Ditiocarbamatos Lc Ms Ms

Journal of Chromatography A, 1028 (2004) 267–276

Determination of dithiocarbamates and metabolites in plants by liquid chromatography–mass spectrometry
C. Blasco, G. Font, Y. Picó∗
Laboratori de Bromatologia i Toxicologia, Facultat de Farmàcia, Universitat de València, Av. Vicent Andrés Estellés s/n, 46100 Burjassot, Spain Received 7 March 2003; received in revised form 15 July 2003;accepted 2 December 2003

Abstract A quantitative matrix solid-phase dispersion and liquid chromatography–atmospheric pressure chemical ionization mass spectrometry (LC–APCI–MS) method is outlined for the simultaneous analysis of dithiocarbamates (DTCs) and their degradation products in plants. Compounds analyzed are dazomet, disulfiram, thiram and the metabolites ethylenthiourea and propylenthiourea.The performance of two different sample preparation protocols, the proposed one and other based on solid-phase extraction, as well as, of both atmospheric pressure ionization sources, APCI and electrospray, were compared. The effect of several parameters on the extraction, separation and detection was studied. Dithiocarbamates and metabolites were dispersed with carbograph, eluted with a mixture ofdichloromethane–methanol, and then, identified by monitoring the base peak of the spectra corresponding to [M + H]+ . The method was validated for avocados, cherries, lemons, nuts, oat, oranges, peaches, rice and tomatoes. Average recoveries varied from 33 to 109%, and relative standard deviation were between 4 and 21% with limits of quantification ranged from 0.25 to 2.5 mg kg−1 , except forthiram and disulfiram, which were not recovered from fruits with high acid content. The procedure was applied to the determination of DTCs and their metabolites in fruits, vegetables and cereals taken from different markets of Valencia, Spain. © 2004 Elsevier B.V. All rights reserved.
Keywords: Food analysis; Dithiocarbamates; Organosulfur compounds; Pesticides

1. Introduction Dithiocarbamates(DTCs) are important organosulfur compounds, which act as inhibitors of metal dependant and sulphydryl enzymes and have a serious consequence on biological systems. They possess variety of applications in agriculture as fungicides, as well as, in the rubber industry as vulcanization accelerators and antioxidants [1]. In this way, DTCs are the main group of fungicides used to control approximately 400pathogens of more than 70 crops and are registered in all the EU member states and many other countries [2,3]. Ethylenthiourea (ETU) and propylenthiourea (PTU) are the most important transformation products of DTCs suspected to cause various pathogenic effects (e.g., goiterogenic, carcinogenic, mutagenic, teratogenic) [4]. Determination of DTCs subclasses is required for toxicological evaluationssince the DTCs and their metabolites
Presented at the 2nd Meeting of the Spanish Society of Chromatography and Related Techniques, Barcelona, 26–29 November 2002. ∗ Corresponding author. Tel.: +34-963543092; fax: +34-963544954. E-mail address: yolanda.pico@uv.es (Y. Pic´ ). o 0021-9673/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.chroma.2003.12.002

differ greatlyin their action mechanism [4,5]. In recent years, concern has been expressed on their presence in foods, drinks and environment [5]. The predominant methods for determining DTCs and metabolites are based on their decomposition to carbon disulfide (CS2 ) in an acid medium, followed mainly by spectrometry [6–10] and head space gas chromatography [11,12]. These methods are time-consuming, neitherselective nor sensitive, and they do not let analysts distinguish between the subclasses of DTCs [1]. In addition, some published papers clearly demonstrate that CS2 values determined by using the acid digestion method of crops rich in secondary metabolism of sulfur compounds have to be interpreted carefully [12]. However, up to now, these methods are used by authorities in Europe and USA to...