Feasibility of desorption electrospray ionization mass spectrometry for rapid screening of anabolic steroid esters in hair

Hormone and veterinary drug screening and forensics can benefit from the recent developments in desorption electrospray ionization (DESI) mass spectrometry (MS). In this work the feasibility of DESI application for the rapid screening of intact esters of anabolic steroids in bovine hair has been studied. Using a linear ion trap both full scan and data-dependent collision induced dissociation MS(n) spectra were acquired in minutes for testosterone cypionate, testosterone decanoate and estradiol benzoate standard solutions deposited on a glass or PTFE surface. However direct analysis of incurred hair failed due to inefficient desorption ionization and the minute quantities of steroid esters present. Therefore a simplified ultrasonic liquid extraction procedure was developed, allowing rapid DESI analysis of a few microliters of the concentrate and a total analysis time of 2-4h per batch instead of 3 days. The potential of this DESI approach is clearly demonstrated by MS(3) data from hair samples incurred with high levels (300-800 μg kg(-1)) of steroid esters, levels which do occur in samples from controlled- and illegally treated animals. For much lower levels state-of-the-art ultra high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) screening methods remain the method of choice and might benefit from the proposed simplified extraction as well.