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HJ 1048-2019 English PDF

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HJ 1048-2019: Water quality - Determination of 17 aniline compounds - Liquid chromatography-triple quadrupole mass spectrometry
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Basic data

Standard ID	HJ 1048-2019 (HJ1048-2019)
Description (Translated English)	Water quality - Determination of 17 aniline compounds - Liquid chromatography-triple quadrupole mass spectrometry
Sector / Industry	Environmental Protection Industry Standard
Classification of Chinese Standard	Z16
Classification of International Standard	13.060
Word Count Estimation	29,246
Date of Issue	2019
Date of Implementation	2020-04-24
Issuing agency(ies)	Ministry of Ecology and Environment

HJ 1048-2019: Water quality - Determination of 17 aniline compounds - Liquid chromatography-triple quadrupole mass spectrometry

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(Water quality-Determination of 17 aniline compounds by liquid chromatography-triple quadrupole mass spectrometry) National Environmental Protection Standard of the People's Republic of China Determination of 17 aniline compounds in water quality Liquid chromatography-triple quadrupole mass spectrometry Water quality-Determination of 17 aniline compounds -Liquid chromatography-triple quadrupole mass spectrometry 2019-10-24 released 2020-04-24 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 ... 3 7 Sample ... 3 8 Analysis steps ... 4 9 Calculation and Representation of Results ... 6 10 Precision and accuracy ... 8 11 Quality Assurance and Quality Control ... 9 12 Waste disposal ... 10 Appendix A (Normative) Method detection limit and determination limit ... 11 Appendix B (informative) Mass spectrometer reference conditions ... 12 Appendix C (informative) Precision and accuracy of the method ... 14

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 aniline compounds in water, and formulate this standard. This standard specifies the liquid phase of 17 aniline compounds in surface water, groundwater, domestic sewage and industrial wastewater. Chromatography-Triple Quadrupole Mass Spectrometry. Appendix A to this standard is a normative appendix, and Appendix B to Appendix C are informative appendixes. 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. Sichuan Ecological Environment Monitoring General Station. Verification units of this standard. Chongqing Ecological Environment Monitoring Center, Guangyuan Environmental Monitoring Center Station, Panzhihua Environmental Monitoring Center Monitoring Center Station, Shengzhou Environmental Monitoring Center Station, Yibin Environmental Monitoring Center Station and Nanchong Environmental Monitoring Center Station. This standard was approved by the Ministry of Ecology and Environment on October 24,.2019. This standard will be implemented from April 24, 2020. This standard is explained by the Ministry of Ecology and Environment. Determination of 17 aniline compounds in water quality Liquid chromatography-triple quadrupole mass spectrometry Warning. The standard materials used in the experiment have high toxicity or carcinogenicity. The reagent preparation and sample preparation process should be Do it in a fume hood; wear protective equipment as required to avoid contact with skin and clothing.

1 Scope

This standard specifies liquid chromatography-triple quadrupole mass spectrometry for the determination of 17 aniline compounds in water. This standard applies to o-phenylenediamine, aniline, benzidine, p-formylamine in surface water, groundwater, domestic sewage and industrial wastewater. Aniline, o-methoxyaniline, o-toluidine, 4-nitroaniline, 2,4-dimethylaniline, 3-nitroaniline, 4-chloroaniline, 2- Nitroaniline, 3-chloroaniline, 2-naphthylamine, 2,6-dimethylaniline, 2-methyl-6-ethylaniline, 3,3'-dichlorobenzidine, and 2,6- Determination of 17 aniline compounds such as diethylaniline. When the direct injection method was used and the injection volume was 10 μl, the method detection limit of 17 aniline compounds was 0.1 μg/L ～ 3 μg/L, the lower limit of determination is 0.4 μg/L ～ 12 μg/L; when the solid phase extraction method is used, the sampling volume is 100 ml (enriched 50 Times), when the injection volume is 10 μl, the method detection limit of 16 aniline compounds is 0.007 μg/L ～ 0.1 μg/L. The lower limit is 0.028 μg/L to 0.4 μg/L. See Appendix A for details.

