Evaluation of volumetric DBS for lead analysis using ICP-MS/MS: addressing matrix effects and hematocrit variability.

BACKGROUND

Lead testing in dried blood spots (DBS) offer a convenient alternative to venous blood draw; however, its adoption has been limited by variable extraction efficiency, matrix effects, and hematocrit-dependent recovery. To mitigate these challenges, we explored the utility of volumetric DBS (vDBS) cards, which are known to deposit a fixed volume of blood that gets analyzed.

MATERIALS AND

METHODS

Samples (quality control, proficiency testing, lead spiked, and patient samples that were positive for lead) were pipetted onto the backs of vDBS cards. Extracts were analyzed using Inductively Coupled Plasma-Tandem Mass Spectrometry in collision/reaction cell mode with oxygen gas. Deming regression analyses evaluated whole blood and vDBS analyzed with aqueous calibrators; vDBS analyzed with aqueous and DBS calibrators. Samples with varying hematocrit were assessed for impact on recovery.

RESULTS

A comparison of vDBS cards (n = 119) prepared from previously tested and lead spiked samples, analyzed against aqueous calibrators and vDBS calibrators, showed linear results: slope 1.024 (95% CI: 0.998 to 1.051) and y-intercept -0.0204 (95% CI: -0.4287 to 0.3879). Bias noted between whole blood lead and vDBS lead samples with varying hematocrit levels was not statistically significant.

CONCLUSION

vDBS can be analyzed without matrix-matched calibrators to simplify routine assessment.