Determination of dimethyl sulfoxide and dimethyl sulfone in urine by gas chromatography-mass spectrometry after preparation using 2,2-dimethoxypropane.

A method for routinely determination of dimethyl sulfoxide (DMSO) and dimethyl sulfone (DMSO2) in human urine was developed using gas chromatography–mass spectrometry. The urine sample was treated with 2,2-dimethoxypropane (DMP) and hydrochloric acid for efficient removal of water, which causes degradation of the vacuum level in mass spectrometer and shortens the life-time of the column. Experimental DMP reaction parameters, such as hydrochloric acid concentration, DMP–urine ratio, reaction temperature and reaction time, were optimized for urine. Hexadeuterated DMSO was used as an internal standard. The recoveries of DMSO and DMSO2 from urine were 97–104 and 98–116%, respectively. The calibration curves showed linearity in the range of 0.15–54.45 mg/L for DMSO and 0.19–50.10 mg/L for DMSO2. The limits of detection of DMSO and DMSO2 were 0.04 and 0.06 mg/L, respectively. The relative standard deviations of intra-day and inter-day were 0.2–3.4% for DMSO and 0.4–2.4% for DMSO2. The proposed method may be useful for the biological monitoring of workers exposed to DMSO in their occupational environment. Copyright © 2009 John Wiley & Sons, Ltd.