey index.In current mensuration water sample, the method for ammonium nitrogen is a lot, as Berthelot spectrophotometry, salicylic acid photometry, chemoluminescence method, the chromatography of ions, molecular absorption spectrometry etc.But the most complicated operation of these methods, is easily disturbed.Flow Injection Analysis (FlowInjectionAnalysis, be abbreviated as FIA) be a kind of novel Continuous Flow Analysis technology that Denmark chemist Lu Qika (RuzickaJ) in 1974 and the Chinese gloomy (HansenEH) propose, achieve the process of solution automatic on-line and mensuration.FIA technology has that device is small-sized, simple, operation is reliable; Automaticity is high, analysis speed is fast; Good reproducibility of analysis results; Required amount of reagent is few; The advantages such as highly sensitive, detectability is low; And FIA technology can with multiple analytical instrument coupling, be widely used in the fields such as environment, agricultural, medicine, food at present.But not yet find based on OPA (o-phthalaldehyde(OPA), o-phthaldialdehyde)-NH at present
3-Na
2sO
3reaction generates aubergine complex compound and adopts flow injection analysis to carry out detecting the report of ammonium nitrogen content in water sample in conjunction with spectrophotometric method.
Summary of the invention
The technical problem to be solved in the present invention is to provide the assay method of ammonium nitrogen content in a kind of new water sample, is specially based on o-phthalaldehyde(OPA)-NH
3-Na
2sO
3the method of ammonium nitrogen in the flow injection spectral photometry water sample of reaction, the method is simple to operate, quick, result there was no significant difference compared with conventional indigo spectrophotometry.
Of the present invention based on o-phthalaldehyde(OPA)-NH
3-Na
2sO
3the method of ammonium nitrogen in the flow injection spectral photometry water sample of reaction, is adopt the ammonium nitrogen in flow injection analyzer and ultraviolet-visible pectrophotometer joint-detection water sample, comprises the following steps:
1) ammonium nitrogen standard solution, OPA-Na is prepared
2sO
3mixed solution and EDTA-NaOH buffer solution;
2) valve position of flow injection analyzer is adjusted to Fill state, starts active efflux, ammonium nitrogen standard solution is pumped in the stored one kind of tubes of flow injection analyzer, the full ammonium nitrogen standard solution of storage in stored one kind of tubes; Meanwhile, pure water flows through the detecting device of ultraviolet-visible pectrophotometer by active efflux, and detecting device measures wavelength and is set to 550nm, returns to zero to detecting device;
3) valve position of flow injection analyzer is switched to Inject state, start active efflux and pair and move pump, active efflux is moved by the ammonium nitrogen standard solution pumped in stored one kind of tubes and pair the reagent OPA-Na that pump pumps
2sO
3mixed solution and the mixing of EDTA-NaOH buffer solution, and be sent in the reaction tube of flow injection analyzer;
4) valve position of flow injection analyzer is switched to Fill state, make the reaction solution insulation reaction certain hour at the reaction temperatures in reaction tube;
5) after arriving the reaction time, start active efflux, reactant liquor in pure water driving a reaction pipe flows through detecting device, absorbance A is measured in 550nm by detecting device, this absorbance signal is by computing machine continuous acquisition, export with the form of elution curve (elution curve is absorbance A curve over time), the absorbance at record elution curve peak height place, and make working curve with the concentration of the absorbance at elution curve peak height place and ammonium nitrogen standard solution;
6) ammonium nitrogen standard solution is replaced with testing sample solution, repeat step 2) to step 5), obtain the elution curve of testing sample solution and the absorbance at described elution curve peak height place, with the absorbance at this elution curve peak height place according to the ammonium nitrogen content in the quantitative testing sample solution of working curve.
In said method, stored one kind of tubes is polyfluortetraethylene pipe, and preferably adopt length to be 1.4-2.0m, internal diameter is that the polyfluortetraethylene pipe of 0.8-1.0mm is as stored one kind of tubes.
In said method, OPA-Na
2sO
3the amount of pumping into of mixed solution preferably controls reaction solution, and (reaction solution is the solution participating in reaction, i.e. ammonium nitrogen standard solution (or testing sample solution) and OPA-Na
2sO
3the mixed solution of mixed solution and EDTA-NaOH buffer solution) in the concentration of OPA be 0.28-0.42g/L, Na
2sO
3concentration be 0.013-0.023g/L; Being more preferably the concentration controlling OPA in reaction solution is 0.35-0.42g/L, Na
2sO
3concentration be 0.017-0.023g/L; The concentration more preferably controlling OPA in reaction solution is 0.35g/L, Na
2sO
3concentration be 0.017g/L.
