Method for determining m-methylphenol residue in industrial wastewater

Abstract

The invention provides a method for determining m-methylphenol residues in industrial wastewater, which comprises the following steps: S1, preparing a test solution: precisely weighing about 500mg of a test sample, placing the test sample in a 50mL measuring flask, dissolving with a dissolving solvent, diluting to a scale, and uniformly shaking; s2, the test solution is detected through liquid chromatography, the temperature of a chromatographic column of a liquid chromatograph is 20-30 DEG C, and the elution time is 25 minutes. S3, the test solution is detected through liquid chromatography, a mobile phase adopted in the liquid chromatography is composed of a phosphate buffer solution and acetonitrile according to the ratio of 807-827: 310-330, and the pH of the mobile phase is adjusted to 3.8-4.2 through phosphoric acid; according to the method, the theoretical concentration and the actually measured concentration have a good linear relation within the investigated concentration range, the average recovery rate is 99%, the detection limit is 2 ppm, and ICHQ3C data are infinitely required.

Description

Technical Field

[0001] The invention relates to the field of wastewater detection, and in particular to a method for determining residual meta-cresol in industrial wastewater. Background Art

[0002] Wastewater and waste liquid discharged during industrial production, which contain industrial production materials, intermediate products, by-products and pollutants generated during the production process, are important causes of environmental pollution, especially water pollution. Meta-cresol is also one of the pollutants in industrial wastewater. If meta-cresol is discharged into the water body in large quantities with industrial wastewater, it will cause water pollution and affect the survival and reproduction of aquatic organisms. Meta-cresol has a certain persistence in the soil. If it enters the soil in large quantities, it will also cause soil pollution and affect the growth of soil microorganisms and plants. For the human body, excessive residual meta-cresol will cause damage to the patient's internal organs.

[0003] Based on the above technical problems, accurate detection of m-cresol is particularly important. However, there is currently no method on the market for determining the residual m-cresol in industrial wastewater. In order to better control the quality of water and further prevent the harm of m-cresol to the human body, it is necessary to provide a measurement method to detect the residual m-cresol. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a method for determining the residual m-cresol in industrial wastewater, comprising the following steps: S1. Prepare the test solution: accurately weigh about 500 mg of the test sample, place it in a 50 mL volumetric flask, dissolve it with a dissolving solvent and dilute it to the scale, and shake well.

[0005] S2. The test solution is detected by liquid chromatography, the temperature of the liquid chromatography column is 20-30° C., and the elution time is 25 minutes.

[0006] S3. The test solution is detected by liquid chromatography, wherein the mobile phase used in the liquid chromatography is phosphate buffer: acetonitrile = 807-827: 310-330 (volume ratio), and the pH of the mobile phase is adjusted to 3.8-4.2 with phosphoric acid.

[0007] Furthermore, the test sample is industrial wastewater.

[0008] Furthermore, the phosphate buffer solution is prepared by taking 2.72 g of anhydrous potassium dihydrogen phosphate and 17.52 g of 10% tetrabutylammonium hydroxide solution and dissolving them in 817 ml of water.

[0009] Furthermore, the dissolving solvent is a saturated sodium bicarbonate solution.

[0010] Furthermore, in step S2, the chromatographic column used in the liquid chromatography method is an octadecylsilane bonded silica gel column.

[0011] Furthermore, the temperature of the chromatographic column is 20-30° C., and the elution time is 25 minutes.

[0012] Furthermore, the flow rate of the liquid chromatograph is 0.8-1.2 ml / min.

[0013] Furthermore, the liquid chromatograph adopts an ultraviolet detector.

[0014] Furthermore, the injection volume of the liquid chromatography method is 20 μl.

[0015] Furthermore, the detection wavelength of the liquid chromatography is 230 nm.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. Aiming at the problem of residual meta-cresol in industrial wastewater, the present invention provides a determination method based on liquid chromatography, which has the characteristics of high sensitivity and good accuracy, and can effectively detect the residual amount of meta-cresol in wastewater, thus providing strong technical support for controlling water quality and preventing the harm of meta-cresol to human body.

[0017] 2. The present invention optimizes the conditions of liquid chromatography, selects a suitable chromatographic column, adjusts the composition and pH value of the mobile phase, sets an appropriate column temperature and elution time, etc., so that the method has higher separation and better reproducibility when determining m-cresol, thereby improving the accuracy and reliability of the determination.

