Calibration Strategies for Correcting Matrix Effects in ICP-MS Multi-Element Analysis Using a Certified Reference Material Followed by Application to Brown Crab (Cancer Pagurus) Tissues

Accurate multi-element quantification in seafood by inductively coupled plasma mass spectrometry (ICP-MS) can be compromised by matrix effects, particularly when aqueous-based calibration is applied to complex biological digests. This study evaluated five calibration strategies for the determination of As, Cd, Cr, Ni, Pb and Se in seafood matrices using a certified reference material (CRM, ERM®-CE278k, mussel tissue) and brown crab (Cancer pagurus) hepatopancreas and claw meat. External calibration (EC), EC with internal standard (EC-IS), standard addition (SA), SA with internal standard (SA-IS), and single-level SA-IS (SLSA-IS) were first compared using the CRM. Matrix effects were quantified from the slope ratio between SA and EC calibration curves. Significant signal suppression of −27.75% was observed for Se with the 95% confidence interval (CI) from −41.2% to −14.3% and −18.1% for Cd (95% CI: −25.2% to −11.0%), while As showed a borderline suppression trend (−15.1 ± 6.2%, p = 0.052) with the 95% CI from −30.6 to 0.3%. External calibration and EC-IS gave acceptable precision but underestimated As, Cd and Se, with biases of −25.66%, −22.63% and −35.54% for EC and −20.16%, −17.03% and −31.47% for EC-IS, respectively. Standard addition-based calibration improved trueness, and SA-IS produced the closest agreement with the certified elemental concentration, with biases of −2.91%, 1.20%, −10.34%, 2.92%, −0.30% and −3.42% for As, Cd, Cr, Ni, Pb and Se, respectively. The performance of SLSA-IS was spike-dependent (1–50 µg/L), with higher spike levels yielding the most accurate predictions. Subsequently, SA-IS was explored in hepatopancreas and claw meat from two brown crabs, providing satisfactory determinations for Cd, Cr, Ni, Pb and Se, whereas As quantification was limited by high native concentrations exceeding the standard-addition range in the present study. Cross-matrix evaluation showed that agreement between MMC and SA-IS was element-, matrix- and batch-dependent, with crab tissue-based MMC generally showing closer agreement than CRM-based MMC. Therefore, MMC deserves further investigation for selected applications.