In said method, the amount of pumping into of described EDTA-NaOH buffer solution is the pH value controlling reaction solution is 10.77-10.95, and the concentration of EDTA in reaction solution is for being more than or equal to 15g/L; Being preferably and controlling the pH value of reaction solution is 10.80-10.95, and the pH value being more preferably reaction solution is the concentration of 10.80, EDTA is 17g/L.
In said method, the reaction solution in described reaction tube preferably reacts under the condition of≤60 DEG C, and temperature of reaction is higher, and the time that reaction arrives balance is corresponding shorter.In the application, preferred reaction is carried out under the condition of 27-55 DEG C, more preferably using 55 DEG C as temperature of reaction.
In said method, pure water is carrier.
In the method for the invention, because Flow Injection Analysis Method precisely controls the reaction time by program, therefore, measure under nonequilibrium condition and also can obtain good repeatability, after namely not needing to wait until molecular balance in the method for the invention, just can carry out next step operation.Therefore, in the method for the invention, as long as the time that reaction solution reacts in reaction tube be greater than 0s time can, common selection is between being greater than between 0s to the equilibration time being less than or equal to reaction.Applicant finds in test, and time longer when reacted, the sensitivity of method is higher, and detectability is low, otherwise sensitivity is low, detects limit for height.During practical measurement, reaction time and temperature of reaction can be selected according to the concentration of actual sample.In the application, when temperature of reaction is defined as 27-55 DEG C, the time that reaction solution reacts in reaction tube is preferably between being greater than 0s to being less than between 340s, more preferably 160-340s.
Applicant also finds in test, and when the flow cell of the reactant liquor reacted by detecting device, flow velocity is larger, and elution curve peak is narrower, and minute is also shorter, is conducive to raising method test sample speed.Consider from this angle of raising test sample speed, the flow velocity when reactant liquor of gained flows through detecting device after the application's preferred reaction completes is >=8.2mL/min.
In the method for the invention, OPA-Na
2sO
3oPA and Na in mixed solution
2sO
3concentration can according to OPA and Na needed for reaction solution
2sO
3amount and pump into volume computing and determine, preferably make the OPA-Na that preparation obtains
2sO
3in mixed solution, the concentration of OPA is 0.85-1.27g/L, Na
2sO
3concentration be 0.04-0.07g/L; The concentration being more preferably OPA is 1.06-1.27g/L, Na
2sO
3concentration be 0.05-0.07g/L; The concentration most preferably being OPA is 1.06g/L, Na
2sO
3concentration be 0.05g/L.The flow velocity pumped into is generally 2.3-3.0mL/min.
In the method for the invention, it is formulated that EDTA-NaOH buffer solution adopts 26.0gEDTA disodium and a certain amount of NaOH to be dissolved in 500mL ultrapure water usually; Preferably, be that to be dissolved in 500mL ultrapure water by 26.0gEDTA disodium and 10.0gNaOH formulated.The flow velocity pumped into is generally 2.3-3.0mL/min.
In the method for the invention, the flow velocity that pure water promotes solution in memotron is 2.3-3.0mL/min.During practical operation, control flow velocity, OPA-Na that pure water promotes solution in memotron
2sO
3mixed solution pumps into flow velocity and EDTA-NaOH buffer solution, and to pump into flow velocity equal.
In the method for the invention, the flow velocity that pumps into of ammonium nitrogen standard solution (or testing sample solution) is generally 4.0-6.0mL/min.
Compared with prior art, the present invention is based on OPA-NH
3-Na
2sO
3reaction generates aubergine complex compound, and this material has strong absorption at 550nm place, and absorbance is directly proportional to ammonium nitrogen concentration in water sample, establishes the Flow Injection Spectrophotometry measuring ammonium nitrogen in water sample.The method detectability can be low to moderate 0.007mmol/L, can meet the mensuration of ammonium nitrogen concentration in all kinds of surface water; The average substrate recovery of standard addition of lake water, river and underground water is respectively 100.4%, 95.2%, 101.7%; And analysis speed fast (even if be the reaction time with 340s, per hour at least also can carry out 8 sample tests).The method of the invention is adopted to carry out detection, result and the indigo spectrophotometry there was no significant difference of ammonium nitrogen in water sample.
Below Optimal Experimental and the method validation experiment that applicant determines the optimum reaction condition of the method for the invention.
1 experimental section
1.1 instruments and reagent
UV-2550 ultraviolet-visible pectrophotometer (Shimadzu); Electrothermal thermostat water bath (Shanghai He De experimental facilities company limited); FIA-3110 Flow Injection Analysis processing instrument (Beijing Jitian Instrument Co., Ltd.).
