Determination of lead in blood by graphite furnace atomic absorption spectrometry with Zeeman background correction: Improving a well-established method to support a lower blood lead reference value for children

Abstract

Lead is ubiquitous in the environment and exposure can have adverse health effects even at low concentrations, particularly in young children. Blood Pb levels are the best indicator of recent Pb exposure. The Centers for Disease Control and Prevention (CDC) recently lowered the blood Pb reference value from 5 μg/dL to 3.5 μg/dL, based on data calculated from the 97.5th percentile of children 1–5 years old in the National Health and Nutrition Examination Survey (NHANES). The established method for determining Pb in blood by GFAAS has an estimated detection limit (LOD) of ≈1 μg/dL. This presents an analytical challenge for its clinical use in the US, given that the current population mean blood Pb level is 0.82 μg/dL. Accuracy and precision may be insufficient to quantitate low blood Pb levels in the 1–5 μg/dL range, which is essential now that the CDC blood Pb reference value is 3.5 μg/dL.The original GFAAS method for blood Pb published in 1993 has been significantly improved to achieve a lower LOD of 0.2 μg/dL, with the ability to quantitate blood Pb levels down to 1 μg/dL. This method is fit for the purpose of detecting blood Pb levels currently, with excellent accuracy and precision in the 1–5 μg/dL range. Results from analyzing SRMs, PT materials and human blood samples were in good agreement between two different GFAAS platforms, as well as with results obtained by ICP-MS. The improvements provide evidence of an GFAAS method capable of achieving lower LODs with improved accuracy and precision at lower blood Pb levels, which can support the lower blood Pb reference value for children at 3.5 μg/dL.