2 Normative references

This standard refers to the following documents or clauses therein. For undated references, the valid version applies to this standard. HJ/T 91 Technical specifications for surface water and sewage monitoring HJ/T 164 Technical Specifications for Groundwater Environmental Monitoring

3 Method principle

Samples were injected directly after filtration or sampled after being enriched and purified by a cation exchange solid phase extraction column. Separation and detection of aniline compounds by heavy quadrupole mass spectrometry. Qualitative analysis based on retention time and characteristic ions, quantification by internal standard method.

4 Interference and cancellation

4.1 When matrix interferences exist in the sample, you can optimize the chromatographic conditions, dilute the sample, reduce the injection volume, and Products are reduced or eliminated by pretreatment. When using solid phase extraction, you can also reduce the sample volume or increase the sample The dilution factor reduces matrix interference. 4.2 When there is interference of isomers in the sample, you can improve the resolution by changing the chromatographic conditions or choose a different The secondary mass ion eliminates interference. 4.3 When oxidizing substances such as residual chlorine are present in the sample, sodium thiosulfate (5.8) can be added during sample collection and storage (7.1) Eliminate interference.

5 Reagents and materials

Unless otherwise stated, all analytical reagents that meet national standards are used for analysis. Standard compound of pure water. 5.1 Methanol (CH3OH). pure by liquid chromatography. 5.2 Ethanol (C2H5OH). excellent grade pure. 5.3 Formic acid (HCOOH). pure liquid chromatography. 5.4 Acetic acid (CH3COOH). pure liquid chromatography. 5.5 Hydrochloric acid. ρ (HCl) = 1.19 g/ml. 5.6 Ammonia. ρ (NH3 · H2O) = 0.91 g/ml, excellent grade pure. 5.7 Sodium hydroxide (NaOH). 5.8 Sodium thiosulfate (Na2S2O3). 5.9 Hydrochloric acid solution. 1 1. 5.10 Formic acid solution. φ (HCOOH) = 0.005%. Accurately transfer 50.0 μl of formic acid (5.3) into a 1 L volumetric flask previously filled with an appropriate amount of water. Mix well. 5.11 Acetic acid solution. 3 97. Mix with acetic acid (5.4) and water in a volume ratio of 3.97. 5.12 methanol solution. 1 9. Mix with methanol (5.1) and water in a volume ratio of 1. 9. 5.13 Sodium hydroxide solution. c (NaOH) = 1 mol/L. Weigh 4 g of sodium hydroxide (5.7) in water and dilute to 100 ml with water. 5.14 Ammonia methanol solution I. 5 95. Mix ammonia (5.6) and methanol (5.1) in a volume ratio of 5.95. 5.15 Ammonia methanol solution II. 19. Mix ammonia (5.6) and methanol (5.1) in a volume ratio of 1. 9. 5.16 Standard stock solution of aniline compounds. ρ = 100 mg/L ～ 1000 mg/L. It can be prepared with standard materials, the purity of standard materials is greater than 99.0%, dissolved in methanol (5.1), frozen below -10 ° C, Keep away from light. You can also purchase a certified standard solution directly and store it in accordance with the manufacturer's product instructions. 5.17 Aniline compounds mixed standard solution. ρ = 1.00 mg/L ～ 10.0 mg/L. Pipette an appropriate amount of standard aniline stock solution (5.16), dilute with methanol (5.1), and prepare 2-nitroaniline and 3- The concentration of nitroaniline is 10.0 mg/L, and the concentration of other aniline compounds is 1.00 mg/L. Frozen and protected from light below -10 ℃, can be stored for one month. 5.18 Internal standard stock solution. ρ = 100 mg/L. The recommended internal standard is aniline-d5. Other isotopes can also be used. Formulated with standard materials, high purity of standard materials Dissolve in 99.0% with methanol (5.1), freeze and store at -10 ° C or less in the dark. You can also buy certified standard solutions directly, Refer to the manufacturer's product manual. 5.19 Internal standard use solution. ρ = 1.00 mg/L (reference concentration). Dilute the internal standard stock solution (5.18) with methanol (5.1) as needed, freeze it below -10 ° C and store it in the dark to protect it. Deposit for 1 month. 5.20 Stock replacement solution. ρ = 100 mg/L. The substitute is benzidine-d8, which is formulated with a standard substance with a purity of greater than 99.0% and dissolved with methanol (5.1). Frozen and stored in the dark below -10 ° C. You can also purchase a certified standard solution directly and store it in accordance with the manufacturer's product instructions. 5.21 Substitute use liquid. ρ = 1.00 mg/L (reference concentration). Dilute the replacement stock solution (5.20) with methanol (5.1) as needed, and freeze it at -10 ° C or less and protect it from light. Save for 1 month. 5.22 Mixed cation exchange solid phase extraction column. The filler is benzenesulfonated polystyrene-divinylbenzene polymer. 150 mg/6 ml, or other equivalent extraction column. 5.23 Silica-based cation-exchange solid-phase extraction column. benzene sulfonated silica gel, 500 mg/6 ml, or other Effective extraction column. 5.24 Filter. 0.22 μm or 0.45 μm PTFE filter. 5.25 Nitrogen. Purity ≥99.99%.

