Journal - Association of Official Analytical Chemists最新文献

A method for the quail-quantitative evaluation of pentachlorophenol (PCP) in solid matrixes has been developed. The procedure is based on solid-liquid extraction of solid samples (leather or wood), followed by purification on a cyanopropyl column and determination of the preservative by second derivative UV spectroscopy considering the PCP A peak-through value (304-297 nm). The method allows rapid PCP determination in the concentration range 1-40 micrograms/mL; any matrix interference is avoided by the purification step and recoveries of the preservative were 99.12% (RSD% 0.13) for the leather matrix and 98.03 (RSD% 0.17) for the wood matrix.

The present study uses gas liquid chromatography (GLC) electron capture detection with packed and capillary columns to detect polychlorinated biphenyls (PCBs) in serum samples from people living near the electric car repair and maintenance facility of the Southeastern Pennsylvania Transit Authority in Paoli, Pennsylvania. Most of the cohort surveyed had serum patterns similar to patterns for Aroclor 1260 (AR 1260); a small portion (3/89) had patterns indicative of an AR with higher chlorination (e.g., AR 1268). In addition to analyzing serum samples from humans, we also analyzed serum samples from canines (pets of some of the subjects). In general, the serum pattern for canines was less descriptive for AR 1260 than the pattern for humans; however, the pattern for several canines (9/16) was that of the higher chlorinated PCBs (e.g., AR 1268). By using mass spectrometry and capillary column GLC, we confirmed the presence of high molecular weight polychlorinated congeners in both human and animal samples. We were not able to show a statistically significant relationship between serum patterns of PCBs in canines and their owners or between canines and certain behavioral traits (e.g., runs free, retrieves, hours outside, hours inside). However, the correlation between PCBs quantified as AR 1268 and canines' residence time was statistically significant.

Bacillus cereus is an environmentally ubiquitous, Gram-positive, spore-forming bacillus responsible for 2 distinct foodborne disease syndromes as well as other manifestations of pathogenicity. The rapid-onset, "emetic," foodborne-disease syndrome is associated with an emetic toxin; the delayed-onset, "diarrheal" syndrome is associated with elaboration of enterotoxin. The majority of methods for detection of these toxins have relied on in vivo testing. More recent work on purification of enterotoxin facilitated the development of a rapid, specific, fluorescent immunodot assay and a tissue culture screening assay for enterotoxin. Work on characterization and detection of emetic toxin is ongoing.

The present paper describes a method for determination of oxolinic acid in salmon muscle tissue. Tissue (0.5-2 g) mixed with 2 g anhydrous sodium sulfate is extracted twice with ethyl acetate, centrifuged, and the extract evaporated. The residue is partitioned in a mixture of hexane and 0.01M oxalic acid and the aqueous phase chromatographed using fluorescence detection at 327 nm excitation and 369 nm emission. Calibration and standard curves are linear from 10-200 ppb and 100-2000 ppb at different sensitivity settings. Recoveries ranged from 71-83% in spiked blanks, with a CV of 4-10.3% over a 2-week period. Preliminary results in treated salmon were variable, possibly because some fish refused to eat medicated feed.

A liquid chromatographic (LC) method for the determination of the antifungal agent tolnaftate was developed. Isolation of the analyte was achieved by direct extraction or dilution with acetonitrile-water (80 + 20) followed by reverse-phase liquid chromatography using a C18 column. The mobile phase was acetonitrile-water (80 + 20) acidified with phosphoric acid. Detection was by UV absorption at a wavelength of 257 nm. The proposed procedure was applied to 20 consumer products comprising 6 formulation types, including solutions, powders, liquid and power aerosols, creams, and gels. The precision (RSD) for the products ranged from 0.23 to 1.16% (n = 5), and recoveries via fortification ranged from 98.1 to 103.0%. Six different brands of C18 columns were evaluated for use with the method. The overall simplicity and versatility of the method suggest possible adaptations to both regulatory and quality-control situations.

The present collaborative study compares recovery of Campylobacter jejuni from food in 2 agar media. Six laboratories analyzed 8 samples each of chicken liver inoculated with Campylobacter jejuni. Samples were enriched in Preston broth and isolation was carried out on Preston agar (PA) and campylobacter blood-free selective medium (CBFS), a charcoal-based medium with cefoperazone and amphoteracin as antibiotic supplements. There was no difference in the recovery rate between the 2 agar media; however, the specificity of CBFS was better than that of PA. There was a slightly better growth of campylobacters, and competing organisms were more inhibited on CBFS than on PA.