Headspace (HS) extraction and preconcentration of volatiles by solid-phase microextraction (SPME) can improve both the sensitivity and selectivity of volatile analyses, and is commonly coupled to gas chromatography-mass spectrometry (GC-MS). A major limitation to this approach is its low-throughput; a typical analysis takes 30 min or longer per sample. Alternatively, ambient ionization-mass spectrometry techniques like Direct Analysis in Real Time (DART) are high-throughput (&lt; 1 min per sample) and well suited to analysis of low molecular weight, non-polar analytes (e.g. volatiles). We have previously demonstrated that volatile analysis by DART-MS, like HS-SPME-GC-MS, can be improved with HS pre-concentration of samples using coated meshes (solid-phase mesh-enhanced sorption from headspace (SPMESH)). Although individual analyses could be performed rapidly (~10 s), this SPMESH approach was challenging to automate and tedious to produce. To improve upon this approach, we have produced an inexpensive, reusable SPMESH sheet by laser-etching thin films of sorbent polymers into a mesh that fits over a standard multiwell plate. Parallel headspace extraction of volatiles from multiple samples can be achieved by positioning the SPMESH sheets over a 24-well plate, and the absorbed volatiles can be transferred to a positioning stage for automated DART-MS quantitation. Using three representative odorants found in grapes (3-isobutyl-2-methoxypyrazine, linalool, and methyl anthranilate) we achieved µg/L – ng/L detection limits with sheet-based SPMESH-DART-MS, with the analysis step requiring only 17 min for 24 samples.

Parallel extraction of grape volatiles onto sorbent sheets prior to automated analysis by Direct Analysis in Real Time mass spectrometry

2019 Spring National Meeting

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