Atrazine, alachlor, and carbofuran contamination of well water in central Maine.
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Acetamides↗
Biomedical subjects
L B Perkins
Publications and source records attributed to L B Perkins.
Determination of carbendazim in blueberries by reversed-phase high-performance liquid chromatography.
A fluorescent reversed-phase high-performance liquid chromatographic method was developed for the analysis of carbendazim in blueberries. Recoveries of fortified blueberries at 27 and 810 ng/g were more than adequate with good precision. Forty commercial blueberry samples were analyzed and the amount of carbendazim ranged from none detected (detection limit of 15 ng/g) to 155 ng/g. Confirmation of carbendazim in the blueberry samples was made by enzyme immunoassay and UV photodiode array.
Benzimidazoles↗
Comparison of enzyme-linked immunosorbent assay and high-performance liquid chromatography for the analysis of atrazine in water from Czechoslovakia.
Twenty-two water samples from Bohemian Paradise in Czechoslovakia were analyzed for atrazine (2-chloro-4-ethylamino-6- isopropylamino-1,3,5-triazine) by enzyme immunoassay (EIA) and high-performance liquid chromatography (HPLC). Three samples were drinking water, the others were creek water. The amount of atrazine found by EIA ranged from 0.2 to 12,700 ng/ml and 0.10 to 10,300 ng/ml by HPLC. Agreement between the methods was good. Nine samples containing the highest concentrations of atrazine were used to check the day-to-day reproducibility of both methods at high atrazine levels. The percent coefficients of variation (% CVs) ranged from 5.9 to 26.2 for the EIA and 1.5 to 33.2 for the HPLC. Day to day % CV values for each calibrator concentration ranged from 5.7 to 10.9 for EIA and 9.9 to 13.9 for HPLC. Sensitivity of the EIA was 0.2 ng/ml while it was 0.1 ng/ml for solid phase extraction HPLC and slightly less than 60 ng/ml for direct injection HPLC.
Atrazine↗
NACHRI study quantifies children's hospitals uniqueness.
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Bed Occupancy↗
Determination of hexazinone in groundwater by direct-injection high-performance liquid chromatography.
Hexazinone has been detected at levels ranging from 0.2 to 50 micrograms/L in many groundwater samples from eastern Maine over the past decade. A rapid and inexpensive direct-injection high-performance liquid chromatographic (HPLC) method has been developed to monitor contamination levels of the herbicide. The method is sensitive (limit of quantitation = 0.33 microgram/L) and is linear to 33.0 micrograms/L (R2 = 0.9995). Direct injection results from 50 field samples compared well (R2 = 0.98) with an HPLC method using solid-phase extraction for concentration and cleanup. The technique is very reproducible (coefficients of variation of 0-8.4% within day and 3.0-13.2% between day) and eliminates loss of analyte because of fewer steps in the procedure.
Chromatography, High Pressure Liquid↗
Liquid chromatographic method for analysis of elemental sulfur in pesticide formulations.
A nonaqueous reverse-phase liquid chromatographic (LC) method has been developed to determine elemental sulfur in pesticide formulations. Samples were extracted in 50 mL of stabilized tetrahydrofuran (THF) by gentle swirling while sonicating for 1 min. A 5 microL aliquot was injected into the LC instrument equipped with a Vydac 218 TP 54 column. The mobile phase was methanol-acetonitrile-stabilized tetrahydrofuran (58.5 + 40 + 1.5). Sulfur was monitored at 280 nm. Retention time was approximately 5 min with total analysis time of 7 min. For 6 different products analyzed 12 times each, the coefficients of variations were all less than 3.5%. Purity of each sulfur peak was checked by using a photodiode array detector in the spectrum and absorbance ratio modes. No impurities were observed at the monitoring wavelength.
Chromatography, Liquid↗
Determination of thiabendazole in potatoes, fruits, and their processed products by liquid chromatography.
A liquid chromatographic method has been developed for analysis of the fungicide thiabendazole (TBZ) in fruits, potatoes, and their processed products. Extraction was performed in a 50 mL polyethylene conical centrifuge tube with a basic solution. TBZ was partitioned into methylene chloride with a polytron. No further cleanup was needed. Separation was carried out on a 5 microns Ultracarb 30 ODS column with fluorescent detection, excitation at 305 nm and emission at 345 nm. Total analysis time including extraction was 25 min per sample. Recoveries ranged from 77 to 135%. Average percent recovery for all sample types spiked from 5 ppb to 387 ppm was 94% with a coefficient of variation (CV) of 11%. Overall intra-assay CVs varied from 1.8 to 23%, and interassay CVs ranged from 1.8 to 15%. Of 194 commercial samples analyzed for TBZ, 129 were positive. TBZ in positive samples ranged from 1.1 ppb to 72.5 ppm. The limit of quantitation varied from 2.5 ppb for juices, 2.5 ppb for fruits and potatoes, and 4.5 ppb for bulk concentrates. Detection limits were 1.0 ppb for juice, fruits, and potatoes and 2 ppb for bulk concentrates. TBZ levels in the positive samples were corroborated by immunoassay.
