TLC Determination of Triazinic Pesticides from Soils A Comparative Study of Some Extraction Methods

摘要

The triazines are the most widely used herbicides. Presenting high risks for human health, they must be determined in very different matrices and at low concentration level. This paper is focused on thin-layer chromatographic (TLC) determination of triazinic herbicides (atrazine, simazine, and propazine) from two types of soils (sandy category and peat). The TLC analyses were carried out on silica plates using multiple developments with toluene-acetone mixtures as mobile phase. Linear calibration curves were obtained in the range of 0.1-1 mg mL~-1 with correlation coefficient R~2 above 0.9855; limit of detection (LOD) and limit of quantification (LOQ) were below 0.7809 and 1.481 u.g/spot, respectively. The analytes extraction was performed using four different techniques: magnetic stirring at room temperature, reflux, ultrasound assisted extraction and microwave assisted extraction. Methanol or methanol-water mixtures were selected as extracting solvent. Blank soil samples were spiked with triazines at 1 mg g~-1 level each. For sandy soils, reflux and microwave assisted extraction prove to be the most efficient techniques, while for soils with high organic matter content (peats) the most suitable technique was ultrasound assisted extraction. In this case the recovery was estimated above 90% and RSD below 4.6% for all analytes.