6 Instruments and equipment

6.1 Liquid chromatography-triple quadrupole mass spectrometer. equipped with electrospray ionization source (ESI), with gradient elution and multiple reaction monitoring Test function. 6.2 Column. C18 reversed-phase liquid chromatography column with a particle size of 3 μm, a column length of 150 mm, and an inner diameter of 2.0 mm or other Similar performance columns. 6.3 Concentration device. nitrogen blowing concentrator or other equivalent equipment. 6.4 Solid phase extraction device. automatic or manual (with vacuum pump), the flow rate can be adjusted. 6.5 Sample bottle. 500 ml ground mouth or brown glass bottle with Teflon inner liner cap. 6.6 Micro-syringe or pipette. 10 μl, 50 μl, 100 μl, 500 μl, 1.0 ml. 6.7 General laboratory instruments and equipment.

7 samples

7.1 Sample collection and storage Collect samples in accordance with the relevant regulations of HJ/T 91 and HJ/T 164. The sample collection should be filled with sample vials (6.5), Leave no gaps. If the pH of the sample is not between 7 and 8 after collection, adjust the pH to 7 to 7 with formic acid (5.3) or ammonia (5.6). 8. Add 40 mg of sodium thiosulfate (5.8) to each 500 ml sample, and store it at 4 ° C or lower in the dark. O-phenylenediamine The analysis must be completed within 3 days. The analysis or extraction of benzidine and 3,3'-dichlorobenzidine are completed within 5 days, and the remaining compounds are analyzed within 7 days. Complete analysis or extraction within. 7.2 Preparation of test specimens 7.2.1 Direct injection method The sample (7.1) was filtered through a 0.22 μm filter (5.24). After discarding at least 1 ml of the initial filtrate, 1.0 ml was removed and filtered. After adding the sample to a brown injection bottle, add 10.0 μl of internal standard use solution (5.19), and mix well for testing. 7.2.2 Solid-phase extraction Fix the mixed cation exchange solid-phase extraction column (5.22) on the solid-phase extraction device (6.4), and use 10 ml in sequence Activate with methanol (5.1) and 10 ml water to ensure infiltration of the column head. Measure 100 ml sample (7.1) and add 20.0 μl The alternative uses liquid (5.21) and passes through the cartridge at a flow rate of no more than 3 ml/min. Sample volume can be appropriate according to the actual situation cut back. The column was washed with 5 ml of acetic acid solution (5.11) and 4 ml of methanol solution (5.12). Then with nitrogen (5.25) Purge or dry the column with a vacuum pump in a solid-phase extraction device for 10 minutes to remove residual water from the column. 7.0 ml ammonia Water methanol solution I (5.14) elutes the column, and the eluate is received in a collection tube. The eluate was passed through a concentration device (6.3) at 50 ° C. Concentrate to slightly less than 1 ml and make up to 1.0 ml with water. Accurately transfer 500 μl of the concentrated solution and make up to 1.0 ml with water (sample Volume V1 should be recorded as 2.0 ml), add 10.0 μl of internal standard use solution (5.19), mix well and place in a brown injection bottle. Measurement. Note 1. The recovery rate of o-phenylenediamine varies with different mixed cation exchange solid phase extraction columns (5.22). O-phenylenediamine and other aniline compounds (except 2-nitroaniline), you can choose a silica-based cation exchange solid phase extraction column (5.23), the sampling volume is preferably 1.0 ml to 5.0 ml, the sample flow rate is less than 1 ml/min, and the eluent is 5.0 ml ammonia methanol Solution II (5.15), other operating conditions are the same as those of the mixed cation exchange solid phase extraction column (5.22). Note 2. If the sample after extraction and concentration cannot be analyzed in time, it should be frozen, protected from light, and sealed. The analysis of benzidine is completed within 4 days. The analysis of co-aniline compounds was completed within 14 days. Note 3. Suspended matter has a greater effect on the enrichment of benzidine. When the suspended solids concentration is too high, the sampling volume can be reduced to avoid blocking the solid phase extraction Take the column. You can also adjust the sample pH to about 3 with hydrochloric acid solution (5.9), shake the sample, and then dip it in ethanol (5.2). Filter with a wet 0.45 μm filter membrane (5.24), adjust the pH of the filtrate to 7-8 with sodium hydroxide solution (5.13), and then solidify Phase extraction. 7.3 Preparation of blank samples Use experimental water to replace the sample, and follow the same steps as the sample preparation (7.2) to prepare a laboratory blank sample Equipment.

