Testing for 2,4-dinitrophenol in human hair by LC-MS/MS and interpretation issues.

2,4-dinitrophenol, initially developed for industrial purposes, is used in the synthesis of dyes and various drugs, including herbicides, fungicides and insecticides. Incidentally, it was discovered that 2,4-dinitrophenol increases human basal metabolic rate. As a consequence, people who want to loose weight can abuse 2,4-dinitrophenol. It is a compound of choice for bodybuilders who abuse it in combination with anabolic steroids and clenbuterol. Numerous deaths have been attributed to 2,4-dinitrophenol. Up to now, 2,4-dinitrophenol was never reported in hair. The authors present an original method to test for 2,4-dinitrophenol in hair after methanolic extraction using LC-MS/MS. The limit of detection of the procedure is 0.01 ng/mg and the method was fully validated in the range 0.1-50 ng/mg. 2,4-dinitrophenol tested positive in the brown hair of a subject deceased from acute poisoning at 5.15, 13.06 and 25.48 ng/mg in the 3 × 3 cm segments. As excessive sweating is associated to 2,4-dinitrophenol abuse, major contribution of this matrix must be taken into consideration when interpreting the data. In this case, there was a regular increase of 2,4-dinitrophenol concentration from root to tip. This specific pattern can be the consequence of sweat contamination, i.e., the older hair being for a longer time in contact with sweat.