Validation d’un procédé automatisé d’extraction sur phase solide de glandes digestives de moules pour l’identification et la quantification des dinophysistoxines en LC/ESI/SM2 par piégeage d’ions quadripolaire

This report presents a new extraction method of the dinophysistoxins (DTXs), confirmed by quantification using high-performance liquid chromatography coupled to mass spectrometry with an ion trap and electro spray interface (HPLC/ESI/MS2). The method originality consists on the adaptation of DTXs basic extraction procedure (liquid/ liquid) to a solid phase extraction (SPE) via a robotic station: ASPEC XLi The parameters of the automatization procedure were optimized to obtain the best DTXs recovery rate. These improvements were loaded with digestive gland mussel homogenat realized on a silica cartridge SPE, activated in hexane/chloroform (50:50), washed with hexane/chloroform (50:50) and extracted by an elution gradient (chloroform methanol (65:35) and methanol (100%)). This method was validated according to two normative referentials (linearity, detection quantification limits and accuracy…) : - The Guide of the Pharmacy industry: Analytical Validation, report of the commission SFSTP 1992 (French Corporation of the Sciences and Technical Pharmaceutical), - - The Procedure of validation of an alternative method in compare to a reference method. (AFNOR, 1998. NF V 03-110). Comparison with the classical liquid/liquid extraction and the automated method present clear advantages. In an analytical method the extraction is generally considered to be the most labor-intensive and error-prone step. This new procedure allowed us to increase throughput, to improve the reproducibility and to reduce the error risks due to the individual manual treatments.

Stockage des poissons fumés et ou séchés : cas de Oreochromis niloticus " Fiha saly " malgache

During storage of smoke-dried fish, various biochemical reactions can occur; they will result in product acceptability or rejection. To determine these changes, pH and humidity were measured and molds were counted on smoke-dried fish stored for 6 months. A sensory analysis was also conducted to assess the quality of the products. Infestations and losses linked to it have been estimated by counting the insects and weighing of fish batches over time. The variability in the quality of smoke-dried fish depending on the time of purchase and storage was also integrated with our study. Biochemical reactions are mainly oxidation phenomena which result in a decrease of pH and release of spoilage odors such as rancid odor (> 1.5/ 3) or sulfur, acid and moldy odors. The growth of mold (1- 36 CFU / g) due to the reabsorption of water by fish contributes to this olfactory and visual spoilage. Beyond 90 days of storage, smoke-dried fish bought in the dry season begins to be rejected (> 2/3), while the fish bought in the wet season is at the limit of acceptability (2/3) even at the beginning of storage. During the first 90 days of storage, the insect infestation generates between 10 and 60 % of losses. A salt content of 8 % appears to be effective against the infestation but contributes to the deterioration of the product when stored in rooms with higher than 65 % relative humidity.