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HJ 1073-2019 English PDF

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HJ 1073-2019: Water quality--Determination of naphthol--High performance liquid chromatography
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HJ 1073-2019	English	399	Add to Cart	4 days [Need to translate]	Water quality--Determination of naphthol--High performance liquid chromatography	Valid	HJ 1073-2019

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Basic data

Standard ID	HJ 1073-2019 (HJ1073-2019)
Description (Translated English)	Water quality--Determination of naphthol--High performance liquid chromatography
Sector / Industry	Environmental Protection Industry Standard
Classification of Chinese Standard	Z16
Classification of International Standard	13.060
Word Count Estimation	17,157
Date of Issue	2019
Date of Implementation	2020-06-30
Issuing agency(ies)	Ministry of Ecology and Environment

HJ 1073-2019: Water quality--Determination of naphthol--High performance liquid chromatography

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Water quality--Determination of naphthol--High performance liquid chromatography National Environmental Protection Standard of the People's Republic of China Water quality-Determination of naphthol-High performance liquid chromatography Water quality-Determination of naphthol -High performance liquid chromatography 2019-12-31 released 2020-06-30 implementation Released by the Ministry of Ecology and Environment

Foreword ... ii 1 Scope ... 1 2 Normative references ... 1 3 Methodology ... 1 4 Interference and cancellation ... 1 5 Reagents and materials ... 2 6 Instruments and equipment ... 2 7 Sample ... 3 8 Analysis steps ... 3 9 Calculation and Representation of Results ... 6 10 Precision and accuracy ... 6 11 Quality Assurance and Quality Control ... 8 12 Waste disposal ... 9 Appendix A (Informative) Summary of Method Precision Data ... 10 Appendix B (Informative) Summary of Method Accuracy Data ... 12

Foreword

In order to implement the "Environmental Protection Law of the People's Republic of China" and the "Law of the People's Republic of China on Water Pollution Control", protect the ecology Environment, protect human health, standardize the determination method of naphthol in water, and formulate this standard. This standard specifies the determination of 1-naphthol (α-naphthol) in surface water, groundwater, domestic sewage, industrial wastewater and seawater. High-performance liquid chromatography of 2-naphthol (β-naphthol). Appendix A and Appendix B of this standard are informative appendices. This standard is issued for the first time. This standard is formulated by the Department of Eco-Environmental Monitoring, Laws and Standards Department of the Ministry of Ecology and Environment. This standard was drafted. Liaoning North Environmental Detection Technology Co., Ltd. Verification units of this standard. Liaoning Province Ecological Environment Monitoring Center, Shandong Province Qingdao Ecological Environment Monitoring Center, Liaoning Province, Shenyang Yang Ecological Environment Monitoring Center, Anshan Environmental Monitoring Center, Liaoning Province, Liaoyang Environmental Monitoring Center, Liaoning Province, and Shenyang Zeer Testing Services Ltd. This standard was approved by the Ministry of Ecology and Environment on December 31,.2019. This standard will be implemented from June 30, 2020. This standard is explained by the Ministry of Ecology and Environment. Water quality-Determination of naphthol-High performance liquid chromatography Warning. The standard materials and organic solvents used in the experiment are all toxic. The reagent preparation and sample preparation have been processed. The process should be carried out in a fume hood, and protective equipment should be worn as required to avoid direct contact with skin and clothing.

1 Scope

This standard specifies the HPLC method for the determination of naphthol in water. This standard applies to 1-naphthol (α-naphthol) and 2- in surface water, groundwater, domestic sewage, industrial wastewater and seawater. Determination of naphthol (β-naphthol). When the sampling volume is 10.0 ml, the eluent volume is 10.0 ml, and the injection volume is 10.0 µl, the emission wavelength is 425 nm. Here, the detection limits of the 1-naphthol and 2-naphthol methods of this standard are 2 μg/L, and the lower detection limits are 8 μg/L. At 360 nm, the detection limit of 2-naphthol by this standard is 0.2 μg/L, and the lower detection limit is 0.8 μg/L. When the sampling volume is 50.0 ml, the eluent volume is 10.0 ml, and the injection volume is 10.0 µl, the emission wavelength is 425 nm. Here, the detection limits of the 1-naphthol and 2-naphthol methods of this standard are both 0.3 μg/L, and the lower detection limits are 1.2 μg/L. At the emission wavelength of 360 nm, the detection limit of the method for the determination of 2-naphthol by this standard is 0.06 μg/L, and the lower detection limit is 0.24 μg/L.

