Use of whole electrophoretic profile and chemometric tools for the differentiation of three olive oil qualities.

Olive oil is a liquid fat obtained from olives (the fruit of Olea europea). It is one of the most important ingredients of the Mediterranean diet, due to its health benefits. Depending on its quality, olive oil can be classified as extra virgin (EVOO), virgin (VOO) and lampante (LOO). Currently, an official method defines the quality parameters of the different categories of olive oil using different analytical techniques and a sensory analysis through a Panel Test. However, the evaluation of olive oil quality by tasting panels has some drawbacks, such as the subjectivity of the analysis and the lack of panels accredited outside Spain. For this reason, fast, simple and reliable analytical methods, which can differentiate the categories of olive oil are needed. In this work, the potential of a method using capillary electrophoresis (CE) with ultraviolet (UV) detection as an additional method to the ones already included in the official method has been investigated. The separations were performed using a 45 mM sodium tetraborate buffer (pH 9), and the analytes were measured at 200 nm. For chemometric model construction, the whole electrophoretic profile was processed. It required a correction of migration time shift, which was solved using two internal standards (naphthol and benzoic acid), and a correction of the drift baseline. The results obtained after applying the method to 130 olive oil samples are very promising, achieving success rates above 91%. Finally, the use of all information found in the electropherogram was compared with that based on the selection and integration of only some peaks.

Innovative coupling of supercritical fluid extraction with ion mobility spectrometry.

This paper describes a pioneer on-line hyphenation between a supercritical fluid extraction (SFE) and an ion mobility spectrometry (IMS) detector through a Tenax TA sorbent trap as retention interface. By means of a simple design, taking advantage of both techniques, this new coupling allows us to extract and preconcentrate analytes and in a second step to determine them. As result, an increase in the accuracy of the analytical process was achieved by elimination of sample transfer from one device to another. In addition, this new coupling reduces the time needed for the optimization of a new SFE method, since the detector can monitor on-line the efficiency of the extraction. The parameters affecting the coupling and its success have been studied in detail via the extraction of benzene and toluene from soil samples. Finally, the suitability of IMS as on-line detector to monitor compounds of industrial interest extracted by SFE was evaluated taking as a model, the extraction and detection of 1,8-cineole (eucalyptol) in rosemary aromatic plants, which could be extrapolated on an industrial scale.

Use of carboxylic group functionalized magnetic nanoparticles for the preconcentration of metals in juice samples prior to the determination by capillary electrophoresis.

Nowadays food industry demands reliable and precise methods to resolve problems related to quality and security control. The pretreatment steps, prior to sample analysis, are necessary to extract the target analytes because of the complexities of the food samples matrices. In this work, we have studied, for the first time, the potential of carboxylic group functionalized magnetic nanoparticles to preconcentrate metals from liquid samples before CE analysis. For the extraction of metals, 10 mL of an aqueous sample containing the metal mixture was added to 2 mg carboxylic group functionalized magnetic nanoparticles. Metals retained in the nanoparticles were re-extracted with 200 µL solution consisting of 0.8 mM 1,10-phenanthroline and 0.04% hydroxylamine chloride at pH 2. The electrophoretic buffer used in this work to separate different metals (Co, Cu, Zn, Ni, and Cd) consisted of 30 mM hydroxylamine chloride, 0.30 mM 1,10-phenanthroline, 80 mM urea, 15 mM ammonium chloride, and 0.1% methanol at pH 3.6. Finally, measurements were made at 270 nm. Under the optimized conditions, detection limits for Co, Zn, Cu, Ni, and Cd were 0.004, 0.003, 0.004, 0.008, and 0.009 mg L(-1) , respectively.

Differentiation of organic goat's milk based on its hippuric acid content as determined by capillary electrophoresis.

Organic foods have lately aroused interest by virtue of their quality and their essential, exclusive characteristics. In this study, we assessed the potential of CE to detect a marker that is able to identify the particular food given to the goats and develop an effective method to determine directly the most abundant organic acid in goat's milk (viz. hippuric acid). In addition, we examined the use of the hippuric acid content of goat's milk as a general marker for authenticating organic goat's milk. The feeding of these goats can be influenced by the time of the year. For this reason, we have collected samples from 20 conventionally fed goats and 20 organically fed goats over a period of 2 months. A threshold value dependent on the hippuric acid content was thus established for the first time with a view to discriminating between conventional and organic goat's milk. Organic acids in goat's milk were separated in a running buffer consisting of 120 mM sodium tetraborate decahydrate and 0.5 mM CTAB set to pH 8. The precision of the ensuing method is acceptable for hippuric acid; thus, the RSD for peak area and migration time was less than 10 and 4%, respectively. Also, calibration curves were linear throughout the studied concentration range.