Trace element characterization of bullet lead by instrumental neutron activation analysis (INAA) is hampered by the high spectral
background due to antimony, normally present in high concentration in bullet lead. Tin is indicated to be a very useful element
for characterization purposes. Beta-active121Sn is a suitable nuclide for quantitation of tin provided it is separated in high radiochemical purity. A radiochemical procedure
capable of determining tin down to 10 ppm in bullet lead, a sequential procedure for its determination along with copper,
arsenic and antimony and the application of this procedure for the determination of the contents of these elements in various
bullet leads are described. This method has been applied to a “Rhinoceros shoot-out” case, referred to our laboratory.
Authors:P. Parthasarathy, H. Desai, and S. Kayasth
Radiochemical neutron activation analysis /RNAA/ has been applied for the determination of individual rare earth elements /REE/, except Tm, in 8 Indian monazites and one each from Malaysia and Thailand. Because of the very low amounts of heavy rare earths /HREE/ compared to light rare earths /LREE/ in monazite, HREE from Ho onwards have been determined only after the separation of the heavy and light rare earth fractions in the irradiated monazite samples. The results indicate significant variations in REE contents from Eu to Lu among different monazite samples. The chondritic normalized REE patterns of all the samples show a prominent negative Eu anomaly with different slopes at the heavy rare earth end. All the individual REE, except Tm, have been reported for the first time in various Indian monazites.
Authors:H. Desai, P. Padmanabhan, and Ch. Venkateswarlu
Copper in distilled water is collected on Zeokarb 226(NH
) and irradiated with thermal neutrons. By comparison of the induced activity of 0.51 MeV photopeak of64Cu with that of a standard, irradiated under comparable conditions, copper at ppb levels is easily determined.
Authors:H. Dang, H. Desai, D. Jaiswal, S. Kayasth, and S. Somasundaram
A simple separation scheme for the analysis of As, Mn, Mo, Cu and Zn using neutron activation is described. It has been checked
using three standard reference materials, A-11 milk powder (IAEA) and bovine liver and orchard leaves (USNBS) and found to
give acceptable results. This scheme was applied for determination of these trace elements in mature human milk samples. The
concentrations of As, Mn, Mo, Cu in samples obtained from two socio-economic groups—low and middle incomes—were not significantly
different. However, Zn levels in samples obtained from the poor income group were significantly lower than in those obtained
from the other group.
Authors:P. Srivastava, H. Raut, H. Puntambekar, and A. Desai
Storage of medicinal plants may cause deterioration of the active principles with time, thus, reducing the efficacy of plants. Therefore, quantification of the active principle is essential before using the crude drug. Phyllanthus amarus (PA) contains lignans, namely, phyllanthin and hypophyllanthin, which shows anti-hepatotoxic activity. In this paper, we highlight the effect of storage conditions on the quantification of bioactive markers by high-performance liquid chromatography (HPLC) analysis in the crude plant material of PA. HPLC analysis of crude PA samples stored for certain period at long-term study (LS, 30 °C and 65% RH), accelerated study (AS, 40°C and 75% RH), and real-time study (RT) conditions was carried out using the LiChroCART Purospher® STAR RP-18 endcapped (250 × 4.6 mm, 5 μm) column along with a Purospher STAR RP 18e (4.0 × 4.0 mm, 5 μm) guard column using methanol:water (70:30) at a flow rate of 0.7 mL min−1 with ultraviolet (UV) detection at 220 nm. The HPLC study indicated that PA samples kept under LS condition are rich in lignan contents as compared to the samples stored under AS and RT study conditions. Therefore, PA should be used fresh to get maximum concentration of active lignans or it should be stored under LS conditions up to 6 months.
Authors:H. Desai, S. Kayasth, R. Parthasarathy, and M. Das
Partial loss of elements in the oxygen flask method for the decomposition of biological materials is described. The irradiated sample is placed in a platinum wire gauze or quartz cup and burnt in an oxygen atmosphere in the presence of carrier solutions. The results obtained by radiochemical neutron activation analysis for the elements like Mn, As, Cu, Sb and Zn in different standard reference materials are presented with a discussion of the possible causes for the lower values.
Authors:Nguyen Van Suc, H. Desai, R. Parthasarathy, and S. Gangadhaŕan
Individual rare earth impurities in high purity La2O3 (99.9%) have been determined by NAA after pre-separation of the matrix (La). The separation is carried out on an anion exchanger (Dowex 1×8) using different mixtures of methanol/nitric acid as eluants. The rare earth elements from Dy to Lu are eluted quantitatively using a 10% 1M HNO3-90% methanol mixture, while the light rare earths from Ce to Gd are eluted quantitatively using a 10% 0.05M HNO3-90% methanol mixture. La, which is retained on the column, is eluted using 0.1M HNO3. The recoveries of the various rare earth elements have been checked using radiotracers and also by spiking the sample with known amount of elements, and the recoveries are found to be quantitative. Results obtained on a typical high purity lanthanum oxide are reported here.
Authors:H. Dang, H. Desai, S. Kayasth, D. Jaiswal, C. Wadhwani, and S. Somasundaram
The daily intakes of trace elements by infants showing optimal pattern of growth are used as the basis to estimate the requirements of Fe, Co and Se during infancy. Since milk is the only food and source of nutrition in the first few months of life, the requirements of these elements are calculated from their average concentrations in human milk and the volume of milk required to supply sufficient amount of energy for maintenance and healthy growth of infants. The concentrations of the three elements in human milk were determined, using the technique of neutron activation followed by radiochemical separation.