920 (2001) 283–289 Journal of Chromatography A, www.elsevier.com / locate / chroma Liquid chromatographic methods for chloral hydrate determination * Maria Concetta Bruzzoniti, Edoardo Mentasti, Corrado Sarzanini , Elisa Tarasco Department of Analytical Chemistry, University of Turin, Via P . Giuria 5, 10125 Turin, Italy Abstract Liquid chromatographic methods, based on reversed-phase (RP) and anion-exchange mechanisms, have been developed for chloral hydrate determination. Both methods are preceeded by derivatization of chloral hydrate. For RP separations, different reagents [namely dansylhydrazine and o-(4-nitrobenzyl)hydroxylamine] have been studied, but the best results have been achieved using 1,2-benzenedithiol with UV detection at 220 nm. The anion-exchange method is based on derivatization with NaOH to form sodium formate that is then analyzed by anion-exchange, with suppressed conductivity detection. Derivatization conditions were optimized in order to reach the best yield of reaction. The optimization of the procedure allowed to determine chloral hydrate with detection limits as low as 0.2 mg / l with good linearity and reproducibility. The anion-exchange method was also applied for chloral hydrate determination in a drinking water sample. A preconcentration procedure has also been studied.  2001 Elsevier Science B.V. All rights reserved. Keywords: Water analysis; Derivatization, LC; Chloral hydrate; Formate; Nitrobenzylhydroxylamine; Dansylhydrazine; Benzenedithiol 1. Introduction to US Environmental Protection Agency (EPA) regulations, up to 1999, the maximum contaminant Chloral hydrate is the stable product of hydration level and the maximum contaminant level goal for of trichloro acetaldehyde, which is poorly stable in chloral hydrate are 60 and 40 mg / l, respectively [2]. aqueous solutions. First synthesized in 1832, it has According to EPA indications, chloral hydrate in very pungent odour and bitter taste and it is com- drinking waters is analyzed after liquid–liquid ex- monly added illicitly to alcoholic beverages, increas- traction by gas chromatography with electron-capture ing their potency [1]. detection. Most of the analytical methods existing for At therapeutic doses, chloral hydrate is an excel- chloral hydrate determination are based on gas lent hypnotic, while toxic doses induce severe respi- chromatography [3,4] and electrochemistry. A ratory depression and very low blood pressure. In combination between a polarographic procedure with drinking waters, chloral hydrate is present as chlori- an amplification reaction for determination of chloral nation disinfection by-product during water treat- hydrate has been presented by Sulaiman and Amin ment. Following the drinking water regulations and [5]. This method, based on redox reactions with health advisories, chloral hydrate has been included iodine to form iodide and then iodate allowed the 26 in the possible human carcinogen group. According determination of 6?10 M chloral hydrate by in- direct measurement. Current literature does not provide LC methods for *Corresponding author. Tel.: 139-011-670-7628; fax: 139- determination of chloral hydrate. Nevertheless, chlor- 011-670-7615. E-mail address: sarzanini@ch.unito.it (C. Sarzanini). al hydrate has been evidenced with LC by Husain et 0021-9673 / 01 / $ – see front matter  2001 Elsevier Science B.V. All rights reserved. PII: S0021-9673(01)00554-4