Hercules, CA, United States
Hercules, CA, United States

Time filter

Source Type

Ahn K.C.,University of California at Davis | Gee S.J.,University of California at Davis | Kim H.-J.,University of California at Davis | Aronov P.A.,University of California at Davis | And 3 more authors.
Analytical and Bioanalytical Chemistry | Year: 2011

Pyrethroid insecticides widely used in forestry, agricultural, industrial, and residential applications have potential for human exposure. Short sample preparation time and sensitive, economical high-throughput assays are needed for biomonitoring studies that analyze a large number of samples. An enzyme-linked immunosorbent assay (ELISA) was used for determining 3-phenoxybenzoic acid (3-PBA), a general urinary biomarker of exposure to some pyrethroid insecticides. A mixed-mode solid-phase extraction reduced interferences from acid hydrolyzed urine and gave 110∈±∈6% recoveries from spiked samples. The method limit of quantification was 2 μg/L. Urine samples were collected from forestry workers that harvest pine cone seeds where pyrethroid insecticides were applied at ten different orchards. At least four samples for each worker were collected in a 1-week period. The 3-PBA in workers classified as high, low, or no exposure based on job analysis over all sampling days was 6.40∈±∈9.60 (n∈=∈200), 5.27∈±∈5.39 (n∈=∈52), and 3.56∈±∈2.64 ng/mL (n∈=∈34), respectively. Pair-wise comparison of the differences in least squares means of 3-PBA concentrations among groups only showed a significant difference between high and no exposure. Although this difference was not significant when 3-PBA excretion was normalized by creatinine excretion, the general trend was still apparent. No significant differences were observed among days or orchards. This ELISA method using a 96-well plate was performed as a high-throughput tool for analyzing around 300 urine samples measured in triplicate to provide data for workers exposure assessment. © 2011 Springer-Verlag.

Ahn K.C.,Cancer Center | Ahn K.C.,PTRL West Inc. | Kasagami T.,Cancer Center | Kasagami T.,Mitsubishi Group | And 7 more authors.
Environmental Science and Technology | Year: 2012

A sensitive, competitive indirect enzyme-linked immunosorbent assay (ELISA) for the detection of the antimicrobial triclocarban (TCC) was developed. The haptens were synthesized by derivatizing the para position of a phenyl moiety of TCC. The rabbit antisera were screened and the combination of antiserum 1648 and a heterologous competitive hapten containing a piperidine was further characterized. The IC 50 and detection range for TCC in buffer were 0.70 and 0.13-3.60 ng/mL, respectively. The assay was selective for TCC, providing only low cross-reactivity to TCC-related compounds and its major metabolites except for the closely related antimicrobial 3-trifluoromethyl-4, 4′-dichlorocarbanilide. A liquid-liquid extraction for sample preparation of human body fluids resulted in an assay that measured low part per billion levels of TCC in small volumes of the samples. The limits of quantification of TCC were 5 ng/mL in blood/serum and 10 ng/mL in urine, respectively. TCC in human urine was largely the N- or N′-glucuronide. TCC concentrations of biosolids measured by the ELISA were similar to those determined by LC-MS/MS. This immunoassay can be used as a rapid, inexpensive, and convenient tool to aid researchers monitoring human/environmental exposure to TCC to better understand the health effects. © 2011 American Chemical Society.

Suzuki Y.,Sumitomo Chemical | Lopez A.,PTRL West Inc. | Ponte M.,PTRL West Inc. | Fujisawa T.,Sumitomo Chemical | And 2 more authors.
Journal of Agricultural and Food Chemistry | Year: 2011

Photodegradation profiles of the pyrethroid insecticide phenothrin on a moistened U.S. soil thin layer was investigated by using its predominant component, the 1R-trans-isomer (I), under continuous exposure to light at >290 nm from a xenon arc lamp. Its degradation was moderately accelerated by irradiation with half-lives of 5.7-5.9 days (dark control 21-24 days), mainly via successive oxidation of the 2-methylprop-1-enyl group and ester cleavage followed by mineralization to carbon dioxide. Spectroscopic and cochromatographic analyses showed that the major degradates were the alcohol and ketone derivatives of I formed via photoinduced oxidation of the 2-methylprop-1-enyl group by singlet oxygen. The photoinduced generation of singlet oxygen in/on the soil surface was confirmed by using chemical trapping reactions together with ESR spectroscopy. © 2011 American Chemical Society.

Loading PTRL West Inc. collaborators
Loading PTRL West Inc. collaborators