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New analytical methods developed at the facilities here, based on two ultra-sensitive mass spectrometry (MS) techniques, inductively coupled plasma sector field mass spectrometer with a desolvator system (Aridus-ICP-SFMS) and accelerator MS (AMS), have been applied in this work for the reassessment of 239Pu in alpha spectrometry (AS) planchets corresponding to spiked human urine samples. The obtained 239Pu minimum detectable activities (MDAs) values by Aridus-ICP-SFMS and AMS were 3 fg (∼6.92 mBq) and 0.4 fg (∼0.92 mBq), respectively, per sample, which are much better than those attainable by AS [50 fg (∼115.3 mBq) of 239Pu per sample, approximately]. Therefore, it is demonstrated that the MS techniques employed in this work are very powerful tools for internal dosimetry studies in human urine samples, giving excellent results when the reassessment of AS planchets is needed (samples with a Pu concentration below or at the MDA levels measurable by AS).

New analytical methods developed at the facilities here, based on two ultra-sensitive mass spectrometry (MS) techniques, inductively coupled plasma sector field mass spectrometer with a desolvator system (Aridus-ICP-SFMS) and accelerator MS (AMS), have been applied in this work for the reassessment of 239Pu in alpha spectrometry (AS) planchets corresponding to spiked human urine samples. The obtained 239Pu minimum detectable activities (MDAs) values by Aridus-ICP-SFMS and AMS were 3 fg (∼6.92 µBq) and 0.4 fg (∼0.92 µBq), respectively, per sample, which are much better than those attainable by AS [50 fg (∼115.3 µBq) of 239Pu per sample, approximately]. Therefore, it is demonstrated that the MS techniques employed in this work are very powerful tools for internal dosimetry studies in human urine samples, giving excellent results when the reassessment of AS planchets is needed (samples with a Pu concentration below or at the MDA levels measurable by AS). This work is the continuation of an article published in J. Anal. At. Spectrom. 25 (1410–1415) 2010.

La presente Memoria de Tesis Doctoral presenta los resultados obtenidos en un proyecto de investigación sobre la aplicación de métodos avanzados de MS para la cuantificación de niveles bajos y ultra-bajos de actínidos en orinas de trabajadores expuestos, por razón de sus cometidos profesionales, a riesgo de contaminación interna por estos radionucleidos. El trabajo que ahora se describe se ha desarrollado en el contexto de la mejora de la calidad de las medidas que son legalmente requeridas para proteger la salud de los trabajadores frente a los riesgos que suponen esas contaminaciones, alcanzando a conseguir mejorar los niveles mínimos de actividad radiactiva detectables mediante las técnicas convencionales de AS, niveles que son considerados insuficientes en el rango de las dosis bajas. Se han desarrollado además procedimientos específicos de preparación radioquímica de orinas para su medida tanto en ICP-MS como en AMS, procedimientos que han demostrado ser adecuados a sus fines y más rápidos en su aplicación que los convencionales para AS.

This work describes two methods for rapid and simple preparation of urine samples for determining the 239Pu content. The preparation of the samples was carried out by evaporation or coprecipitation of Pu, followed by acidic digestion in a microwave oven. The concentration and purification of Pu were achieved by using ion exchange resins AG1X2 and AG1X8 (Bio-Rad Laboratories). The quantification of 239Pu was carried out employing three different instrumental techniques, the more conventional Alpha Spectrometry (AS), and two mass spectrometry methods: High-Resolution Inductively Coupled Plasma Mass Spectrometry (HR-ICP-MS) and a low-energy Accelerator Mass Spectrometry (AMS). The chemical yield was determined by AS being, on average, 76 ± 7%. The minimum detectable activity (MDA) for AS, HR-ICP-MS and AMS was, respectively, about 50 fg (∼0.1 mBq), 23 fg (∼0.05 mBq) and 0.44 fg (∼1 Bq) per sample, respectively. The results presented in this work demonstrate the excellent performance and suitability of the mass spectrometric techniques for the routine measurement of 239Pu at ultratrace levels in human urine samples, and also for the reassessing of AS planchets if it were needed. The application of HR-ICP-MS and low-energy AMS reduces the sample processing time, and helps us to improve the laboratory productivity, also giving better MDA values when compared to the classical radiometric methods. © 2011 The Royal Society of Chemistry.

A new and highly sensitive method for the determination of 239Pu in human urine has been developed permitting the reassessment of planchets initially prepared for alpha spectrometry (AS) analysis in the context of internal dosimetry. A set of urine samples (volume: 500 mL) was spiked with known quantities of 239Pu, ranging from 2 to 120 fg (4.6 mBq–0.3 mBq), employing 14 pg (2.05 mBq) of 242Pu as internal standard. The Pu was purified by ion-chromatography using BioRad AG1X2 anion-exchange resins (Bio-Rad Laboratories Inc.). The chemical yield was determined by alphaspectrometry, being about 80%. Afterwards, the planchets so obtained were leached with diluted HNO3 and the dissolved plutonium was determined by Accelerator Mass Spectrometry (AMS) at the Centro Nacional de Aceleradores (CNA) in Seville, Spain. The minimum detectable activity (MDA) for the AMS measurements was determined through the study of a set of procedural blanks, giving figures of about 0.44 fg (1 mBq) per sample. This contrasts with the MDA obtained by AS for the same set of samples, of about 50 fg (0.1 mBq). The results now presented helps to demonstrate that the routine measurement of 239Pu at ultra trace levels in human urine samples is possible with the new-generation of compact AMS systems, offering a highly sensitive method for the reassessing of planchets prepared for bioassay purposes.