Trace analysis of sulfonylurea herbicides in water by on-line continuous flow liquid membrane extraction–C18 precolumn liquid chromatography with ultraviolet absorbance detection

Abstract

An on-line system that consists of continuous-flow liquid membrane extraction (CFLME), C precolumn, and liquid 18 chromatography with UV detection was applied to trace analysis of sulfonylurea herbicides in water. During preconcentration by CFLME, five target compounds, including metsulfuron methyl, bensulfuron methyl, tribenuron methyl, 21 sulfometuron methyl, and ethametsulfuron, were enriched in 960 ml of 0.5 mol l Na CO -NaHCO (pH 10.8) buffer used 2 3 3 as acceptor. This acceptor was on-line neutralized and transported to the C precolumn where the analytes were absorbed 18 and focused. Then the focused analytes were injected onto a C analytical column for separation and detection at 240 nm. 18The proposed method was applied to determine sulfonylurea herbicides in water, river, and reservoir water with detection 21 limits of 10-50 ng l when enriching a 120-ml sample. Throughput is typically one sample per hour. 

Approaches for on-line coupling of extraction and chromatography

“…Membranes can be utilised in sample preparation in several ways [75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115]. Very generally, a membrane can be classified as a selective barrier between two phases [75,76,77].…”

“…Problems can be avoided by adding an extra step, such as on-line neutralisation or dilution. In addition, applications combining continuous flow LLE and SLM in combination with LC have been reported [102]. Combining SLM with GC is not as straightforward because the aqueous extract is not suitable for GC as such.…”

“…Several applications involving membrane-based sample pretreatment combined with liquid chromatography have been published. Dialysis-LC, and to some extent SLM-LC and MMLLE-LC, has been used in the determination of drugs in biological samples, and in the determination of various compounds in food and environmental matrices [75,76,77,78,79,80,81,82,83,84,85,93,94,95,96,97,98,99,100,101,102,105,107,112,176]. A few applications of on-line coupling of electrodialysis or filtration with chromatography have also been reported [86,87,88,89,90,91,92].…”

Rapid and accurate hplc-dad method for the determination of the herbicide bispyribac-sodium in surface water, and its validation

“…7 Recent publications show that there is a tendency to utilize sophisticated techniques such as GC-MS and LC-MS in the determination of pesticide residues in water. [7][8][9] However, methods that utilize HPLC with ultraviolet absorbance or diode array detection are widely used [10][11][12][13][14] and are fitting for the analysis of herbicides in water, without requiring an elevated investment in instrumentation.…”

“…SPE is the most common technique for the determination of pesticide residues by chromatographic methods in aqueous samples. [7][8][9][10][11][12][13][14][15] The objectives of this study were: to develop and validate a simple and quick method, utilizing SPE and HPLC-DAD, to quantify the herbicide bispyribac-sodium in samples from surface water, especially those with high organic content, like river water and irrigated rice water. …”