A technique for the analysis of lac and cochineal colors using reversed-phase TLC and scanning densitometry is described. The technique involves the following three steps: 1) clean-up of the colors with a C18 cartridge, 2) separation of the colors by reversed-phase C18-TLC using methanol-0.5mol/L oxalic acid (5.5:4.5) as a solvent system, and 3) measurement of visible absorption spectra of the colors using scanning densitometry without isolation of the colors. In order to investigate the capability of the present method, 122 commercial foods were analyzed, and their chromatographic behaviors and spectra were observed. The separation and the spectra obtained were not affected by coexisting substances in the foods and the spots always gave the same Rf values and spectra as the standards, with good reproducibility. The present method is considered to be useful for the rapid analysis of lac and cochineal colors in foods.
A simultaneous determination method was developed for 89 polymer additives including 34 plasticizers in polyvinyl chloride. The samples were prepared by means of a published procedure for determination of antioxidants, ultraviolet stabilizers and lubricants in polyethylene. Additives were extracted with a mixed solution of cyclohexane and 2-propanol (1:1) by soaking overnight at 37°C, oligomers were removed by concentration and redissolution in warm acetonitrile, then analyzed by using GC/MS and HPLC. The recoveries of 34 plasticizers spiked in polyvinyl chloride were between 69.3-119.5% and the limits of quantitation were 50-500μg/g in polyvinyl chloride. Nonylphenol and bisphenol A could also be analyzed by this method.
The safety profile of an extractive from Salacia reticulata (Celastraceae) trunk (SE) was examined using an oral single dose toxicity test and chromosomal aberration test. In the oral toxicity test, SD rats were given SE at a dose of 5, 000mg/kg. No deaths or abnormalities in gross pathological findings were observed during the study period. The rats given SE had diarrhea for a few days due to the pharmacological properties. Moreover, body weight gain was suppressed in both male and female rats given SE, compared to the controls, at 1 day after administration. In the chromosomal aberration test using cultured mammalian cells (CHL/IU), no cells with chromosomal aberrations were observed. These results suggest that SE has no serious acute toxicity or mutagenicity.
Shiokara, a traditional fermented seafood in Japan, has never been reported to cause bacterial food poisoning. In this study, shiokara products were inoculated with Staphylococcus aureus, Vibrio parahaemolyticus, and Clostridium botulinum type E and the fates of these pathogens were determined during the fermentation of squid shiokara. V. parahaemolyticus declined rapidly and was not detectable after 12 days of fermentation. When shiokara was inoculated with mixtures of vegetative cells and spores of C. botulinum type E, the number of vegetative cells declined rapidly within 2 days, though the viable spores remained. S. aureus survived but did not grow or produce enterotoxin during the fermentation. These results confirmed the safety of traditional shiokara with respect to bacterial food hygiene. However, strict control of contamination by S. aureus throughout the manufacturing process is necessary, because the organism remained viable during fermentation.
A determination method for the antitripanosomal agent, isometamidium (IMD) in cattle muscle, liver, fat and milk has been developed by using HPLC. The drug was extracted from a sample with acetonitrile-0.25mol/L ammonium formate methanol solution, and purified by liquid-liquid partition with ethyl acetate and water, followed by extraction of the water layer in the presence of NaCl with acetonitrile. After evaporation of acetonitrile, the residue was taken up in 1mL of 0.25mol/L ammonium formate methanol solution. The drug was determined by HPLC with detection at 380nm using an octyl column (TSK-GEL Octyl-80Ts, 4.6mm i. d.×150mm), and acetonitrile-0.03mol/L citric acid containing 0.005mol/L sodium 1-heptanesulfonate (3:7) as an eluent. Recoveries of the drug from cattle muscle, liver, fat and milk were 76.0, 75.3, 88.0 and 89.0%, respectively, when 0.1μg/g of IMD was spiked. The detection limit was 0.01μg/g. The analysis of IMD by LC/MS was also investigated.