2 Normative references

This standard refers to the following documents or clauses therein. For undated references, the valid version is applicable to this standard. GB 17378.3 Marine Monitoring Code Part 3. Sample Collection, Storage and Transportation HJ 91.1 Technical Specifications for Sewage Monitoring HJ/T 91 Technical specifications for surface water and sewage monitoring HJ/T 164 Technical Specifications for Groundwater Environmental Monitoring

3 Method principle

Take a certain amount of acidified sample (pH value 1 ~ 2), extract it with a C18 solid phase extraction column, and elute with methanol. The naphthol was separated by liquid chromatography and detected by a fluorescence detector. Qualitative according to retention time, quantified by external standard method.

4 Interference and cancellation

4.1 Basic organic compounds such as naphthylamine and aniline in water will not be solidified by C18 under acidic conditions (pH 1-2) Adsorption by extraction column does not interfere with the determination of naphthol. 4.2 Common phenolic compounds (including phenol, 2,4-dinitrophenol, 2,6-dimethylphenol, 2-methylphenol, 3-methylphenol, 4-methylphenol, 4-chlorophenol, 2,4-dichlorophenol, 2,4,6-trinitrophenol, 1,3-benzenediol, p-nitrophenol, o-chlorophenol, o-nitro Phenol, 2,4-xylenol, 4-chloro-m-cresol, 4,6-dinitro-o-cresol, 2,4,6-trichlorophenol and pentachlorophenol, etc.) It does not interfere with the determination of naphthol at a fixed fluorescence detection wavelength. 4.3 Other acidic or neutral organic compounds with similar retention time to naphthol may interfere with the determination of naphthol. Changing the ratio of the mobile phase improves the resolution, and you can choose to measure at a relatively interference-free detection wavelength to avoid interference.

5 Reagents and materials

Unless otherwise stated, analytical reagents that meet national standards are used in the analysis. The test water is free of target compounds. Distilled water or water produced by pure water equipment. 5.1 Acetonitrile (CH3CN). pure by liquid chromatography. 5.2 Methanol (CH3OH). pure by liquid chromatography. 5.3 Sodium hydroxide (NaOH). 5.4 Ascorbic acid (C6H8O6). 5.5 1-naphthol. w (C10H7OH) ≥99.5%. 5.6 2-naphthol. w (C10H7OH) ≥99.5%. 5.7 Hydrochloric acid. ρ (HCl) = 1.18 g/ml. 5.8 hydrochloric acid solution. 1 1. 5.9 Hydrochloric acid solution. c (HCl) = 0.01 mol/L. Measure 1.8 ml of hydrochloric acid solution (5.7) and dilute to 1000 ml with water. 5.10 Sodium hydroxide solution. c (NaOH) = 5 mol/L. Weigh 20 g of sodium hydroxide (5.3) and dissolve in 100 ml of water. 5.11 Methanol solution. w (CH3OH) = 0.2%. Take 2.0 ml of methanol (5.2) and dilute to 1000 ml with water. 5.12 Naphthol mixed standard stock solution. ρ≈1000 mg/L. Weigh 0.10 g (accurate to 0.0001 g) of 1-naphthol (5.5) and 2-naphthol (5.6) respectively in a 100 ml beaker, Add 100 mg ascorbic acid (5.4), dissolve with a small amount of methanol (5.2), transfer to a 100 ml volumetric flask, and use methanol (5.2) Dilute to the mark and mix well. Divided into brown sample bottles (6.4), sealed, refrigerated below 4 ° C, protected from light Save for 3 months. You can also purchase a commercially available certified standard solution and store it as required by the standard solution certificate. 5.13 Naphthol mixed standard solution I. ρ = 100 mg/L. Measure an appropriate amount of naphthol mixed standard stock solution (5.12) in a 10 ml volumetric flask, and dilute to the standard with methanol (5.2). Line and mix. Separately into brown sample bottles (6.4), sealed, refrigerated below 4 ° C, protected from light, and can be stored for 3 months. 5.14 Naphthol mixed standard use solution II. ρ = 10.0 mg/L. Measure 1.00 ml of naphthol mixed standard solution Ⅰ (5.13) into a 10 ml volumetric flask, and make up the volume with methanol (5.2). Mix well. Sealed in a brown sample bottle (6.4), refrigerated below 4 ° C, protected from light, and can be stored for 3 months. 5.15 C18 solid phase extraction column. The packing is octadecyl bonded silica, 500 mg/6 ml. 5.16 Microporous membrane. pore size ≤0.45 μm, made of polytetrafluoroethylene.

