Evaluation of the solid‐phase extraction ( SPE ) cartridge method in combination with thermal desorption‐gas chromatography‐mass spectrometry ( TD ‐ GC ‐ MS ) for the analysis of different VOC s in liquid matrices in varying p H conditions

In this study, the solid‐phase extraction ( SPE ) method combined with thermal desorption‐gas chromatography‐mass spectrometry ( TD ‐ GC ‐ MS ) method is evaluated for the analysis of liquid‐phase volatile organic compounds ( LVOC s). Calibration experiments were performed on a number of polar and nonpolar LVOC s (including aromatic compounds, ester, ketones, and alcohol) as a function of solution p H . If the relative sensitivity of the SPE ‐ TD ‐ GC ‐ MS method is compared between different VOC s across a wide range of p H (1, 4, 7, 10, and 13), optimum sensitivities for most VOC s are derived at the neutral p H . However, there were some exceptions to the general trend with the maximum sensitivity occurring either at a moderately basic p H (methyl isobutyl ketone and butyl acetate) or extremely acidic conditions (isobutyl alcohol). It was also noticed that the relative ordering of sensitivity was changed, as the p H conditions of the solution vary. The use of internal standard ( IS : chlorobenzene) resulted in a notable improvement in both relative sensitivity and reproducibility for most compounds.