The determination method of total arsenic (As) and the speciation method of inorganic As for non-glutinous rice reported in our preceding paper were applied to several varieties of rice under optimized experimental conditions. In the determination of total As with ICP-MS, acetic acid was added to increase the sensitivity and an internal reference method with germanium was adopted to increase the precision. The extraction temperature in the partial-digestion method with nitric acid to speciate inorganic As was raised to 100ῌ, because extraction e$ciency over 90῍ was obtained from glutinous rice and colored rice at this temperature. In the investigation of polished and unpolished forms of non-glutinous, glutinous, and colored rice, the amounts of total and inorganic As were 0.04ῌ0.54 mg/kg and 0.02ῌ0.41 mg/kg, respectively. The color of rice was not related to total or inorganic As content. These results indicate that the inorganic As content in commercial rice should be carefully monitored.

Furan is a 5-membered ring compound with high volatility. The U.S. Food and Drug Administration (FDA) has recently published a report on the occurrence of furan in a large number of thermally processed foods. However, the FDA's analytical method, using standard curve addition, is not suitable for high-throughput routine laboratory operations. We developed a rapid and improved method for determination of furan in foods by headspace GC/MS. Quantification was achieved by using an internal standard of d 4 -furan and an external calibration curve of furan normalized against the internal standard. The incubation temperature for equilibration was set at 60῍ to avoid the formation of furan during analysis. The levels of furan in baby foods and infant formulas were determined with this method. Validation data showed good precision and accuracy. The LOD and LOQ were 0.2ῌ0.5 ng/g and 0.5ῌ2 ng/g for various food matrixes, respectively. The level of furan detected was in the range of 1.4 to 90 ng/g in baby foods and in the range of non-detectable to 36 ng/g in infant formulas.Key words: furan; headspace; gas chromatography-mass spectrometry; baby food; infant formula Introduction Furan (C 4 H 4 O) is a colorless, volatile (boiling point 31῍) and lipophilic organic compound 1) . It is considered to be a hazardous chemical and is classified by the International Agency for Research on Cancer (IARC) as possibly carcinogenic to humans (group 2B; IARC) 2) . The U.S. Food and Drug Administration (FDA)῍ 1 has recently published a report on the occurrence of furan in a large number of thermally processed foods, such as canned and jarred foods, including baby foods and infant formulas. The FDA analyzed approximately 340 food samples and found furan levels ranging from non detectable to approximately 170 ng/g. The Swiss Federal O$ce of Public Health has presented an analytical method for the determination of furan in foodstu#s and used it to measure furan levels in a variety of foods on the Swiss market 3) . The European Food Safety Authority (EFSA) 4) has recently published a report on furan, in which they concluded that a more detailed risk assessment was required.The primary source of furan in food was considered to be thermal degradation of carbohydrates, such as glucose, lactose and fructose 5) . Perez-Locas and Yaylayan suggested that ascorbic acid had the highest potential to produce furan on thermal treatment, followed by some sugar/amino acids mixtures 6) . Health Canada has recently reported the formation of furan via the oxidation of polyunsaturated fatty acids at elevated temperatures, and from the decomposition of ascorbic acid derivatives 7) . Fan has recently studied the formation of furan from sugars, ascorbic acid and organic acids under the influence of ionizing radiation and thermal treatments 8) . It was reported that the pH and concentration of sugars and ascorbic acid solution profoundly influenced furan formation during irradiation or thermal treatment.As furan is a small, volatile molecule, headspace gas chrom...

Because there is a great di#erence between the toxicity of inorganic arsenic (As) and organic As in food, the JECFA has set a PTWI value for inorganic As (iAs) rather than for total As. The di#erence in As toxicity makes it necessary to extract iAs completely from food samples for toxicological analysis, but complete extraction of As from most foods including seaweed has not been achieved to date. We developed a partial-digestion method that uses nitric acid as a solvent in order to extract almost all arsenicals from the solid matrix of hijiki (Hizikia fusiforme, a brown alga) samples. In this method, organic As species were not converted into iAs. HPLC/ICP-MS was then used to determine the concentration of iAs. Total As was measured by hydride generationatomic absorption spectrometry. The adopted conditions for 0.1 g of ground fine powder sample were: 2 mL of 0.3 mol/L nitric acid; heating, 80ῌ for 1 hr. Intra-laboratory validation of the method showed good precision and accuracy. The repeatability and intermediate precision for iAs were 1.5῍ and 1.5῍, respectively. The LOD and LOQ for iAs were 0.14 and 0.46 mg/kg dry weight, respectively. Recovery studies performed by spiking 0.5 mg/kg dry weight as the LOQ level and by spiking 3 mg/kg dry weight as the iAs concentration of an un-spiked hijiki sample showed good accuracy. The method was applied to hijiki samples after a water soaking process and a water soaking and simmering process. The results suggested that the As concentration in hijiki after both processes was lower than that before the treatments and that the water soaking and simmering process reduced the iAs concentration much more e#ectively than the water soaking process.

Arsenic (As) uptake in human occurs via the food chain mainly. The Joint FAO/WHO Expert Committee on Food Additives has established the provisional tolerable weekly intake level for As as an inorganic As (iAs) value, because iAs in food is much more toxic than organic As. In this study, we studied an acid based partial-digestion method for the complete extraction of arsenicals from rice. HPLC/ICP-MS was used to determine the concentration of iAs selectively. The conditions adopted to extract arsenicals from a 0.5 g of finely ground rice sample were addition of 2 mL of 0.15 mol/L nitric acid and heating at 80ῌ for 2 hr. The LOD and LOQ for iAs were 0.0024 and 0.0079 mg/kg dry weight, respectively. Recovery studies showed good accuracy. When the method was applied to ten short-grain brown rice samples, the iAs concentrations were 0.108ῌ 0.227 mg/kg dry weight and the total As concentrations were 0.118ῌ0.260 mg/kg dry weight. Although dimethylarsinic acid was also detected in most samples, the percentage of iAs content in total As content was 62.2ῌ96.3῍. Thus, iAs was the principal As species in the short-grain brown rice samples tested.