Cha, Eunju Jeong, Eun Sook Cha, Sangwon Lee, Jaeick 2024-01-20T02:00:37Z 2024-01-20T02:00:37Z 2021-09-01 2017-04 0003-2670 https://pubs.kist.re.kr/handle/201004/122902 In this study, gas chromatography (GC) was interfaced with high resolution mass spectrometry (HRMS) with electrospray ionization source (ESI) and the relevant parameters were investigated to enhance the ionization efficiency. In GC-ESI, the distances (x-, y- and z) and angle between the ESI needle, GC capillary column and MS orifice were set to 7 (x- distance), 4 (y- distance), and 1 mm (z-distance). The ESI spray solvent, acid modifier and nebulizer gas flow were methanol, 0.1% formic acid and 5 arbitrary units, respectively. Based on these results, analytical conditions for GC-ESI/HRMS were established. In particular, the results of spray solvent flow indicated a concentration-dependent mechanism (peak dilution effect), and other parameters also greatly influenced the ionization performance. The developed GC-ESI/HRMS was then applied to the analysis of anabolic steroids as trimethylsilyl (TMS) derivatives in human urine to demonstrate its application. The ionization profiles of TMS-derivatized steroids were investigated and compared with those of underivatized steroids obtained from gas chromatographyelectrospray ionization/mass spectrometry (GC-ESI/MS) and liquid chromatography-electrospray ionization/mass spectrometry (LC-ESI/MS). The steroids exhibited ionization profiles based on their structural characteristics, regardless of the analyte phase or derivatization. Groups I and II with conjugated or unconjugated keto functional groups at C3 generated the [M+H](+) and [M+H-TMS](+) ions, respectively. On the other hand, Groups III and IV gave rise to the characteristic fragment ions [M+H-TMS-H2O](+) and [M+H-2TMS-H2O](+), corresponding to loss of a neutral TMS center dot H2O moiety from the protonated molecular ion by in-source dissociation. To the best of our knowledge, this is the first study to successfully ionize and analyze steroids as TMS derivatives using ESI coupled with GC. The present system has enabled the ionization of TMS derivatives under ESI conditions and this method has potential as a novel ionization tool. It is also useful for the simultaneous analysis of steroids as TMS derivatives. (C) 2017 Elsevier B.V. All rights reserved. English ELSEVIER SCIENCE BV Coupling of gas chromatography and electrospray ionization high resolution mass spectrometry for the analysis of anabolic steroids as trimethylsilyl derivatives in human urine Article 10.1016/j.aca.2017.01.058 1 ANALYTICA CHIMICA ACTA, v.964, pp.123 - 133 ANALYTICA CHIMICA ACTA 964 123 133 N scie scopus 000398434700011 2-s2.0-85011407772 Chemistry, Analytical Chemistry Article ANDROGENIC STEROIDS LC-ESI/MS/MS Gas chromatography Electrospray ionization Anabolic steroids Trimethylsilylation