After this manuscript was submitted, an article appeared describing the 31P NMR relaxation of 140 base pair long DNA.23 The correlation time for internal motion of the phosphate of DNA was found to be 0.4 ns, which is in agreement with the value obtained here for larger DNA. Both values for long, double-stranded DNA are In contrast to the correlation time determined for deoxyollgonucleotldes which was reported to be at least 1 ns16 for reasons discussed In the text. ( 23) L. Kievan, I. M. Armitage, and D. M. Crothers, Nucleic Acids Res., 6, 1607.(24) We have recently examined rat-liver ribosomes (P. Bolton, G. Clawson, and T. L. James, submitted) and find that the RNA in intact ribosomes exhibits local motion which is restricted by about an order of magnitude relative to free RNA.
This article reviews modern analytical instrumentation in forensic toxicology for identification and quantification of drugs and toxins in biological fluids and tissues. A brief description of the theory and inherent strengths and limitations of each methodology is included. The focus is on new technologies that address current analytical limitations. A goal of this review is to encourage innovations to improve our technological capabilities and to encourage use of these analytical techniques in forensic toxicology practice.
Understanding cocaine and metabolites urinary excretion following smoking is important for interpretation of urine test results in judicial, workplace and treatment settings. In National Institute on Drug Abuse approved studies on a secure research unit, six subjects smoked placebo, 10, 20, and 40 mg cocaine with a precise dose delivery device and six different subjects smoked 42 mg cocaine in a glass pipe. Urine specimens (n = 700) were collected for up to seven days and analyzed for cocaine (COC), benzoylecgonine (BE), ecgonine methylester (EME), mhydroxybenzoylecgonine (mOHBE), p-hydroxybenzoylecgonine (pOHBE), norbenzoylecgonine (NBE), and ecgonine (EC) by gas chromatography-mass spectrometry. Results (mean ± SE) for the 40-mg precise delivery doses are as follows: COC BE EME mOHBE pOHBE NBE EC Cutoff (ng/mL)
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