Derivatization in trace organic analysis: use of an all-glass conical reaction vial.
Abdel-Baky-S; Allam-K; Giese-RW
Anal Chem 1992 Nov; 64(22):2882-2884
A previously reported analytical procedure for diol epoxide polyaromatic hydrocarbon (DEPAH) DNA adducts, in which isolated adducts were subjected to three sequential chemical steps before detection by gas chromatography electron capture negative ion mass spectrometry, was complicated by severe irreproducibility. The problem was due to microscopic brown, black specks in the commercial vials and polytetrafluoroethylene (PTFE) lined plastic caps used for the assay. When vials fabricated in house were used, reproducibility was attained. The chemical steps involved were: acid hydrolysis to release the DEPAH as a tetrol from DNA; oxidation of the tetrol with potassium superoxide to a corresponding dicarboxyl PAH; and esterification of the latter compound with pentafluorobenzyl-bromide. Irreproducibility occurred at the 100 picogram level of tetrol analyte, even though the vials were cleaned with detergent, nitric-acid, and methanol. Although the vials appeared clean visibly, closer microscopic examination revealed recalcitrant tiny brown and black specks stuck to the inner wall that varied from vial to vial. In addition, when the plastic cap fitted with a PTFE liner was screwed down tightly onto a vial to seal it, white particles were dislodged into the vial. The vials were replaced with all glass vials with ground glass stoppers, and reproducibility of the blanks and tetrol analyte were improved. The authors conclude that all glass vials are useful for their convenience and reproducibility.
NIOSH-Publication; NIOSH-Grant; Chromatographic-analysis; Polycyclic-aromatic-hydrocarbons; Chemical-analysis; Qualitative-analysis; Laboratory-equipment; Microscopy; Quantitative-analysis; Equipment-reliability
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