Pitfalls in drug testing by hyphenated low‐ and high‐resolution mass spectrometry

Abstract

This paper reviews various pitfalls observed during developing, validation, application, and interpretation of drug testing approaches using GC-MS and low-and high-resolution LC-MS. They include sampling and storage of body samples, sample adulteration and contamination, analyte stability, sample preparation without or with cleavage of conjugates, extraction, derivatization, internal standardization, false negative and positive results by GC-MS or LC-MS screening and/or confirmation procedures including artifact formation, ion suppression or enhancement by electrospray ionization, and finally pitfalls in data interpretation. Conclusions and prospects close the Tutorial. K E Y W O R D S

Simultaneous quantification of all B vitamins and selected biosynthetic precursors in seawater and bacteria by means of different mass spectrometric approaches

“…Masses of other, untargeted compounds get lost. Incorrect fragment ion masses or retention time windows lead to false negative results, even if the analyte is present in the sample, or might lead conversely to a signal appearance even though the analyte is not present (false positive) [ 19 ].…”

Hyphenated high-resolution mass spectrometry—the “all-in-one” device in analytical toxicology?

“…Of course, also for HRMS, potential pitfalls have to be considered and details can be found in ref. [9]. Today, HRMS is the only technique that fulfills the criteria of an all-in-one device for the various applications needed in analytical toxicology.…”

“…Interestingly, GC coupled to HRMS (GC-HRMS) was applied for a high-throughput screening for detection of about 300 drugs and poisons in human blood using an OT analyzer [18]. However, considering the limitations of GC [9] such as risk of thermal degradation, limited volatility without derivatization, and less sensitivity, the advantage over corresponding LC-HRMS approaches cannot be assessed. In the last few years, a clear trend to highly selective and sensitive screening by LC-HRMS/MS with QTOF or QOT analyzers was observed [19][20][21], particularly since hundreds of so-called new psychoactive substances (NPS) appeared on the drugs of abuse market per year [2-6, 12, 22].…”

“…The elemental composition of a molecule can be calculated by accurate determination of the parent and fragment masses allowing provisional identification of unknown compounds, e.g., by comparing with lists of the exact masses and empirical formulas of potential poisons [8]. However, isomeric compounds can only be differentiated by different fragmentation [9]. The increasing number of HRMS presentations at scientific meetings, corresponding original papers, and review articles [2-7, 10-12] may lead to the presumption that HRMS has or will become the all-in-one device for targeted or non-targeted (also named untargeted) screening, quantification, drug metabolism, and metabolomics in analytical toxicology, namely in clinical and forensic toxicology, forensic chemistry, doping control, etc.…”

Substance Identification in Anti-Doping Control-Some Issues

“…The first quadrupole selects one diagnostic ion, which is then colliding with a target gas in the second quadrupole, followed by the selection of product ions by the third quadrupole. Selected reaction monitoring (also called multiple reaction monitoring) uses two diagnostic precursor-product ion transitions (qualifier ions) and one ion transition for normalization (target ion) [2]. In WADA terminology the target ion is called base peak and serves to normalize the other signals between 0 and 100%.…”