This is tested chemicals used and is and analyzes pure rank (Aladdin company), except the medicine having a special instruction.
Experimental water is the ultrapure water that resistivity is greater than 18.2M Ω cm.
Ammonium nitrogen standard solution the: be used in (NH that 110 DEG C are dried to constant weight
4)
2sO
4, be mixed with the ammonium nitrogen standard reserving solution that ammonium nitrogen concentration is 20mmol/L, in 4 DEG C of stored refrigerated; The ammonium nitrogen standard reserving solution dilution of the ammonium nitrogen standard solution 20mmol/L of variable concentrations obtains.
10.60g/L o-phthalaldehyde(OPA) solution: take 2.65gOPA, after being dissolved in 50mL methanol solution (Aladdin, chromatographically pure), then is diluted to 250mL with ultrapure water, shakes up sealing lucifuge stored refrigerated.
1.00g/LNa
2sO
3solution: take 0.50g anhydrous Na
2sO
3solid, after being dissolved in 500mL ultrapure water, adding 0.20mL formalin (preventing sodium sulfite solution from going bad) wherein, shakes up stored refrigerated.
OPA-Na
2sO
3mixed solution: the 10.60g/LOPA solution of certain volume and 1.00g/LNa
2sO
3solution mixed diluting forms; In the experimental technique optimized, OPA-Na
2sO
3oPA, Na in mixed solution
2sO
3concentration be respectively 1.06g/L and 0.050g/L.
EDTA-NaOH buffer solution: taking 26.0gEDTA disodium and a certain amount of NaOH, to be dissolved in 500mL ultrapure water formulated; In the experimental technique optimized, it is formulated that EDTA-NaOH buffer solution is dissolved in 500mL ultrapure water by 26.0gEDTA disodium and 10.0gNaOH.
1.2 Flow Injection Analysis flow circuit diagram and experimental techniques
As shown in Figure 1, Flow Injection Analysis program lists in table 1 to Flow Injection Analysis flow circuit diagram.During analysis, put into by sample feeding pipe in solution to be measured (ammonium nitrogen standard solution or water sample), the water bath with thermostatic control that reaction tube is placed in uniform temperature is heated.Working procedure, flow injection instruments is started working.At the 1st Walk, the valve position of flow injection instruments is Fill state, and active efflux starts, and solution to be measured is crossed stored one kind of tubes by pump, the full solution to be measured of storage in stored one kind of tubes; Meanwhile, pure water, under the driving of active efflux, flows through 2mm (the i.d.) × 1cm flow cell in UV, visible light spectrophotometric detector; Detecting device measures wavelength and is set to 550nm, when spectrophotometer stable reading, returns to zero to it; 2nd Walk, the valve position of flow injection instruments switches to Inject state, and move the driving of pump at active efflux and pair under, pure water pushes and is stored in solution to be measured in stored one kind of tubes and reagent OPA-Na
2sO
3mixed solution, EDTA-NaOH buffer solution mix, and just proceed to reaction tube stop at a certain temperature reaction 160s (step 3); Afterwards, the 4th Walk, flow injection instruments valve position is Fill state, and active efflux starts, and the pure water reactant liquor that push in reaction tube flows through the flow cell 2mm ((i.d.) × 1cm) in detecting device, measures absorbance A by detecting device in 550nm; This signal is by computing machine continuous acquisition, and every 0.5sec records 1 data, exports with the form of elution curve (absorbance A is curve over time); Absorbance (the H at elution curve peak height place
a), the foundation that namely in sample, ammonium nitrogen is quantitative.In order to ensure the reliability of data, during analysis, sample introduction from low concentration to high concentration, should will run 1-2 blank sample, prevent sample from influencing each other between unknown sample.
Table 1 Flow Injection Analysis program
2 results and discussion
2.1 absorption spectrum
Compound concentration is the ammonium nitrogen standard solution of 0.500mmol/L, test by 1.2 experimental techniques, at program the 4th Walk, access the purplish red solution of outflow in detector back with 1cm light path cuvette, mixing, be placed in the absorption spectrum that UV-2550 ultraviolet-visible pectrophotometer (Shimadzu) measures this solution, as shown in Figure 2.Fig. 2 shows, this solution has absorption maximum at 550nm.Therefore, this experiment is using 550nm as mensuration wavelength.
