Determination of haloacetic acids, formaldehyde, and phenols in tap water by low-pressure GC/MS using nitrogen as carrier gas

In this study, we developed of a simple, rapid and low-cost method for low-pressure-GC/MS (LP-GC/MS) with nitrogen as a carrier gas. The LP-GC/MS setup involves the use of a short non-coated microbore capillary (2 m×0.1 mm internal diameter) at the injector side connected with a zero dead-volume connector to a short megabore column (10 m×0.53 mm internal diameter×1 μm) to be used with higher gas velocities. Then, the samples were spiked with haloacetic acids (0.002 mg L^-1), formaldehyde (0.008 mg L^-1), or phenols (0.0001 mg L^-1). The method was validated with limits of quantitation low enough to determine the haloacetic acids, formaldehyde, and phenols (at least 1/10 the concentrations of that specified in the drinking water quality standards). The linearity, as demonstrated by the coefficient of determination, ranged between 0.998 and 1.000 for the concentration range of haloacetic acids (0.025-1.250 mg L^-1), formaldehyde (0.08-1.00 mg L^-1), and phenols (0.01-0.20 mg L^-1). The extraction recoveries (accuracy) varied over 89.4-101.2 %. The LP-GC/MS method has good repeatability; the intra-day precision (repeatability) was calculated as %RSD below 5.2 %, while the inter-day precision (intermediate precision) was below 12.2 % (n = 10). The proposed method was almost the same as those by the conventional GC/MS (He carrier).