Abstract
Two 2,4-dinitrophenylhydrazine (DNPH) sampling tubes were connected in series, and a deozonation column was connected to the front-end. After sampling for 25 min, the tube was sealed with a sealer, and stored below 4℃. The DNPH sampling tubes were settled at 25℃ for 2 h, and eluted with 5 mL of acetonitrile, with the flow direction of the eluate opposite to that of the air during sampling. The eluate was collected, diluted to 5 mL with acetonitrile, passed through a 0.22 μm filter membrane, mixed with an equal volume of water as the filtrate, and introduced into ultra-high performance liquid chromatograph. Gradient elution was performed on a Shim-pack GISS column (50 mm×2.1 mm, 1.9 μm) with acetonitrile-water solution at different volume ratios, and the 13 aldehydes and ketones (formaldehyde, acetaldehyde, acetone, acrolein, proponaldehyde, butenal, butyraldehyde, benzaldehyde, valeraldehyde, p-methylbenzaldehyde, hexanal, methylacrolein and butanone) were separated. The above compounds separated were ionized by tandem mass spectrometer with negative electrospray spray ion source mode, detected with multiple reaction monitoring mode, and quantified by external standard method. It was shown that the DNPH derivatives of the 13 aldehydes and ketones achieved baseline separation within 8 min with little matrix interference. The linear ranges of the standard curves were 0.005-0.20 mg·L-1, with detection limits (3.143s) in the range of 0.09-0.32 μg·m-3. Tests for precision and recovery were carried out, giving RSDs (n=6) of the determined values of each target in the range of 0.90%-7.1%, and recoveries ranged from 81.8% to 104%. The prescribed method was applied to the analysis of the ambient air sample, and formaldehyde, acetaldehyde, acetone, acrolein, proponaldehyde, butyraldehyde and valeraldehyde were detected, and the detected amounts were 5.24, 5.52, 31.2, 11.8, 3.42, 7.10, 4.27 μg·m-3, respectively.
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