Supported liquid membrane technique for time-integrating field sampling of acidic herbicides at sub parts per billion level in natural waters

Abstract

A method for continuous sampling of acidic herbicides in natural waters based on supported liquid membrane extractions has been developed. A porous PTFE membrane was impregnated with an organic solvent, ensuring only uncharged molecules passed through the membrane. Selecting the pH in the donor and acceptor phases selectively enriched acidic substances on the acceptor side. The herbicides (bentazon, 2,4-D, dicamba, dichlorprop, MCPA, and mecoprop) were continuously sampled during 24 h. After collection, the samples were taken to the laboratory for quantification using liquid chromatography with UV detection. The extraction efficiences for the herbicides were ca. 0.70, resulting in detection limits of ca. 40 ng/L, sample volumes of 1 L (24-h sampling), in clean aqueous samples. The detection limits in natural waters are somewhat higher and are estimated to ca. 0.1 pg/L. Changes in both air and water temperatures had no significant effect on the extraction efficiencies.

Passive extraction and clean-up of phenoxy acid herbicides in samples from a groundwater plume using hollow fiber supported liquid membranes

“…While the former two derivatization/SPME methods [18,19], with low sensitivity and poor repeatability, can only be used as screening technique; the later one [20] possesses sufficient sensitivity and good repeatability for determining phenoxy acid herbicides in real wastewater and groundwater samples. Supported liquid membrane (SLM) extraction, both flat membrane based [21] and hollow fiber membrane based [22,23], were also used as an alternative sample preparation technique for the determination of phenoxy acid herbicides. These methods have the merits of high selectivity, low cost, negligible consumption of organic solvent, and are readily couplied with LC.…”

Continuous flow liquid membrane extraction: a novel automatic trace-enrichment technique based on continuous flow liquid–liquid extraction combined with supported liquid membrane

“…SLM extraction has been applied to a variety of sample preparation and enrichment in environmental and biological analysis [16], as it has many advantages such as high selectivity, high degree of concentration enrichment, very low consumption of organic solvents and convenient to be on-line coupled with chromatographic and spectroscopic instruments [3,4,18]. Traces of sulfonylurea [19,20] and triazine herbicides [21][22][23], phenoxy acids [24,25], chlorophenols [26], aniline derivates [27] and metal ions [28,29] have been enriched from water samples by SLM. SLM extraction was also found suitable for enrichment of basic drugs in human plasma [30,31].…”

Membrane-Based Extraction for Environmental Analysis

“…Flat-sheet SLM (three-phase) [1][2][3][4]14,15,20,[24][25][26][27][28][29][30][31]36,37,40,59,60,84,90,[107][108][109]114,120,161,[176][177][178][179][180][181] Flat-sheet MMLLE (two-phase) [59][60][61]104,116,162,172 Three-phase LPME (hollow fiber) Static 5,9,10,12,21,23,38,64,65,67,68,[74]…”