P. J. Reddy

Studies on matrix interferences during uranium analysis by extractive liquid scintillation technique

The efficiency of ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) in reducing the influence of salinity and extraction of iron and calcium into the organic phase along with uranium was studied. DTPA has been observed to be more suitable complexing agent compared to EDTA. Iron and calcium were found to be separated quantitatively with more than 95% recovery for uranium, facilitating its rapid and interference free analysis in the presence of DTPA. Uranium recovery under high salinity conditions was also observed to be in the range 89.7–98.6% in the presence of DTPA.

Validation of efficiency tracing and zero detection threshold techniques using liquid scintillation analyser TriCarb.

Efficiency tracing with unquenched 14C and zero detection threshold with unquenched 3H as tracers are practical and simple techniques which have been implemented to quantify the activity of various beta emitters using liquid scintillation analyser. These techniques are used to study the influence of quench level on activity quantification and the activity levels up to which these techniques are applicable. The results indicate that, for an activity level of 166.67 Bq, both the techniques are in good agreement with the reference activity with a relative discrepancy of ≤4.6 %. The relative discrepancy of ~10 % is observed for extreme quench values of ~111. For all the radionuclides with the activity level of 1.67 Bq, the uncertainty in activity quantification raises to ~8 % and for the activity level from 8.33 to 100 Bq, the uncertainty reduces to 1 %.

Sequential analysis of uranium and plutonium in environmental matrices by extractive liquid scintillation spectrometry

Abstract A methodology for sequential separation of uranium (U) and plutonium (Pu) followed by their estimation, using extractive liquid scintillation spectrometry was standardized for matrices like soil, fish and sediment. Various parameters for selective and efficient extraction and separation of Pu and U in the presence of interfering matrix elements with HDEHP bis(2-ethylhexy1) phosphoric acid as an extracting agent were investigated. Quenching effect of the various extracting reagents on resolution of α spectrum of analytes and reduction in these interferences is discussed in the current study. Standardized procedure gave about 91% of extraction of spiked Pu into the organic phase. Performance of the method was tested by separating and estimating U and Pu in International Atomic Agency (IAEA) certified reference materials like soil/sediment/fish.

Calibration and optimization of alpha-beta separation procedures for determination of radium/radon in single- and two-phase liquid scintillation systems

Liquid scintillation alpha beta discrimination technique based on pulse shape analysis (PSA) was evaluated for determination of 226Ra and 222Rn in water samples. In view of the significance of calibration, for the reliable and precise determination of 226Ra and 222Rn concentrations in water samples, calibration procedures were standardized for single and two phase systems using Quantulus 1220 liquid scintillation counter. PSA optimization and efficiency calibrations were performed using 226Ra standard rather than conventionally used pure alpha and beta standards and substantiated by measuring the activity concentrations of 226Ra and 222Rn in the spiked water samples.

Study of liquid scintillation alpha spectral properties

Alpha spectra were acquired with Quantulus 1220 liquid Scintillation Counter (LSC) and correlations among parameters, such as alpha particle energy, sample quenching, peaks centroid and resolution were established. The effect of quenching and factors such as types of counting vials, extractive reagents and composition of extractive scintillation cocktail on alpha spectral resolution, was experimentally studied.

Study on urea breath test a tool for Helicobacter pylori infection

Urea breath test (UBT) is commonly used diagnostic test for detecting the presence of Helicobacter pylori bacteria in the stomach. The patient undergoing the UBT ingests one microcurie of urea capsule containing labeled carbon-14. After ingestion of the capsule, the patient blows into a trapping solution. H. pylori bacteria in the stomach releases enzyme urease which breaks urea capsule to release carbon dioxide tagged with carbon-14 in the exhaled breath. Carbon-14 in the trapping solution is counted in liquid scintillation counter. In this study, 261 patients suspected of H. pylori infection had undergone UBT. It was found that 52% of the patients tested positive for H. pylori infection. No significant difference observed between various age groups. There was no statistically significant difference between the infection rates in males and females.

Concentration of 3H in ground water and estimation of committed effective dose due to ground water ingestion in some places in the Maharashtra state, India.

The measurement of tritium in environmental samples requires highest possible sensitivity. In the present study, the authors have optimised the counting window for the analysis of (3)H in environmental samples using the recently installed Ultra Low Level Quantulus 1220 Liquid Scintillation Counting at BARC to improve the detection limit of the system. The optimised counting window corresponding to the highest figure of merit of 883.8 was found to be 20-162 channels. Different brands of packaged drinking waters were analysed to select a blank that would define the system background. The minimum detectable activity (MDA) achieved was 1.5 Bq l(-1) for a total counting time of 500 min. The concentration of tritium in well and bore well water samples collected from the villages of Pune, villages located at 1.8 km from Tarapur Atomic Power Station, Kolhapur and Ratnagiri, was analysed. The activity concentration ranged from 0.55 to 3.66 Bq l(-1). The associated age-dependant dose from water ingestion in the study area was estimated. The effective committed dose recorded for different age classes is negligible compared with World Health Organization and US Environmental Protection Agency dose guidelines.

Application of liquid scintillation inclusion method for the simultaneous determination of alpha and beta activities in composite samples

Present work highlights liquid scintillation Automatic Efficiency Control (AEC) as a tool for simultaneous determination of gross α and β activities in composite samples. AEC which is in-built feature in Packard Tri-Carb 2900TR Liquid Scintillation Counter (LSC) provides automatic counting region adjustments for single and dual label samples according to the degree of quench present in sample. In the present study, α/β spiked composite samples were treated as dual label samples with α and β radio-nuclides as two distinct entities contributing to the gross activities and analyzed employing AEC technique. Instrument discriminator settings and regions of interest (ROI) were evaluated to determine optimum counting conditions for present technique. Three sets of pure alpha and pure beta standards simulating the activity concentrations of real samples in terms of α/β activity ratios were used to calibrate LSC. Calibration methodology for Packard Tri-Carb 2900TR LSC with respect to the above measurements using 241 Am, 36 Cl calibration standards is explained in detail. The practicability and working performance of AEC technique was checked by the validation trials with spiked synthetic samples covering range of α/β activity ratios from 1:1 to 1:30 and 30:1.