A new method of determination of malachite green (MG) in sediment has been developed by high performance liquid chromatography with fluorescence detection (HPLC-FLD). It is based on use of a deoxidation reaction which converts malachite green (MG) into LMG in the process of extraction. The sediment samples were extracted with a solution of formic acid and acetonitrile. Clean up and isolation was performed on MCX solid phase extraction (SPE) column. Chromatographic separation was achieved by using C18 column with an isocratic mobile phase consisting of acetonitrile and ammonium acetate buffer (0.05 M, pH 4.5) (80:20, v/v). High performance liquid chromatography with fluorescence detector (λex=265 nm and λem=360 nm) was used for the determination of LMG. The recovery values of MG in sediment samples fortified with MG were determined by measuring the amount of MG in the samples, after carrying out deoxidation reaction with potassium borohydride, which converts the MG into LMG. Under the optimized conditions, the average recoveries of MG from sediment at three levels (1.0, 10 and 50 μg/kg) were 85.0% (range from 80.8 to 87.6%). Relative standard deviations (RSD) of recoveries at all fortification levels were less than for 9.57% for MG. The method detection limit obtained for MG was 0.5 μg/kg.

This study evaluated the extraction of oil from sturgeon (Acipenser baeri) muscle using supercritical fluids. Response surface methodology (RSM) was used to identify and quantify the variables, namely extraction pressure, extraction time and CO2 flow rate on the yield of oil. Statistical analysis indicated that for all three variables, the quadratic terms and interactions between the variables had significant effects on yield (p < 0.05). Polynomial regression model predictions were in good agreement with the experimental results, with a coefficient of determination of 0.9936 for yield. Maximum yield from sturgeon muscle was 26.83% with a pressure of 315.8 bar, extraction time of 10.8 min and CO2 flow rate of 3.5 l/min, which closely matched the predicted value (26.70%). The characteristics of the fish oil extracted with the supercritical fluids were superior to those of oil obtained by other methods.

In the present study, the crude polysaccharides were extracted from the microalgae Gracilaria lemaneiformis with ultrasonic-assisted extraction method and purified by DEAE-52 cellulose chromatography and Sephadex G-100 size-exclusion chromatography in that order. Two main fractions, GPC-1and GPC-2, were obtained through the extraction and purification steps. Then partial characterizations, such as chemical composition, ultraviolet (UV) spectrum and infrared (IR) spectrum of the two fractions were analyzed in this study. The results indicated that the total sugar contents of GPC-1and GPC-2 were 89.32% and 88.79%, and the protein contents of these two fractions were only 0.35% and 0.76%, compared with that of crude polysaccharides of 75.49% and 1.92%, respectively. Moreover, both the UV spectrum and the IR spectrum demonstrated that the two fractions were typical purified polysaccharides. As a consequence, these investigated characterizations could be considered as a favorable evidence for the identification of polysaccharides from Gracilaria lemaneiformis.

A novel Schiff base, 2-(Salicylideneamino)pyridine (2-SAP) synthesized by 2-aminopyridine and salicylaldehyde was used as a fluorescence probe to determine superoxide anion radical (O2•-) in this study. The synthetic product was characterized by IR, 1H-NMR and GC-MS methods. A fluorescence quenching reaction occurs between 2-SAP and O2•-, and the fluorescence intensity decreased significantly. The effect of pyrogallol concentration (2.0×10-5 M to1.0×10-3 M) was discussed in this study. In the range from 2.0×10-5 M to 1.0×10-4 M, relative fluorescence intensity (y) and pyrogallol concentration (x) shown a good linear relationship, y=37.801x+76.854, r=0.993. Based on this phenomenon, the O2•- generated by pyrogallol autoxidation could be determined simply with high sensitivity.

This article focused on the study of frozen storage temperatures effect on protein of crisp grass carp, and then induced changes of texture of crisp grass carp muscle. During frozen storage, lower temperature, better texture of crisp grass carp muscle. The little changes of texture characteristics of crisp grass carp were related to lower changes of drip loss, cooking loss, protein solubility and thermal stability. The results indicated that lower temperature of frozen storage was beneficial to maintain the mastication of crisp grass carp.