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Le Touquet – Paris-Plage, France

Sarazin C.,Central Laboratory Of The Prefecture Of Police
Analytical chemistry | Year: 2011

Capillary electrophoresis (CE) appeared as an interesting alternative to chromatographic methods for carbohydrate analysis, but it can be difficult to implement, because of the lack of easily ionizable functions and chromophore groups. Recently, a promising method was proposed by Rovio et al. for the CE separation under extremely high alkaline conditions of neutral carbohydrates under their alcoholate form and their direct UV detection [Rovio et al. Electrophoresis 2007, 28, 3129-3135; and Rovio et al. J. Chromatogr. A 2008, 1185, 139-144], which is claimed to be due to the absorption of enediolate at 270 nm. Even so, most of the detected compounds in Rovio's paper (for example, sucrose) cannot give such enediolate, lacking a carbonyl group. In this work, a deeper insight was paid to the understanding of detection mechanism. In effect, unusual detection phenomena were observed in comparing reducing and nonreducing carbohydrate behaviors, which pointed to the existence of photochemical reactions in the detection window. A more systematic study of the influence of many parameters (carbohydrate nature, electrolyte pH, residence time in the detection window, and capillary diameter) was undertaken. In addition to this, most of this work was performed under cathodic (reversed) electro-osmotic flow conditions (using Polybrene-modified capillaries), to obtain much faster separations than under Rovio's conditions. This study also opens up new avenues for the detection in mid-UV range of non-UV-absorbing compounds bearing reducing moieties, such as amino acids.

Sarazin C.,Central Laboratory Of The Prefecture Of Police | Sarazin C.,Chimie Paristech | Sarazin C.,University Pierre and Marie Curie | Sarazin C.,CNRS Physical Chemistry of Electrolytes and Interfacial Nanosystems | And 8 more authors.
Talanta | Year: 2012

A new capillary electrophoresis method dedicated to the analysis of neutral underivatized carbohydrates was recently developed by our group. It involved a background electrolyte composed of 98 mM NaOH and 120 mM NaCl, and direct UV detection via the formation of an absorbing intermediate in the detection window by photooxidation. This article focuses on the validation of this method for the determination of fructose, glucose, lactose, and sucrose in forensic, pharmaceutical, and beverage samples. Intermediate precisions were about 2.3% for normalized corrected peak areas and 1.8% for normalized migration times using naphthalenesulfonate as internal standard. Limits of detection varying from 5 μM for sucrose and lactose to 7 μM for glucose and 10 μM for fructose were obtained. Potential matrix effects were statistically studied for soil, cloth, plastic, cotton, red wine, and with simulated iron, calcium, and sucrose-based matrices, containing various inorganic anions and cations, sometimes at high levels. No significant matrix effect was observed. Finally, analyses of real post-explosion residues, smoke device, cough syrup, red wine, and apple juice were successfully performed. © 2012 Elsevier B.V.

Sarazin C.,Central Laboratory Of The Prefecture Of Police | Sarazin C.,Chimie Paristech | Sarazin C.,University Pierre and Marie Curie | Sarazin C.,French National Center for Scientific Research | And 11 more authors.
Journal of Separation Science | Year: 2012

This paper focuses on the optimization with a design of experiments of a new CE method for the simultaneous separation of four carbohydrates of interest (fructose, glucose, lactose, and sucrose) and five potentially interfering carbohydrates (ribose, xylose, maltose, mannose, and galactose) with a highly alkaline separation electrolyte for subsequent applications to food, beverage, forensic, or pharmaceutical samples. First, the factors that potentially affect the carbohydrate migration were identified: NaOH concentration in the separation electrolyte, separation temperature, and separation electrolyte conductivity. A central composite design was then carried out to determine and model the effects of these three factors on normalized migration times and separation efficiency. From the model, an optimization of the separation was carried out using a desirability analysis based on resolutions between adjacent peaks and analysis time. The optimum conditions obtained were a separation electrolyte composed of 98 mM NaOH and 120 mM NaCl to adjust the conductivity at 4.29 S/m and a separation temperature fixed at 26.5°C. Finally, these conditions were experimentally confirmed and the robustness of the obtained separation was checked. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sarazin C.,Central Laboratory Of The Prefecture Of Police | Delaunay N.,Chimie Paristech | Varenne A.,Chimie Paristech | Costanza C.,Central Laboratory Of The Prefecture Of Police | And 2 more authors.
Journal of Separation Science | Year: 2010

Bursts resulting from the chemical reaction between hydrochloric or nitric acid with aluminum foils are very often committed by the young delinquency in western countries because of its easiness of achievement. A fast, simple, selective, and cost-effective method allowing the simultaneous detection of chloride and nitrate anions and aluminum(III) was thus required. This article focused on the development and validation of a CE method using a BGE containing 2,6-pyridinedicarboxylic acid (PDC) acting as both an anionic chromophore and as an aluminum(III) complexing agent. First, the achievement of the speciation diagram of Al(III) in the presence of PDC allowed the choice of pH conditions for which aluminum(III) was globally anionic. The study of the selectivity for Al(III) in the presence of ten other cationic species potentially present in post-blast residues dictated the choice of the PDC concentration at 20 mM. The validation step next demonstrated the figures of merit of the method, with an intermediate precision for Al(III) of 2% on normalized migration times and 3.5% on corrected areas. Finally, this method was used for analyses of real post-blast extracts from acidaluminum mixtures. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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