Paralytic shellfish poison (PSP)-contaminated bivalves, the surf clam Pseudocardium sachalinensis and hard clam Meretrix lamarckii, were extracted with water and each extract was divided into several portions, which were adjusted to various acidic pH values and autoclaved at 120°C for up to 120min. Irrespective of the species, the extract adjusted to pH 5 or 6 lost most of the toxicity when autoclaved for 15min, whereas at pH 3, the extract maintained its toxicity level throughout the autoclaving. HPLC analysis demonstrated that regardless of pH, each extract exhibited a PSP composition differing from the initial one when autoclaved for 15min. The extract showed no more changes in PSP composition at longer periods of autoclaving, even when the toxicity level was decreased at near-neutral pH. The present results indicate that the stability of PSP during autoclaving is pH-dependent and that PSP components or gonyautoxins 1-4 may attain mutual equilibria during 15min of autoclaving. A mixture of purified gonyautoxins gave essentially the same results as did the extracts.
A rapid and simple method for the simultaneous determination of saccharin (SA) and acesulfame K (AK) in foods by GC-NPD was developed. A good extraction rate was obtained by using ethyl acetate as an extraction solvent and high sensitivity was obtained by using GC-NPD. Interfering substances were removed or reduced effectively by clean-up using an acidic alumina cartridge column. The detection limit was 5 ppm in samples, and SA and AK were confirmed by GC/MS. The proposed method was applied to 89 samples of imported foods, such as soft drinks, instant cocoa and confectionery.
As an index for evaluation of marine environmental pollution by spilled C heavy oil from the sunken vessel Nakhodka, we carried out mutagenic activity tests of several fishes. Some gave positive results in direct and indirect mutagenicity tests. The strength of the mutagenicity was not high compared with that of authentic mutagenic compounds, such as AF-2. Though fishes caught in the polluted sea area were not dangerous from the viewpoint of mutagenicity, continuous observation is required to guarantee the safety of sea food resources.
We investigated a simplified determination of dymron in agricultural products by HPLC with UV detection. Homogenates of agricultural products were extracted with acetone. Each crude extract was purified on Bond Elut® extraction Cartridge PSA and SAX using a mixture of acetonitrile and diethyl ether. Dymron was analyzed by HPLC with UV detection (243nm). The HPLC separation was performed on a ODS column with acetonitrile-water (50:50) as the mobile phase. Recoveries of dymron from several agricultural products fortified at the level of 0.10ppm were in the range of 93.3-105.2%. The limit of detection was 0.005ppm in samples.
The effect of preservation on production of furanocoumarin stress compounds, psoralen, xanthotoxin and bergapten, in edible young leaves and stems of Glehnia littoralis was investigated. The shoots obtained from several local markets were preserved under different conditions. A time course study of the furanocoumarin contents by HPLC analysis indicated that these stress compounds accumulated especially in and around cut ends during preservation. When the shoots were cut into pieces and preserved, the stress compounds accumulated to a much greater extent. Since these furanocoumarins are potent photosensitizers, these results indicate that the aged cut ends should be removed before use as a vegetable, and that the cut shoots should be used without preservation.
Mean concentration and daily intake of preservatives were estimated based on the results of analysis of 112, 131 samples of food obtained at official inspections by Japanese local governments in fiscal year 1996. The mean concentration of benzoic acid was 7.8% of the allowable limits, and those of dehydroacetic acid, p-hydroxybenzoic acid, propionic acid and sorbic acid were 0.4%, 2.9%, 1.7% and 14.1%, respectively. Daily intakes of these preservatives per person estimated from the concentrations and daily consumption of the foods were 11.0mg, 0.0474mg, 1.06mg, 5.43mg and 26.0mg, respectively, and assuming a body weight of 50kg, these amounts of benzoic acid, p-hydroxybenzoic acid, and sorbic acid were 4.4%, 0.2% and 2.1% of the acceptable daily intakes, respectively. These values were similar to those based on the results of the official inspection in fiscal year 1994.