Sol−Gel Glass Immunosorbent-Based Determination of s-Triazines in Water and Soil Samples Using Gas Chromatography with a Nitrogen Phosphorus Detection System

A rapid and efficient method for the selective extraction of s-triazine herbicides in environmental samples was developed using an immunosorbent of monoclonal antiatrazine antibodies, which were encapsulated in a sol−gel glass matrix. The cross-reactivity of the antibody for analytes structurally related with atrazine enabled the simultaneous extraction of several s-triazine herbicides (atrazine, propazine, terbuthylazine, cyanazine, desethyl atrazine). After trace enrichment on the immunoextraction column, the s-triazines were desorbed by means of an acidic buffer (pH 2.5) and further extracted with ethyl acetate before being injected into the GC. Compared to liquid−liquid extraction and solid-phase extraction with a hydrophobic SDB-L support, the GC-NPD chromatograms obtained after immunoaffinity enrichment of surface water (river water) samples or soil extracts and analysis were free from matrix interferences. Nonspecific adsorption of humic acids was not observed. The method allows for the determination of the herbicides in linear ranges up to 1.5 μg/L with correlation coefficients higher than 0.99 and relative standard deviations between 4% and 7% (n = 5). The LODs for 50-mL water samples were in the range 0.02 μg/L (atrazine, propazine) to 0.1 μg/L (desethyl atrazine) (S/N = 3). In addition to its high selectivity, the immunosorbent proved to be reusable for a significant number of preconcentration runs. However, the composition of samples may influence the lifetime of the column.