Determination of aldehydes in drinking water and river water by headspace GC/negative-ion chemical-ionization MS

A method for the analysis of 7 aldehydes in drinking water and river water was developed using an headspace sampler in combination with a GC/MS with negative-ion chemical ionization (NICI). A sample (15 ml) was simply transfered to a 20 ml headspace vial, followed by the addition of a 0.1% O-(pentafluorobenzyl) hydroxylamine (PFBOA) solution (1 ml) and NaCl (2 g), in which aldehydes were converted to their O-(pentafluorobenzyl) oximes with PFBOA within two hours. A sample was put in the headspace sampler, which was set to heat at 80 degrees C for 20 min. The gas of PFBOA derivatives was then injected into the GC/NICI-MS with methane as the reagent gas by high-pressure pulsed split injection. The detection limits; of the 7 aldehydes ranged from 3.7 pg/ml to 15.3 pg/ml. The overall recoveries of the aldehydes in drinking water and river water samples were from 82% to 103% (RSD (n = 5) were from 3.4% to 7.1%) and from 89% to 95% (RSD (n = 5 were from 3.2% to 6.5%)}, respectively.