Abstract An ion exchange procedure was developed for the enrichment, separation and quantification of butyltin and phenyltin species, which show very close half wave potentials by their voltammetric determination. As a case study the separation of dibutyltin (DBT) from triphenyltin (TPT) was investigated. Among different ion exchangers tested, the strong acid ion exchanger PUROLITE C100H, used for industrial purposes, was found to be the most suit- able. By using a resin bed volume of 25 mL, a flow rate of the feed solution of 1 mL/min and 3 M HCl in methanol as eluent with a flow rate of 0.5 mL/min, a recovery rate of each species of about 80% could be achieved. The detec- tion limit for the determination of DBT and TPT by anodic stripping voltammetry after their separation and enrich- ment by the above mentioned ion exchange procedure was found to be 0.4 ng/mL for DBT and 6 ng/mL for TPT in the feed solution, respectively. The applicability of the whole procedure was tested on a sediment candidate reference material of BCR (Bureau of Reference Community). Introduction Speciation of organotin compounds, especially butyltin and phenyltin species, is very important due to their species-dependent toxicity and their widespread applica- tion as biocides for antifouling paints, crop protection and wood preservation, as well as stabilizers for PVC [1–3]. Because of their high toxicity, tributyltin (TBT) and triph- enyltin (TPT) are included in the European Union pollu- tant list (EU, Directive 76/464) and they cause environ- mental problems at very low concentrations even in the range of ng/L in waterways. The tributyl- and triphenyltin compounds undergo a degradation in the environment forming dibutyltin (DBT), monobutyltin (MBT) and di- phenyltin (DPT), monophenyltin (MPT) species, respec- tively, which are less toxic than TBT and TPT and have a different bioavailability. The final product of the degrada- tion process is inorganic tin, which is practically harmless. In order to evaluate the effectiveness of the regulations on the application of these compounds and their longer time scale environmental pollution effects, several analyti- cal approaches have been developed for their accurate and precise determination in ultratrace concentrations in environmental samples, such as sediments, marine organ- isms or surface waters. Typically, these methods involve separation of the butyltin species from the matrix and en- richment by an adsorption, extraction or volatilization process, separation of the compounds from each other by a chromatographic process, such as GC or HPLC and mea- surement with an element or species specific detection system, such as AAS, ICP-AES, ICP-MS and GC-MIP- AED [3–5]. Furthermore an additional derivatization step is necessary in most of the above mentioned techniques. Since it has been found that butyltin and phenyltin species are electroactive, voltammetric techniques, which are low cost techniques, simple to handle and less compli- cated than the above mentioned techniques, can be used for the determination of the organotin species [6–8]. By carrying out their extraction with dichloromethane, inor- ganic tin remains in the aqueous phase and does not inter- fere the polarographic determination of butyl- and phenyl- tins in the organic phase [8]. Furthermore, it has been found that by using anodic stripping voltammetry (ASV) at a hanging mercury drop electrode (HMDE), an im- provement of the detection limits of DBT by a factor of 30 and of TPT by the factor 6 could be achieved in compari- son to the ACP technique [9]. An other observation was the appearance of double peaks for DBT and MPT species with different half wave potentials, due to the formation of other electroactive species like radicals, dimeric or polymeric organotin species [9–11]. K. M. Ochsenkühn · M. Ochsenkühn-Petropoulou · F. Tsopelas · L. Mendrinos Separation of organotin compounds by ion-exchange chromatography and their determination by inverse voltammetry Fresenius J Anal Chem (2001) 369 : 633–637 © Springer-Verlag 2001 Received: 2 November 2000 / Revised: 31 January 2001 / Accepted: 2 February 2001 SPECIAL ISSUE PAPER K. M. Ochsenkühn NCSR “Demokritos”, Laboratory for Trace Element Studies, Institute of Physical Chemistry, Aghia Paraskevi Attikis, 153 10 Athen, Greece M. Ochsenkühn-Petropoulou () · F. Tsopelas · L. Mendrinos National Technical University of Athens, Department of Chemical Engineering, Laboratory of Inorganic and Analytical Chemistry, Iroon Polytechniou 9, 157 73 Athens, Greece e-mail: oxenki@hermes.central.ntua.gr