Evaluation of the Radiometer Ion Scanning System 820 for the analysis of lead in urine

We have evaluated the application and performance characteristics of a system that utilizes potentiometric stripping analysis (PSA); an electrochemical technique recently proposed for use in the routine determination of lead in urine. Its advantages over current methods for urinary lead are its low cost and minimal requirements for sample pretreatment. We adapted the published procedure to enable the use of a single protocol over a wide lead concentration range (10-500 microgram/L). Using spiked urine pools, we found the precision and recovery to be acceptable for clinical usage over this range. A comparative study using individual spiked patient urines demonstrated good correlation with a bismuth hydroxide coprecipitation/atomic absorption (AA) procedure [Y (microgram/L, PSA) = -11 microgram/L + 1.10X (microgram/L, AA); S y times x = 32 microgram/L; Sa = 15 microgram/L; Sb = 0.08, N = 22]. Approximately 10% of the randomly chosen urines in this study exhibit negative interferences with the PSA method. However, these interferences were readily recognizable when using a standard addition technique to obtain concentrations from analytical signals, and were resolvable following either dilution with dilute acid or addition of Triton X-100. While we consider the system's performance characteristics acceptable, the length of time required for each urine lead determination (approximately 40 minutes) is a notable limitation to the routine clinical adoption of the instrument in its current configuration.