Journal of Chromatography B, 868 (2008) 116–119 Contents lists available at ScienceDirect Journal of Chromatography B journal homepage: www.elsevier.com/locate/chromb Short communication Development of an analytical method to confirm toxic trimethylated tin in human urine Yoshihiro Suzuki a , Yoko Endo a,∗ , Masanori Ogawa a , Yangho Kim b , Nobuhiko Onda a , Kenzo Yamanaka c a Research Center for Occupational Poisoning, Tokyo Rosai Hospital, Japan Labour Health and Welfare Organization, 4-13-21 Omoriminami, Ohta-ku, Tokyo 143-0013, Japan b Department of Occupational and Environmental Medicine, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan 682-060, South Korea c Department of Environmental Toxicology and Carcinogenesis, Nihon University College of Pharmacy, Funabashi, Chiba 274-8555, Japan article info Article history: Received 9 January 2008 Accepted 23 April 2008 Available online 29 April 2008 Keywords: Dimethylated tin Trimethylated tin HPLC–MS/MS HPLC–ICP–MS abstract Dimethyltin dichloride (DMTC) is widely used as a heat stabilizer in manufacturing the polyvinyl chloride. We previously reported a case of acute DMTC poisoning with neurological manifestations very similar to trimethylated tin (TMT) encephalopathy, based on results of speciation analysis of methylated tins in the patient’s urine with use of a combination of high performance liquid chromatography and inductively coupled plasma–mass spectrometry (HPLC–ICP–MS), which yielded peaks corresponding to DMT and TMT. In this study, we developed an analytical method to confirm TMT in urine using high performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS), and found TMT molecular ion in the patient’s urine. © 2008 Elsevier B.V. All rights reserved. 1. Introduction Dimethyltin dichloride (DMTC) is widely used as a heat sta- bilizer in rigid polyvinylchloride resins [1,2]. Recently, DMTC has been used to produce transparent conductive films for liquid crys- tal panels [2]. Among the methylated tins, trimethylated tin (TMT) is the most toxic, and its marked neurotoxicity in humans has been demonstrated in cases of accidental exposures [3–6]. In animal experiments, however, the toxicity of dimethylated tin (DMT) dif- fers from that of TMT [7–10]. We previously reported a case of acute poisoning due to DMTC exposure [11]. Since the clinical signs in this patient were the severe neurological manifestations very sim- ilar to those of TMT encephalopathy, the methylation of DMT to TMT was suspected. We then developed a method of speciation analysis of methylated tins, such as monomethylated tin (MMT), DMT, and TMT, using a combination of high performance liquid chromatography and inductively coupled plasma–mass spectrom- etry (HPLC–ICP–MS), and chromatographic peaks corresponding to each DMTC and trimethyltin chloride (TMTC) were detected in the patient’s urine, whereas peaks for methyltin trichloride (MMTC) and inorganic tin were not [11]. ∗ Corresponding author. Tel.: +81 3 3742 7301; fax: +81 3 5735 9977. E-mail address: yokoendo@tokyoh.rofuku.go.jp (Y. Endo). Previous in vitro and in vivo experimental studies have shown that organotin compounds undergo biotransformation by dealkylation [12]. No methylation of such compounds has been reported in animal experiments. If methylation of DMT to TMT occurs to a significant extent in humans, the severe neurotox- icity of DMT in the patient can be explained. In this study, we developed an analytical method to confirm TMT using high performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS). 2. Experimental 2.1. Chemicals Methyltin trichloride (MMTC), dimethyltin dichloride (DMTC), trimethyltin chloride (TMTC), methanol (HPLC grade), formic acid (99% approximately, LC–MS grade), and hydrochloric acid (35–37%, analytical grade) were purchased from Wako Pure Chem- ical Industries (Osaka, Japan). Ammonia solution (25.0–27.9%, atomic absorption grade) and germanium standard solution were purchased from Kanto Chemical Co. (Tokyo, Japan). Ammo- nium formate (99.995+%) was purchased from Sigma–Aldrich (St. Louis, MO, USA). Tap water was purified through Milli-Q Ele- ment A10 (Millipore Japan, Tokyo, Japan) and used as ultra-pure water. 1570-0232/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.jchromb.2008.04.032