Chromatography, Liquid↗
Determination of methyl 2-benzimidazolecarbamate in bulk fruit juice concentrates by competitive-inhibition enzyme immunoassay.
A polyclonal enzyme immunoassay (EIA) was used to quantitate methyl 2-benzimidazolecarbamate (MBC or carbendazim), a degradation product of benomyl, in bulk fruit juice concentrates. These concentrates are used by industrial producers to prepare juice or juice concentrates sold in supermarkets. Total sample analysis time was less than 18 min without cleanup or 35 min with cleanup. As many as 8 samples can be analyzed simultaneously, with a limit of quantitation of 10 ppb. The assay's dynamic range ran from 0.5 to 20 ppb MBC but was best from 0.5 to 10 ppb. Intra-assay coefficients of variation (CVs) varied from 4.0 to 13% for standards and from 4.1 to 26% for samples. Interassay CVs varied from 4.5 to 47% for standards and 5.6 to 22% for samples. Average recovery of several juice concentrates spiked at 10 to 290 ppb was 97%. A total of 140 juice concentrates comprising 20 different kinds of juice were analyzed by 2 EIA methods and one liquid chromatographic (LC) procedure. MBC-positive samples gave the following correlation coefficients: 0.954 for EIA without cleanup vs LC, 0.956 for EIA with cleanup vs LC, and 0.978 for EIA with cleanup vs EIA without cleanup. MBC concentrations in MBC-positive juice samples ranged from 5 to 2960 ppb.
Benzimidazoles↗
Determination of thiabendazole in fruits and vegetables by competitive-inhibition enzyme immunoassay.
An enzyme immunoassay (EIA) was developed for analysis of thiabendazole (TBZ) in fruits and vegetables. A commercial kit using a polyclonal antibody for benomyl-carbendazim was used. Total analysis time, including sample preparation, was 35 min. As many as 8 samples can be analyzed simultaneously, with a limit of quantitation of 9 ppb. The assay's dynamic range ran from 9 to 304 ppb TBZ. Intra-assay coefficients of variation (CVs) ranged from 5.0 to 9.6% for standards and 11 to 30% for samples. Interassay CVs varied from 4.4 to 15% for standards and from 10 to 24% for samples. Average recovery from 29 samples spiked at 50-50,000 ppb was 116%. A total of 107 food products comprising 12 different fruits and vegetables and their processed products were analyzed for their TBZ content by EIA and liquid chromatography (LC). Of these samples, 84 were positive for TBZ by both methods, with a correlation coefficient (r) of 0.989. Eight samples had none detected by either technique, and 15 were positive for carbendazim. Concentrations of TBZ ranged from 11 to 94,000 ppb. The immunoassay with methanol sonication shows promise as a rapid screening method for TBZ in foods.
Binding, Competitive↗
Determination of methyl 2-benzimidazolecarbamate in wine by competitive inhibition enzyme immunoassay.
A benomyl polyclonal enzyme immunoassay (EIA) commercial kit was used to quantitate methyl 2-benzimidazolecarbamate (MBC), a degradation product of benomyl in wine. Total analysis time, including sample preparation, was 30 min. As many as 8 samples can be analyzed simultaneously with a limit of quantitation of 5 ppb. The assay logarithmic response was linear from 0.4 to 26 ppb MBC. Intra-assay percent coefficients of variation (%CVs) ranged from 2.4 to 13 for standards and from 7.4 to 21 for actual wine samples. Interassay %CVs varied from 2.6 to 15 for the standards and from 6.9 to 23 for the samples. Average recovery from samples spiked at 10-10,000 ppb was 93% for evaporated red and white wines. MBC was determined in 134 different wines by immunoassay and liquid chromatography (LC). Of these samples, 98 were positive for MBC by both methods with a correlation coefficient (r) of 0.986. The other 36 samples had MBC levels that either were not detectable by either procedure or were below the 10 ppb limit of quantitation for LC. Concentrations of MBC in wine ranged from 5 to 1329 ppb, with the majority ranging from 10 to 300 ppb. Also, a mini-study was conducted using the plate EIA format.
Animals↗