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The acidic herbicides are an important class of chemical compounds that are used to control a variety of weeds that threaten many crops. Owing to their low microbial activity levels, the acidic herbicides exhibit a residual activity remaining for periods of up to several months in soils and water. The principal objective of this study was to develop an analytical method based on liquid-liquid and solid-phase extraction followed by HPLC, for the determination of 2,4-D in paddy field water. The residues were verified via tandem mass spectrometry (MS/MS) in negative-ion electrospray ionization (ESI) mode. Linearity was good over a concentration range of 1-100 µg/L with a correlation coefficient (r(2) ) of 0.999. The mean recovery rates of triplicate results ranged from 85.2 to 90.85%. The limits of detection and quantitation were 0.4 and 1.0 µg/L, respectively. The method proposed herein was applied to field samples acquired from Hampyung and Sunchang counties, Republic of Korea. The analyte was detected at a concentration range of 6.8-12.8 and 3.55-24.0 µg/L, respectively., (Copyright © 2010 John Wiley & Sons, Ltd.)

In a continuation of our earlier work, a multiresidual analytical method using 48 frequently used neutral pesticides in a water matrix was developed and validated in this study. The samples were extracted with dichloromethane and the pesticides were analyzed via GC-NPD followed by confirmation with GC-MS. Good linearity was detected over a concentration range of 0.01-1.0 microg/mL with correlation coefficients (r(2) ) in excess of 0.982. The recoveries were measured between 70.7 and 111.4% for the majority of the targeted pesticides with relative standard deviations (RSDs) of less than 20%. The LODs and LOQs were in ranges of 0.1-2 and 0.33-6.6 microg/L, respectively. A total of 66 water samples were collected from different locations in Yeongsan and the Sumjin River, Republic of Korea, and were analyzed in accordance with the developed method. None of the water samples were determined to contain any of the targeted pesticides. The method has been shown to be simpler, faster, and more cost-effective than the method established by the Environmental Protection Agency (EPA)., (Copyright © 2010 John Wiley & Sons, Ltd.)

The principal objective of the present study was to develop a multiresidue analytical method for 62 pesticides in a soil matrix. Soil samples were fortified with known quantities of pesticides at two different concentration levels (0.1 and 0.01 microg/g) and the analytes were extracted via a liquid-solid extraction method. The pesticides were separated on an HP5 capillary column and were detected by gas chromatography coupled to an electron capture detector (GC-ECD). The method was validated, considering its good linearities (r(2) = 0.978-0.999), specificity and recovery characteristics. Recoveries were found between 70.3 and 113.4% for all pesticides except edifenphos (67.5%) and dichlobenil (69.5%) spiked at a 0.1 microg/mL concentration level and 74.5-117% except ethalfluralin (63.3%) and dichlobenil (51.9%) spiked at a concentration of 0.01 microg/mL. The developed method could be utilized as a simple and cost-effective method for the routine analysis of 62 pesticides in soil samples.