Application of micellar electrokinetic capillary chromatography to the analysis of uncharged pesticides of environmental impact

Chromatographic Methods for Detection and Quantification of Carbendazim in Food

Carbendazim (CBZ), which is a fungicide widely used for the management of plant diseases, has been detected in a number of food products. The negative effects of CBZ to human health have stimulated the reduction of the maximum residue limits (MRLs), and subsequently the development of reliable and sensitive detection methods. Here, we are reviewing for the first time all reported chromatographic methods for the detection and quantification of CBZ in food. Several techniques, including liquid chromatography (LC), thin layer chromatography (TLC), micellar electrokinetic chromatography (MEKC), and supercritical fluid chromatography (SFC), were used for the separation and detection of CBZ, showing diverse characteristics and sensitivity. Some methods allowed the specific determination of CBZ, whereas other methods were successfully applied for the simultaneous quantification of a huge number of pesticides. Most reported methods showed limits of detection (LOD) and quantification (LOQ) lower than the MRLs. Relevant efforts in the field have been directed toward the simplification and optimization of the extraction steps prior to the chromatographic separation to increase the recovery and reduce the matrix effects. In this Review, the matrices, extraction procedures, and separation and detection parameters are detailed and compared in order to provide new insights on the development of new reliable methods for the detection of CBZ in food.

Micellar liquid chromatographic determination of carbaryl and 1-naphthol in water, soil, and vegetables

A liquid chromatographic procedure has been developed for the determination of carbaryl, a phenyl-N-methylcarbamate, and its main metabolite 1-naphthol, using a C18 column (250 mm  ×  4.6 mm) with a micellar mobile phase and fluorescence detection at maximum excitation/emission wavelengths of 225/333 nm, respectively. In the optimization step, surfactants sodium dodecyl sulphate (SDS), Brij-35 and N-cetylpyridinium chloride monohydrate, and organic solvents propanol, butanol, and pentanol were considered. The selected mobile phase was 0.15 M SDS-6% (v/v)-pentanol-0.01 M NaH₂PO₄ buffered at pH 3. Validation studies, according to the ICH Tripartite Guideline, included linearity (r > 0.999), limit of detection (5 and 18 ng mL⁻¹, for carbaryl and 1-naphthol, resp.), and limit of quantification (15 and 50 ng mL⁻¹, for carbaryl and 1-naphthol, resp.), with intra- and interday precisions below 1%, and robustness parameters below 3%. The results show that the procedure was adequate for the routine analysis of these two compounds in water, soil, and vegetables samples.

Micellar electrokinetic chromatography with amperometric detection and off-line solid-phase extraction for analysis of carbamate insecticides

Six selected primary carbamate insecticides, methomyl, carbaryl, carbofuran, propoxur, isoprocarb, and promecarb, were hydrolyzed in alkaline solution, resulting in electroactive derivatives detectable at a platinum (Pt) electrode poised at +0.8 V vs Ag/AgCl (3 M NaCl). The Pt electrode was inserted into a small electrochemical cell and positioned close to the capillary outlet as an end-column detector to detect the carbamate derivatives after electrophoretic separation. Based on their predicted pK(a) values and aqueous solubilities, micellar electrokinetic chromatography (MEKC) was optimized for baseline separation of the derivatives using 20 mM borate, pH 10.2 containing 20 mM sodium dodecyl sulfate as a running buffer. When combined with solid-phase extraction (SPE) on octadecyl silica, a preconcentration factor of 100-fold achieved detection to 0.5 microM methomyl and to 0.01 microM for the remaining five pesticides, significantly below the level regulated by government agencies of most countries. The SPE-MEKC method when applied to the separation and analysis of spiked river water and soil samples, yielded results with excellent reproducibility, recovery and selectivity.

Pesticides analysis by liquid chromatography and capillary electrophoresis

Nowadays, a wide range of pesticides are used in agricultural production, and their monitoring in samples of environmental and alimentary interest is of extreme importance to ensure, among others, the safety of consumption of foods. The aim of this work is to provide updated information about the major developments in CE and HPLC in pesticide analysis, covering relevant publications between 2004 and early 2006. The use of different sample pretreatment steps to provide a suitable extraction of these compounds from the different matrices as well as to increase the sensitivity of the determination is also discussed.

Recent advances in the application of capillary electromigration methods for food analysis

This article reviews the latest developments in the application of capillary electromigration methods for the analysis of foods and food components. Nowadays, methods based on CE techniques are becoming widely used in food analytical and research laboratories. This review covers the application of CE to analyze amino acids, biogenic amines, peptides, proteins, DNAs, carbohydrates, phenols, polyphenols, pigments, toxins, pesticides, vitamins, additives, small organic and inorganic ions, chiral compounds, and other compounds in foods, as well as to investigate food interactions and food processing. The use of microchips as well as other foreseen trends in CE analysis of foods is discussed. Papers that were published during the period June 2002-June 2005 are included following the previous review by Frazier and Papadopoulou (Electrophoresis 2003, 24, 4095-4105).

Determination of organic contaminants in food by capillary electrophoresis

This review addresses recent advances in the analysis of organic contaminants, such as antibiotics, pesticides, biological toxins, and food-borne pathogens, in foods by capillary electrophoresis (CE). Special attention is paid to those aspects that increase sensitivity and/or selectivity, such as sample extraction and concentration, on-line preconcentration techniques (stacking), affinity capillaries or/and specific detectors (laser induced fluorescence (LIF), mass spectrometry (MS)). The various CE modes used to separate the compounds and the quantification strategies are also examined. As a result, this work presents an updated overview on the principal applications of CE, together with a discussion of their main advantages and drawbacks, and an outline of future trends in the analysis of organic contaminants in food.