RESUMEN
Pome fruit growers and crop consultants have expressed concerns about the seasonal release performance of commercial codling moth mating disruption dispenser products. Because of these concerns, we developed a laboratory flow-through volatile collection system (VCS) for measuring the volatile release of the codling moth sex pheromone, codlemone, from commercially available hand-applied dispensers. Under controlled air-flow and temperature conditions, the released vapor was trapped onto a polyurethane foam adsorbent followed by solvent extraction, solvent reduction, and GC/MS determination. Method recovery and breakthrough validations were performed to demonstrate system reliability before determining codlemone release from commercial dispensers field-aged over 140 days. The volatile collection was carried out in a consistent manner among five dispenser types most commonly used by growers, so that direct comparison of performance could be made. The comparison showed differences in the amount of pheromone released and in the patterns of release throughout the season between dispenser types. The variation in release performance demonstrates the need for routine evaluation of commercially marketed mating disruption dispensers. We believe that the simple and cost-effective volatile collection system can assist pheromone dispenser manufacturers in determining seasonal dispenser performance before new products are introduced into the commercial market and in rapidly verifying dispenser release when field-aged dispenser efficacy is in question.
Asunto(s)
Dodecanol/análogos & derivados , Dodecanol/administración & dosificación , Control de Insectos/instrumentación , Mariposas Nocturnas , Agricultura/métodos , Animales , Dodecanol/análisis , Cromatografía de Gases y Espectrometría de Masas , Control de Insectos/métodos , Estaciones del Año , VolatilizaciónRESUMEN
Acephate is a commonly used organophosphate insecticide applied on agricultural crops and in residential communities. Because very little acephate is metabolized prior to excretion, the parent pesticide compound can be measured in human urine. The residue method must be sensitive enough to determine human exposure and potential health risk for both agricultural workers and their families who may be exposed by pesticide drift or by inadvertent carry-home residues. A reliable and sensitive method was developed to measure acephate concentrations in human urine. Urine was diluted with water and acetone, adjusted to a neutral pH, and partitioned twice in acetone-methylene chloride (1 + 1, v/v), with NaCl added to aid separation. The solvent-reduced organic phase extracts were clarified by activated charcoal solid-phase extraction and then adjusted to a final volume with the addition of a D-xylose analyte protectant solution to reduce matrix enhancement effects. Acephate concentrations in urine were determined by gas chromatography using pulsed flame photometric detection. The method limit of detection was established at 2 microg/L, with a method limit of quantitation of 10 microg/L. The average recovery from urine fortified with 10-500 microg/L was 102 +/- 12% (n = 32).
Asunto(s)
Insecticidas/análisis , Insecticidas/orina , Compuestos Organotiofosforados/análisis , Compuestos Organotiofosforados/orina , Urinálisis/métodos , Acetona/análisis , Química Orgánica/métodos , Cromatografía de Gases , Humanos , Concentración de Iones de Hidrógeno , Insecticidas/química , Cloruro de Metileno/análisis , Modelos Químicos , Compuestos Organofosforados/análisis , Compuestos Organotiofosforados/química , Residuos de Plaguicidas/análisis , Fosforamidas , Estándares de Referencia , Reproducibilidad de los Resultados , Riesgo , Sensibilidad y Especificidad , Cloruro de Sodio/química , Solventes , Orina , Xilosa/químicaRESUMEN
A rugged and sensitive method was developed to monitor urinary concentrations of O,S-dimethyl hydrogen phosphorothioate (O,S-DMPT), a specific biomarker of exposure to the organophosphate insecticide methamidophos. After pH adjustment and C18 solid phase extraction column cleanup, the urine was lyophilized at a low temperature to prevent loss of possibly highly volatile and unstable O,S-DMPT metabolite. The dried residue was derivatized using N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide and 1% tert-butyldimethylchlorosilane (MTBSTFA + 1% TBDMCS) in acetonitrile. After it was filtered, the derivatized product was analyzed and quantified by gas chromatography using a pulse flame photometric detector specific for phosphorus compounds. The limit of detection for this method was 0.004 ppm with a limit of quantitation of 0.02 ppm of urine. The mean recovery value for O,S-DMPT from 17 urine samples fortified at varying concentrations was 108% with a standard deviation of 12%.
Asunto(s)
Biomarcadores/orina , Exposición a Riesgos Ambientales , Insecticidas , Compuestos Organotiofosforados/orina , Cromatografía de Gases , Frío , Liofilización , Concentración de Iones de HidrógenoRESUMEN
OBJECTIVE: To evaluate the elimination kinetics of chlorhexidine in milk when used as an intramammary infusion to stop lactation in cows. DESIGN: Prospective study. ANIMALS: 6 cows. PROCEDURE: The study was performed in 2 phases. Three cows were studied in each phase. All cows were treated with chlorhexidine suspension by infusion into a mastitic mammary gland quarter after 2 milkings 24 hours apart. Foremilk samples (100 mL) were collected from treated and untreated (controls) mammary gland quarters of each cow. Chlorhexidine was extracted from raw milk, and residue concentrations were quantified by use of high-performance liquid chromatography. Foremilk samples from days 2, 5, and 8 were analyzed in phase I, and samples from time 0 and days 3, 7, 14, 21, 28, 35, and 42 were analyzed in phase II. RESULTS: In phases I and II, there was no quantifiable transference of chlorhexidine to milk in untreated mammary gland quarters. Measurable chlorhexidine residues were found in milk from treated mammary gland quarters of 2 cows throughout the 42-day sample period in phase II. Estimated mean elimination half-life for chlorhexidine in milk was 11.5 days. CONCLUSIONS AND CLINICAL RELEVANCE: On the basis of the long elimination half-life of chlorhexidine in milk from treated mammary gland quarters, the lack of human dietary exposure data to suggest a food tolerance for chlorhexidine in food products, and the Food and Drug Administration's published zero tolerance for chlorhexidine in uncooked edible calf tissues, we do not recommend extralabel use of chlorhexidine suspension as a treatment to stop lactation in mastitic mammary gland quarters of cows.
Asunto(s)
Antiinfecciosos Locales/farmacocinética , Clorhexidina/farmacocinética , Residuos de Medicamentos/análisis , Mastitis Bovina/metabolismo , Leche/metabolismo , Animales , Antiinfecciosos Locales/uso terapéutico , Bovinos , Clorhexidina/uso terapéutico , Cromatografía Líquida de Alta Presión/métodos , Cromatografía Líquida de Alta Presión/veterinaria , Femenino , Lactancia/efectos de los fármacos , Mastitis Bovina/tratamiento farmacológico , Leche/química , Estudios ProspectivosRESUMEN
A residue method was developed as part of a pharmacokinetics study to determine the elimination of chlorhexidine in raw milk after intramammary infusion into dairy cows affected with bovine mastitis. The developed liquid/liquid and solid-phase extraction procedures effectively reduced sources of milk product interferences in the final extract. By optimizing mobile-phase pH buffer/acetonitrile gradient conditions and employing an end-capped reverse-phase polar embedded-phase chromatographic column, excellent peak resolution was achieved without the additional need of mobile-phase amine modifiers or ion-pairing reagents. The combined cleanup and chromatographic method steps reported herein were sensitive and reliable for determining the pharmacokinetic elimination of chlorhexidine following intramammary infusion. The residue method was found to be rugged with a lower detection limit of 0.1 ppm.