The optimization of 2.2 experiment parameters
2.2.1 the length of stored one kind of tubes is determined
Stored one kind of tubes is used for the storage of solution to be measured, solution to be measured mixes with reaction reagent under the promotion of current-carrying (pure water), stop reaction and then proceed to detecting device is detected, in the process, there are diffusion phenomena in the contact liquid level between pure water and reaction solution to be measured.As stored one kind of tubes is too short, because of diffusion, reaction solution to be measured is diluted, and elution curve peak height is less than normal; In theory, after stored one kind of tubes length reaches certain value, part middle in stored one kind of tubes can affect from diffusion dilution, thus obtains larger elution curve peak height value.For this reason, with the ammonium nitrogen standard solution of 0.500mmol/L for investigating object, within the scope of 0.4-2.0m, by changing the stored one kind of tubes of different length, fixing other experiment parameter as described in 1.2 experimental techniques, investigating elution curve peak height place absorbance (H
a) with the relation of stored one kind of tubes length, result is as shown in Figure 3.Fig. 3 shows, along with stored one kind of tubes length increases, and H
apresent the trend first increasing and tend towards stability afterwards, when stored one kind of tubes length is greater than 1.4m, H
abe tending towards constant, visible, when stored one kind of tubes length is 1.4-2.0m, elution curve can obtain maximum peak height value H
a.Stored one kind of tubes is longer, and required testing liquid is long-pending larger, and required analysis time is longer.Consider, under this experiment condition, choose the optimum length that 1.6m is stored one kind of tubes.
2.2.2 the optimization of reagent dosage
OPA, Na
2sO
3the pH value of consumption and reaction solution can affect OPA-NH
3-Na
2sO
3the extent of reaction and reaction rate.This experiment adopts single_factor method, with the ammonium nitrogen standard solution of 0.500mmol/L for investigating object, respectively to OPA, Na
2sO
3the pH value of consumption and reaction solution is optimized.
The optimization of OPA consumption: by changing OPA-Na
2sO
3in mixed solution, the configuration concentration of OPA, changes OPA-Na within the scope of 0.106-1.27g/L
2sO
3the concentration of OPA in mixed solution, fixes other experiment parameter as described in experimental technique 1.2, investigates elution curve peak height (H
a) and OPA-Na
2sO
3the relation of OPA concentration in mixed solution, result as shown in Figure 4.Fig. 4 shows, along with the increase of OPA concentration, and H
apresent the trend first increasing and reach maximum platform afterwards, work as OPA-Na
2sO
3when in mixed solution, OPA concentration changes in 0.85-1.27g/L (in reactant liquor, OPA concentration is 0.28-0.42g/L) scope, H
aremain unchanged, visible, 0.85-1.27g/L is OPA-Na
2sO
3the preferred concentration scope of OPA in mixed solution, this method selects 1.06g/L to be OPA-Na
2sO
3the optium concentration of mixed solution, namely selecting to control OPA concentration in reactant liquor is 0.35g/L.
Na
2sO
3the optimization of consumption: by changing OPA-Na
2sO
3na in mixed solution
2sO
3configuration concentration, within the scope of 0.005-0.07g/L, change OPA-Na
2sO
3na in mixed solution
2sO
3concentration, fix other experiment parameter as described in experimental technique 1.2, investigate elution curve peak height (H
a) and OPA-Na
2sO
3na in mixed solution
2sO
3the relation of concentration, result as shown in Figure 5.Fig. 5 shows, along with Na
2sO
3the increase of concentration, H
afirst increase and be tending towards constant afterwards, work as Na
2sO
3when concentration changes within the scope of 0.04-0.07g/L, H
areach maximum and remain unchanged; Visible, 0.04-0.07g/L is OPA-Na
2sO
3na in mixed solution
2sO
3preferred concentration scope (i.e. Na in reactant liquor
2sO
3concentration is 0.013-0.023g/L), this method selects 0.05g/L to be OPA-Na
2sO
3na in mixed solution
2sO
3optium concentration, namely control Na in reactant liquor
2sO
3concentration is 0.017g/L.
