PNNL

Abstract

Biomonitoring of lead (Pb) in blood and urine enables quantitative evaluation of human occupational and environmental exposures to Pb. The state-of-the-art ICP-MS instruments analyze metals in laboratories, resulting in lengthy turn around time, and are expensive. In response to the growing need for metal analyzer for on-site, real-time monitoring of trace metals in individuals, we developed a portable microanalyzer based on flow-injection / adsorptive stripping voltammetry and used it to analyze Pb in rat blood and urine. Fouling of electrodes by proteins often prevents the effective use of electrochemical sensors in biological matrices. Minimization of such fouling was accomplished with the suitable sample pretreatment and the turbulent flowing of Pb contained blood and urine onto the glassy electrode inside the microanalyzer, which resulted in no apparent electrode fouling even when the samples contained 50% urine or 10% blood by volume. There was no matrix effect on the voltammetric Pb signals even when the samples contained 10% blood or 10% urine. The microanalyzer offered linear concentration range relevant to Pb exposure levels in human (0-20 ppb in 10%-blood samples, 0-50 ppb in 50%-urine samples). The device had excellent sensitivity and reproducibility; Pb detection limits were 0.54 ppb and 0.42 ppb, and % RSDs were 4.9 and 2.4 in 50%-urine and 10%-blood samples, respectively. It offered a high throughput (3 min per sample) and had economical use of samples (60 µL per measurement), making the collection of blood being less invasive especially to children, and had low reagent consumption (1 µg of Hg per measurement), thus minimizing the health concerns of mercury use. Being miniaturized in size, the microanalyzer is portable and field-deployable. Thus, it has a great potential to be the next-generation analyzer for biomonitoring of toxic metals.