New derivatization strategies for the ultrasensitive analysis of non-aromatic analytes with APLI-TOF-MS

Nontargeted Screening Using Gas Chromatography-Atmospheric Pressure Ionization Mass Spectrometry: Recent Trends and Emerging Potential

Gas chromatography–high-resolution mass spectrometry (GC–HRMS) is a powerful nontargeted screening technique that promises to accelerate the identification of environmental pollutants. Currently, most GC–HRMS instruments are equipped with electron ionization (EI), but atmospheric pressure ionization (API) ion sources have attracted renewed interest because: (i) collisional cooling at atmospheric pressure minimizes fragmentation, resulting in an increased yield of molecular ions for elemental composition determination and improved detection limits; (ii) a wide range of sophisticated tandem (ion mobility) mass spectrometers can be easily adapted for operation with GC–API; and (iii) the conditions of an atmospheric pressure ion source can promote structure diagnostic ion–molecule reactions that are otherwise difficult to perform using conventional GC–MS instrumentation. This literature review addresses the merits of GC–API for nontargeted screening while summarizing recent applications using various GC–API techniques. One perceived drawback of GC–API is the paucity of spectral libraries that can be used to guide structure elucidation. Herein, novel data acquisition, deconvolution and spectral prediction tools will be reviewed. With continued development, it is anticipated that API may eventually supplant EI as the de facto GC–MS ion source used to identify unknowns.

Thermogravimetry coupled to an atmospheric pressure photo ionization quadrupole mass spectrometry for the product control of pharmaceutical formulations and the analysis of plasticizers in polymers

The development of a thermogravimetry coupled to an atmospheric pressure photoionization mass spectrometry (TG-APPI-MS) with a high temperature and flexible transfer line is presented. A method was developed to analyze plasticizers in solution which consist of a solvent evaporation step and subsequent evaporation of the analyte. These solutions of dibutyl phthalate (DBP) in hexane were used to investigate the repeatability (RSD: 3.6%) and linearity (R²: 0.9995) of the new developed system. With the new device the detection of different phthalates in a standardized PVC (polyvinyl chloride) polymer is shown. On the example of ASA, the degradation of a pharmaceutical drug is investigated. The dimerization and the possible trimerization of ASA during the thermal degradation is shown. Ten tablets of different ASA manufacturers were analyzed with the new developed analysis platform. The active substance was found in every tablet. Differences in mass spectral data as well as the studying of the pack insert were used to assign the tablets to companies and their subsidiaries. A unique formulation of ASA was found to have a different mass pattern when analyzed with TG-APPI-qMS. The developed device is a promising tool for the product control and the identification of falsified drugs.

GC-APLI-MS as a powerful tool for the analysis of BaP-tetraol in human urine

For the first time gas chromatography (GC) coupled to atmospheric pressure laser ionization-mass spectrometry (APLI-MS) has been applied to the analysis of trans-anti-benzo[a]pyrene-tetraol (BaP-tetraol) formed from anti-benzo[a]pyrene diolepoxide (BPDE), the ultimate carcinogen of benzo[a]pyrene. This tetraol is considered to be an ideal urinary biomarker for polycyclic aromatic hydrocarbon (PAH) exposure as it reflects internal body burden and potentially adverse health effects. Optimization of the derivatization and the instrumental set-up led to an instrumental LOD of 0.5 fg, an improvement of the lowest instrumental LOD reported in literature of 6.4 fg by a factor of 10. The optimized procedure includes derivatization of hydroxyl groups using methyl iodide and cool on-column injection to prevent degradation of the analyte. First measurements of urine samples demonstrate that the method is capable of detecting BaP-tetraol in human urine collected from both smokers and non-smokers. Although results of analysis indicate a certain underestimation compared with literature data, this method can be expected to serve as an excellent method for the analysis of the biomarker BaP-tetraol in the future if an adequate internal standard such as ¹³C-labeled BaP-tetraol is applied.