Control variables from collection through ICP-MS

For blood lead, use trace-element-free EDTA whole blood and lead-free collection materials. CLSI C40 identifies ICP-MS, graphite-furnace atomic absorption spectrometry, and disposable screen-printed electrode anodic stripping voltammetry as method families. Method suitability at current low blood-lead decision levels depends on a documented analytical performance limit in the laboratory's validated procedure; retirement of an older approach alone does not establish unsuitability.

In ICP-MS, a polyatomic or isobaric ion can share the analyte mass-to-charge ratio. Collision or reaction cell technology can reduce these spectral interferences, but the gas mode and interference rules belong to the local validated method. An internal standard near the analyte mass helps correct drift and matrix effects only if it is free from relevant interference.

Carryover is analytical contamination, not a collection defect. Rinse protocol, sample order, blanks, controls, and action limits are instrument-specific and must follow the manufacturer instructions for use and local procedure. The installed instrument, reagent lot, calibrator, software, and reportable range determine the released result details.

For a spot urine result, element concentration in mg/L divided by creatinine in g/L yields mg/g creatinine. Low creatinine makes the normalized result rise, and high creatinine makes it fall. Values below about 30 mg/dL or above about 300 mg/dL are practical screening conventions, not universal rejection rules.

Separate collection contamination, spectral interference, and carryover because each has a different control.