Natural radioactivity determination in samples of Peperomia pellucida commonly used as medicinal herb

The radionuclide concentration in different environmental matrixes is reported in literature; however, studies of the distribution of 238U and 232Th decay products in plant species are sparse. In this study concentration of naturally occurring radionuclides 238U, 234U, 232Th, 230Th, 226Ra, 228Ra and 210Pb was determined in sample of Peperomia pellucida and in the surrounding soil. Peperomia pellucida has a rich history of medicinal uses. The content of U and Th isotopes in the leaves, aerial parts, roots and soil was determined by alpha spectrometry after with radiochemical separation by ionic exchange resins and measurement with a silicon surface-barrier detector. The radionuclides measurement of 226Ra, 228Ra and 210Pb were carried out by gross alpha and beta counting after radiochemical separation. The radionuclide activity concentrations mean in samples analyzed ranged from 4.3 to 38 Bq kg-1 for 238U, from 42 to 129 Bq kg-1 for 234U, from 2.1 to 38 Bq kg-1for 230Th, from 1.7 to 124 Bq kg-1 for 232Th, from 8.5 to 37 Bq kg-1for 226Ra, from 3.2 to 46 Bq kg-1for 228Ra, from 39 to 93 Bq kg-1 for 210Pb. It was also determined the percentage of radionuclides 226Ra, 228Ra and 210Pb in the extraction and infusion of the drug analyzed. The arithmetical mean value recovery was from 23% to 60% in maceration and 24% to 75% in infusion. (author)