Assessment of the toxicity of linear alkylbenzene sulfonate and quaternary alkylammonium chloride by measuring 13C-glycerol in Dunaliella sp.

The toxic effects of linear alkylbenzenesulfonate (LAS) and quaternary alkylammonium chloride on Dunaliella sp. were studied by measuring 13C-glycerol. 13C-glycerol (five isomers of [1,2,1′-13C1,2,3]-glycerol) was produced in Dunaliella sp. from 13C-sodium bicarbonate added and the amounts of 13C-glycerol was lowered quantitatively with increased concentration of surfactants. The ratio of glycerol to 13C-glycerol was found to be about 45 : 55 by gas chromatographic/mass spectrometric analysis. The 24-h median effective concentration (EC50-24h) were 3.5 mg/l for LAS, 0.79 mg/1 for alkyltrimethyl-ammonium chloride (TM), 18 mg/l for dialkyldimethylammonium chloride (DM) and 1.3 mg/l for alkyldimethylbenzylammonium chloride (BM) : the toxic potencies were in the order of TM>BM>LAS>DM. The suppression of 13C-glycerol formation by LAS seemed to be related to the process of photosynthesis from 13C-sodium bicarbonate.