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At least 55 records · Page 3Linked to original sources
USGS2000

Methods of analysis by the U.S. Geological Survey Organic Geochemistry Research Group; determination of chloroacetanilide herbicide metabolites in water using high-performance liquid chromatography-diode array detection and high-performance liquid chromatography/mass spectrometry

Analytical methods using high-performance liquid chromatography-diode array detection (HPLC-DAD) and high-performance liquid chromatography/mass spectrometry (HPLC/MS) were developed for the analysis of the following chloroacetanilide herbicide metabolites in water: acetochlor ethanesulfonic acid (ESA), acetochlor oxanilic acid (OXA), alachlor ESA, alachlor OXA, metolachlor ESA, and metolachlor OXA. Good precision and accuracy were demonstrated for both the HPLC-DAD and HPLC/MS methods in reagent water, surface water, and ground water. The mean HPLC-DAD recoveries of the chloroacetanilide herbicide metabolites from water samples spiked at 0.25, 0.50, and 2.0 mg/L (micrograms per liter) ranged from 84 to 112 percent, with relative standard deviations of 18 percent or less. The mean HPLC/MS recoveries of the metabolites from water samples spiked at 0.05, 0.20, and 2.0 mg/L ranged from 81 to 125 percent, with relative standard deviations of 20 percent or less. The limit of quantitation (LOQ) for all metabolites using the HPLC-DAD method was 0.20 mg/L, whereas the LOQ using the HPLC/MS method was 0.05 mg/L. These metabolite-determination methods are valuable for acquiring information about water quality and the fate and transport of the parent chloroacetanilide herbicides in water.

Open-File Report↗
USGS2001

Methods of analysis by the U.S. Geological Survey Organic Geochemistry Research Group--Update and additions to the determination of chloroacetanilide herbicide degradation compounds in water using high-performance liquid chromatography/mass spectrometry

An analytical method using high-performance liquid chromatography/mass spectrometry (HPLC/MS) was developed by the U.S. Geological Survey in 1999 for the analysis of selected chloroacetanilide herbicide degradation compounds in water. These compounds were acetochlor ethane sulfonic acid (ESA), acetochlor oxanilic acid (OXA), alachlor ESA, alachlor OXA, metolachlor ESA, and metolachlor OXA. The HPLC/MS method was updated in 2000, and the method detection limits were modified accordingly. Four other degradation compounds also were added to the list of compounds that can be analyzed using HPLC/MS; these compounds were dimethenamid ESA, dimethenamid OXA, flufenacet ESA, and flufenacet OXA. Except for flufenacet OXA, good precision and accuracy were demonstrated for the updated HPLC/MS method in buffered reagent water, surface water, and ground water. The mean HPLC/MS recoveries of the degradation compounds from water samples spiked at 0.20 and 1.0 g/L (microgram per liter) ranged from 75 to 114 percent, with relative standard deviations of 15.8 percent or less for all compounds except flufenacet OXA, which had relative standard deviations ranging from 11.3 to 48.9 percent. Method detection levels (MDL's) using the updated HPLC/MS method varied from 0.009 to 0.045 ?g/L, with the flufenacet OXA MDL at 0.072 g/L. The updated HPLC/MS method is valuable for acquiring information about the fate and transport of the parent chloroacetanilide herbicides in water.

Open-File Report↗
USGS2001

Method of analysis and quality-assurance practices by the U. S. Geological Survey Organic Geochemistry Research Group—Determination of four selected mosquito insecticides and a synergist in water using liquid-liquid extraction and gas chromatography/mass spectrometry

A method of analysis and quality-assurance practices were developed for the determination of four mosquito insecticides (malathion, metho-prene, phenothrin, and resmethrin) and one synergist (piperonyl butoxide) in water. The analytical method uses liquid-liquid extraction (LLE) and gas chromatography/mass spectrometry (GC/MS). Good precision and accuracy were demonstrated in reagent water, urban surface water, and ground water. The mean accuracies as percentages of the true compound concentrations from water samples spiked at 10 and 50 nanograms per liter ranged from 68 to 171 percent, with standard deviations in concentrations of 27 nanograms per liter or less. The method detection limit for all compounds was 5.9 nanograms per liter or less for 247-milliliter samples. This method is valuable for acquiring information about the fate and transport of these mosquito insecticides and one synergist in water.

Kansas↗
USGS2001

Methods of analysis by the U.S. Geological Survey Organic Geochemistry Research Group—Determination of glyphosate, aminomethylphosphonic acid, and glufonsinate in water using online solid-phase extraction and high-performance liquid chromatography/mass spectrometry

An analytical method for the determination of glyphosate, its principal degradation compound, aminomethylphosphonic acid (AMPA), and glufosinate in water with varying matrices has been developed. Four different sample matrices fortified at 0.2 and 2.0 μg/L (micrograms per liter) were analyzed using precolumn derivatization with 9-fluorenylmethylchloroformate (FMOC). After derivatization, cleanup and concentration were accomplished using automated online solid-phase extraction followed by elution with the mobile phase allowing for direct injection into a liquid chromatograph/mass spectrometer (LC/MS). Analytical conditions for MS detection were optimized, and quantitation was carried out using the following representative ions: 390 and 168 for glyphosate; 332, 110, and 136 for AMPA; and 402, 180, and 206 for glufosinate. Matrix effects were minimized by utilizing standard addition for quantification and an isotope-labeled glyphosate (2- 13 C, 15 N) as the internal standard. Method detection limits (MDLs) were 0.084 μg/L for glyphosate, 0.078 μg/L for AMPA, and 0.057 μg/L for glufosinate. The method reporting limits (MRLs) were set at 0.1 μg/L for all three compounds. The mean recovery values ranged from 88.0 to 128.7 percent, and relative standard deviation values ranged from 5.6 to 32.6 percent.

