1. A method for simultaneously detecting 11 common substances in a water body by utilizing ion chromatography is characterized by comprising the following steps: the 11 common substances are fluoride, chloride, nitrate, sulfate, chlorite, chlorate, bromate, nitrite, dichloroacetic acid, trichloroacetic acid and glyphosate, and the detection method comprises the following steps:

1) preparing a mixed standard solution containing fluoride, chloride, nitrate, sulfate, chlorite, chlorate, bromate, nitrite, dichloroacetic acid, trichloroacetic acid and glyphosate by using a standard substance, drawing a standard curve, and calculating a regression equation;

2) carrying out sample introduction detection on a water sample to be detected, and calculating the concentration of each substance in the water sample to be detected according to the peak area of each substance in the water sample to be detected and the regression equation obtained in the step 1);

step 1) and step 2) ion chromatography using an IonPacAS27 (4X 250mm) column, an IonPacAG 27 (4X 50mm) protective column; the ion chromatography working parameters are as follows: the flow rate is 1.0 mL/min; the column temperature is 30 ℃; the sample injection volume is 25-250 mu L; the current set point is 124 mA; conductivity detector, sample measurement time: 55 min; KOH mobile phase gradient elution procedure: the initial concentration is 8.00mmol/L, the final concentration is 50.00mmol/L, the concentration is maintained at 8.00mmol/L in the range of 0 to 30.00min, the gradient is started for 30.00min, the end time is 45.00min, the elution concentration of the mobile phase is increased from 8.0mmol/L to 50mmol/L, the concentration is maintained at 50mmol/L in the range of 45min to 50min, the concentration is maintained at 8mmol/L in the range of 50min to 55min, and the gradient period is 55 min.

2. The method of claim 1, wherein: the inhibitor is ADRS 6004mm anion inhibitor.

3. The method of claim 1, wherein: the concentrations of fluoride, chloride, nitrate, sulfate, chlorite, chlorate, bromate, nitrite, dichloroacetic acid, trichloroacetic acid and glyphosate in the mixed standard solution are respectively 0.500mg/L, 50.0mg/L, 5.00mg/L, 100.0mg/L, 1.00mg/L, 1.00mg/L, 0.050mg/L, 0.500mg/L, 0.100mg/L, 0.100mg/L and 0.500 mg/L; the standard solutions 25. mu.L, 50. mu.L, 100. mu.L, 150. mu.L, 200. mu.L and 250. mu.L were mixed by injection to obtain standard curves of mass concentration and peak area.

4. The method of claim 1, wherein: in the method, the peak emergence time of fluoride, chlorite, bromate, chloride, dichloroacetic acid, nitrite, chlorate, nitrate, trichloroacetic acid, sulfate and glyphosate is 6.883, 10.807, 11.840, 14.773, 17.660, 19.520, 23.533, 31.460, 37.293, 42.540 and 50.420min respectively.

5. The method of claim 1, wherein: the detection limits of the fluoride, the chlorite, the bromate, the chloride, the dichloroacetic acid, the nitrite, the chlorate, the nitrate, the trichloroacetic acid, the sulfate and the glyphosate are respectively 0.521ppb,0.436ppb,0.950ppb,0.094ppb,0.900ppb,0.444ppb,2.294ppb,0.931ppb,10.2ppb,0.203ppb and 0.199ppb, and the lower detection limits are respectively 2.1ppb,1.7ppb,3.8ppb,0.4ppb,3.6ppb,1.8ppb,9.2ppb,3.7ppb,40.8ppb,0.8ppb and 0.8 ppb.

