Interlaboratory comparison study on lead in blood, in external quality assessment schemes since 1996: a progress report

Abstract

In 1992, at the request of the French labor ministry, an External Quality Control for lead in whole blood (F-EQCPbB) came into being. After 15 years (1996–2011), the ministry wished to exploit the database collected with a sufficient number of laboratories. Indeed, the number of participating laboratories had decreased from 73 to 41. However, the key finding pertained to the highly improved performance of the laboratories, which was associated with a spread of the results over the entire range of tested PbB (9 and 700 µg/l). So, it was that in laboratories having participated for >10 years, the good scores rose between 1996 and 2011 from 49% to 93%. To sum up, analysis has shown progressive and highly pronounced diminution of CVs (%) for all the ranges having undergone testing. We have observed increasing use of inductively coupled plasma with mass spectrometry (from 9% in 2005 to 29% in 2011) and decreasing use of electrothermal atomic absorption spectrometry. That said, and provided that they are based on the same degree of expertise in metrology, on all tested concentrations the two analytical techniques yield results that are not statistically different. Thanks to the F-EQCPbB, laboratories have enhanced their proficiency and registered demonstrably improved performance.

• Electrothermal atomic absorption spectrometry
• external quality control scheme
• inductively coupled plasma mass spectrometry
• lead
• Zeeman effect