Evaluation of Septa Quality for Automatic SPME-GC-MS Trace Analysis

Abstract

The vials used for the preparation of breath samples for automated solid-phase microextraction-gas chromatography-mass spectrometry analysis are crimped with septa. These septa often emit specific volatile organic compounds (VOCs) confounding the measurement results of breath samples. In the current paper, 14 different brands of magnetic caps with silicone-polytetrafluoroethylene (PTFE), butyl-PTFE, or butyl rubber septa were tested. The total emission of septa over a 4 h period was also evaluated. The tested septa emitted 39 different compounds, which are mainly hydrocarbons, alcohols, and ketones. Acetone and toluene are the most abundant out-gassing products. The concentration of acetone was in the range from 55 to 694 ppb for butyl-PTFE septum (brand 14) and butyl rubber (brand 10), respectively. The measured toluene amount was 69-1323 ppb for the septum brand 14 and brand 8 (silicone-PTFE), respectively. Generally, the butyl rubber septa released higher amounts of contaminants in comparison to the silicone ones.

A mechanistic investigation of the Pd-catalyzed cross-coupling betweenN-tosylhydrazones and aryl halides

“…Previous mass spectrometric research has reported vulcanizing agents and antioxidants leaching into reaction mixtures. [116][117][118][119] The incidental contact of solvent to rubber septa results in the leaching of interfering ions into the reaction mixture, and this process is especially efficient when the reaction solvent is heated. Primary and secondary antioxidants are often used to prolong or inhibit the free radical chain mechanism of oxidative decomposition in rubber, plastics, and foods.…”

A fully integrated standalone portable cavity ringdown breath acetone analyzer

“…Gas chromatographymass spectrometry (GC-MS) [5][6][7][8][9][10] has been regarded as a gold-standard method for trace gas analysis for its high sensitivity and high accuracy. However, the GC-MS method is not suitable for breath analysis using a large number of samples due to its complicated sample preparation procedure, time-consuming test process, and high instrumentation and operational costs.…”

Applications of a confined DART (direct analysis in real time) ion source for online in vivo analysis of human breath

“…The above procedure has been widely used for the preparation of standard mixtures for gas analyzers. 46,47 The calibration curves were obtained based on the analysis of the gaseous mixture of the standard compounds diluted with nitrogen, as shown in Fig. 3(b).…”