A gas diffusion sequential injection system with amperometric detection using a boron-doped diamond electrode was developed for the determination of sulfite. A gas diffusion unit (GDU) was used to prevent interference from sample matrices for the electrochemical measurement. The sample was mixed with an acid solution to generate gaseous sulfur dioxide prior to its passage through the donor channel of the GDU. The sulfur dioxide diffused through the PTFE hydrophobic membrane into a carrier solution of 0.1M phosphate buffer (pH 8)/0.1% sodium dodecyl sulfate in the acceptor channel of the GDU and turned to sulfite. Then the sulfite was carried to the electrochemical flow cell and detected directly by amperometry using the boron-doped diamond electrode at 0.95 V (versus Ag/AgCl). Sodium dodecyl sulfate was added to the carrier solution to prevent electrode fouling. This method was applicable in the concentration range of 0.2-20 mg SO32−/L and a detection limit (S/N = 3) of 0.05 mg SO32−/L was achieved. This method was successfully applied to the determination of sulfite in wines and the analytical results agreed well with those obtained by iodimetric titration. The relative standard deviations for the analysis of sulfite in wines were in the range of 1.0-4.1 %. The sampling frequency was 65 h−1.

Thirty-nine Thai rice cultivars, including 17 non-colored rice cultivars and 22 colored rice cultivars (black rice cultivars and red rice cultivars), were investigated for γ-oryzanol content. The γ-oryzanol content of non-colored rice cultivars and colored rice cultivars was found to be 226.40 ± 17.50 μg/g to 411.80 ± 19.80 μg/g and 295.80 ± 15.40 μg/g to 459.80 ± 6.60 μg/g, respectively. Black rice cultivars seem to have higher γ-oryzanol content than do red rice and non-colored rice cultivars. The highest γ-oryzanol levels were identified in Khao Jao Dam Sa-Nit, a black rice cultivar, which contained 1.55 and 2.03 times more γ-oryzanol than Khao Man Bpoo, a red rice cultivar with lowest γ-oryzanol levels, and Khao Gor Kor 57, a non-colored rice cultivar with lowest γ-oryzanol levels, respectively. For further investigation, the effects of gamma irradiation on the γ-oryzanol content of four germinated Thai market rice cultivars, Khao Pathum Thani 1, Khao Gor Kor 31, Khao Gor Kor 41, and Khao Gor Kor 57, was investigated. The highest increase in γ-oryzanol content among the gamma irradiated rice cultivars was identified in Khao Pathum Thani 1 and Khao Gor Kor 31, which had γ-oryzanol levels approximately 1.27 times higher than that of the control rice (non-gamma irradiated rice). Our report contains basic knowledge about creating new rice lines that are rich in highly beneficial nutrients.

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A sequential injection analysis (SIA) system for the determination of total calcium in blood has been implemented. The assay principle is based on the arsenazo III method, in which the indicator’s complex with calcium forms a blue-purple colour. The absorbance peak height at 650 nm was proportional to the calcium content in samples. A linear range was obtained from 2.5 - 15 mg?dL–1 (r2 = 0.999), with a detection limit of 0.430 mg?dL–1 (3σ). Magnesium, glucose, hae-moglobin, and bilirubin at 123, 1,000, 50, and 0.5 mg?dL–1, respectively, were not found to interfere with the proposed system significantly (recovery 99.1% - 104.4%). The sampling frequency was 30 h–1, in which the carry-over effect was negligible (0.69%). The proposed SIA system was successfully applied to the determination of calcium from serum samples (r2 = 0.970; n = 30)

This study evaluated the cyanide content, bio-active compounds profile, volatile compounds profile, and biological activity of fresh and boiled sliced bamboo. Cyanide was only detected in fresh bamboo shoots, at a content of 140.40±5.34 mg/kg. Furthermore, the fresh bamboo shoots extracts had free radical scavenging properties, as demonstrated by ABTS･ + and DPPH･ assays, and contained phytochemical compounds, such as flavonoid, terpenoid, and reducing sugar. Indeed, the total phenolic and flavonoid contents were 12.12±0.12 mg gallic acid equivalent/dw and 1.60±0.11 mg quercetin equivalent/dw, respectively. In addition, these extracts demonstrated inhibitory activity against α-glucosidase (61.30±0.45%), α-amylase (37.00±1.82%), and tyrosinase (26.57±0.57%). Some volatile compounds, such as 2-methoxyphenol and 2-pentylfuran, show α-glucosidase inhibitory activity, and these compounds exerted α-amylase inhibitory activity in the fresh sliced bamboo shoots. The major volatile compound 4-methylphenol (68.15%), which exerts tyrosinase inhibitory activity, was also detected in fresh sliced bamboo shoots. The boiled sliced bamboo shoots extracts also contained bio-active compounds and exhibited biological activity similar to those in the fresh sliced bamboo shoots extracts. However, the boiling process and sliced technique reduced the bio-active compounds and biological properties as well as some of volatile compounds.