6 Instruments and equipment

Unless otherwise stated, all Class A glass measuring instruments are used in accordance with national standards for analysis. 6.1 HPLC. with fluorescence detector. 6.2 Column. 250 mm (length) x 4.6 mm (inside diameter) x 5 µm (particle size), packed with octadecyl bonded silica (C18), other equivalent liquid chromatography columns can also be used. 6.3 Sampling bottle. 250 ml or 500 ml screw-top brown glass bottle or ground bottle with Teflon liner. 6.4 Vial. 2 ml, 10 ml or 50 ml screw-top brown glass bottle with Teflon liner. 6.5 Solid phase extraction device. 6.6 General laboratory equipment.

7 samples

7.1 Collection and storage of samples The layout of sampling points and the collection of samples are performed in accordance with HJ/T 91, HJ 91.1 or HJ/T 164, GB 17378.3 Regulations. Collect the sample into the sampling bottle (6.3), add 0.5 g of ascorbic acid (5.4) to each liter of sample, and wait for it to completely dissolve. After the solution, adjust the pH of the sample to 1-2 with hydrochloric acid solution (5.8) or sodium hydroxide solution (5.10) and seal. At 4 ℃ Store and refrigerate under dark, refrigerated, and complete analysis within 14 days. 7.2 Preparation of test specimens C18 solid phase extraction column (5.15) was fixed on the solid phase extraction device (6.5), and 9 ml of methanol (5.2) and 9 ml were used in this order. The hydrochloric acid solution (5.9) was activated and the column head was kept wet at all times. The sample (7.1) was equilibrated to room temperature and shaken. According to the sample Content of target compound, measure 10.0 ml ～ 50.0 ml of the sample in the sample bottle (6.4), and then make the sample at 3 ～ 4 ml/min The flow rate passed through the extraction column. Rinse the vial twice with 5 ml of water just before the column packing is exposed to air. detergent Transfer to the column and discard the flow-through. After extruding or draining water from the extraction column under pressure, wash with 10.0 ml of methanol (5.2) Take off, receive the eluate in a 10 ml sample bottle (6.4), after the initial eluate flows out, close the piston and soak the solid phase extraction Column for at least 5 min. Open the plunger, collect all the eluent, make up to 10.0 ml with methanol (5.2), mix well and use a microwell Filter membrane (5.16) is filtered, to be tested. Note 1. For samples with complex matrix and unknown organic content, in order to avoid penetration, two solid phase extraction columns can be used to extract different bodies. Volume of the same sample. For example, extract 10.0 ml and 20.0 ml samples, respectively. When the former is 20% lower, it means that the adsorption capacity of the latter has reached saturation. It is necessary to appropriately reduce the sample volume or dilute the sample before solid phase extraction. Note 2. For clean samples (excluding high salt water and sea water), the sample (7.1) can also be filtered through a microporous membrane (5.16) and directly Inject. The detection limit of the method can refer to the relevant data of both the sampling volume and the eluent volume being 10.0 ml. 7.3 Preparation of blank samples Use experimental water to replace the sample, and follow the same steps as in sample preparation (7.2) to prepare a blank sample.

