1. Investigación

Asimple and rapid capillary electrophoresis method for low-molecular mass carboxylic acids measurement in coffee has been optimised and validated. Regarding separation conditions, phosphate concentration in the background electrolyte, surfactant type [cetyltrimethylammonium bromide (CTAB), tetradecyltri methylammonium bromide (TTAB) and hexadimethrine bromide (HDB)], percentages of organic modifier and pH were assayed. The best conditions were: 500mM phosphate buffer at pH 6.25 with CTAB 0.5 mM. The separation was carried out with an uncoated fused-silica capillary (57 cm×50 m i.d.) which was operated at −10 kV potential. Detection was performed at 200 nm. In such conditions 17 short-chain organic acids: oxalic, formic, fumaric, mesaconic, succinic, maleic, malic, isocitric, citric, acetic, citraconic, glycolic, propionic, lactic, furanoic, pyroglutamic, quinic acids plus nitrate were separated, identified and measured. Validation parameters of the method allow us to consider it lineal, accurate and precise and, therefore, reliable for its employment in food composition studies or for quality control. Results in coffees with different industrial treatment allow the detection of important differences in the organic acid profile.

This review article is a comprehensive survey of capillary electrophoresis methods developed for the measurement of short-chain organic acids and inorganic anions in a wide variety of matrices, such as food and beverages, environmental, industry, and other applications, as well as clinical applications in body fluids such as urine, plasma or cerebrospinal fluid. Details of sample pretreatment and of electrophoretic conditions have been collected in tables, arranged by the type of matrix. Strategies employed for method development for the analysis of these compounds by capillary electrophoresis in real samples are discussed.

A method has been developed for the analysis of a cough syrup containing dextromethorphan, guaifenesin, benzoic acid, saccharin and other components. Forced degradation was also studied to demonstrate that the method could be employed during a stability study of the syrup. Final conditions were phosphate buffer (25 mM, pH 2.8) with triethylamine (TEA)–acetonitrile (75:25, v/v). In such conditions, all the actives, excipients and degradation products were baseline resolved in less than 14 min, and different wavelengths were used for the different analytes and related compounds.

Short-chain organic acid contents in serum of natural latex are interesting to measure and capillary electrophoresis (CE) has proved to be a good tool for their study. In the present work a method has been developed to identify the short-chain organic acids present in sera of natural rubber latex (oxalic, formic, fumaric, aconitic, succinic, malic, glutaric, citric, acetic, glycollic, propionic and quinic acids), the separation was optimised and the quantification method validated. The separation was performed on a CE system with UV detection at 200 nm. The separation was carried out with an uncoated fused-silica capillary (57 cm350 mm I.D.) and was operated at 210 kV potential. The separation buffers were prepared with 0.5 M H PO , 0.5 mM cetyltrimethylammonium bromide and pH adjusted by adding NaOH to 6.25 except for propionic acid 3 4 which was better measured at pH 7.00. Validation parameters are adequate and limits of detection range from 0.005 mM to 1.6 mM. Short-chain organic acids were measured with this method in sera of three different types of latex.

A screening often different Mediterranean crops was carried out to test their tolerance to soils polluted with copper and zinc. The methods for copper and zinc determination in plants have been improved, avoiding the time consuming acid digestion. Results showed that zinc toxicity was higher than copper for the assayed plants. In copper-polluted soils, Lupinus luteus (lupin) 549µgg- 1 and Zea mays (corn) 213µgg- 1 showed the highest amounts dried weight of accumulated metal, mainly detected associated to the root system without significant reduction of biometrical parameters of the plants. In zinccontaminated soils, corn (1304 µgg- 1 ), Triticum durum (wheat) (933 µgg- 1 ) and lupin (654µgg- 1 ) showed the highest amounts of metal accumulated mainly in the roots, and in all cases, without biometrical reduction.