The determination of reaction solution pH and wherein EDTA consumption: by changing the configuration concentration of NaOH in EDTA-NaOH damping fluid, the pH of reactant liquor is changed within the scope of 8.91-10.95, fix other experiment parameter as described in experimental technique 1.2, investigate elution curve peak height (H
a) with the relation of reactant liquor pH, result is as shown in Figure 6.Fig. 6 shows, pH within the scope of 8.91-10.95, H
avalue first increases and tends towards stability afterwards, when pH changes within the scope of 10.77-10.95, and H
avalue reaches maximum and remains unchanged.Therefore, the better usable range of reactant liquor pH is 10.77-10.95, and the optimal pH that reactant liquor is chosen in experiment is 10.80.EDTA is except being formed except buffer solution with NaOH, and another object is to prevent Ca in actual water sample
2+, Mg
2+deng metallic ion within the scope of 8.91-10.95 and OH
-generate precipitation.By repeatedly testing, when in actual water sample, EDTA content is more than or equal to 15g/L, river, mountain spring water, pure water, the actual water sample such as tap water are all can not generate precipitation within the scope of 8.91-10.95 at pH, for the purpose of insurance, the concentration controlling EDTA in reactant liquor is 17g/L.Therefore, in EDTA-NaOH damping fluid, when EDTA concentration be 52g/L, NaOH concentration is 20g/L, test by 1.2 experimental techniques, can control EDTA and pH in reactant liquor is optimum value.
2.2.3 the determination of temperature of reaction and reaction time
In order to investigate temperature of reaction to OPA-NH
3-Na
2sO
3the impact of reaction rate, changes the heating-up temperature (i.e. temperature of reaction) of coil pipe 2 within the scope of 27-65 DEG C, determines the peak height value H of the ammonium nitrogen standard solution elution curve of 0.500mmol/L under different temperatures under the different residence time
a, result as shown in Figure 7.Fig. 7 shows, under the identical residence time, temperature of reaction is increased to 55 DEG C from 27 DEG C, H
apresent increase trend, illustrate that, in this temperature range, temperature more high reaction rate is faster; But, when the residence time more than 300s after, the H of 65 DEG C
abe slightly less than the H at 55 DEG C on the contrary
a, this is because when temperature is increased to 65 DEG C, part aubergine complex decomposes fades and causes.Equilibration time under different temperatures also can reflect the speed of reaction rate, and Fig. 7 shows, when temperature of reaction is lower than 45 DEG C, reacting balance time is more than 650s ((a) in Fig. 7, (b), (c)); When temperature of reaction is 55 DEG C, reacting balance time is 340s (Fig. 7 (d)); When temperature of reaction is 65 DEG C, can be observed reacting balance time from Fig. 7 (e) is 220s; Visible, when temperature of reaction is higher, reacting balance time is shorter, and namely reaction rate is faster.In addition, Germicidal efficacy arrives, and when temperature of reaction is 65 DEG C, produces many bubbles in pipeline, is not easy to measure.Therefore, consider reaction rate and measure stability, the temperature of reaction being the method with 55 DEG C; Certainly, also can be used as temperature of reaction lower than 55 DEG C, lower temperature of reaction, only reduce the sensitivity of method, do not have other impact.
From testing above, 55 DEG C, reacting balance time is 340s.Because Flow Injection Analysis Method precisely controls the reaction time by program, therefore, measure under nonequilibrium condition and also can obtain good repeatability.Therefore, the residence time can be chosen arbitrarily within the scope of 0-340s, and the residence time is long, method highly sensitive, and detectability is low, otherwise sensitivity is low, detects limit for height.Therefore, during practical measurement, the residence time and temperature of reaction can be selected according to the concentration of actual sample.
The optimization of sample introduction flow velocity when 2.2.4 measuring
Sample introduction flow velocity to refer in table 1 the 4th Walk in flow injection program, and in reaction tube, solution flows through the speed of spectrophotometer flow cell under the promotion of pure water.Fix other to test from parameter as described in 1.2, within the scope of 2.4-8.2mL/min, change sample introduction flow velocity, under recording different sample introduction flow velocity respectively by method described in 1.2, the elution curve of the ammonium nitrogen standard solution of 0.900mmol/L, result as shown in Figure 8, in Fig. 8, from left to right, curve is labeled as a respectively, b, c, d, e, f, g, h.Fig. 8 shows, along with slowing down of sample introduction flow velocity, and the peak height H of elution curve
apresent slowly downtrending, this should be that solution diffusion causes; In addition, sample introduction flow velocity is larger, and elution curve peak is narrower, and minute is shorter, is conducive to raising method test sample speed.Therefore, 8.20mL/min is chosen in this experiment is best sample introduction flow velocity.