8 Analysis steps

8.1 Instrument Reference Conditions 8.1.1 Reference conditions for liquid chromatography Mobile phase A. formic acid solution (5.10), mobile phase B. methanol (5.1), gradient elution procedure is shown in Table 1; flow rate. 0.2 ml/min; column temperature. 40 ° C; injection volume. 10 μl. Table 1 Gradient elution procedure Time (min) Mobile phase A (%) Mobile phase B (%) 0.0 95 5 0.5 95 5 10.0 10 90 10.1 95 5 15.0 95 5 8.1.2 Mass spectrometry conditions Ion source. Electrospray ion source (ESI), positive ion mode. Monitoring method. Multiple response monitoring (MRM). For the remaining conditions, see Appendix B. 8.1.3 Instrument tuning There are some differences in the tuning parameters of instruments from different manufacturers, and they should be adjusted within the specified time and frequency according to the instrument's instruction manual. The mass spectrometer is calibrated for instrument mass and resolution to ensure that the instrument is in the best test condition. 8.2 Calibration 8.2.1 Establishment of standard curve Take appropriate amount of aniline compound standard solution (5.17) and substitute solution (5.21), dilute with water, Prepare a standard series solution with at least 5 concentration points. Mass concentration of 2-nitroaniline and 3-nitroaniline in the standard solution Respectively 10.0 μg/L, 50.0 μg/L, 100 μg/L,.200 μg/L, 500 μg/L, and 1000 μg/L, and the rest of the aniline compounds And alternative mass concentrations are 1.00 μg/L, 5.00 μg/L, 10.0 μg/L, 20.0 μg/L, 50.0 μg/L, and 100 μg/L (This is the reference concentration), transfer 1.0 ml of the standard series solution to a brown injection bottle, and add 10.0 μl of the internal standard use solution (5.19), mix well to be tested. According to the instrument reference conditions (8.1), the standard series solutions were measured from low concentration to high concentration. Target The mass concentration of the compound (μg/L) is the abscissa, and the ratio of the corresponding response value to the response value of the internal standard and the concentration of the internal standard The product of degrees is the ordinate, and a standard curve is established. 8.2.2 Standard Reference Spectrum Under the instrument reference conditions recommended by this standard, the total ion chromatogram of the target compound is shown in Figure 1 (2-nitroaniline and The mass concentration of 3-nitroaniline is.200 μg/L, and the mass concentrations of the remaining aniline compounds are 20.0 μg/L). 1-o-phenylenediamine; 2-aniline-d5 (internal standard); 3-aniline; 4-benzidine-d8 (alternative); 5-benzidine; 6-p-toluidine; 7- O-methoxyaniline; 8-o-toluidine; 9-4-nitroaniline; 10-2,4-dimethylaniline; 11-3-nitroaniline; 12-4-chloroaniline; 13-2- Nitroaniline; 14-3-chloroaniline; 15-2-naphthylamine; 16-2,6-dimethylaniline; 17-2-methyl-6-ethylaniline; 18-3,3'-diamine Chlorobiphenyl Amine; 19-2,6-diethylaniline. Figure 1 Total ion chromatograms of 17 aniline compounds, internal standards, and substitutes 8.3 Sample determination Test the sample (7.2) according to the same instrument conditions as the standard curve establishment (8.2.1). 