Analytical methods based on spectroscopic techniques were developed and validated for the determination of diethyl phthalate (DEP) and polyhexamethylene guanidine (PHMG), which may occur in unrecorded alcohol. Analysis for PHMG was based on UV-VIS spectrophotometry after derivatization with Eosin Y and 1H NMR spectroscopy of the DMSO extract. Analysis of DEP was performed with direct UV-VIS and 1H NMR methods. Multivariate curve resolution and spectra computation methods were used to confirm the presence of PHMG and DEP in the investigated beverages. Of 22 analysed alcohol samples, two contained DEP or PHMG. 1H NMR analysis also revealed the presence of signals of hawthorn extract in three medicinal alcohols used as surrogate alcohol. The simple and cheap UV-VIS methods can be used for rapid screening of surrogate alcohol samples for impurities, while 1H NMR is recommended for specific confirmatory analysis if required. 1. Introduction The consumption of surrogate alcohols (i.e., illegal alcohol not originally intended for human consumption) from different sources is a significant problem in Russia [1–3]. Several cases of poisoning by alcohol-containing liquids were recorded during the last decade [4]. Surrogate alcohols (disinfectants, medicinal alcohols, and perfumes) from unidentified sources were consumed in all cases [4, 5]. During chemical investigation of the consumed beverages, diethyl phthalate (DEP) and polyhexamethylene guanidine (PHMG) were found [5]. PHMG has been used as an effective antiseptic compound, and DEP has been applied as denaturing agent for ethyl alcohol (denaturing of alcohol is undertaken for the purposes of exemption from excise duty that is applied to nondenatured forms, see [1] for details). Therefore, these compounds may be contained in surrogate alcohols prepared from disinfectants or denatured alcohols. In this situation, particular attention should be paid to developing fast methods for quantitative and qualitative analysis of the two compounds in alcohol samples. Qualitative analysis of DEP can be carried out based on the reactions with pyrogallol in acidic medium or with potassium hydroxide [4]. DEP can be further quantified in alcoholic beverages with gas chromatography (GC) with mass spectrometry (MS) [6] or flame-ionization detector (FID) [7]. These chromatographic methods are very sensitive and accurate but also time consuming and expensive. However, for the determination of typical amounts of DEP in beverages that contain denatured alcohol (200–1270？mg/L [6, 7]), the sensitivity of trace GC analysis is not
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