Multiresidue Herbicide Analysis in Soil:  Subcritical Water Extraction with an On-Line Sorbent Trap

Abstract

We evaluated the feasibility of extracting selectively and rapidly herbicide residues in soils by hot water and collecting analytes with a Carbograph 4 solid-phase extraction (SPE) cartridge set on-line with the extraction cell. Phenoxy acid herbicides and those nonacidic and acidic herbicides which are often used in combination with phenoxy acids were selected for this study. Five different soil samples were fortified with target compounds at levels of 100 and 10 ng/g (30 ng/g of clopyralid and picloram) by following a procedure able to mimic weathered soils. Herbicides were extracted with water at 90 °C and collected on-line by the SPE cartridge. After the cartridge was disconnected from the extraction apparatus, analytes were recovered by stepwise elution to separate nonacidic herbicides from acidic ones. The two final extracts were analyzed by liquid chromatography/mass spectrometry with an electrospray ion source. At the lowest spike level considered, analyte recoveries ranged between 81 and 93%, except those for 2,4-DB and MCPB, which were 63%. For 16 herbicides out of 18, the ANOVA test showed recoveries were not dependent on the type of soil. The method detection limit was in the 1.7-10 ng/g range. For the analytes considered, method comparison showed this extraction method was overall more efficient than Soxhlet and sonication extraction techniques.

Chemometric Strategies for the Extraction and Analysis Optimization of Herbicide Residues in Soil Samples

“…The same water volume used in the previous experiments was taken for the OA due to its utility in mixtures with acetic acid and acetone. Due to different solvent volumes, water percentages changed from 14.3% to 33.3%, acetic acid percentages changed from 0.3% to 1.7%, and organic solvent percentages changed from 65.3% to 85.3%, covering the values found in the references (Ahmed & Bertrand, 1989;Crescenzi et al, 1999;Smith & Milward, 1981;Sutherland et al, 2003;Thorstensen & Christiansen, 2001). Three levels for each control factor instead of two were chosen to detect any quadratic or non-linear relation between the factors and the output variable, and to obtain information over wider ranges of the variables.…”

A simple and rapid confirmatory assay for analyzing antibiotic residues of the macrolide class and lincomycin in bovine milk and yoghurt: hot water extraction followed by liquid chromatography/tandem mass spectrometry

“…The design of the laboratory-made extraction apparatus used in this work was very similar to that described in a previous paper, 25 with the exception that nitrogen was bubbled in water to eliminate any traces of dissolved oxygen and the analyte-containing water leaving the extraction cell was collected in a calibrated glass tube instead of a sorbent cartridge. Briefly, the extraction apparatus consisted of a LC single pump to force water to pass through the extraction cell, a gas chromatography oven containing a 5-m pre-heated stainless steel coil and an extraction cell (8.1 cm  8.3 mm i.d.…”

“…Mobile phase component A was methanol and component B was water, both acidified with 10 mmol/L formic acid. At 1.0 mL/min, the mobile phase gradient profile was as follows (t in min): t 0 , A ¼ 15%; t 5 , A ¼ 25%; t 6 , A¼ 35%; t 20 , A¼ 79%; t 21 , A¼ 100%; t 24 , A ¼ 100%; t 25 , A ¼ 15%; t 34 , A ¼ 15%. Retention times of analytes varied no more than 2% over 2 weeks.…”

Enhancing concentration and mass sensitivities for liquid chromatography trace analysis of clopyralid in drinking water

“…LC was also occasionally used but sensitivity was not as good [6][7][8]. In the 1990s, with the need to analyze polar pesticides and the advancement of LC column technology, LC gained more attention [9][10][11][12][13][14][15] because it avoided the chemical derivatization, which was otherwise required in GC. In the same period, GC with MS detection attained popularity because it not only demonstrated a lower limit of detection (LOD) particularly with selective ion monitoring mode as compared with electron capture detection, but more importantly, it also provided reliable identification to minimize false positives in pesticide residue screening [15][16][17].…”