8 Analysis steps

8.1 Instrument Reference Conditions Mobile phase A. acetonitrile (5.1), mobile phase B. methanol solution (5.11). Elution procedure. mobile phase A/mobile phase B = 47/53 (V/V); flow rate. 1.2 ml/min; injection volume. 10.0 μl; column temperature. 35 ° C; Detector. fluorescence detector; excitation wavelength. 228 nm; Emission wavelength. When measuring 1-naphthol and 2-naphthol at the same time, select 425 nm as the quantitative detection wavelength and 435 nm as the quantitative detection wavelength. Auxiliary qualitative wavelength; when only 2-naphthol is measured or when 2-naphthol is interfered at 425 nm, 360 nm is selected for quantification Detection wavelength, 350 nm as auxiliary qualitative wavelength. For samples with complex matrices, gradient elution should be used. See Table 1 for the gradient elution reference procedure. Table 1 Reference procedure for gradient elution Time/min Mobile phase A /% Mobile phase B /% 8.2 Calibration 8.2.1 Preparation of standard series Take an appropriate amount of Naphthol Mixed Standard Solution Ⅱ (5.14) or Naphthol Mixed Standard Solution Ⅰ (5.13) in 10 ml. In a brown volumetric flask, make up to volume with methanol (5.2) and prepare a standard series containing at least 5 concentration points. Standard series solution The preparation and its reference concentration are shown in Table 2. Table 2 Standard series solution preparation and its reference concentration 8.2.2 Establishment of the standard curve According to the instrument reference conditions (8.1), the standard series solution (8.2.1) is sequentially injected from low concentration to high concentration, and Detect the target compound and record the retention time and peak height or area. Based on the mass of the target compound in each standard series solution Degree (µg/L) is the abscissa, and its corresponding peak height or area is used as the ordinate to establish a standard curve. 8.2.3 Chromatogram of standard sample Figure 1 shows the chromatogram of gradient elution of 1-naphthol and 2-naphthol standard samples (500 µg/L) under the reference conditions of the instrument (8.1). Figure (emission wavelength of 425 nm). Figure 2 shows the gradient of 2-naphthol standard sample (1.00 mg/L) under the reference condition of the instrument (8.1). Eluted chromatogram (360 nm emission). 1-2-naphthol; 2--1-naphthol. Figure 1 Gradient elution chromatogram of naphthol standard sample (emission wavelength of 425 nm) 1-2-naphthol; 2--1-naphthol. Figure 2 Gradient elution chromatogram of naphthol standard sample (emission wavelength 360 nm) 8.3 Determination of sample Test the sample (7.2) according to the same instrument conditions as the standard curve establishment (8.2.2). 8.4 Blank test The blank sample (7.3) was measured under the same instrument conditions as the sample measurement (8.3).

