An online method for the analysis of volatile organic compounds in electronic cigarette aerosol based on proton transfer reaction mass spectrometry.

RATIONALE: Due to the recent rapid increase in electronic cigarette (e-cigarette) use worldwide, there is a strong scientific but also practical interest in analyzing e-cigarette aerosols. Most studies to date have used standardized but time-consuming offline technologies. Here a proof-of-concept for a fast online quantification setup based on proton transfer reaction mass spectrometry (PTR-MS) is presented. METHODS: The combination of a novel sampling interface with a time-of-flight PTR-MS instrument specially designed for three scenarios is introduced: (i) mainstream aerosol analysis (aerosol that the user inhales prior to exhalation), and analysis of exhaled breath following (ii) mouth-hold (no inhalation) and (iii) inhalation of e-cigarette aerosols. A double-stage dilution setup allows the various concentration ranges in these scenarios to be accessed. RESULTS: First, the instrument is calibrated for the three principal constituents of the e-cigarettes' liquids, namely propylene glycol, vegetable glycerol and nicotine. With the double-stage dilution the instrument's dynamic range was easily adapted to cover the concentration ranges obtained in the three scenarios: 20-1100 ppmv for the mainstream aerosol characterisation; 4-300 ppmv for the mouth-hold; and 2 ppbv to 20 ppmv for the inhalation experiment. CONCLUSIONS: It is demonstrated that the novel setup enables fast, high time resolution e-cigarette studies with online quantification. This enables the analysis and understanding of any puff-by-puff variations in e-cigarette aerosols. Large-scale studies involving a high number of volunteers will benefit from considerably higher sample throughput and shorter data processing times.

Selective reagent ionisation-time of flight-mass spectrometry: a rapid technology for the novel analysis of blends of new psychoactive substances.

In this study we demonstrate the potential of selective reagent ionisation-time of flight-mass spectrometry for the rapid and selective identification of a popular new psychoactive substance blend called 'synthacaine', a mixture that is supposed to imitate the sensory and intoxicating effects of cocaine. Reactions with H3O(+) result in protonated parent molecules which can be tentatively assigned to benzocaine and methiopropamine. However, by comparing the product ion branching ratios obtained at two reduced electric field values (90 and 170 Td) for two reagent ions (H3O(+) and NO(+)) to those of the pure chemicals, we show that identification is possible with a much higher level of confidence then when relying solely on the m/z of protonated parent molecules. A rapid and highly selective analytical identification of the constituents of a recreational drug is particularly crucial to medical personnel for the prompt medical treatment of overdoses, toxic effects or allergic reactions.

Headspace analysis of new psychoactive substances using a Selective Reagent Ionisation-Time of Flight-Mass Spectrometer.

The rapid expansion in the number and use of new psychoactive substances presents a significant analytical challenge because highly sensitive instrumentation capable of detecting a broad range of chemical compounds in real-time with a low rate of false positives is required. A Selective Reagent Ionisation-Time of Flight-Mass Spectrometry (SRI-ToF-MS) instrument is capable of meeting all of these requirements. With its high mass resolution (up to m/Δm of 8000), the application of variations in reduced electric field strength (E/N) and use of different reagent ions, the ambiguity of a nominal (monoisotopic) m/z is reduced and hence the identification of chemicals in a complex chemical environment with a high level of confidence is enabled. In this study we report the use of a SRI-ToF-MS instrument to investigate the reactions of H3O+, O2+, NO+ and Kr+ with 10 readily available (at the time of purchase) new psychoactive substances, namely 4-fluoroamphetamine, methiopropamine, ethcathinone, 4-methylethcathinone, N-ethylbuphedrone, ethylphenidate, 5-MeO-DALT, dimethocaine, 5-(2-aminopropyl)benzofuran and nitracaine. In particular, the dependence of product ion branching ratios on the reduced electric field strength for all reagent ions was investigated and is reported here. The results reported represent a significant amount of new data which will be of use for the development of drug detection techniques suitable for real world scenarios.

Distinguishing two isomeric mephedrone substitutes with selective reagent ionisation mass spectrometry (SRI-MS).

The isomers 4-methylethcathinone and N-ethylbuphedrone are substitutes for the recently banned drug mephedrone. We find that with conventional proton transfer reaction mass spectrometry (PTR-MS), it is not possible to distinguish between these two isomers, because essentially for both substances, only the protonated molecules are observed at a mass-to-charge ratio of 192 (C12 H18NO(+)). However, when utilising an advanced PTR-MS instrument that allows us to switch the reagent ions (selective reagent ionisation) from H3O(+) (which is commonly used in PTR-MS) to NO(+), O2(+) and Kr(+), characteristic product (fragment) ions are detected: C4H10N(+) (72 Da) for 4-methylethcathinone and C5 H12N(+) (86 Da) for N-ethylbuphedrone; thus, selective reagent ionisation MS proves to be a powerful tool for fast detection and identification of these compounds.