Fast-response flow-based method for evaluating 131I from biological and hospital waste samples exploiting liquid scintillation detection.

This paper presents a fast and automatic flow-based method to extract 131I from biological samples and hospital waste, previous to liquid scintillation detection. 131I is a radionuclide extensively used in Nuclear Medicine due to their beta and gamma disintegrations, whereby hospitals have to manage the associated waste generation. The automatic developed system is based on Lab-On-Valve (LOV) flow-technique exploiting Cl-resin (135 mg per extraction). This methodology allows performing sample extractions and measurements on the same day, since the extraction frequency takes 1.4-4 h-1, depending on the analysed sample volume, plus up to 2 h of measurement for each vial. 131I is retained as iodine ion and eluted with sodium sulphide 0.2 mol L-1. The maximum sample volume that can be preconcentrated is 20 mL, reaching an extraction efficiency of 85 ±â€¯5%. The minimum detectable activity (MDA) is 0.05 Bq, showing a precision of 7% RSD (n = 5). Both, biological samples (urine and saliva) and hospital waste samples can be satisfactorily analysed by the proposed system, obtaining recoveries between 90 and 110%. The developed method is then suitable to implement in hospitals, improving the surveillance of the 131I environmental release.

Avaliação do método de espectrometria por cintilação em meio líquido para a medida das atividades alfa e beta total em água: aplicação a águas de abastecimento público no estado de Goiás, Brasil / Evaluation of the liquid scintillation spectrometry method for measurement of the gross alpha and beta activities in water: application to drinking water from Goiás state, Brazil

RESUMO Uma revisão da determinação de alfa e beta total em água, usando espectrometria de cintilação em meio líquido, é apresentada. Foram identificados os principais fatores que influenciam a exatidão e a repetibilidade dos resultados analíticos: pré-concentração térmica, tipo de ácido, janela de contagem e padrão de calibração. Um procedimento analítico foi estabelecido e aplicado a amostras de água de abastecimento público do estado de Goiás para avaliação das radioatividades alfa e beta total. O resumo estatístico dos dados foi realizado por meio dos métodos de análise de dados censurados. Os resultados estão consistentes com os valores de referência do Ministério da Saúde.

ABSTRACT A review to determine the gross alpha and beta in water by using liquid scintillation spectrometry is presented. The main factors that influence the accuracy and repeatability of the analytical results are: thermal pre-concentration, acid type, counting window, and calibration standard. Accordingly, an analytical procedure was established and carried out to samples of the public water supplies in the state of Goiás, Brazil, to evaluate the gross alpha and beta radioactivities. The statistical summary of data was conducted by using analysis methods of censored data. The results comply with the guideline values from the Brazilian Department of Health.

Determination of (226)Ra in produced water by liquid scintillation counting.

It is proposed a method for the determination of (226)Ra in offshore platform liquid effluent samples (produced water). The method is based on a two-phase liquid scintillation counting system and allows for the direct and simple determination of (226)Ra content. Samples with high barium content may also have high (226)Ra concentration. Therefore, the sample volume is based on the barium concentration and ranges from 10 mL to 100 mL. Our new method was tested using multiple real samples and was compared with the BaSO4 precipitation method. The results based on the LSC were 30% higher than the precipitation method, which is attributed to the self-absorption of alpha particles in the BaSO4 precipitate. The determination of both (226)Ra and (228)Ra in the liquid effluent of offshore oil platforms is mandatory in Brazil. Thus, a second method of accurately assessing (228)Ra content remains necessary.