2.3 working curves and detectability
Under the experiment condition that 1.2 selected parts are selected, at temperature of reaction 55 DEG C, determine the working curve of tri-different residence time of 160s, 250s, 340s respectively, experimental result is as shown in table 2; Under the 160s residence time, the elution curve of variable concentrations as shown in Figure 9.As shown in Table 2, under tri-different residence time of 160s, 250s, 340s, elution curve peak height value H
avalue is all directly proportional to ammonium nitrogen standard working solution, and the corresponding range of linearity is respectively 0.100-0.900mmol/L, 0.100-0.900mmol/L, 0.100-0.700mmol/L; Method detectability reference literature (Gao Ruomei, Liu Honggao. the comprehensive discussion of detection limit conceptual issues discussion-IUPAC and the definition of other detection limit and experimental demonstration [J]. analytical chemistry, 1993,21 (10): 1232-1236.) establish, i.e. detectability=0.01/ slope, detectability is respectively 0.007mmol/L, 0.015mmol/L, 0.036mmol/L; Corresponding analysis speed is 12,10,8 times/h respectively.I class surface water ammonium nitrogen limit value is 0.011mmol/L, and visible, this method can meet the mensuration of ammonium nitrogen concentration in all kinds of surface water.Meanwhile, under it should be noted that the different residence time, can obtain different detectabilities, corresponding analysis speed is not identical yet.Therefore, when measuring actual sample, the suitable residence time can be selected according to the concentration range of actual sample, to obtain analysis speed high as far as possible.
Table 2 working curve and correlation parameter
The checking of 2.4 methods
2.4.1 substrate mark-on reclaims
This experiment respectively with lake water, river, underground water for substrate, spiked levels is respectively 0.100,0.200,0.300,0.500,0.700mmol/L, under the residence time is 160s, record substrate mark-on curve, calculate the average substrate recovery of standard addition of preparation method divided by working curve slope on the same day with substrate mark-on curve, result is as shown in table 3.As shown in Table 3, the average substrate recovery of standard addition of lake water, river, underground water is respectively 100.4%, 95.2%, 101.7%, and all between 90%-110%, the ammonium nitrogen adopted in this method mensuration lake water, river, underground water is described, substrate is noiseless.
Table 3 substrate recovery of standard addition
2.4.2 with the comparing of indophenol blue spectrophotometric method
Indigo spectrophotometry is the classical analysis method of widely used mensuration ammonium nitrogen, this research this law and indigo spectrophotometry (JotaKanda.Determinationofammoniuminseawaterbasedontheind ophenolreactionwithO-phenylphenol (OPP) [J] .Wat.Res..1995,29 (12): 2746-2750.) two the lake water samples taking from Guilin Electronic Science and Technology Univ. Hua Jiang school district are measured, and t statistical test is done to both results, the results are shown in table 4.Table 4 data show, the calculated value of the statistic t of two lake water samples is all less than critical value when degree of confidence is 95%, illustrate that this law is used for lake water determination, without significant difference compared with indigo spectrophotometry result.
Table 4 this law compares with indigo spectrophotometry measurement result
3 conclusions
The method of the invention is based on OPA-NH
3-Na
2sO
3reaction generates aubergine complex compound, and this material has strong absorption at 550nm place, and absorbance is directly proportional to ammonium nitrogen concentration in water sample, establishes the Flow Injection Spectrophotometry measuring ammonium nitrogen in water sample.The method detectability can be low to moderate 0.007mmol/L, can meet the mensuration of ammonium nitrogen concentration in all kinds of surface water; The average substrate recovery of standard addition of lake water, river and underground water is respectively 100.4%, 95.2%, 101.7%; Analysis speed at least 8 sample/h.Lake water sample is measured, both measurement result there was no significant differences with this law and indigo spectrophotometry.
Accompanying drawing explanation
Fig. 1 is method Flow Injection Analysis flow circuit diagram described in this, and the valve that wherein (a) is flow injection analyzer is Fill state, and the valve that (b) is flow injection analyzer is Inject state;
In addition the abosrption spectrogram of Fig. 2 to be concentration be ammonium nitrogen standard solution of 0.500mmol/L;
Fig. 3 is elution curve peak height place absorbance (H
a) with the relation curve of stored one kind of tubes length;
Fig. 4 is elution curve peak height place absorbance (H
a) with the relation curve of OPA concentration in reaction solution;
Fig. 5 elution curve peak height place absorbance (H
a) with reaction solution in Na
2sO
3the relation curve of concentration;
Fig. 6 elution curve peak height place absorbance (H
a) with the relation curve of reacting solution pH value;
Under Fig. 7 different temperatures, the differential responses time is to the interact relation curve of absorbance, and wherein a is 27 DEG C; B is 35 DEG C; C is 45 DEG C; D is 55 DEG C; E is 65 DEG C;
Fig. 8 sample introduction flow velocity is to the interact relation curve of elution curve, and wherein a is 8.2mL/min; B is 8.0mL/min; C is 7.4mL/min; D is 6.6mL/min; E is 5.8mL/min; F is 4.9mL/min; G is 3.7mL/min; H is 2.4mL/min;
Fig. 9 when reacted between when being 160s, the elution curve of different ammonium nitrogen concentration, a is 0mmol/L; B is 0.100mmol/L; C is 0.300mmol/L; D is 0.500mmol/L; E is 0.700mmol/L; F is 0.900mmol/L.