6. The method of claim 1, wherein: filtering the water sample to be detected by using a second-stage ultrafiltration device before sample introduction in the step 2), wherein the second-stage ultrafiltration device comprises a first-stage ultrafiltration chamber (1), a second-stage ultrafiltration chamber (2), a first sample introduction pipe (3), a second sample introduction pipe (4) and a third sample introduction pipe (5), the first sample introduction pipe (3) is communicated with the lower half cabin of the first-stage ultrafiltration chamber (1) through the top end, and the bottom end is used for connecting the water sample to be detected; the bottom end of the second sample inlet pipe (4) is communicated with the upper half cabin of the first-stage super filter (1), and the top end of the second sample inlet pipe is communicated with the lower half cabin of the second-stage super filter (2); the bottom end of the third sample inlet pipe (5) is communicated with the upper half cabin of the second-stage super filter (2), and the top end of the third sample inlet pipe is used for being connected with an ion chromatograph sample injector; the diameters of the first sample inlet pipe (3), the second sample inlet pipe (4) and the third sample inlet pipe (5) are reduced in sequence, and the lower half bins of the first-stage super filter (1) and the second-stage super filter (2) are connected with a waste liquid pipe (6);

during detection, a water sample to be detected is connected with the bottom end of the first sample inlet pipe (3) and enters a sample injector of the ion chromatograph after passing through the first-stage super filter (1) and the second-stage super filter (2).

7. The method of claim 6, wherein: the filter membrane of the first-stage ultrafiltration filter (1) is a 0.45 mu m filter membrane, and the filter membrane of the second-stage ultrafiltration filter (2) is a 0.22 mu m filter membrane.

Background

The method for detecting dichloroacetic acid and trichloroacetic acid recommended by the town water supply water quality standard test method (CJ/T141-2018) adopts a chromatographic column of IonPacAS 19 (4X 250mm), a protective column of IonPacAG 19 (4X 50mm), an ASRS 300 anion suppressor, a column temperature of 30 ℃, an inhibition current of 75mA, a sample injection volume of 1.0mL, a leacheate of a potassium hydroxide solution, a leacheate flow rate of 1.0mL/min, gradient leaching and a gradient leaching time of 0-35 min: 8 mmol/L; 35-43 min: 50 mmol/L; 43-48 min: 8mmol/L, can be separated from common anions such as fluoride, chloride, nitrate, sulfate, chlorite, chlorate, bromate, nitrite, and the like.

The method conditions of CJ/T141-2018 recommendation of glyphosate are that an IonPac AS 19 (4X 250mm) chromatographic column, an IonPacAG 19 (4X 50mm) protective column and an ASRS 300 anion inhibitor are used, the column temperature is 30 ℃, the inhibition current is 75mA, the sample injection volume is 25 mu L, the flow rate of a leaching solution is 1.0mL/min, the concentration of the leaching solution is 30mmol/L, and isocratic leaching is adopted. Sample pretreatment, sample injection after filtration with a needle filter with a pore size of 0.45 μm.

When the hydroxide radical system is used for conventional analysis and detection of anions such as fluoride, chloride, nitrate, sulfate, chlorite, chlorate and the like, the detection is generally carried out by a method of isocratic elution and trace volume sample injection. Dichloroacetic acid and trichloroacetic acid are detected by a method of gradient elution and large volume sample injection, glyphosate is detected by a method of isocratic elution and micro volume sample injection, and each detection item is detected in batches under different method conditions.

With the increase of detection items in drinking water, a plurality of items need to be detected, the detection method and conditions are different due to the fact that the existing method needs to detect a plurality of items respectively, and when all the items are detected, multiple operations are needed, the operation flow is complex, the working efficiency is low, and the total detection cost is high.

Disclosure of Invention

The invention aims to solve the problems and provides a method for simultaneously detecting 11 common substances in a water body by using ion chromatography.