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 Select one parent ion and two product ions to monitor the target compound. Under the same experimental conditions, The absolute value of the relative deviation of the retention time of the target compound from the retention time of the target compound in the standard sample should be less than 2.5%; and the relative abundance (Ksam) of the qualifier ions of the target compound in the sample corresponds to that in a standard solution with a close concentration The relative abundance (Kstd) of the qualitative ions of There is a corresponding target compound. 2  Ksam (1) In the formula. Ksam--the relative abundance of the qualifier ions of the target compound in the sample,%; A2--The response value of the qualitative ion of the target compound in the sample by mass spectrometry. A1--Secondary mass spectrometer response of the target compound in the sample. 2  std std std K (2) In the formula. Kstd--the relative abundance of the qualifier ions of the target compound in the standard sample,%; Astd2--Response value of qualitative ions of target compounds in the secondary mass spectrometry of the standard compound; Astd1--Secondary mass spectrometer response of the target compound in the standard sample. Table 2 Maximum allowable deviation of relative ion abundance during qualitative confirmation Kstd /% Ksam allowable deviation /% Kstd ＞ 50 ± 20 20 ＜ Kstd≤50 ± 25 10 ＜ Kstd≤20 ± 30 Kstd≤10 ± 50 9.2 Result calculation 9.2.1 Direct injection method The concentration of aniline compounds in the sample (μg/L) is calculated according to formula (3). Dii  1 (3) In the formula. i-the mass concentration of the i-th aniline compound in the sample, μg/L; i1-mass concentration of aniline compound in sample obtained from the standard curve, μg/L; D--Dilution multiple. 9.2.2 Solid Phase Extraction The mass concentration (μg/L) of aniline compounds in the sample is calculated according to formula (4). Vi i   11  (4) In the formula. i-the mass concentration of the i-th aniline compound in the sample, μg/L; i1-mass concentration of aniline compound in sample obtained from the standard curve, μg/L; V1--sample volume, ml; V--sampling volume, ml; D--Dilution multiple. 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 10.1.1 Direct injection method Six laboratories have spiked 2-nitroaniline and 3-nitroaniline at 10.0 μg/L, 100 μg/L, and 500 μg/L. The spiking concentrations of the remaining aniline compounds were 1.00 μg/L, 10.0 μg/L and 50.0 μg/L. Six repeated determinations. the relative standard deviations in the laboratory were 1.5% to 15%, 0.79% to 11%, and 0.55% to 10%; The relative standard deviations between laboratories were 2.2% to 9.8%, 3.2% to 8.6%, and 3.1% to 6.9%, respectively. The repeatability limits were 0.1 μg/L ～ 2 μg/L, 1.3 μg/L ～ 17 μg/L and 4.9 μg/L ～ 66 μg/L; the reproducibility limits are 0.1 μg/L ～ 3 μg/L, 1.7 μg/L ～ 21 μg/L and 6.7 μg/L ～ 73 μg/L. Six laboratories have spiked concentrations of 2-nitroaniline and 3-nitroaniline at 100 μg/L and 500 μg/L, and the rest of the anilines Compounds with spiked concentrations of 10.0 μg/L and 50.0 μg/L of surface water were spiked in 6 replicates. laboratory The internal relative standard deviations are 1.1% to 17% and 0.59% to 19%, and the relative standard deviations between laboratories are 4.8% to 10% and 4.1% ～ 8.3%; repeatability limits are 1.5 μg/L ～ 21 μg/L and 6.1 μg/L ～ 99 μg/L, respectively; They are 2.1 μg/L ～ 28 μg/L and 8.2 μg/L ～ 126 μg/L. Six laboratories have spiked concentrations of 2-nitroaniline and 3-nitroaniline at 100 μg/L and 500 μg/L, and the rest of the anilines The compound was spiked at 10.0 μg/L and 50.0 μg/L in industrial wastewater fortified samples. Six repeated determinations were performed. The