Embodiment
Below in conjunction with specific embodiment, the present invention is described in further detail, and to understand content of the present invention better, but the present invention is not limited to following examples.
Embodiment 1: the detection of concrete water sample
1) ammonium nitrogen standard solution, OPA-Na is prepared
2sO
3mixed solution and EDTA-NaOH buffer solution;
Ammonium nitrogen standard solution: each 20mL of ammonium nitrogen standard solution of 0 μm of ol/L, 0.100 μm of ol/L, 0.300 μm of ol/L, 0.500 μm of ol/L, 0.700 μm of ol/L, 0.900 μm of ol/L;
Preparation OPA-Na
2sO
3mixed solution, wherein OPA, Na
2sO
3concentration be respectively 1.06g/L and 0.050g/L.
Preparation EDTA-NaOH buffer solution, it is formulated that EDTA-NaOH buffer solution is dissolved in 500mL ultrapure water by 26.0gEDTA disodium and 10.0gNaOH.
2) valve position of flow injection analyzer is adjusted to Fill state, start active efflux, (stored one kind of tubes is polyfluortetraethylene pipe the ammonium nitrogen standard solution of 0 μm of ol/L to be pumped into the stored one kind of tubes of flow injection analyzer, its length is 1.4-2.0m, internal diameter is 1mm) in, the full ammonium nitrogen standard solution of storage in stored one kind of tubes; Meanwhile, pure water flows through the detecting device of ultraviolet-visible pectrophotometer by active efflux, and detecting device measures wavelength and is set to 550nm, when spectrophotometer stable reading, returns to zero to detecting device; Wherein, Flow Injection Analysis program is as shown in table 5;
3) valve position of flow injection analyzer is switched to Inject state, start active efflux and pair and move pump, active efflux is moved by the ammonium nitrogen standard solution pumped in stored one kind of tubes and pair the reagent OPA-Na that pump pumps
2sO
3mixed solution and the mixing of EDTA-NaOH buffer solution, and be sent in the reaction tube of flow injection analyzer; Wherein, Flow Injection Analysis program is as shown in table 5;
4) valve position of flow injection analyzer is switched to Fill state, make the reaction solution insulation reaction 340s under 55 DEG C of conditions in reaction tube;
5) after arriving the reaction time, start active efflux, reactant liquor in pure water driving a reaction pipe flows through detecting device, absorbance A is measured in 550nm by detecting device, this absorbance signal is by computing machine continuous acquisition, export with the form of elution curve (i.e. absorbance A curve over time), the absorbance H at record elution curve peak height place
a; Wherein, Flow Injection Analysis program is as shown in table 5;
6) step 2 is repeated) to step 5), replace 0 μm of ol/L ammonium nitrogen standard solution with 0.100 μm of ol/L, 0.300 μm of ol/L, 0.500 μm of ol/L, 0.700 μm of ol/L, 0.900 μm of ol/L ammonium nitrogen standard solution respectively, obtain the absorbance H at the elution curve peak height place of above-mentioned concentration ammonium nitrogen standard solution respectively
a; And with these absorbance H
aworking curve is made with the concentration of ammonium nitrogen standard solution;
7) actual water sample is got as testing sample solution, 0 μm of ol/L ammonium nitrogen standard solution is replaced with testing sample solution, repeat step 2) to step 5), obtain the absorbance at testing sample solution elution curve peak height place, with the absorbance at the testing sample solution elution curve peak height place obtained according to the ammonium nitrogen content in working curve quantitatively every part of testing sample solution.
Table 5
On July 14th, 2015, adopt the ammonium nitrogen concentration of method described in above-described embodiment 1 to sewage treatment plant of Guilin City 3 turnover water sample to measure, the working curve equation that the same day draws is H
a=0.6468C
n-0.0577 (n=6, R
2=0.9949), record the elution curve peak height value of water sample, and the ammonium nitrogen concentration calculating water sample thus lists in table 6 simultaneously.Table 6 shows, 3 sewage treatment plant's ammonium removals of mensuration are respond well, and water outlet all can qualified discharge, and visible the method for the invention can be used for the mensuration of sewage treatment plant's Wastewater Sample.