In order to achieve the purpose, the invention adopts the technical scheme that:

a method for simultaneously detecting 11 common substances in a water body by using an ion chromatography method, wherein the 11 common substances are fluoride, chloride, nitrate, sulfate, chlorite, chlorate, bromate, nitrite, dichloroacetic acid, trichloroacetic acid and glyphosate, and the detection method comprises the following steps:

1) preparing a mixed standard solution containing fluoride, chloride, nitrate, sulfate, chlorite, chlorate, bromate, nitrite, dichloroacetic acid, trichloroacetic acid and glyphosate by using a standard substance, drawing a standard curve, and calculating a regression equation; 2) carrying out sample introduction detection on a water sample to be detected, and calculating the concentration of each substance in the water sample to be detected according to the peak area of each substance in the water sample to be detected and the regression equation obtained in the step 1);

step 1) and step 2) ion chromatography using an IonPacAS27 (4X 250mm) column, an IonPacAG 27 (4X 50mm) protective column; the ion chromatography working parameters are as follows: the flow rate is 1.0 mL/min; the column temperature is 30 ℃; the sample injection volume is 25-250 mu L; the current set point is 124 mA; a conductivity detector, wherein the sample measuring time is 55 min; KOH mobile phase gradient elution procedure: the initial concentration is 8.00mmol/L, the final concentration is 50.00mmol/L, the concentration is maintained at 8.00mmol/L in the range of 0 to 30.00min, the gradient is started for 30.00min, the end time is 45.00min, the elution concentration of the mobile phase is increased from 8.0mmol/L to 50mmol/L, the concentration is maintained at 50mmol/L in the range of 45min to 50min, the concentration is maintained at 8mmol/L in the range of 50min to 55min, and the gradient period is 55 min.

Preferably, the suppressor is an ADRS 6004mm anion suppressor.

In the above technical scheme, the concentrations of fluoride, chloride, nitrate, sulfate, chlorite, chlorate, bromate, nitrite, dichloroacetic acid, trichloroacetic acid and glyphosate in the mixed standard solution are respectively 0.500mg/L, 50.0mg/L, 5.00mg/L, 100.0mg/L, 1.00mg/L, 1.00mg/L, 0.050mg/L, 0.500mg/L, 0.100mg/L, 0.100mg/L and 0.500 mg/L; the standard solutions 25. mu.L, 50. mu.L, 100. mu.L, 150. mu.L, 200. mu.L and 250. mu.L were mixed by injection to obtain standard curves of mass concentration and peak area.

In the method, the peak emergence time of fluoride, chlorite, bromate, chloride, dichloroacetic acid, nitrite, chlorate, nitrate, trichloroacetic acid, sulfate and glyphosate is 6.883, 10.807, 11.840, 14.773, 17.660, 19.520, 23.533, 31.460, 37.293, 42.540 and 50.420min respectively.

In the above technical means, the detection limits of the fluoride, chlorite, bromate, chloride, dichloroacetic acid, nitrite, chlorate, nitrate, trichloroacetic acid, sulfate and glyphosate are 0.521ppb,0.436ppb,0.950ppb,0.094ppb,0.900ppb,0.444ppb,2.294ppb,0.931ppb,10.2ppb,0.203ppb and 0.199ppb respectively, and the lower limit of the measurement is 2.1ppb,1.7ppb,3.8ppb,0.4ppb,3.6ppb,1.8ppb,9.2ppb,3.7ppb,40.8ppb,0.8ppb and 0.8ppb respectively.

Preferably, a second-stage ultrafiltration device is used for filtering before the sample of the water sample to be detected in the step 2) is fed, the second-stage ultrafiltration device comprises a first-stage ultrafiltration chamber (1), a second-stage ultrafiltration chamber (2), a first sample feeding pipe (3), a second sample feeding pipe (4) and a third sample feeding pipe (5), the first sample feeding pipe (3) is communicated with the lower half cabin of the first-stage ultrafiltration chamber (1) through the top end, and the bottom end is used for connecting the water sample to be detected; the bottom end of the second sample inlet pipe (4) is communicated with the upper half cabin of the first-stage super filter (1), and the top end of the second sample inlet pipe is communicated with the lower half cabin of the second-stage super filter (2); the bottom end of the third sample inlet pipe (5) is communicated with the upper half cabin of the second-stage super filter (2), and the top end of the third sample inlet pipe is used for being connected with an ion chromatograph sample injector; the diameters of the first sample inlet pipe (3), the second sample inlet pipe (4) and the third sample inlet pipe (5) are reduced in sequence, and the lower half bins of the first-stage super filter (1) and the second-stage super filter (2) are connected with a waste liquid pipe (6);

during detection, a water sample to be detected is connected with the bottom end of the first sample inlet pipe (3) and enters a sample injector of the ion chromatograph after passing through the first-stage super filter (1) and the second-stage super filter (2).