[0018] 3. This method is not only suitable for the residual determination of meta-methylphenol in industrial wastewater, but can also be applied to the detection of other samples containing meta-methylphenol, such as soil, food, medicine, etc. It has broad application prospects and important practical value.

[0019] 4. The present invention can timely detect and control the pollutant content in wastewater discharge by accurately measuring the residual amount of m-cresol in industrial wastewater, which is helpful to protect the safety of water environment and soil environment.

[0020] 5. The present invention has a good linear relationship between the theoretical concentration and the measured concentration within the concentration range investigated (r=1.000), an average recovery rate of 99%, a detection limit of 2ppm, and the unlimited requirement data of ICHQ3C. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the liquid chromatogram of the blank solution in Experiment 1; Figure 2 This is the liquid chromatogram of the control solution in Experiment 1; Figure 3 This is the spiked liquid chromatogram of the test solution in Experiment 1; Figure 4 This is the linear graph in Experiment 1; Figure 5 It is the liquid chromatogram of Example 2; Figure 6 It is the liquid chromatogram of Example 4; Figure 7 It is the liquid chromatogram of Comparative Example 1; Figure 8 It is the spiked liquid chromatogram of Comparative Example 2; Fig. 9 This is the spiked liquid chromatogram of Comparative Example 3. DETAILED DESCRIPTION

[0022] Example 1 A method for determining residual m-cresol in industrial wastewater comprises the following steps: S1. Prepare the test solution: accurately weigh about 500 mg of the test sample, place it in a 50 mL volumetric flask, dissolve it with a dissolving solvent and dilute it to the scale, and shake well; S2, the test solution is detected by liquid chromatography, and the chromatographic column used in the liquid chromatography is an octadecylsilane bonded silica gel column; S3. The test solution is detected by liquid chromatography. The mobile phase used in the liquid chromatography is phosphate buffer (take 2.72g of anhydrous potassium dihydrogen phosphate, 17.52g of 10% tetrabutylammonium hydroxide solution, dissolve in 817ml of water)-acetonitrile (817:320), and the pH is adjusted to 4.0 with phosphoric acid.

[0023] The temperature of the chromatographic column is 25° C., and the elution time is 25 minutes.

[0024] Moreover, the industrial wastewater is industrial production wastewater.

[0025] Moreover, in the step S2, the chromatographic column used in the liquid chromatography method is an octadecylsilane bonded silica gel column.

[0026] Furthermore, the flow rate of the liquid chromatograph is 0.8 ml / min.

[0027] Moreover, the detector adopted by the liquid chromatograph is an ultraviolet detector.

[0028] Furthermore, the injection volume of the liquid chromatography was 20 μl.

[0029] Furthermore, the detection wavelength of the liquid chromatography is 230 nm.

[0030] Example 2 A method for determining residual m-cresol in industrial wastewater comprises the following steps: S1. Prepare the test solution: accurately weigh about 500 mg of the test sample, place it in a 50 mL volumetric flask, dissolve it with a dissolving solvent and dilute it to the scale, and shake well; S2, the test solution is detected by liquid chromatography, and the chromatographic column used in the liquid chromatography is an octadecylsilane bonded silica gel column; S3. The test solution is detected by liquid chromatography. The mobile phase used in the liquid chromatography is phosphate buffer (take 2.72g of anhydrous potassium dihydrogen phosphate, 17.52g of 10% tetrabutylammonium hydroxide solution, dissolve in 817ml of water)-acetonitrile (817:320), and the pH is adjusted to 4.0 with phosphoric acid.

[0031] The temperature of the chromatographic column is 25° C., and the elution time is 25 minutes.

[0032] Moreover, the industrial wastewater is industrial production wastewater.

[0033] Moreover, in the step S2, the chromatographic column used in the liquid chromatography method is an octadecylsilane bonded silica gel column.

[0034] Furthermore, the flow rate of the liquid chromatograph was 1.2 ml / min.

[0035] Moreover, the detector adopted by the liquid chromatograph is an ultraviolet detector.

[0036] Furthermore, the injection volume of the liquid chromatography was 20 μl.

[0037] Furthermore, the detection wavelength of the liquid chromatography is 230 nm.

[0038] Example 3 A method for determining residual m-cresol in industrial wastewater comprises the following steps: S1. Prepare the test solution: accurately weigh about 500 mg of the test sample, place it in a 50 mL volumetric flask, dissolve it with a dissolving solvent and dilute it to the scale, and shake well; S2, the test solution is detected by liquid chromatography, and the chromatographic column used in the liquid chromatography is an octadecylsilane bonded silica gel column; S3. The test solution is detected by liquid chromatography. The mobile phase used in the liquid chromatography is phosphate buffer (take 2.72g of anhydrous potassium dihydrogen phosphate, 17.52g of 10% tetrabutylammonium hydroxide solution, dissolve in 817ml of water)-acetonitrile (817:320), and the pH is adjusted to 4.0 with phosphoric acid.