Open-File Report↗
USGS2002

Methods of analysis by the U.S. Geological Survey Organic Geochemistry Research Group: Determination of triazine and phenylurea herbicides and their degradation products in water using solid-phase extraction and liquid chromatography/mass spectrometry

An analytical method for the determination of 7 triazine and phenylurea herbicides and 12 of their degradation products in natural water samples using solid-phase extraction and liquid chromatography/mass spectrometry is presented in this report. Special consideration was given during the development of the method to prevent the formation of degradation products during the analysis. Filtered water samples were analyzed using 0.5 gram graphitized carbon as the solid-phase extraction media followed by liquid chromatography/mass spectrometry. Three different water-sample matrices ground-water, surface-water, and reagent-water samples?spiked at 0.2 and 2.0 micrograms per liter were analyzed. Method detection limits ranged from 0.013 to 0.168 microgram per liter for the parent triazine herbicides and the triazine degradation products. Method detection limits ranged from 0.042 to 0.141 microgram per liter for the parent phenylurea herbicides and their degradation products. Mean recoveries for the triazine compounds in the ground- and surface-water samples generally ranged from 72.6 to 117.5 percent, but deethyl-cyanazine amide was recovered at 140.5 percent. Mean recoveries from the ground- and surface-water samples for the phenylurea compounds spiked at the 2.0-micrograms-per-liter level ranged from 82.1 to 114.4 percent. The mean recoveries for the phenylureas spiked at 0.2-microgram per liter were less consistent, ranging from 87.0 to 136.0 percent. Mean recoveries from reagent-water samples ranged from 87.0 to 109.5 percent for all compounds. The triazine compounds and their degradation products are reported in concentrations ranging from 0.05 to 2.0 micrograms per liter, with the exception of deethylcyanazine and deethylcyanazine amide which are reported at 0.20 to 2.0 micrograms per liter. The phenylurea compounds and their degradation products are reported in concentrations ranging from 0.20 to 2.0 micrograms per liter. The upper concentration limit was 2.0 micrograms per liter for all compounds without dilution.

Open-File Report↗
USGS2003

Methods of analysis by the U.S. Geological Survey Organic Geochemistry Research Group: Determination of acetamide herbicides and their degradation products in water using online solid-phase extraction and liquid chromatography/mass spectrometry

An analytical method for the determination of 6 acetamide herbicides (acetochlor, alachlor, dimethenamid, flufenacet, metolachlor, and propachlor) and 16 of their degradation products in natural water samples using solid-phase extraction and liquid chromatography/mass spectrometry is described in this report. Special consideration was given during the development of the method to prevent the formation of degradation products during the analysis. Filtered water samples were analyzed using octadecylsilane as the solid-phase extraction media on online automated equipment followed by liquid chromatography/mass spectrometry. The method uses only 10 milliliters of sample per injection. Three different water-sample matrices, a reagent-water, a ground-water, and a surface-water sample spiked at 0.10 and 1.0 microgram per liter, were analyzed to determine method performance. Method detection limits ranged from 0.004 to 0.051 microgram per liter for the parent acetamide herbicides and their degradation products. Mean recoveries for the acetamide compounds in the ground- and surface-water samples ranged from 62.3 to 117.4 percent. The secondary amide of acetochlor/metolachlor ethanesulfonic acid (ESA) was recovered at an average rate of 43.5 percent. The mean recoveries for propachlor and propachlor oxanilic acid (OXA) were next lowest, ranging from 62.3 to 95.5 percent. Mean recoveries from reagent-water samples ranged from 90.3 to 118.3 percent for all compounds. Overall the mean of the mean recoveries of all compounds in the three matrices spiked at 0.10 and 1.0 microgram per liter ranged from 89.9 to 100.7 percent, including the secondary amide of acetochlor/metolachlor ESA and the propachlor compounds. The acetamide herbicides and their degradation products are reported in concentrations ranging from 0.05 to 2.0 micrograms per liter. The upper concentration limit is 2.0 micrograms per liter for all compounds without dilution. With the exception of the secondary amide of acetochlor/metolachlor ESA, good precision and accuracy for the chloroacetanalide herbicides and their degradation compounds were demonstrated for the method in buffered reagent water, ground water, and surface water. The extraction method as used did not optimize the recovery of the secondary amide of acetochlor/metolachlor ESA.

Open-File Report↗