Optimization of Silver ion Coordination IonSpray Mass Spectrometry

Abstract

Metal ion coordination ionspray-mass spectrometry (M+CIS-MS) is a powerful technique to enhance the ionization efficiency and sensitivity of nonpolar substances which were difficult to ionize under general electrospray (ESI) conditions. Silver ion coordination ionspray mass spectrometry (Ag+CIS-MS) has been used for the ionization and detection of nonpolar substances such as olefins, vitamins, peptides, proteins, variety peroxidation product and steroids. In this study, we optimized and developed a highly sensitive liquid chromatography-silver ion coordination ionspray/tandem mass spectrometric (LC-Ag+CIS/MS/MS) method for simultaneous ionization and detection of anabolic androgenic steroids. The charged complexes were formed via the addition of silver ions and the anabolic steroids were successfully ionized and detected by LC-Ag+CIS/MS/MS. The MS parameters, concentrations of silver ions and organic solvents have been optimized to increase the intensity of silver ion coordinated complexes. Columns and gradient conditions were also optimized for complete chromatographic separation. As a result, a combination of 25 μM of silver ions and methanol showed the best sensitivity. The advantage of newly developed method is the possibility to ionize, detect and identify anabolic steroids in a single run. In addition, this method was useful for the detection of the trace levels of anabolic steroids in human urine samples.