Preferably, the filter membrane of the primary ultra-filtration tank (1) is a 0.45 μm filter membrane, and the filter membrane of the secondary ultra-filtration tank (2) is a 0.22 μm filter membrane.

The invention has the beneficial effects that: the method can be used for simultaneously detecting 11 common anions and compounds in a water sample, and can separate and detect each detection item by using one method condition without switching the method. According to the experimental map and experimental data, when the method is used for detecting fluoride, chlorite, bromate, chloride, dichloroacetic acid, nitrite, chlorate, nitrate, trichloroacetic acid, sulfate and glyphosate, the peak appearance is good, each item to be detected can be well separated, and the precision and the accuracy meet the standard requirements. The method is more beneficial to batch detection, saves working time and reduces detection cost.

Drawings

FIG. 1 is a schematic view of the structure of a two-stage ultrafiltration apparatus in example 1.

FIG. 2 is a peak appearance chart of 11 test substances in example 2.

FIG. 3 is a peak appearance chart of 11 test substances in example 3.

Detailed Description

The invention is further illustrated by the following examples, which are not intended to be limiting.

The experimental methods in the following examples are all conventional methods unless otherwise specified; the chemical reagents used are conventional reagents and are commercially available unless otherwise specified.

EXAMPLE 1 British blue two-stage Ultrafiltration device

The British blue ultrafiltration used for the ion chromatograph on the market at present only has one-level ultrafiltration, but when the impurity is more in the sample to be measured, can dispel coarse particle impurity earlier, carries out the fine filtration again, filters step by step in grades and makes the filtration more thorough.

Therefore, the invention manufactures the British blue two-stage ultrafiltration device shown in figure 1, which is used for filtering a water sample to be detected step by step and reducing impurities. The British blue secondary ultrafiltration device shown in FIG. 1 mainly comprises a primary ultrafiltration chamber 1, a secondary ultrafiltration chamber 2, a first sample injection pipe 3, a second sample injection pipe 4 and a third sample injection pipe 5. The first sample inlet pipe 3 is communicated with the lower half cabin of the first-stage super filter 1 through the top end, and the bottom end is used for connecting a water sample to be detected; the bottom end of the second sample inlet pipe 4 is communicated with the upper half cabin of the first-stage super filter 1, and the top end is communicated with the lower half cabin of the second-stage super filter 2; the bottom end of the third sample inlet pipe 5 is communicated with the upper half cabin of the second-stage super filter 2, and the top end is used for being connected with an ion chromatograph sample injector; the diameters of the first sample inlet pipe 3, the second sample inlet pipe 4 and the third sample inlet pipe 5 are reduced in sequence, and the lower half bins of the first-stage super filter 1 and the second-stage super filter 2 are connected with a waste liquid pipe 6; the filter membrane of the first-stage ultra-filtration tank 1 is a 0.45 mu m filter membrane, and the filter membrane of the second-stage ultra-filtration tank 2 is a 0.22 mu m filter membrane. During detection, a water sample to be detected is connected with the bottom end of the first sample inlet pipe 3 and enters a sample injector of the ion chromatograph after passing through the first-stage super filter 1 and the second-stage super filter 2.

