Aqueous-nonaqueous solvent-switching ion chromatography of halide impurities in ionic liquids.

We here propose an efficient solvent-switching preconcentration method for the ion-chromatographic (IC) determination of halide impurities contained ionic liquids (ILs). Because halide impurities strongly affect the physicochemical properties of ILs, their analysis is an important task for the successful utilization of ILs. Although IC is an efficient method for this purpose, its application still involves significant challenges. The major halide impurities, such as F- and Cl-, show much smaller retention in aqueous anion-exchange chromatography than IL component anions. Therefore, if an IL sample is directly analyzed by IC with aqueous mobile phases, the halide impurities are eluted earlier, whereas the IL component anion is hardly eluted and gives a large peak once eluted. Thus, the introduction of the IL component anions into the IC separation column should be avoided for efficient analyses and also for preventing the degradation of the column by the accumulation of the IL anions in it. This problem, which arises from the ion-exchange selectivity in aqueous media, is solved by a solvent switching preconcentration method. The anion-exchange selectivity in aqueous media is reversed by a use of an aprotic solvent, such as acetonitrile (MeCN). Hence, we have come up with the idea of preconcentrating anions in MeCN and stripping them with an aqueous mobile phase for IC analysis. The introduction of the IL component anions into the IC separation column is substantially reduced while maintaining high sensitivity for the halide impurities. Sub µM impurities are detectable in the mM level of ILs.

Fish protein hydrolysate exhibits anti-obesity activity and reduces hypothalamic neuropeptide Y and agouti-related protein mRNA expressions in rats.

Fish protein is a source of animal protein that is consumed worldwide. Although it has been reported that the intake of Alaska pollack protein (APP) reduces body fat accumulation and increases muscle weight in rats, the mechanisms underlying these effects are poorly understood. As a possibility, peptides released from APP in the gastrointestinal tract are important to the functions of APP. In the present study, we examined the effects of APP hydrolysate digested artificially with pepsin and pancreatin on white adipose tissue and skeletal muscle. We found that APP hydrolysate group shows significantly lower weight of white adipose tissue and higher weight of soleus muscle than the control group. We also found that APP hydrolysate group reduces food intake and mRNA expressions of neuropeptide Y and agouti-related protein in the hypothalamus compared with the control group. These results may imply that APP hydrolysate exhibits anti-obesity activity by the reduction of appetite and the enhancement of basal energy expenditure by skeletal muscle hypertrophy in rats. The downregulation of orexigenic gene by APP hydrolysate in the hypothalamus may contribute to the reduction of appetite. These results suggest that the effect of APP on anti-obesity and muscle hypertrophy may be induced by peptides released from APP in the gastrointestinal tract.