Gas Chromatographic/Nitrogen-Phosphorus Detection Method for Determination of Ethylene Thiourea in Finished Drinking Waters: Collaborative Study

1993 ◽  
Vol 76 (5) ◽  
pp. 1113-1120 ◽  
Author(s):  
James E Longbottom ◽  
Kenneth W Edgell ◽  
Elizabeth J Erb ◽  
Viorica Lopez-Avila ◽  
◽  
...  
Keyword(s):  
Gas Chromatography ◽  
Drinking Water ◽  
Drinking Waters ◽  
Relative Standard ◽  
The Mean ◽  
Ethylene Thiourea ◽  
Standard Deviations ◽  
Nitrogen Phosphorus Detector ◽  
Nitrogen Phosphorus

Abstract A joint U.S. Environmental Protection Agency (USEPA)-AOAC interlaboratory method validation study was conducted on USEPA National Pesticide Survey (NPS) Method 6, "Determination of Ethylene Thiourea (ETU) in Finished Drinking Water by Gas Chromatography with a Nitrogen-Phosphorus Detector." The purpose of the study was to determine and compare the mean recoveries and precision for determination of ETU in reagent water and finished drinking waters. The study design was based on Youden's nonreplicate plan for collaborative tests of analytical methods. The waters were spiked with ETU at 6 concentrations levels, prepared as 3 Youden pairs. In the method, the test water is extracted by passing the sample through an absorbent matrix type tube. ETU is recovered from the tube with methylene chloride, the extract is solvent-exchanged to ethyl acetate, and an aliquot of each extract is analyzed by gas chromatography using a nitrogen-phosphorus detector. Twelve laboratories participated in the study. Data were analyzed using a USEPA computer program, which measured recovery and precision for ETU and compared the performance of the method between the 2 water types. Over the concentration range tested, the mean percent recoveries of ETU were 82-92% in reagent water and 85-98% in finished drinking water. The range of the betweenlaboratory relative standard deviations (RSDR) for the 6 concentrations was 5-24% in reagent water, but was only 4-9% in finished drinking water. The range of the within-laboratory relative standard deviations (RSDr) was 6-14% for reagent water and 6- 10% for finished drinking water. Results for the 2 water matrixes showed no statistically significant differences. The method has been adopted first action by AOAC International for determination of ETU in finished drinking waters.

Capillary Column Gas Chromatography with Nitrogen-Phosphorus Detection for Determination of Nitrogen- and Phosphorus-Containing Pesticides in Finished Drinking Waters: Collaborative Study

1991 ◽  
Vol 74 (2) ◽  
pp. 295-309
Author(s):  
Kenneth W Edgell ◽  
Elizabeth L Jenkins ◽  
Viorica Lopez-Avila ◽  
James E Longbottom
Keyword(s):  
Gas Chromatography ◽  
Drinking Water ◽  
Matrix Effects ◽  
Collaborative Study ◽  
Nitrogen And Phosphorus ◽  
Drinking Waters ◽  
Phosphorus Containing ◽  
Nitrogen Phosphorus Detector ◽  
Nitrogen Phosphorus

Abstract A joint U.S. Environmental Protection Agency/AOAC interlaboratory method validation study was conducted on EPA Method 507, Determination of Nitrogen- and Phosphorus- Containing Pesticides In Finished Drinking Water by Gas Chromatography with a Nitrogen-Phosphorus Detector, to determine the mean recovery and precision for analyses of 45 nitrogen- or phosphorus-containing pesticides in reagent water and finished drinking waters. The study design was based on Youden's nonreplicate plan for collaborative tests of analytical methods. The waters were spiked with 45 nitrogen- or phosphorus-containing pesticides at 6 concentration levels, prepared as 3 Youden pairs. Ten volunteer laboratories extracted the spiked test waters with methylene chloride, performed a solvent exchange with methyl ferf-butyl ether, and analyzed an aliquot of each extract by gas chromatography using a nitrogen-phosphorus detector. Results were analyzed using an EPA computer program, which measured recovery and precision for each of the 45 pesticides and compared the performance of the method between water types. Method 507 was judged acceptable for all analytes tested except merphos, which thermally decomposed in the Injection port of the gas chromatograph. Five compounds (carboxin, disulfoton, metolachlor, pronamlde, and slmazlne) exhibited statistically significant matrix effects for the finished drinking water. The method has been adopted official first action by AOAC.

Isolation and Gas Chromatographic Determination of Chlorsulfuron in Milk

1989 ◽  
Vol 72 (5) ◽  
pp. 813-815
Author(s):  
Austin R Long ◽  
Lily C Hsieh ◽  
Marsha S Malbrough ◽  
Charles R Short ◽  
Steven A Barker
Keyword(s):  
Gas Chromatography ◽  
Chromatographic Determination ◽  
Packing Material ◽  
Thermally Induced ◽  
Average Percentage ◽  
Milk Samples ◽  
Induced Decomposition ◽  
Nitrogen Phosphorus Detector ◽  
Nitrogen Phosphorus

Abstract A method for the isolation and gas chromatographic determination of chlorsulfuron in milk is presented. Blank or chlorsulfuron-spiked milk samples were blended into C-18 (octadecylsilyl derivatized silica, ODS) packing material. A column made from the C-18/milk matrix was washed with hexane after which chlorsulfuron was eluted with dichloromethane (DCM). The DCM eluate contained chlorsulfuron which was free from interfering co-extractants when analyzed by gas chromatography utilizing a nitrogen/phosphorus detector. Chlorsulfuron was found to undergo a thermally induced decomposition to give 2-amino-4-methoxy-6-methyl-l,3,5-triazine, which was detected and quantitated by this method. Standard curves for these analyses were linear (r = 0.992 ± 0.004, n = 5), with an average percentage recovery of 91.6 ± 10.8%, over the concentration range examined (62.5-2000 ng/mL). The inter- and intra-assay variabilities were 11.6 ± 7.5% and 6.2%, respectively.

scholarly journals Matrix Solid-Phase DispersionMicroextraction and Determination of Pesticide Residues in Medicinal Herbs by Gas Chromatography with a Nitrogen-Phosphorus Detector

2006 ◽  
Vol 89 (2) ◽  
pp. 498-502 ◽  
Author(s):  
Feng Tang ◽  
Yongde Yue ◽  
Rimao Hua ◽  
Haiqun Cao
Keyword(s):  
Solid Phase ◽  
Paeonia Lactiflora ◽  
Isatis Indigotica ◽  
Chromatography Method ◽  
Phase Dispersion ◽  
Relative Standard ◽  
Screening Protocol ◽  
Nitrogen Phosphorus Detector ◽  
Nitrogen Phosphorus

Abstract Agas chromatography method for the determination of residues of 6 pesticides in Isatis indigotica Fort and Paeonia lactiflora Pall is described. Optimizations of different parameters were performed. The method used 0.5 g herb sample, silica gel as thematrix solid-phase dispersion sorbent, and acetone as the eluting solvent. Recoveries at spiked concentrations between 0.1 and 5mg/kg were between 80.63 and 110.12, with relative standard deviations ranging from 0.43 to 17.67. The limits of quantitation were 0.01 mg/kg for metalaxyl, triadimefon, and paclobutrazol and 0.05mg/kg for vinclozolin, tebuconazole, and fenarimol. The method may be useful as a screening protocol for the determination of these pesticides in medicinal herb samples.

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