Toshiharu Kawabata

Gas chromatographic determination of methylguanidine, guanidine and agmatine as their hexafluoroacetylacetonates

Abstract Seven derivatives each of methylguanidine, guanidine and agmatine have been prepared, and the specificity and volatility of their gas chromatographic detection have been studied. The hexafluoroacetylacetonates have been found to be the most specific for the three guanidines, and are highly sensitive to alkali flame ionization and electron-capture detections. These derivatives are also fairly resistant to hydrolysis occurring in the derivatization process.

Gas chromatographic separation of hydroxylated N-nitrosamines.

Derivatives of six hydroxylated N-nitrosamines were prepared by acylation, trifluoroacylation, trimethylsilylation and methylation, and the volatilities and sensitivities of these derivatives on gas chromatographic detection were compared. All six nitrosamines were successfully derivatized by either acylation or trimethylsilylation. The acylated derivatives were easy to prepare; in addition, acylation was more specific than trimethylsilylation for the reaction with hydroxyl groups in the molecule.

Studies on the destruction of Salmonella in fish meals produced in the coastal areas of Japan - II. Decontamination of Salmonella from the coastal fish meals by 60Co .GAMMA. ray irradiation.

The decontamination of salmonellae from fish meal samples by irradiation which 60Coγ ray was examined. Sixteen strains of Salmonella were used. A composite fish meal sample was prepared by mixing with different coastal meals, and after radiation sterilization at a dose of 20 kGy 60Coγ ray, which was employed as the salmonella-free meal sample. D10 values of test strains determined in buffered saline were found to range from 0.08 to 0.36 kGy, and inactivation factors at a dose of 1 kGy ranged from 102.8 to 1013. D10 values of test strains determined in the salmonella-free meal sample ranged from 0.59 to 1.64 kGy, and the inactivation factors at a dose of 10 kGy were found to range from 106.1 to 1017. Interestingly the D10 values of salmonellae determined in fish meal samples were 10 times as much compared with those determined in buffered saline. From the commercial aspects of coastal fish meal production, destruction of salmonellae in fish meals by 60Coγ ray irradiation was found to be much more practical than other methods such as dry heating and ethylene oxide fumigation.

Occurrence and formation of volatile N-nitrosamines in fish meal - III. Mechanism of N-nitrosothiazolidine formation at the stage of fish meal preparation.

Both cysteamine (CysA) and thiazolidine (THZ) are considered to be the precursors of N-nitrosothiazolidine (NTHZ). Regarding the occurrence of these compounds in foods, how-ever, almost no data has been available so far. Present study has revealed the existence of about 200μg/kg of CysA in fresh sardine meat, while the CysA content in the meat de-creased below 30% of the initial level after being boiled, and only 5% of CysA was retained in the meal samples after freeze-drying of the boiled meat. On the contrary, very small quantity of THZ were detected in the fresh sardine meat, however, the contents remarkably increased upon boling to reach 128μg/kg, and the levels did not change even after lyophiliza-tion. Fish meal samples made from whole bodies of fresh sardines were found to contain larger amounts of THZ than those of CysA, in contrast; the THZ levels in the samples made from decomposed fish were appearently lower than those made from fresh materials. It was confirmed that nitrosothiazolidine-4-carboxilic acid (NTZC) was formed in the sardine meal samples after treatment with NO2 gas, and the yield of NTZC reduced by lowering the fresh-ness of raw fish materials. Based on the afbrementioned results, it may be proposed that the following two pathways exist in the formation of NTHZ in fish meal during manufacturing process, viz., (1) formation of NTHZ by nitrosation of THZ, and (2) formation of NTHZ by decarboxylation of NTZC.