Patrick L. Williams

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A novel technique of on-line photochemical derivatization is described which can enhance considerably both the sensitivity and specificity of detection in high-performance liquid chromatography (HPLC).. Material eluting from the column is irradiated with a high flux of UV light, which may induce a reaction to form fluorescent or highly UV-absorbing(More)
A high-performance liquid chromatography-radioimmunoassay method for the measurement of cannabinoids in urine is described. The method involves chromatographing a hydrolysed urine sample with high-performance liquid chromatography and quantifying the eluting cross-reacting cannabinoids with radioimmunoassay. It has been applied to the analysis of(More)
A high-pressure liquid chromatography-radioimmunoassay (HPLC-RIA) method for the measurement of cannabinoid levels in plasma is described. The method is capable of quantifying 0.1 ng of a cannabinoid in 1 ml of plasma. The experimental procedure consists of an initial separation of cannabinoids in a plasma extract by HPLC followed by collection of the HPLC(More)
A high-performance liquid chromatography-radioimmunoassay method for the measurement of cannabinoids in plasma and urine is described. The experimental procedure consists of chromatographing a plasma extract or hydrolysed urine sample by high-performance liquid chromatography and quantifying the eluting cross-reacting cannabinoids with radioimmunoassay. The(More)
A delta 9-THC metabolite has been identified in human urine as an ester linked glucuronide of delta 9-THC-11-oic acid. Its identity was established by a comparison of mass spectra from the metabolite extracted from human urine and synthetically prepared material. delta 9-THC-11-oic acid glucuronide was found to be responsible for the major part of RIA(More)
To investigate the long-term weathering of oil from the Deepwater Horizon (DWH) incident, oil-soaked sand patties were collected from Gulf of Mexico beaches from Florida to Alabama over a three-year period from 2012 to 2014. Analysis of oil residues by gas chromatography with flame ionization detection (GC-FID), thin-layer chromatography with flame(More)
The purpose of this study was to evaluate the disposition of elemental platinum (Pt) derived from cisplatin (CDDP) or carboplatin (CBDCA) in the isolated, perfused tumor and skin flap (IPTSF). Flaps were perfused with either 3.0 μg CDDP/ml perfusion medium (n=4 tumor,n=4 control) or 15 μg CBDCA/ml (n=4 tumor,n=3 control) at a rate of 1 ml/min for 3 h. A 2-h(More)
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