Further Studies on Interfering Peaks in Gas Chromatographic Exclusion Screening of Direct Chloroform Extracts of Blood

• NCJ Number: 70072
• Author(s): S K Niyogi; F Rieders
• Date Published: 1969
• Length: 10 pages
• Sale Source: National Institute of Justice/
• Language: English
• Country: United States of America
• Note: Presented at the 5th International Meeting of Forensic Sciences, Toronto, Canada, June 5-11, 1969

Annotation

This report presents a continuation of previous work on the interference by endogenous biochemicals in the gas chromatographic exclusion screening of directly extractable drugs.

Abstract

Gas chromatographic retentions were determined using the 3 percent solutions of these biogenic compounds: indole, 2-phenylethylamine, beta-hydroxybutyric acid, glycine, cholesterol, cortisol, urea, tyramine, and stearic acid. Gas chromatographs with flame ionization detector and 4 ft by one-eighth inch stainless steel column packed with 3 percent OV 17 on 80 one-hundredths mesh chromosorb G HP (Supelco) were used. H2 and air flows were adjusted daily for maximum response to the test mixture components. With glycine, cholesterol, cortisol, urea, tyramine, and stearic acid, no response was obtained with 60 gamma at an attenuation of about x 1000. The detection limits of indole, 2-phenylethylamine and beta-hydroxybutric acid by gas chromatography is 300 nanogram, 300 nanogram, and 2.5 microgram respectively. Whether or not the three agents under study actually interfere depends also on their extractability in this procedure. In the procedure, a portion of the chloroform extract is evaporated on a solid injector prior to introduction into the gas chromatograph. The results obtained when 1 ml blood containing 0.4mg percent indole, 50 mg percent 2-phenylethylamine and 75 mg percent beta-hydroxybutyric acid was extracted with 0.2 ml chloroform, 2 microliters of the extract were evaporated on a solid injector and introduced into the gas chromatograph at an attenuation of x 32. Theoretically corresponding to 4 gamma indole; 500 gamma phenylethylamine and 750 gamma betabeta-hydroxybutyric acid, the actual amounts seen correspond to less than 1 percent of this. By this procedure, individually determined limits for indole, 2-phenylethylamine, and beta-hydroxybutyric acid in blood were found. These three endogenous agents have the same or alsmost coincidence retention distance with some drugs. So interference is evident. These and sometimes even high concentrations may reasonably be expected at times in postmortem blood. Thus, these agents can result in false positives and in falsely elevated values of drugs with the same or similar retention times. Further methodological explanations tables and figures are provided.