Using Isotopic Fractionation to Link Precursor to Product in the Synthesis of (±)-Mephedrone: A New Tool for Combating “Legal High” Drugs

A novel high-temperature combustion interface for compound-specific stable isotope analysis of carbon and nitrogen via high-performance liquid chromatography/isotope ratio mass spectrometry

RATIONALE

In aqueous samples compound-specific stable isotope analysis (CSIA) plays an important role. No direct method (without sample preparation) for stable nitrogen isotope analysis (δ(15) N SIA) of non-volatile compounds is known yet. The development of a novel HPLC/IRMS interface based on high-temperature combustion (HTC) for both δ(13) C and δ(15) N CSIA and its proof of principle are described in this study.

METHODS

To hyphenate high-performance liquid chromatography (HPLC) with isotope ratio mass spectrometry (IRMS) a modified high-temperature combustion total organic carbon analyzer (HTC TOC) was used. A system to handle a continuously large amount of water (three-step drying system), favorable carrier and reaction gas mix and flow, an efficient high-temperature-based oxidation and subsequent reduction system and a collimated beam transfer system were the main requirements to achieve the necessary performance.

RESULTS

The proof of principle with caffeine solutions of the system succeeded. In this initial testing, both δ(13) C and δ(15) N values of tested compounds were determined with precision and trueness of ≤0.5 ‰. Further tests resulted in lower working limit values of 3.5 μgC for δ(13) C SIA and 20 μgN for δ(15) N SIA, considering an accuracy of ±0.5 ‰ as acceptable.

CONCLUSIONS

The development of a novel HPLC/IRMS interface resulted in the first system reported to be suitable for both δ(13) C and δ(15) N direct CSIA of non-volatile compounds. This highly efficient system will probably open up new possibilities in SIA-based research fields. Copyright © 2016 John Wiley & Sons, Ltd.

An overview of recent developments in the analytical detection of new psychoactive substances (NPSs)

New psychoactive substances (NPSs), sometimes referred to as "legal highs" in more colloquial environments/the media, are a class of compounds that have been recently made available for abuse (not necessarily recently discovered) which provide similar effects to the traditional well studied illegal drugs but are not always controlled under existing local, regional or international drug legislation. Following an unprecedented increase in the number of NPSs in the last 5 years (with 101 substances discovered for the first time in 2014 alone) its, occasionally fatal, consequences have been extensively reported in the media. Such NPSs are typically marketed as 'not for human consumption' and are instead labelled and sold as plant food, bath salts as well as a whole host of other equally nondescript aliases in order to bypass legislative controls. NPSs are a new multi-disciplinary research field with the main emphasis in terms of forensic identification due to their adverse health effects, which can range from minimal to life threatening and even fatalities. In this mini-review we overview this recent emerging research area of NPSs and the analytical approaches reported to provide detection strategies as well as detailing recent reports towards providing point-of-care/in-the-field NPS ("legal high") sensors.

Dual element ((15)N/(14)N, (13)C/(12)C) isotope analysis of glyphosate and AMPA by derivatization-gas chromatography isotope ratio mass spectrometry (GC/IRMS) combined with LC/IRMS

To assess sources and degradation of the herbicide glyphosate [N-(phosphonomethyl) glycine] and its metabolite AMPA (aminomethylphosphonic acid), concentration measurements are often inconclusive and even (13)C/(12)C analysis alone may give limited information. To advance isotope ratio analysis of an additional element, we present compound-specific (15)N/(14)N analysis of glyphosate and AMPA by a two step derivatization in combination with gas chromatography/isotope ratio mass spectrometry (GC/IRMS). The N-H group was derivatized with isopropyl chloroformate (iso-PCF), and remaining acidic groups were subsequently methylated with trimethylsilyldiazomethane (TMSD). Iso-PCF treatment at pH <10 gave too low (15)N/(14)N ratios indicating an incomplete derivatization; in contrast, too high (15)N/(14)N ratios at pH >10 indicated decomposition of the derivative. At pH 10, and with an excess of iso-PCF by 10-24, greatest yields and accurate (15)N/(14)N ratios were obtained (deviation from elemental analyzer-IRMS: -0.2 ± 0.9% for glyphosate; -0.4 ± 0.7% for AMPA). Limits for accurate δ(15)N analysis of glyphosate and AMPA were 150 and 250 ng injected, respectively. A combination of δ(15)N and δ(13)C analysis by liquid chromatography/isotope ratio mass spectrometry (LC/IRMS) (1) enabled an improved distinction of commercial glyphosate products and (2) showed that glyphosate isotope values during degradation by MnO2 clearly fell outside the commercial product range. This highlights the potential of combined carbon and nitrogen isotopes analysis to trace sources and degradation of glyphosate.