By adopting the British blue secondary ultrafiltration device, a water sample is firstly filtered into coarse particles by a 0.45 mu m filter membrane of the primary ultrafiltration chamber 1 and then is finely filtered by a 0.22 mu m filter membrane of the secondary ultrafiltration chamber 2. The diameters of the first sampling pipe 3, the second sampling pipe 4 and the third sampling pipe 5 are reduced in sequence, and the filtering is easier due to the flow difference of the pipe diameters. The lower half bins of the first-stage super filter 1 and the second-stage super filter 2 are also connected with a waste liquid pipe 6, so as to ensure enough sample injection amount and discharge redundant water samples.

By adopting the British blue secondary ultrafiltration device, the independent water sample pretreatment process can be omitted, secondary filtration is adopted, the filtration effect is better, the detection result is not easily influenced by impurities, the detection result is more accurate, batch detection is more facilitated, and the working time is saved.

The following examples 2 and 3 were carried out by connecting the apparatus of the British blue secondary ultrafiltration of FIG. 1 to an autosampler of an ion chromatograph.

Example 2 preliminary experiments

Ion chromatography using an IonPac AS27 (4X 250mm) column, an IonPac AG 27 (4X 50mm) guard column; the ion chromatography working parameters are as follows: the flow rate is 1.0 mL/min; the column temperature is 30 ℃; the sample injection volume is 50 mu L; the current set value is 50 mA; a conductance detector; ADRS 6004mm suppressor; sample measurement time: 40 min; KOH flow equivalentsthe elution was 20mmol/L, with peak times for fluoride, chlorite, bromate, chloride, dichloroacetic acid, nitrite, chlorate, nitrate, glyphosate, sulfate and trichloroacetic acid of 4.377, 6.243, 6.780, 8.250, 9.620, 10.660, 12.783, 16.823, 20.363, 21.500 and 32.577min (as shown in FIG. 2). The difference between the peak emergence time of the chlorite and the peak emergence time of the bromate is about 0.54min, when the concentration of the nitrite in a water sample to be detected is higher, the peak emergence time of the chlorite and the peak emergence time of the bromate are partially overlapped, and when the content of the sulfate is higher, the partial peak emergence of the glyphosate is covered, so that the accuracy of the concentration of substances to be detected of the chlorite, the bromate, the glyphosate and the sulfate in the sample is influenced.

In the experiment, gradient elution is used for replacing isocratic elution, low-concentration 8.00mmol/L elution is kept in 0-30.00 min, fluoride, chlorite, bromate, chloride, dichloroacetic acid, nitrite and chlorate which are easy to elute are eluted by a mobile phase with lower concentration, the peak-out time difference between the elution time and the elution time is more than 1min, and the elution time can be completely separated without mutual influence. And (3) gradient elution is carried out for 30.00min to 45.00min, the elution concentration of the mobile phase is increased from 8.0mmol/L to 50mmol/L, nitrate, trichloroacetic acid and sulfate are eluted in the time period, 8mmol/L is kept for 50min to 55min, glyphosate is eluted, the peak emergence time of nitrate, trichloroacetic acid, sulfate and glyphosate is far away, and accurate quantification can be carried out.

Example 3

1 reagents, instruments and working conditions

Required reagents: nitrogen with a purity greater than or equal to 99.999%, potassium hydroxide leacheate (brand: Thermo).

The instrument comprises the following steps: a Siemens ion chromatograph, a Dionex Aquion-Rfic ion chromatograph, a Dionex AS-AP autosampler, an IonPac AS27 (4X 250mm) chromatographic column (Diaonex, U.S.), an IonPacAG 27 (4X 50mm) protective column (Diaonex, U.S.), an ADRS 6004mm suppressor (Diaonex, U.S.), a flow rate of 1.0mL/min, a column temperature of 30 ℃, a sample injection volume of 25-250. mu.L, a current setting value of 124mA, a conductivity detector, and a sample measurement time of 55 min. The instrument test conditions are shown in Table 1.