[0039] The temperature of the chromatographic column is 20° C., and the elution time is 25 minutes.

[0040] Moreover, the industrial wastewater is industrial production wastewater.

[0041] Moreover, in the step S2, the chromatographic column used in the liquid chromatography method is an octadecylsilane bonded silica gel column.

[0042] Furthermore, the flow rate of the liquid chromatograph is 1 ml / min.

[0043] Moreover, the detector adopted by the liquid chromatograph is an ultraviolet detector.

[0044] Furthermore, the injection volume of the liquid chromatography was 20 μl.

[0045] Furthermore, the detection wavelength of the liquid chromatography is 230 nm.

[0046] Example 4 A method for determining residual m-cresol in industrial wastewater comprises the following steps: S1. Prepare the test solution: accurately weigh about 500 mg of the test sample, place it in a 50 mL volumetric flask, dissolve it with a dissolving solvent and dilute it to the scale, and shake well; S2, the test solution is detected by liquid chromatography, and the chromatographic column used in the liquid chromatography is an octadecylsilane bonded silica gel column; S3. The test solution is detected by liquid chromatography. The mobile phase used in the liquid chromatography is phosphate buffer (take 2.72g of anhydrous potassium dihydrogen phosphate, 17.52g of 10% tetrabutylammonium hydroxide solution, dissolve in 817ml of water)-acetonitrile (817:320), and the pH is adjusted to 4.0 with phosphoric acid.

[0047] The temperature of the chromatographic column is 30° C., and the elution time is 25 minutes.

[0048] Moreover, the industrial wastewater is industrial production wastewater.

[0049] Moreover, in the step S2, the chromatographic column used in the liquid chromatography method is an octadecylsilane bonded silica gel column.

[0050] Furthermore, the flow rate of the liquid chromatograph is 1 ml / min.

[0051] Moreover, the detector adopted by the liquid chromatograph is an ultraviolet detector.

[0052] Furthermore, the injection volume of the liquid chromatography was 20 μl.

[0053] Furthermore, the detection wavelength of the liquid chromatography is 230 nm.

[0054] Example 5 A method for determining residual m-cresol in industrial wastewater comprises the following steps: S1. Prepare the test solution: accurately weigh about 500 mg of the test sample, place it in a 50 mL volumetric flask, dissolve it with a dissolving solvent and dilute it to the scale, and shake well; S2, the test solution is detected by liquid chromatography, and the chromatographic column used in the liquid chromatography is an octadecylsilane bonded silica gel column; S3. The test solution is detected by liquid chromatography. The mobile phase used in the liquid chromatography is phosphate buffer (take 2.72g of anhydrous potassium dihydrogen phosphate, 17.52g of 10% tetrabutylammonium hydroxide solution, dissolve in 817ml of water)-acetonitrile (817:320), and the pH is adjusted to 3.8 with phosphoric acid.

[0055] The temperature of the chromatographic column is 25° C., and the elution time is 25 minutes.

[0056] Moreover, the industrial wastewater is industrial production wastewater.

[0057] Moreover, in the step S2, the chromatographic column used in the liquid chromatography method is an octadecylsilane bonded silica gel column.

[0058] Furthermore, the flow rate of the liquid chromatograph is 1 ml / min.

[0059] Moreover, the detector adopted by the liquid chromatograph is an ultraviolet detector.

[0060] Furthermore, the injection volume of the liquid chromatography was 20 μl.

[0061] Furthermore, the detection wavelength of the liquid chromatography is 230 nm.

[0062] Example 6 A method for determining residual m-cresol in industrial wastewater comprises the following steps: S1. Prepare the test solution: accurately weigh about 500 mg of the test sample, place it in a 50 mL volumetric flask, dissolve it with a dissolving solvent and dilute it to the scale, and shake well; S2, the test solution is detected by liquid chromatography, and the chromatographic column used in the liquid chromatography is an octadecylsilane bonded silica gel column; S3. The test solution is detected by liquid chromatography. The mobile phase used in the liquid chromatography is phosphate buffer (take 2.72g of anhydrous potassium dihydrogen phosphate, 17.52g of 10% tetrabutylammonium hydroxide solution, dissolve in 817ml of water)-acetonitrile (817:320), and the pH is adjusted to 4.2 with phosphoric acid.

