No abstract

Low-molecular-weight (LMW) carbonyl compounds (i.e. aldehydes (RCOH) and ketones (RCOR′)) in the troposphere are mainly formed by photochemical oxidation process of anthropogenic and biogenic hydrocarbon. [1][2][3] They are also emitted directly by the combustion of fossil fuels and biomass by motor vehicles and industrial processes. 1 LMW carbonyl compounds in the atmosphere are easily dissolved in rain, cloud water and dew. 2,4 They are active participants in atmospheric chemical reactions in both gas and liquid phases, and they are involved in the generation of acids in atmospheric water. LMW carbonyl compounds are deposited on the ground and the sea surface as rain. For surface water, atmospheric deposition is one of the most important sources of formaldehyde, since the concentrations of formaldehyde in rain are higher than those in surface water such as seawater and river water, by three orders of magnitude, or more. LMW carbonyl compounds are exchanged directly between the surface water phase and the atmosphere. 3,4 In natural water, LMW carbonyl compounds are produced by the photochemical degradation of dissolved organic matter (DOM). [6][7][8] The LMW carbonyl compounds in natural water are biologically labile, because they are taken up quickly by microorganisms. 6,7 Aldehyde formation in the ozonization treatment for drinking water has been reported. The migration of carbonyl compounds from polyethylene terephthalate (PET) bottles into commercial bottled mineral water has also been investigated. 9 In Japan, the concentration of formaldehyde in tap water is regulated at less than 80 μg/L (= 2.7 μM), and is monitored regularly.Some analytical methods have been reported for LMW carbonyl compounds in water. The 2,4-dinitrophenylhydrazine (DNPH) derivatization method, in which aldehyde-DNPH derivatives are subsequently separated by high performance liquid chromatography (HPLC) and detected by ultraviolet absorption, has been applied to rain and dew samples. 3,4 A solid phase extraction (SPE) technique has been used in attempts to lower the detection limits for aqueous samples. Kieber and Mopper have reported on the determination of picomolar concentrations of carbonyl compounds in seawater by using a DNPH derivatization/C-18 SPE cartridge with large-volume injection and large-bore column HPLC. [6][7][8] A gas chromatography (GC) method based on the DNPH derivatization was also reported, although DNPH derivatives have low volatility and poor thermal stability. 10 HPLCfluorescence using dansylacetamidooxyamine is also a sensitive method for the determination of carbonyl compounds. 11 Gas chromatography/mass spectrometry (GC/MS) coupled with o- (2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBOA) derivatization is one of the most sensitive methods for determining aldehydes in water. 9,[12][13][14][15][16] The concentrations of 4 aldehydes in tap water and bottled mineral water, determined by using head space-GC/MS with PFBOA derivatization, have been reported. 13 In Japan, a method based on GC/MS with PFBOA deriv...