Chromatography-Mass Spectrometry in Forensic Toxicology

LIQUID CHROMATOGRAPHY-MASS SPECTROMETRY IN FORENSIC TOXICOLOGY 

The arrival of useable and practical atmospheric-pressure ionization (API) technology offered a solution to the analysis of compoimds having any of the attributes of low dose, thermal sensitivity, or high polarity. LC—MS also offered superior identification capability compared to LC—DAD. Pharmaceutical researchers were quick to exploit the advantages of LC—MS, and consequently, drugs of lower therapeutic concentration could be evaluated in clinical trials and finally approved for the marketplace. Once these drugs reached the community, LC—MS inevitably became an essential part of the modem forensic toxicology laboratory. 

For a time, LC—MS foimd itself a niche in the forensic toxicology laboratory, for the analysis of those drugs not detectable by GC, due to thermal instability or high polarity, or not detectable by LC—LTV techniques, due to low dose or poor selectivity. Now however, LC—MS is not just supplementing traditional GC and LC—spectrophotometric techniques, it is becoming a preferred detection method for a diverse range of drugs. This section discusses various aspects of the use of LC—MS in forensic 

By the late 1990s, electrospray ionization (ESI) and atmospheric-pressure chemical ionization (APCI) had become the dominant interfaces in use for the analysis of biomolecules and pharmaceuticals. This was largely due to their wide range of applicabilify compatibility with LC flow rates, relative simplicity, and robust performance [21—23]. APCI and ESI are bofh relafively low-energy processes and, more often than not, produce only a protonated or deprotonated molecular ion, which has consequences for reliable identification, which is discussed later. 

Essentially, ESI is said to rely on the production of ions while in solution, before being coaxed into the gas phase through nebulization, droplet evaporation, and coulombic explosions [29]. Therefore, it is a general rule that basic drugs should be analyzed using an acidic mobile phase to facilitate production of positively charged, protonated analytes. 

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Van Bocxlaer JF, Clauwaert KM, Lambert WE, et al. (2000) Liquid chromatography-mass spectrometry in forensic toxicology. Mass Spectrometry Review 19(4) 165-214. 

A Comparison of Enzyme Immunoassay and Gas Chromatography/Mass Spectrometry in Forensic Toxicology J. Forensic Sci. 25(2) 314-319 (1980) CA 93 20145z... 

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