title: Determination of 2,4-dichlorophenoxyacetic acid (2,4-D) in human urine with mass selective detection.
abstract: Method development and validation studies have been completed on an assay that will allow the determination of 2,4-dichlorophenoxyacetic acid (2,4-D) in human urine. The accurate determination of 2,4-D in urine is an important factor in monitoring worker and population exposure. These studies successfully validated a method for the detection of 2,4-D in urine at a limit of quantitation (LOQ) of 5.00 ppb (parts per billion) using gas chromatography with mass selective detection (GC/MSD). The first study involved the determination of 2,4-D in control human urine and urine samples fortified with 2,4-D. Due to chromatographic interference, a second study was conducted using 14C-2,4-D to verify the recoverability of 2,4-D from human urine at low levels using the GC/MSD method. The second study supports the results of the original data. The 2,4-D was extracted from human urine using a procedure involving hydrolysis using potassium hydroxide, followed by a liquid-liquid extraction into methylene chloride. The extracted samples were derivatized with diazomethane. The methylated fraction was analyzed by GC/MSD. Quantitation was made by comparison to methylated reference standards of 2,4-D. Aliquots fortified at 5-, 50-, and 500-ppb levels were analyzed. The overall mean recovery for all fortified samples was 90.3% with a relative standard deviation of 14.31%.
authors.affiliation: Covance Laboratories Inc, Madison, WI 53704-7545, USA. donald.hughes@covance.com
authors.forename: D L
authors.initials: DL
authors.lastname: Hughes
authors.forename: D J
authors.initials: DJ
authors.lastname: Ritter
authors.forename: R D
authors.initials: RD
authors.lastname: Wilson
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000302:isolation & purification* / Q000652:urine*; D002138:Calibration; D004781:Environmental Exposure; D004784:Environmental Monitoring; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D015084:2,4-Dichlorophenoxyacetic Acid