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Elemental Status of Bangladeshi Tea using Instrumental Neutron Activation Analysis Method

Corresponding Author : M. Oyes Kurni (h.ahsan@sust.edu)

Authors : Tanwir O. Ahsan , Faisal Kabir , Syed Mohammod Hossain , M.H. Ahsan (h.ahsan@sust.edu)

Keywords : Instrumental Neutron Activation Analysis (INAA), gamma spectrometry, certified reference material, permissible level

Abstract :

Elemental status of Bangladeshi tea was checked using nuclear reactor based Instrumental Neutron Activation Analysis (INAA) method. The analytical results of thirteen samples have been reported here. Irradiation of samples and standards were performed at the dry central thimble (DCT) facility of the 3.0 MW TRIGA Mark-II research reactor of AERE, Savar, Dhaka. The irradiated samples and standards were measured twice with different decay intervals depending on the half lives of the interested elements using High Purity Germanium (HPGe) detectors coupled with PC based digital gamma spectrometry system. The gamma peak analysis was performed using the software Hypermet PC version 5.12. The concentration calculations were performed based on relative standardization approach. The quality control of the analysis was performed by analyzing Certified Reference Material NIST 1515 (Apple leaves), NIST 1547 (Peach leaves), NBS 1572 (Citrus leaves) and NIST 1573a (Tomato leaves) relative to NIST 1633b (Coal fly ash) and comparing the measured values with certified ones. The uncertainties were calculated based on the total uncertainty budget of the NAA method. Almost all the source of uncertainty was considered for this calculation. Based on the long irradiation, the elements samarium (Sm), Lanthanum (La), Bromine (Br), Sodium (Na), Potassium (K), Cerium (Ce), Chromium (Cr), Cesium (Cs), Scandium (Sc), Rubidium (Rb), Cobalt (Co) and Iron (Fe) were determined quantitatively and qualitatively. The results showed that that Bangladeshi tea contained high concentration of Na and K; and low concentration of Sm and Sc. The concentrations of Na and K are in the range of 146.4 – 5969.6 µg/g and 11764.2 – 20557.0 µg/g, respectively. The measured concentration of all these elements compared with the world reference values. Most of the elements are in the normal level whereas some elements like Na and Cr exceeded our reference values, but do not exceed the accepted permissible level. The analytical result gives a baseline data of elemental content of Bangladeshi tea and will help to assess further information in future. 

Published on December 30th, 2012 in Volume 20, Issue 3, Applied Sciences and Technology