title: In matrix derivatization of trichloroethylene metabolites in human plasma with methyl chloroformate and their determination by solid-phase microextraction-gas chromatography-electron capture detector.
abstract: Trichloroethylene (TCE) is a common industrial chemical that has been widely used as metal degreaser and for many industrial purposes. In humans, TCE is metabolized into dichloroacetic acid (DCA), trichloroacetic acid (TCA) and trichloroethanol (TCOH). A simple and rapid method has been developed for the quantitative determination of TCE metabolites. The procedure involves the in situ derivatization of TCE metabolites with methyl chloroformate (MCF) directly in diluted plasma samples followed by extraction and analysis with solid-phase microextraction (SPME) coupled to gas chromatography-electron capture detector (GC-ECD). Factors which can influence the efficiency of derivatization such as amount of MCF and pyridine (PYR), ratio of water/methanol were optimized. The factors which can affect the extraction efficiencies of SPME were screened using 2(7-4) Placket-Burman Design (PBD). A central composite design (CCD) was then applied to further optimize the most significant factors for optimum SPME extraction. The optimum factors for the SPME extraction were found to be 562.5mg of NaCl, pH at 1 and an extraction time of 22 min. Recoveries and detection limits of all three analytes in plasma were found to be in the range of 92.69-97.55% and 0.036-0.068 μg mL(-1) of plasma, respectively. The correlation coefficients were found to be in the range of 0.990-0.995. The intra- and inter-day precisions for TCE metabolites were found to be in the range of 2.37-4.81% and 5.13-7.61%, respectively. The major advantage of this method is that MCF derivatization allows conversion of TCE metabolites into their methyl esters in very short time (≤30 s) at room temperature directly in the plasma samples, thus makes it a solventless analysis. The method developed was successfully applied to the plasma samples of humans exposed to TCE.
authors.affiliation: Analytical Chemistry Section, CSIR-Indian Institute of Toxicology Research, M G Marg, Lucknow 226001, UP, India. mohanitrc@gmail.com
authors.forename: Mohana Krishna Reddy
authors.initials: MK
authors.lastname: Mudiam
authors.forename: Rajeev
authors.initials: R
authors.lastname: Jain
authors.forename: Meenu
authors.initials: M
authors.lastname: Varshney
authors.forename: Ratnasekhar
authors.initials: R
authors.lastname: Ch
authors.forename: Abhishek
authors.initials: A
authors.lastname: Chauhan
authors.forename: Sudhir Kumar
authors.initials: SK
authors.lastname: Goyal
authors.forename: Haider A
authors.initials: HA
authors.lastname: Khan
authors.forename: R C
authors.initials: RC
authors.lastname: Murthy
mesh_terms: D005561:Formates / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006801:Humans; D057230:Limit of Detection; D016014:Linear Models; D016273:Occupational Exposure / Q000032:analysis; D015203:Reproducibility of Results; D052617:Solid Phase Microextraction / Q000379:methods*; D014241:Trichloroethylene / Q000031:analogs & derivatives* / Q000097:blood* / Q000737:chemistry / Q000378:metabolism
chemical_list: D005561:Formates; D014241:Trichloroethylene; C014667:methyl chloroformate