Table 6 sewage treatment plant Inlet and outlet water measurement result (mmol/L)
ND represents and does not detect
Visible, the method for the invention is successfully applied to the turnover water sample of mensuration 3 sewage treatment plants.This method has the advantages such as online, easy and simple to handle, analysis speed is fast, has the application potential of on-site measurement.
Claims (10)
1. based on o-phthalaldehyde(OPA)-NH
3-Na
2sO
3the method of ammonium nitrogen in the flow injection spectral photometry water sample of reaction, is adopt the ammonium nitrogen in flow injection analyzer and ultraviolet-visible pectrophotometer joint-detection water sample, comprises the following steps:
1) ammonium nitrogen standard solution, OPA-Na is prepared
2sO
3mixed solution and EDTA-NaOH buffer solution;
2) valve position of flow injection analyzer is adjusted to Fill state, starts active efflux, ammonium nitrogen standard solution is pumped in the stored one kind of tubes of flow injection analyzer, the full ammonium nitrogen standard solution of storage in stored one kind of tubes; Meanwhile, pure water flows through the detecting device of ultraviolet-visible pectrophotometer by active efflux, and detecting device measures wavelength and is set to 550nm, returns to zero to detecting device;
3) valve position of flow injection analyzer is switched to Inject state, start active efflux and pair and move pump, active efflux is moved by the ammonium nitrogen standard solution pumped in stored one kind of tubes and pair the reagent OPA-Na that pump pumps
2sO
3mixed solution and the mixing of EDTA-NaOH buffer solution, and be sent in the reaction tube of flow injection analyzer;
4) valve position of flow injection analyzer is switched to Fill state, make the reaction solution insulation reaction certain hour at the reaction temperatures in reaction tube;
5) after arriving the reaction time, start active efflux, reactant liquor in pure water driving a reaction pipe flows through detecting device, absorbance A is measured in 550nm by detecting device, this absorbance signal is by computing machine continuous acquisition, export with the form of elution curve (absorbance A is curve over time), the absorbance at record elution curve peak height place, and make working curve with the concentration of the absorbance at elution curve peak height place and ammonium nitrogen standard solution;
6) ammonium nitrogen standard solution is replaced with testing sample solution, repeat step 2) to step 5), obtain the elution curve of testing sample solution and the absorbance at described elution curve peak height place, with the absorbance at this elution curve peak height place according to the ammonium nitrogen content in the quantitative testing sample solution of working curve.
2. method according to claim 1, is characterized in that: the length of stored one kind of tubes is 1.4-2.0m, and internal diameter is 0.8-1.0mm.
3. method according to claim 1, is characterized in that: OPA-Na
2sO
3the amount of pumping into of mixed solution is the concentration controlling OPA in reaction solution is 0.28-0.42g/L, Na
2sO
3concentration be 0.013-0.023g/L.
4. method according to claim 1, is characterized in that: the amount of pumping into of described EDTA-NaOH buffer solution is the pH value controlling reaction solution is 10.77-10.95, and in reaction solution, the concentration of EDTA is for being more than or equal to 15g/L.
5. the method according to any one of claim 1-4, is characterized in that: the temperature that reaction solution carries out reacting in reaction tube is≤60 DEG C.
6. the method according to any one of claim 1-4, is characterized in that: the temperature that reaction solution carries out reacting in reaction tube is 27-55 DEG C.
7. the method according to any one of claim 1-4, is characterized in that: the time that reaction solution reacts in reaction tube is between being greater than between 0 to the equilibration time being less than or equal to reaction.
8. the method according to any one of claim 1-4, is characterized in that: the time that reaction solution reacts in reaction tube is between being greater than 0s to being less than between 340s.
9. the method according to any one of claim 1-4, is characterized in that: the time that reaction solution reacts in reaction tube is 160-340s.
10. the method according to any one of claim 1-4, is characterized in that: the flow velocity when reactant liquor having reacted rear gained flows through detecting device is >=8.2mL/min.
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| CN110132949A (en) * | 2019-04-25 | 2019-08-16 | 中国中材国际工程股份有限公司 | The method for measuring cement plant flue gas the escaping of ammonia |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN107091823A (en) * | 2016-02-18 | 2017-08-25 | 常州罗盘星检测科技有限公司 | A kind of low-concentration ammonia-nitrogen fluoroscopic examination solid reagent and its detection method |
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| CN109580507B (en) * | 2018-11-28 | 2021-05-14 | 国电南瑞科技股份有限公司 | Parallel quality control water quality analysis device and method |
| CN110132949A (en) * | 2019-04-25 | 2019-08-16 | 中国中材国际工程股份有限公司 | The method for measuring cement plant flue gas the escaping of ammonia |
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