On-line solid-phase extraction coupled with liquid chromatography/electrospray ionization mass spectrometry for the determination of trace tributyltin and triphenyltin in water samples Qian Sun 1,2,3 , Zuliang Chen 2,3 * , Dongxing Yuan 1 , Mallavarapu Megharaj 2,3 and Ravendra Naidu 2,3 1 State Key laboratory of Marine Environmental Science, Environmental Science Research Center, Xiamen University, Xiamen, China, 361005 2 Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, SA 5095, Australia 3 CRC for Contamination Assessment and Remediation of Environment, Mawson Lakes Boulevard, Mawson Lakes, South Australia 5095, Australia Received 16 July 2009; Revised 30 September 2009; Accepted 1 October 2009 On-line solid-phase extraction (SPE) for pre-concentration and sample cleanup is one strategy to reduce matrix effects and to simultaneously improve detection sensitivity in liquid chromatography/ mass spectrometry (LC/MS). This paper describes an on-line SPE-LC/MS method for the determi- nation of tributyltin (TBT) and triphenyltin (TPhT) at trace levels in water samples. The direct coupling of an on-line C 18 pre-column to LC/MS was used to pre-concentrate TBT and TPhT at trace levels from waters and to remove interfering matrix effects. Pre-concentration was followed by separation of TBT and TPhT on a C 18 column using a mobile phase containing 0.1% (v/v) HCOOH/ 5 mM HCOONH 4 and methanol. While both electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) can be interfaced with MS for the detection of TBT and TPhT, ESI-MS was preferred for this application. The calibration curve for the targets was linear in the concentration range 0.1–30 mgL 1 . The detection limit (signal-to-noise (S/N) ratio ¼ 3) was 0.02 mgL 1 when 3.0 mL of sample was enriched on the C 18 pre-column. The recoveries of TBT and TPhT in spiked waters were from 81.0 to 101.9%. The reproducibilities for the analysis of the standard mixture (10 mgL 1 ) for TBT and TPhT were 13.1 and 5.0%, respectively. The developed method was an easy and fast way to analyze TBT and TPhT in water samples. Copyright # 2009 John Wiley & Sons, Ltd. In recent years, analytical methods for the environmental analysis of organotin (OT) species have become necessary because of the wide use of tributyltin (TBT) and triphenyltin (TPhT) in anti-fouling paints and pesticides. 1 Since TBT and TPhT are highly toxic and can promote harmful effects on aquatic organisms even at trace levels, 2,3 analytical methods for TBT and TPhT with high sensitivity, high selectivity and simple operation are required. Gas chromatography (GC) is often used for the determi- nation of OTs 4–7 because of its high resolution and the high detector sensitivity. However, the GC analysis of OTs requires derivatization prior to detection due to their poor volatility. Alkylation by means of Grignard reactions from a pre-extraction eluate or ethylation with NaBEt 4 directly from aqueous solution are the most common derivatization procedures, but all are tedious and time-consuming. 1 As an alternative, liquid chromatography (LC) methods provide simple and rapid techniques for the analysis of OTs in various matrices since the OTs do not require to be derivatized. Hence, LC coupled with various detection techniques, such as mass spectrometry (MS) or inductively coupled plasma mass spectrometry (ICP-MS), can be used for the analysis of OTs at trace levels. Since ICP-MS provides excellent sensitivity, selectivity, wide linear dynamic range and the ability to perform isotopic analysis, 8 LC/ICP-MS coupled with various separation modes (ion-exchange, 9,10 ion-pairing, 11,12 and reversed-phase chromatography 13,14 ) has been used for the speciation of OTs. However, the hyphenation of LC with ICP-MS is limited because the organic-based mobile phase in LC is often not compatible with the plasma source. For example, a high concentration of organic solvents in the mobile phase results in poor plasma stability and may even cause the plasma to be extinguished. In addition, carbon deposits may form on the sampler and the skimmer cones within the ICP-MS interface region, which contributes to high noise and reduced signal intensities. 1 Furthermore, it is often necessary to confirm the OT species at trace level in real samples, as ICP-MS is only an element- specific detector and it cannot provide the inherent information required to characterize or confirm specific OT species. However, these issues can be solved by using LC/MS, which provides molecular information to confirm RAPID COMMUNICATIONS IN MASS SPECTROMETRY Rapid Commun. Mass Spectrom. 2009; 23: 3795–3802 Published online in Wiley InterScience (www.interscience.wiley.com) DOI: 10.1002/rcm.4321 *Correspondence to: Z. L. Chen, Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, SA 5095, Australia. E-mail: zuliang.chen@unisa.edu.au Copyright # 2009 John Wiley & Sons, Ltd.