Determination of ETU in Tomatoes and Tomato Products by HPLC-PDA. Evaluation of Cleanup Procedures

Abstract

An HPLC-PDA method for the determination of ethylenethiourea (ETU), the main degradation product of the organic fungicides ethylene bis(dithiocarbamate)s (EBDCs), in tomatoes and tomato products is reported. Solid-matrix liquid-liquid (l-l) partitioning and separatory funnel l-l partitioning for the cleanup were examined. The effect of salt addition, pH, and phase ratio on analyte recovery at the cleanup step was studied. It was found that solid-matrix l-l partitioning afforded higher precision and more selective separation of the analyte. According to the method proposed, the samples were extracted with methanol/water (3:1, v/v) and cleaned up on an Extrelut 20 column. ETU was eluted with dichloromethane and separated on a reversed phase HPLC column. For tomato products with degrees Brix > 20 further purification through silica cartridge was adopted. The method was validated over the following ranges of concentrations: 0.01-0.5 mg/kg for tomatoes, 0.01-0.1 mg/kg for tomato juice, and 0.05-0.25 mg/kg for tomato paste. The accuracy (recoveries > 70%) and the precision obtained (%RSD < 10%) were satisfactory.

Determination of dithiocarbamates and metabolites in plants by liquid chromatography–mass spectrometry

“…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 evaluations since the DTCs and their metabolites differ greatly in their action mechanism [4,5]. In recent years, concern has been expressed on their presence in foods, drinks and environment [5].…”

“…Determination of DTCs subclasses is required for toxicological evaluations since the DTCs and their metabolites differ greatly in 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 (CS 2 ) in an acid medium, followed mainly by spectrometry [6][7][8][9][10] and head space gas chromatography [11,12].…”

Optimization of a matrix solid-phase dispersion method with subsequent clean-up for the determination of ethylene bisdithiocarbamate residues in almond samples

“…is less than 5%. Taking into account the preparation of samples, LOQs were set at 0.05 and 0.07 mg kg −1 for ETU and EBIS, [20,34], making the method suitable for routine analysis. From a critical point of view, the proposed method represents a valuable alternative to more laborious methods based on MSPD or SPE, which involves larger amounts of sample and organic solvents and reports lower recoveries for the test compounds [18,22].…”

“…As a consequence, there is a clear tendency toward the application of liquid chromatography coupled with UV (LC-UV) [17][18][19][20], mass spectrometry (LC-MS) [21,22] or electrochemical detectors [23,24]. Previous experiments have demonstrated the suitability of coupling LC-UV for the simultaneous determination of ETU and EBIS in tomatoes.…”

Voltammetric Determination of Thiourea at Conductive Diamond Electrodes

“…Nevertheless, detection limits down to 2 mg L À1 have been reported for the determination of TU and its derivatives by use of high-performance liquid chromatography, both in waste-water [13] and natural products [17]. Fourier transform infrared spectrometry was successfully used for TU determination [18], and low detection limits were also provided by chemiluminescence measurements [19].…”