Validation of uranium determination in urine by ICP-MS.

A rapid procedure--dilution of urine+ICP-MS measurement--for the determination of uranium in urine was validated. Large ranges of concentration and isotopic composition were studied on urine samples excreted by occupationally exposed workers. The results were consistent with those obtained by fluorimetry and by alpha spectrometry after a purification procedure, two currently used techniques. However, the proposed procedure is limited for determination of the minor isotope 234U. Thus for worker monitoring, the conversion of 234U mass concentration into activity concentration can lead to an erroneous value of the effective dose, in particular for a contamination at very low level with highly enriched uranium. A solution to avoid this hazard is to perform a chemical purification prior to ICP-MS measurement to lower uncertainty and detection limit for 234U.

PROCORAD's international intercomparisons highlight the evolution of techniques used to determine uranium in urine.

Inter-laboratory tests are a means of assessing the analytical coherence of medical laboratories. In radiotoxicology, this kind of exercise makes it possible to keep up with laboratory know-how and with the evolution and relative performances of analytical techniques. The intercomparison exercises organised by PROCORAD (Association for the Promotion of Quality Controls in Radiotoxicological Bioassays) provide an opportunity to compare and contrast radiochemistry and metrology for the in vitro analysis of urine and faeces. For uranium compounds, the development of new techniques such as inductively coupled plasma-mass spectrometry (ICP-MS), alpha spectrometry, and laser spectrofluorimetry makes it possible to compare the effectiveness of these protocols with respect to radiation protection monitoring, both in routine and special situations. Detection limits, flexibility, repeatability, reproducibility and isotopic quantification are the criteria considered in this study. The authors present the evolution of performances for the analysis of uranium in urine over the years. However, the goal of the laboratories taking part in these annual exercises is not only to check the accuracy of their results but also to have analytical discussions and the opportunity to exchange experiences that will enrich the group's general competence.

[Neuroblastoma in children: clinical and biological aspects. An experience of screening in France]. / Le neuroblastome de l'enfant: aspects cliniques et biologiques. Une expérience de dépistage en France.

Neuroblastoma is the commonest solid tumour in children under the age of 5 years (50% of cases before 2 years, 90% before 5) and the second cause of death after accidents. Approximately one child in 10,000 develops neuroblastoma by the age of 15 years. The situation in other European and North American countries is similar to that in France. As neuroblastoma is derived from the sympathetic nervous tissues, it is associated with the production of large amounts of catecholamines and their metabolites which are excreted in the urine. Less than 5% of cases do not produce catecholamines. Vanillylmandelic acid (VMA), homovanillic acid (HVA) and dopamine (DA) are the most useful chemical markers for the diagnosis and clinical control of neuroblastoma. They are generally measured using the reliable and sensitive high pressure liquid chromatography (HPLC). Survival is related to stage (the Evan's staging protocol has been superseded by the INNS staging), and age at diagnosis. There is almost 100% survival for stages I and IIa before the age of 12 months, and less than 20% for stage IV when diagnosed after 2 years of age. Multiple copies of the N-myc oncogene, deletions of chromosome 1p, and diploidy in tumour cells are associated with poor prognosis.(ABSTRACT TRUNCATED AT 250 WORDS)