[0063] The temperature of the chromatographic column is 25° C., and the elution time is 25 minutes.

[0064] Moreover, the industrial wastewater is industrial production wastewater.

[0065] Moreover, in the step S2, the chromatographic column used in the liquid chromatography method is an octadecylsilane bonded silica gel column.

[0066] Furthermore, the flow rate of the liquid chromatograph is 1 ml / min.

[0067] Moreover, the detector adopted by the liquid chromatograph is an ultraviolet detector.

[0068] Furthermore, the injection volume of the liquid chromatography was 20 μl.

[0069] Furthermore, the detection wavelength of the liquid chromatography is 230 nm.

[0070] Example 7 A method for determining residual m-cresol in industrial wastewater comprises the following steps: S1. Prepare the test solution: accurately weigh about 500 mg of the test sample, place it in a 50 mL volumetric flask, dissolve it with a dissolving solvent and dilute it to the scale, and shake well; S2, the test solution is detected by liquid chromatography, and the chromatographic column used in the liquid chromatography is an octadecylsilane bonded silica gel column; S3. The test solution is detected by liquid chromatography. The mobile phase used in the liquid chromatography is phosphate buffer (2.72 g of anhydrous potassium dihydrogen phosphate, 17.52 g of 10% tetrabutylammonium hydroxide solution, dissolved in 817 ml of water)-acetonitrile (807:330), and the pH is adjusted to 4.0 with phosphoric acid.

[0071] The temperature of the chromatographic column is 25° C., and the elution time is 25 minutes.

[0072] Moreover, the industrial wastewater is industrial production wastewater.

[0073] Moreover, in the step S2, the chromatographic column used in the liquid chromatography method is an octadecylsilane bonded silica gel column.

[0074] Furthermore, the flow rate of the liquid chromatograph is 1 ml / min.

[0075] Moreover, the detector adopted by the liquid chromatograph is an ultraviolet detector.

[0076] Furthermore, the injection volume of the liquid chromatography was 20 μl.

[0077] Furthermore, the detection wavelength of the liquid chromatography is 230 nm.

[0078] Example 8 A method for determining residual m-cresol in industrial wastewater comprises the following steps: S1. Prepare the test solution: accurately weigh about 500 mg of the test sample, place it in a 50 mL volumetric flask, dissolve it with a dissolving solvent and dilute it to the scale, and shake well; S2, the test solution is detected by liquid chromatography, and the chromatographic column used in the liquid chromatography is an octadecylsilane bonded silica gel column; S3. The test solution is detected by liquid chromatography. The mobile phase used in the liquid chromatography is phosphate buffer (2.72 g of anhydrous potassium dihydrogen phosphate, 17.52 g of 10% tetrabutylammonium hydroxide solution, dissolved in 817 ml of water)-acetonitrile (827:310), and the pH is adjusted to 4.0 with phosphoric acid.

[0079] The temperature of the chromatographic column is 25° C., and the elution time is 25 minutes.

[0080] Moreover, the industrial wastewater is industrial production wastewater.

[0081] Moreover, in the step S2, the chromatographic column used in the liquid chromatography method is an octadecylsilane bonded silica gel column.

[0082] Furthermore, the flow rate of the liquid chromatograph is 1 ml / min.

[0083] Moreover, the detector adopted by the liquid chromatograph is an ultraviolet detector.

[0084] Furthermore, the injection volume of the liquid chromatography was 20 μl.

[0085] Furthermore, the detection wavelength of the liquid chromatography is 230 nm.

[0086] Comparative Example 1 Different from Example 8, the mobile phase in step S3 is phosphate buffer (2.72 g of anhydrous potassium dihydrogen phosphate, 17.52 g of 10% tetrabutylammonium hydroxide solution, dissolved in 817 ml of water)-acetonitrile (817:250), and the pH is adjusted to 4.0 with phosphoric acid.

[0087] Comparative Example 2 Different from Example 8, the mobile phase in step S3 is phosphate buffer (2.72 g of anhydrous potassium dihydrogen phosphate, 17.52 g of 10% tetrabutylammonium hydroxide solution, dissolved in 817 ml of water)-acetonitrile (817:400), and the pH is adjusted to 4.0 with phosphoric acid.