indoor relative standard deviations are 1.0% to 18% and 0.68% to 15%, and the relative standard deviations between laboratories are 6.8% to 12% and 5.9% to 11%; repeatability limits are 1.3 μg/L to 28 μg/L and 5.5 μg/L to 76 μg/L; reproducibility limits are respectively It is 2.4 μg/L to 32 μg/L and 10 μg/L to 117 μg/L. 10.1.2 Solid Phase Extraction Six laboratories have spiked concentrations of 2-nitroaniline and 3-nitroaniline at 0.400 μg/L, 2.00 μg/L, and 10.0 μg/L. The rest of the aniline compounds were spiked at a uniform blank spiked concentration of 0.040 μg/L, 0.200 μg/L, and 1.00 μg/L. Six repeated determinations were performed. the relative standard deviations in the laboratory were 2.5% to 16%, 3.6% to 14%, and 1.1% to 14%; The relative standard deviations among laboratories were 4.6% to 13%, 3.4% to 13%, and 5.0% to 10%, respectively; the repeatability limits were 0.007 μg/L ～ 0.10 μg/L, 0.032 μg/L ～ 0.46 μg/L, and 0.13 μg/L ～ 2.0 μg/L; the reproducibility limits are respectively 0.008 μg/L to 0.11 μg/L, 0.039 μg/L to 0.89 μg/L, and 0.20 μg/L to 3.0 μg/L. Six laboratories have spiked concentrations of 2-nitroaniline and 3-nitroaniline at 2.00 μg/L and 10.0 μg/L, and the rest of the aniline The spiked samples of surface water with the concentration of 0.200 μg/L and 1.00 μg/L were measured in 6 replicates. The relative standard deviations in the laboratories are 1.7% to 18% and 2.1% to 16%; the relative standard deviations in the laboratories are 6.6% ～ 13% and 4.9% ～ 11%; repeatability limits are 0.034 μg/L ～ 0.66 μg/L and 0.14 μg/L ～ 2.1 μg/L; Reproducibility limits were 0.046 μg/L to 0.77 μg/L and 0.21 μg/L to 3.4 μg/L, respectively. Six laboratories have spiked concentrations of 2-nitroaniline and 3-nitroaniline at 4.00 μg/L and 20.0 μg/L, and the rest of the aniline The spiked samples of industrial waste water with the spiked concentrations of 0.400 μg/L and 2.00 μg/L were subjected to 6 repeated determinations. The relative standard deviations in the laboratory are 1.4% to 15% and 1.1% to 17% respectively; the relative standard deviations between the laboratories are 3.8% to 16% and 6.8% to 14%; repeatability limits are 0.057 μg/L to 0.82 μg/L and 0.27 μg/L to 5.1 μg/L; Reproducibility limits are 0.062 μg/L to 1.6 μg/L and 0.42 μg/L to 8.4 μg/L, respectively. See Appendix C for method precision summary data. 10.2 Accuracy 10.2.1 Direct injection method Six laboratories have spiked concentrations of 2-nitroaniline and 3-nitroaniline at 100 μg/L and 500 μg/L, and the rest of the anilines Surface water samples with the spiked concentrations of 10.0 μg/L and 50.0 μg/L of the compound were subjected to 6 repeated spiking analyses. The standard recovery rates range from 80.1% to 112% and 81.5% to 105%, respectively. The final recoveries are 90.6% ± 18.4% ～ 98.4% ± 12.6% and 91.5% ± 15.2% ～ 96.0% ± 9.4%. Six laboratories have spiked concentrations of 2-nitroaniline and 3-nitroaniline at 100 μg/L and 500 μg/L, and the rest of the anilines The industrial waste water samples with the spiked concentrations of 10.0 μg/L and 50.0 μg/L of the compound were subjected to 6 repeated spiking analyses. The spiked recovery ranges were 77.7% to 116% and 80.0% to 107%, respectively. The final spiked recovery values were 87.8% ± 13.2% to 96.8% ± 15.2% and 89.3% ± 15.8% to 96.1% ± 11.2%. 10.2.2 Solid Phase Extraction Six laboratories have spiked concentrations of 2...

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