Epithermal instrumental neutron activation analysis of biological reference materials for iodine

Simultaneous determination of 76As, 122Sb and 153Sm in Chinese medicinal herbs by epithermal neutron activation analysis

Optimal conditions for the simultaneous determination of As, Sb and Sm in Chinese medicinal herbs using epithermal neutron activation analysis were investigated. The minimum detectable concentrations of 76As, 122Sb and 153Sm in lichen and medicinal herbs depended on the weight of the irradiated sample, and irradiation and decay durations. Optimal conditions were obtained by wrapping the irradiated target with 3.2 mm borated polyethylene neutron filters, which were adopted to screen the original reactor fission neutrons and to reduce the background activities of 38Cl, 24Na and 42K. Twelve medicinal herbs, commonly consumed by Taiwanese children as a diuretic treatment, were analysed since trace elements, such as As and Sb, in these herbs may be toxic when consumed in sufficiently large quantities over a long period. Various amounts of medicinal herbs, standardised powder, lichen and tomato leaves were weighed, packed into polyethylene bags, irradiated and counted under different conditions. The results indicated that about 350 mg of lichen irradiated for 24 h and counted for 20 min following a 30-60 h decay period was optimal for irradiation in a 10(11)n/cm s epithermal neutron flux. The implications of the content of the studied elements in Chinese medicinal herbs are discussed.

Contribution of mass spectrometry to assess quality of milk-based products

The vast knowledge of milk chemistry has been extensively used by the dairy manufacturing industry to develop and optimize the modern technology required to produce high-quality milk products to which we are accustomed. A thorough understanding of the chemistry of milk and its numerous components is essential for designing processing equipment and conditions needed for the manufacture and distribution of high-quality dairy products. Knowledge and application of milk chemistry is also indispensable for fractionating milk into its principal components for use as functional and nutritional ingredients by the food industry. For all these reasons, powerful analytical methods are required. Because of the complexity of the milk matrix, mass spectrometry, coupled or not to separation techniques, constitutes a key tool in this area. In the present manuscript, we review the contribution and potentialities of mass spectrometry-based techniques to assess quality of milk-based products.

Optimal conditions for identifying 80Br and 128I in health food Angelica keiskei using rapid epithermal neutron activation analysis

This study presents an optimal rapid epithermal neutron activation analysis (ENAA) technique, using a 1mm Cd filter in reactor neutron flux, to analyze 80Br and 128I in the roots, stems, and leaves of health food Angelica keiskei (AK). Various sample weights of lichen (IAEA-336) for each portion of AK, under various periods of irradiation and counting, were used to optimize the elemental analysis. Selecting the analytical conditions depends on the minimum detectable concentration (MDC), required sensitivities and the quantitative accuracy of Br and I elements. These findings imply that the MDCs of Br and I, measured under 10min activation and 5min counting followed by 10min decaying, using 350mg of lichen are ideal for elemental analysis. Moreover, each portions of AK were analyzed under optimal conditions. The elemental concentrations of Br, Cl, I, Mg, Mn and Na and their implications are discussed.

The application of preirradiation combustion and neutron activation analysis technique for the determination of iodine in food and environmental reference materials

The pre-irradiation combustion (PC) of samples to liberate iodine, followed by trapping the iodine on charcoal and quantifying the element by neutron activation analysis (NAA), has been used at the National Institute of Standards and Technology for the determination of iodine in biological materials. The applicability of this technique to numerous environmental and dietary matrices is illustrated by analysis of a range of certified reference materials (CRMs) and a powdered grass material that was prepared as an in-house reference material (RM). Because of the combustion step involved, samples with low or no fat content (e.g., cereal products, selected botanical specimens, and nonfat milk powder) and inorganic materials (e.g., coal fly ash and dried sediments) are more suited for analysis by this method. In general, the results for several types of samples obtained by this method agreed with those obtained by a second radiochemical (R) NAA, as well as by a third method using inductively coupled plasma mass spectrometry (ICP-MS). PC-NAA is a useful technique for determining iodine in biological and environmental samples, especially for verification of iodine results obtained from other methods.

The study of iodine in Chinese total diets

In this work, China was divided into four area groups according to their geographical positions and dietary habits. All foods were divided into 12 types and the iodine contents in various diets were determined using epithermal neutron activation analysis (NAA). The intakes for China were evaluated. The results indicate that the intakes of iodine in northern areas are slightly higher and in south areas lower than the lowest recommended intake, and the average intake in China is 166 micrograms/person per day, which is within the recommended range. In addition, one province were chosen from each area groups. The dietary intakes of iodine were investigated in different ages and sex using total mixed diet method. Our results indicate that the average iodine intake of four provinces was lower than the recommended value, which suggests that it is necessary to supplement iodine in foods in China.