[0088] Comparative Example 3 Different from Example 8, the mobile phase in step S3 is phosphate buffer (2.72 g of anhydrous potassium dihydrogen phosphate, 17.52 g of 10% tetrabutylammonium hydroxide solution, dissolved in 817 ml of water)-acetonitrile (817:500), and the pH is adjusted to 4.0 with phosphoric acid.

[0089] Experimental Section

[0090] Experiment 1 1. Instruments and HPLC conditions instrument: Shimadzu LC-20AT liquid chromatograph, octadecylsilane bonded silica gel chromatographic column with a column size of 250 mm × 4.6 mm × 5 μm, Mettler-Toledo XPR205DR electronic balance; Chromatographic conditions: Detector: UV; Flow rate: 1 ml / min; Injection volume: 20 μl; Detection wavelength: 230 nm; Column temperature: initial temperature is 25°C, elution time: 25 minutes.

[0091] 2. Materials Sodium bicarbonate: AR grade, batch number S0722205001, provided by Tianjin Komiou Chemical Reagent Co., Ltd. Potassium dihydrogen phosphate: AR grade, batch number S0262208001, provided by Tianjin Komiou Chemical Reagent Co., Ltd.

[0092] 10% tetrabutylammonium hydroxide solution: AR grade, batch number S1662201001, provided by Shanghai Roen Chemical Technology Co., Ltd.

[0093] Phosphoric acid: AR grade, batch number S1102206001, provided by Tianjin Komiou Chemical Reagent Co., Ltd.; Acetonitrile: chromatographic grade, batch number S6272211003, provided by SIGMA-ALDRICH.

[0094] 3. Measurement of different test products Blank solution: saturated sodium bicarbonate; Preparation of control solution: Accurately weigh about 60 mg of m-cresol reference substance, place it in a 100 mL volumetric flask, dissolve it with a dissolving solvent and dilute it to the mark, shake well. Take 1 mL of the obtained solution, place it in a 100 mL volumetric flask, dilute it to the mark with a dissolving solvent, shake well; take 2 mL of the solution obtained in the last step, place it in a 20 mL volumetric flask, dilute it to the mark with a dissolving solvent, shake well, and obtain (concentration is 0.60 μg / mL), prepare two copies in parallel; Preparation of test solution: Accurately weigh about 500 mg of the test sample (production wastewater of United Pharmaceutical (Inner Mongolia) Co., Ltd.), place it in a 50 mL volumetric flask, dissolve it with a dissolving solvent and dilute it to the scale, shake well, and the concentration is 10 mg / mL.

[0095] Accurately measure 20 μL of each of the above solutions and inject them into the liquid chromatograph, record the peak area, and measure the content of residual m-cresol by the external standard method. The results are shown in Table 1.

[0096] Table 1 Determination results of industrial wastewater

[0097] 4. Methodological Validation Because the residual amount of meta-methylphenol in wastewater is low or undetectable, in order to demonstrate this method more clearly, the test solution is prepared by adding standards: accurately weigh an appropriate amount of meta-methylphenol reference substance, dissolve it in a dissolving solvent and dilute it to make a solution containing 6 μg per 1 ml to make a stock solution containing meta-methylphenol; accurately weigh about 500 mg of the test sample, place it in a 50 mL volumetric flask, accurately add 5 ml of the above solution, dilute it to the scale with a dissolving solvent, shake well, and obtain a solution containing 60 ppm of meta-methylphenol.

[0098] 4.1 Exclusivity The blank solution, control solution and test solution determined by the above method are shown in Table 1. Figure 1-Figure 3 , Figure 1 is the liquid chromatogram of the blank solution. Figure 2 is the liquid chromatogram of the reference solution. Figure 3 This is the liquid chromatogram of the test solution. It can be seen from the figure that the test sample peak does not interfere with the determination of m-methylphenol.

[0099] 4.2 Linearity In the range of m-cresol concentration from 0.05581μg / ml to 0.8918μg / ml, the linear relationship was good. Figure 4 , linear equation: Y=23063.6388X-146.9173, correlation coefficient: 1.000.

[0100] 4.3 Limit of detection and limit of quantification When the detection limit S / N≥3, LOD=2ppm, when the quantification limit S / N≥10, LOQ=6ppm.

[0101] 4.4 Precision Six samples from the same batch (wastewater batch number: CS2206001) were taken for parallel determination and injected into the liquid chromatograph respectively. The average content was not detected, and the average value of the spiked results was 59ppm, RSD=1%. At two different times, six spiked solutions of the test sample were prepared in parallel using different instruments and injected into the liquid chromatograph. The average result (n=12) was 59ppm, RSD=1%.

