Toxic effects of linear alkylbenzene sulfonate, quaternary alkylammonium chloride and their complexes onDunaliellasp. andChlorella pyrenoidos

Abstract

AbstractThe toxic effects of linear alkylbenzene sulfonate (LAS), quaternary alkylammonium chlorides (cationic surfactants[CS]), and their complexes (LAS‐CS) were examined inDunaliellasp. by proton nuclear magnetic resonance spectroscopic analysis of glycerol and inChlorella pyrenoidosaby growth inhibition. The glycerol content decreased quantitatively with increased concentrations of LAS, CS, and LAS‐CS complexes. The 24‐h median effective concentration (EC50] values of LAS and CS in free form were 0.38 to 18 mg/L and the toxic effects were in the order alkyltrimethylammonium chloride (TM) > alkyldimethylbenzylam‐monium chloride (BM) > LAS > dialkyldimethylammonium chloride (DM). The 24‐h EC50 values of LAS‐CS complexes at molar ratios of 1:1 and 2:1 were 1.3 to 13 and 5.6 to 9.6 mg/L as LAS‐equivalent concentration, respectively. The order of toxic effects was LAS‐TM > LAS = LAS‐BM > 2LAS‐BM > 2LAS‐DM > 2LAS‐TM > LAS‐DM. The toxic effect of LAS was enhanced by equimolar complex formation with TM. The 96‐h EC50 values of LAS and CS on the inhibition of growth inC. pyrenoidosawere 0.28 to 29 mg/L for the compounds in free form and their toxic effects were in the order TM > BM ≫ DM > LAS. The 96‐h EC50 values of LAS‐CS complexes at molar ratios of 1:1 and 2:1 were 1.4 to 59 and 11 to 86 mg/L, respectively, and the order of toxic effects was LAS‐BM > LAS‐TM > 2LAS‐BM > 2LAS‐TM > LAS > LAS‐DM > 2LAS‐DM. The toxic effects of LAS were also enhanced by the formation of complexes with TM or BM at molar ratio of 1:1 and 2:1. Thus, not only LAS but also its CS complexes might exert toxic effects on organisms in the environment.