9 Calculation and representation of results

9.1 Qualitative analysis Qualitatively based on retention time, or the peak height ratio of the target compound at different emission wavelengths in the sample and the standard sample Comparison (its relative deviation should be ≤5%) assists qualitative analysis. 9.2 Result calculation The mass concentration (µg/L) of the target compound in the sample is calculated according to formula (1). Note 1. When the response of the target compound in the sample exceeds the upper limit of the standard curve (10 mg/L), the sample should be appropriately diluted or reduced After the sample volume, prepare the sample (7.2). Note 2. When the total amount of 1-naphthol and 2-naphthol in the sample needs to be calculated, the target compounds not detected are not involved in the calculation. If two targets None of the compounds were detected and their respective detection limits were reported. 9.3 Representation of results The number of digits after the decimal point in the measurement result is the same as the detection limit of the method. A maximum of three significant digits are retained. 10 Precision and accuracy 10.1 Precision Uniform blanks at six laboratories for 1-naphthol and 2-naphthol spiked at 2.00 μg/L, 100 μg/L, and 1.00 mg/L The spiked samples were subjected to 6 repeated determinations. the relative standard deviations in the laboratory for the determination of 1-naphthol were 1.6% ～ 5.9%, 0.7% to 7.0%, and 0.7% to 6.2%; the relative standard deviations between laboratories were 9.2%, 9.2%, and 3.2%, respectively; Refolding limits are 0.2 μg/L, 8.9 μg/L, and 0.089 mg/L; reproducibility limits are 0.6 μg/L, 28 μg/L, and 0.13 mg/L. The relative standard deviations in the laboratory for the determination of 2-naphthol were 1.9% to 4.1%, 0.7% to 8.5%, and 0.8% to 6.1%; the relative standard deviations between laboratories are 5.1%, 7.6%, and 5.5%; the repeatability limits are 0.18 μg/L, 10 μg/L and 0.088 mg/L; reproducibility limits are 0.33 μg/L, 23 μg/L, and 0.18 mg/L, respectively. Uniform blanks at six laboratories for 1-naphthol and 2-naphthol spiked at 10.0 μg/L, 500 μg/L, and 9.00 mg/L The spiked samples were measured 6 times repeatedly. The relative standard deviations in the laboratory for the determination of 1-naphthol were 0.7% ～ 9.4%, 0.5% to 8.9%, and 0.6% to 3.4%; the relative standard deviations between laboratories were 10%, 5.3%, and 6.9%, respectively; Refolding limits were 2 μg/L, 54 μg/L, and 0.41 mg/L, respectively; reproducibility limits were 3 μg/L, 89 μg/L, and 1.7 mg/L, respectively. The relative standard deviations in the laboratory for the determination of 2-naphthol were 1.4% to 15%, 0.4% to 7.1%, and 0.5% to 5.1%; Interlaboratory relative standard deviations were 8.5%, 3.1%, and 7.4%, respectively; repeatability limits were 2 μg/L, 43 μg/L, and 0.52 mg/L; reproducibility limits are 3 μg/L, 60 μg/L, and 1.8 mg/L, respectively. Six laboratories spiked 1-naphthol at 2.00 μg/L, 10.0 μg/L, 100 μg/L, and 500 μg/L surface water samples The product has been tested 6 times. the relative standard deviations in the laboratory are 2.5% ～ 11%, 1.1% ～ 11%, 0.96% ～ 2.2% and 0.94% ～ 9.3%; the relative standard deviations among laboratories are 8.8%, 5.9%, 8.6% and 4.9%; Repeatability limits are 0.38 μg/L, 1.5 μg/L, 4.5 μg/L, and 50 μg/L; reproducibility limits are 0.61 μg/L, 2.1 μg/L, 24 μg/L, and 81 μg/L. Six laboratories have spiked 2-naphthol at concentrations of 0.10 μg/L, 0.40 μg/L, 2.00 μg/L, 10.0 μg/L, 100 μg/L And 500 μg/L surface water samples were measured 6 times. the relative standard deviations in the laboratory were 2.1% ～ 14%, 1.7% to 10%, 1.1% to 5.0%, 0.82% to 8.3%, 0.72% to 2.6%, and 0.64% to 2.7%; between laboratories The relative standard deviations were 12%, 4.0%, 11%, 6.4%, 8.9%, and 2.5%, respectively; the repeatability limits were 0.021 μg/L, 0.069 μg/L, 0.20 μg/L, 1.3 μg/L, 5.3 μg/L, and 24 μg/L; the reproducibility limits are 0.037 μg/L, 0.076 μg/L, 0.66 μg/L, 2.1 μg/L, 26 μg/L, and 42 μg/L. Six laboratories tested three types of laboratories containing 1-naphthol at average concentrations of 48.4 μg/L, 45.7 μg/L, and 0.541 mg/L. Industry waste water samples were measured 6 times. the relative standard deviations in the laboratory were 1.8% ～ 11% and 1.5% ～ 5.5% and 1.2% -4.3%; the relative standard deviations between laboratories were 22%, 19%, and 11%, respectively. Six laboratories tested three types of laboratories containing 2-naphthol at average concentrations of 0.950 mg/L, 2.62 mg/L, and 153 μg/L. Industry wastewater samples were repeated 6 times. the relative standard deviations in the laboratory ranged from 0.6% to 2.4% and 0.9% to 5.6% and 0.7% to 8.1%; the relative standard deviations between laboratories were 8.0%, 10%, and 15%. One laboratory spiked 1-naphthol at 10.0 μg/L, 400 μg/L, and 1000 μg/L municipal wastewater samples Six replicates were performed. the relative standard deviations were 2.6%, 1.6%, and 0.3%, respectively. One laboratory spiked 2-naphthol at concentrations of 0.50 μg/L, 10.0 μg/L, 400 μg/L, and 1000 μg/L Water samples were tested in 6 replicates. the relative