[0102] 4.5 Accuracy According to the preparation method of the control solution, accurately weigh an appropriate amount of m-cresol, add a dissolving solvent to dissolve and dilute to make a solution containing 6 μg per 1 ml.

[0103] Accurately weigh 9 portions of the test sample, each weighing about 500 mg, and place them in a 50 ml volumetric flask. Accurately add 4 ml, 5 ml, and 6 ml of the reserve solution, respectively. Dilute to the scale with a dissolving solvent, shake well, and prepare solutions equivalent to 80%, 100%, and 120% of the limit concentration. Prepare 3 portions in parallel for each concentration, conduct tests, and calculate the recovery rate of m-methylphenol.

[0104] Table 2 Results of m-cresol recovery

[0105] Experiment 2 The technical schemes of Examples 2 and 4 were used to measure the m-cresol content in industrial wastewater. The results are as follows: Figure 5 , Figure 6 As shown in the figure, it can be seen that the peaks in the sample are completely eluted, the baseline is stable, the detection repeatability is good, there is no interference at the target peak position, the detection time is short, and the detection efficiency is high.

[0106] The technical scheme of Comparative Example 1 was used to determine m-cresol (same as Experiment 1, using spiked test solution). The results are as follows Figure 7 As shown, from Figure 7 It can be seen that when the mobile phase ratio is phosphate buffer-acetonitrile (817:250), m-methylphenol does not elute within 60 minutes, and the final elute time of impurities in the wastewater is around 30 minutes. The detection time is too long and the detection efficiency is low.

[0107] The technical scheme of Comparative Example 2 was used to determine m-cresol (same as Experiment 1, using spiked test solution). The results are as follows: Figure 8 As shown, from Figure 8 It can be seen that when the mobile phase ratio is phosphate buffer-acetonitrile (817:400), the blank interferes with the detection of m-cresol.

[0108] The technical scheme of Comparative Example 3 was used to determine m-cresol (same as Experiment 1, using spiked test solution). The results are as follows Fig. 9 As shown, from Fig. 9 It can be seen that when the mobile phase ratio is phosphate buffer-acetonitrile (817:500), m-methylphenol peaks at around 11.5 minutes. The detection baseline here is not stable, and there are many impurities in the wastewater. The early peak will affect the separation degree between the main peak and the impurities.

Claims

1. A method for determining residual m-cresol in industrial wastewater, characterized in that: The steps include: S1. Prepare the test solution: accurately weigh about 500 mg of the test sample, place it in a 50 mL volumetric flask, dissolve it with a dissolving solvent and dilute it to the scale, and shake well; S2. The test solution is tested by liquid chromatography, the temperature of the liquid chromatography column is 20-30°C, and the elution time is 25 minutes; S3. The test solution is detected by liquid chromatography, wherein the mobile phase used in the liquid chromatography is phosphate buffer: acetonitrile = 807-827: 310-330, and the pH of the mobile phase is adjusted to 3.8-4.2 with phosphoric acid.

2. A method for determining residual m-cresol in industrial wastewater according to claim 1, characterized in that: The test sample is industrial wastewater.

3. A method for determining residual m-cresol in industrial wastewater according to claim 1, characterized in that: The phosphate buffer solution is prepared by taking 2.72 g of anhydrous potassium dihydrogen phosphate and 17.52 g of 10% tetrabutylammonium hydroxide solution and dissolving them in 817 ml of water.

4. A method for determining residual m-cresol in industrial wastewater according to claim 1, characterized in that: The dissolving solvent is a saturated sodium bicarbonate solution.

5. A method for determining residual m-cresol in industrial wastewater according to claim 1, characterized in that: In the step S2, the chromatographic column used in the liquid chromatography method is an octadecylsilane bonded silica gel column.

6. A method for determining residual m-cresol in industrial wastewater according to claim 1, characterized in that: The temperature of the chromatographic column is 20-30° C., and the elution time is 25 minutes.

7. A method for determining residual m-cresol in industrial wastewater according to claim 1, characterized in that: The flow rate of the liquid chromatograph is 0.8-1.2 ml / min.

8. A method for determining residual m-cresol in industrial wastewater according to claim 1, characterized in that: The liquid chromatograph adopts an ultraviolet detector.

9. A method for determining residual m-cresol in industrial wastewater according to claim 1, characterized in that: The injection volume for the liquid chromatography was 20 μl.

10. The method for determining residual m-cresol in industrial wastewater according to claim 1, wherein: The detection wavelength of the liquid chromatography is 230 nm.

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