KOH mobile phase gradient elution procedure: the initial concentration is 8.00mmol/L, the final concentration is 50.00mmol/L, the concentration is maintained at 8.00mmol/L in the range of 0 to 30.00min, the gradient is started for 30.00min, the end time is 45.00min, the elution concentration of the mobile phase is increased from 8.0mmol/L to 50mmol/L, the concentration is maintained at 50mmol/L in the range of 45min to 50min, the concentration is maintained at 8mmol/L in the range of 50min to 55min, and the gradient period is 55 min.

Water for experiment: ultrapure water produced by Millipore ultrapure water purifier, the resistivity was 18.2 M.OMEGA.cm.

TABLE 1 Instrument test Condition parameters

And (3) standard substance: the concentrations of fluoride, bromate, chloride and chlorate are 1000mg/L, the concentrations of chlorite and nitrite standard substances are 100mg/L, the concentration of nitrate is 500mg/L and the concentration of sulfate is 5000mg/L, and all the concentrations are purchased from the institute of environmental protection department standard samples; the trichloroacetic acid concentration is 1000mg/L, the glyphosate concentration is 100mg/L, and the trichloroacetic acid and the glyphosate are purchased from Beijing Tan ink quality testing technology Co., Ltd; the concentration of dichloroacetic acid is 1000mg/L, and is purchased from Beijing coast Hongmon Standard substance technology, LLC. The matrix of each standard was pure water except that the matrix of dichloroacetic acid and trichloroacetic acid was methanol.

The working conditions of the invention are as follows: IonPac AS27 (4X 250mm) chromatography column; IonPac AG 27 (4X 50mm) guard column; the flow rate is 1.0 mL/min; the column temperature is 30 ℃; the sample injection volume is 25-250 mu L; the current is 124 mA; ADRS 6004mm suppressor; gradient leaching; the determination time is 55 min; each detection item is oneAnd (4) secondary sample introduction, separation detection and no switching of method conditions. Wherein fluoride (F)^-) Chlorite (ClO)₂ ^-) Bromate (BrO)₃ ^-) Chloride (Cl)^-) Dichloroacetic acid (DCA), Nitrite (NO)₂ ^-) Chlorate (ClO)₃ ^-) Nitrate (NO)₃ ^-) Trichloroacetic acid (TCA), Sulfate (SO)₄ ^2-) And the peak emergence time of the glyphosate (CGL) is 6.883, 10.807, 11.840, 14.773, 17.660, 19.520, 23.533, 31.460, 37.293, 42.540 and 50.420min respectively, the peak emergence time of each component is shown in figure 3, the peak emergence shape is better, the components can be well separated, and the peaks are mutually free of interference.

2 detection method

2.1 drawing of Standard Curve and determination of sample injection volume

Standard curves are prepared according to the limit value of 0.05mg/L dichloroacetic acid, 0.1mg/L trichloroacetic acid, 0.7mg/L glyphosate, 0.01mg/L bromate (when ozone is used), 0.7mg/L chlorite (when chlorine dioxide is used for disinfection), 0.7mg/L chlorate (when composite chlorine dioxide is used for disinfection), and approximate concentrations of various substances in water bodies and sample injection volumes are determined according to the sanitary Standard for Drinking Water (GB 5749-2006).