standard deviations were 4.0%, 2.9%, 1.6%, and 0.3%, respectively. One laboratory performed seawater samples spiked with 1-naphthol at 10.0 μg/L, 400 μg/L, and 1000 μg/L Six repeated determinations. the relative standard deviations were 3.0%, 2.9%, and 6.7%, respectively. One laboratory spiked 2-naphthol at concentrations of 0.50 μg/L, 10.0 μg/L, 400 μg/L, and 1000 μg/L. Water samples were tested in 6 replicates. the relative standard deviations were 7.0%, 3.5%, 1.9%, and 6.7%, respectively. For a summary of method precision data, see Appendix A. 10.2 Accuracy Uniform blanks at six laboratories for 1-naphthol and 2-naphthol spiked at 10.0 μg/L, 500 μg/L, and 9.00 mg/L The spiked samples were tested 6 times repeatedly. the relative error ranges in the laboratory for the determination of 1-naphthol were -14% to 11%, -12% to 2.0% and -17% to 0.1%; the final relative errors are -5.5% ± 19%, -4.9% ± 10%, and -6.5% ± 13%. The relative laboratory error ranges for the determination of 2-naphthol are -12% to 6.0%, -8.6% to -1.0%, -18% ～ 2.0%; the final relative errors are -4.3% ± 16%, -4.1% ± 6.0%, and -5.3% ± 14%. Uniform blanks at six laboratories for 1-naphthol and 2-naphthol spiked at 2.00 μg/L, 100 μg/L, and 1.00 mg/L The spiked samples were tested 6 times repeatedly. the relative error ranges in the laboratory for the determination of 1-naphthol were -13% to 11%, -3.0% to 21% and -2.9% to 4.0%; the final relative errors are -3.4% ± 18%, 2.0% ± 19%, and 1.6% ± 6.6%. The relative indoor error ranges for the determination of 2-naphthol are -7.0% to 7.0%, -20% to 0.8%, and -7.5% to 8.0%; the final relative errors were -2.2% ± 10%, -5.8% ± 15%, and 1.9% ± 11%. Six laboratories performed six repeated measurements of 1-naphthol spiked surface water samples at 10.0 μg/L and 500 μg/L Determination. The recovery ranges of standard addition in the laboratory are 88% to 99% and 89% to 103%, respectively; the final recovery values of standard addition are 94% ± 11% and 97% ± 9%. Six laboratories conducted surface water samples spiked with 2-naphthol at concentrations of 0.40 μg/L, 10.0 μg/L, and 500 μg/L. 6 Repeated determinations. The recoveries in the laboratory range from 91% to 100%, 85% to 101% and 96% to 103% The final recoveries were 95% ± 7%, 94% ± 12% and 100% ± 5%. Six laboratories performed 6 replicate determinations of 1-naphthol spiked surface water samples at 2.00 μg/L and 100 μg/L. The recoveries in the laboratory range from 91% to 116% and 92% to 117% respectively; the final recoveries are 101% ± 17% and 100% ± 17%. Six laboratories performed surface water samples spiked with 2-naphthol at 0.10 μg/L, 2.00 μg/L, and 100 μg/L 6 repeated determinations. The recovery ranges of standard addition in the laboratory are 84% ～ 114%, 86% ～ 121% and 95% ～ 119% respectively; The final spiked recoveries were 96% ± 22%, 100% ± 23%, and 101% ± 18%. The average concentrations of 1-naphthol in the six laboratories were 48.4 μg/L, 45.7 μg/L and 540 μg/L. The spiked concentrations were Three types of industrial wastewater samples of 50.0 μg/L, 50.0 μg/L, and 400 μg/L were tested in 6 replicates. spiked back Yields range from 80% to 101%, 82% to 116%, and 90% to 109%; the final recovery rates are 91% ± 18%, 99% ± 23%, and 99% ± 14%. Six laboratories have average concentrations of 2-naphthol at 0.950 mg/L, 2.62 mg/L, and 153 μg/L. Six repeated determinations of three types of industrial wastewater samples of 1.00 mg/L, 5.00 mg/L, and.200 μg/L. spiked The recoveries range from 76% to 102%, 82% to 109%, and 94% to 122%, respectively; the final recoveries are 93%. ± 18%, 103% ± 29%, and 105% ± 20%. A laboratory performed 1-naphthol spiked municipal wastewater samples at 10.0 μg/L, 400 μg/L, and 1000 μg/L Six repeated determinations. the spiked recoveries were 87%, 91%, and 84%, respectively. One laboratory spiked 2-naphthol at concentrations of 0.50 μg/L, 10.0 μg/L, 400 μg/L, and 1000 μg/L Water samples were tested in 6 replicates. spiked recoveries were 91%, 89%, 93%, and 87%, respectively. One laboratory performed six seawater samples spiked with 1-naphthol at 10.0 μg/L, 400 μg/L, and 1000 μg/L Repeated determination. The spiked recoveries were 82%, 92%, and 84%, respectively. Seawater samples spiked with 2-naphthol at 0.50 μg/L, 10.0 μg/L, 400 μg/L, and 1000 μg/L by a laboratory 6 repeated determinations of the product. the spiked recoveries were 80%, 94%, 93% and 87%, respectively; For a summary of method accuracy data, see Appendix B. 11 Quality Assurance and Quality Control 11.1 Every 20 samples or each batch (≤20 samples/batch) samples shall be measured at least 1 blank sample, the measurement results shall be Below method detection limit. 11.2 Before analyzing samples, a standard curve of at least 5 concentration points should be established, and the correlation coefficient of the curve should be ≥0.995. each 20 samples or each batch (≤20 samples/batch) should be measured in a standard series of intermediate concentration point solutions. The relative error of concentration at this point should be within ± 10%. 11.3 Every 20 samples or eac...

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