Determination of Benzothiazole and Alkylphosphates in Water Samples from the Great Lakes Drainage Basin by Gas Chromatography/Atomic Emission Detection

Abstract

Abstract Benzothiazole, tri-n-butylphosphate tris(2-chloroethyl)phosphate, tris((β-chloro-propyDphosphate and two isomers of this last chemical were detected in all archived water extracts collected from permanent sampling stations located at Fort Erie, Niagara-on-the-Lake and Wolfe Island. The archived samples initially extracted using a Goulden large sample extractor (GLSE) after centrifuging, were analyzed using gas chromatography/atomic emission detection (GC-AED) for P-, S-, and N-containing compounds. All samples also contained atrazine and metolachlor whose concentrations had previously been determined using gas chromatography/mass spectrometry (GC/MS). The concentration values of atrazine in the 38 archived samples as determined by the AED method were similar to those determined by the GC/MS method. However, the concentrations of metolachlor in the 38 archived samples calculated from the GC/AED generally differed by a factor of 2 relative to concentrations determined for the extracts by GC/MS. The atrazine and metolachlor concentrations determined by GC/AED were in the range 12-141 ng/L compared to 10-89 ng/L determined using GC/MS. The trialkylphosphate concentrations were in the range 5-23 ng/L and the benzothiazole concentrations were in the range 1-10 ng/L. Other archived samples from the St. Lawrence River above and below Montréal also contained the above five trialkylphosphates and benzothiazole, as did fresh samples from the eastern and western basins of Lake Erie. Nonpolar fractions from silica gel cleanup of the St. Clair River sample extracts contained none of the compounds of interest, but the compounds were found in the methanol eluates of the cleanup column material. One sample collected from the middle of Lake Huron contained tris(2-chloroethyl)phosphate. Rain samples collected about Lake Ontario contained benzothiazole and the alkylphosphates.