Respectively sucking 1.00mL of standard fluoride, bromate, dichloroacetic acid, chlorate and trichloroacetic acid and 2.00mL of glyphosate, respectively diluting the standard fluoride, the bromate, the dichloroacetic acid, the chlorate and the trichloroacetic acid to 100mL volumetric flasks by using ultrapure water to prepare a medium stock solution with the concentrations of the fluoride, the bromate, the dichloroacetic acid, the chlorate and the trichloroacetic acid being 10.0mg/L and the concentration of the glyphosate being 2.00 mg/L. Respectively sucking 2.5mL, 0.25mL, 0.5mL, 5.0mL, 0.5mL, 12.5mL of stock solution in fluoride, bromate, dichloroacetic acid, chlorate, trichloroacetic acid and glyphosate, respectively sucking 2.5mL, 0.50mL, 1.0mL, 0.5mL and 0.25mL of standard products of chloride, nitrate, sulfate, chlorite and nitrite, respectively, adding the standard products into a volumetric flask and diluting to 50.0mL to prepare a mixed standard solution with the concentrations of fluoride, chloride, nitrate, sulfate, chlorite, chlorate, bromate, nitrite, dichloroacetic acid, trichloroacetic acid and glyphosate respectively being 0.500mg/L, 50.0mg/L, 5.00mg/L, 100.0mg/L, 1.00mg/L, 1.00mg/L, 0.050mg/L, 0.500mg/L, 0.100mg/L, 0.100mg/L and 0.500 mg/L. The trace amount of matrix methanol in the standard dichloroacetic acid and trichloroacetic acid does not interfere with the detection of the sample. The mixed standard solutions were injected in amounts of 25. mu.L, 50. mu.L, 100. mu.L, 150. mu.L, 200. mu.L and 250. mu.L, respectively, to obtain standard curves of mass concentration and peak area, and the equation of the curve and the correlation coefficient are shown in Table 2.

Table 211 working curves of the test substances

2.2 detection limits of the method

The concentrations of fluoride, chlorite, bromate, chloride, dichloroacetic acid, nitrite, chlorate, nitrate, trichloroacetic acid, sulfate and glyphosate prepared by using the standard substances are respectively 0.010mg/L,0.020mg/L,0.010mg/L,0.010mg/L,0.020mg/L,0.020mg/L,0.010mg/L,0.010mg/L, 0.100mg/L and 0.050mg/L, the detection limits of the detection items are respectively 0.521ppb,0.436ppb,0.950ppb,0.094ppb,0.900ppb,0.444ppb,2.294ppb,0.931, 10.2ppb,0.203ppb and 0.199ppb according to the signal-to-noise ratio (S/N) of the instrument, the detection limits are respectively 2.1ppb,1.7ppb,3.8ppb,0.4ppb,3.6, 1.8ppb, 3.8ppb, 8ppb and 8ppb, the results are shown in Table 3.

Table 311 detection limits and lower measurement limits of detection substances

Detecting items	F-	ClO2 -	BrO3 -	Cl-	DCA	NO2 -	ClO3 -	NO3 -	TCA	SO4 2-	CGL
												Concentration (mg/L)	0.010	0.020	0.010	0.010	0.010	0.020	0.020	0.010	0.010	0.100	0.050
S/N (mean value)	57.6	137.7	31.6	320.3	33.3	135.1	26.2	32.2	2.9	1478.6	753.7
												Detection limit (ppb)	0.521	0.436	0.950	0.094	0.900	0.444	2.294	0.931	10.2	0.203	0.199
Lower limit of measurement (ppb)	2.1	1.7	3.8	0.4	3.6	1.8	9.2	3.7	40.8	0.8	0.8

2.3 precision and accuracy

The concentrations of fluoride, chlorite, bromate, chloride, dichloroacetic acid, nitrite, chlorate, nitrate, trichloroacetic acid, sulfate and glyphosate prepared by using the standard substance are respectively 0.010mg/L,0.020mg/L,0.010mg/L,0.010mg/L,0.020mg/L,0.020mg/L,0.010mg/L,0.010mg/L, 0.100mg/L and 0.050mg/L, the measurement is repeated for 7 times, the precision of the measurement result is calculated, and the result is listed in Table 4.

Taking ultrapure water and factory water, respectively performing standard addition recovery, performing parallel measurement for 5 times, calculating the standard addition recovery rate, and obtaining the results shown in Table 5.

Low concentration precision of 411 test substances

TABLE 511 accuracy of measurement results of the test substances

In summary, as can be seen from the experimental data in fig. 3 and tables 2 to 5, when the method of the present invention is used to detect fluoride, chlorite, bromate, chloride, dichloroacetic acid, nitrite, chlorate, nitrate, trichloroacetic acid, sulfate and glyphosate, the peak appearance is good, each item to be detected can be well separated, and the precision and accuracy can also meet the requirements.