A miniaturized sample preparation method for routine elemental determination in whole blood using volumetric absorptive microsampling by ICP-QQQ

Volumetric absorptive microsampling (VAMS) has emerged as a simple and safe tool for collecting and storing blood samples in clinical and bioanalytical fields. This study presents a novel method for determining essential and non-essential trace elements (As, Be, Cd, Cs, Cu, Fe, Mg, P, Pb, S, Sb, Se, Tl, V, U) in VAMS-collected blood samples using microwave-assisted digestion with diluted acid as sample preparation method and an inductively coupled plasma triple quadrupole mass spectrometry (ICP-QQQ) as determination technique. While certain elements posed challenges due to VAMS tip background issues (Al, Ti, Cr, Mn, Co, Ni, Sn, Mo, Ba), the method demonstrated high precision and accuracy for the targeted analytes. It was demonstrated that 4.5 mol L −1 HNO 3 plus 100 μL H 2 O 2 30% (w/w) was suitable for an efficiency digestion for further elemental determination using micro-analysis (spending less than 300 μL analytical solution) by ICP-QQQ, given that the residual carbon content (RCC) after the digestion procedure was lower than 5%. All the results higher than limit of quantification (LOQ) were in agreement with reference values for all analytes. Accuracy was assessed through reference material analysis and recovery tests using spiked samples. Moreover, suitable agreements (p > 0.05) between this method (VAMS-M) and the comparative method (liquid sampling method) were obtained for all analytes > LOQ. Furthermore, all results > LOQ showed good precision according to precision requirements (Horwitz equation). In this way, the use of dilute acid, low dilution factor (30-fold) and excellent digestion efficiency (> 95%), the proposed method was able to achieve an excellent detection limit, precision and accuracy for 15 elements: As, Be, Cd, Cs, Cu, Fe, Mg, P, Pb, S, Sb, Se, Tl, V and U using ICP-MS/MS, without the need of matrix-matched calibration curves. This research showcases an innovative analytical approach using VAMS for blood samples, offering biosafety, practicality, sensitivity, versatility, and robustness. This method contribute to the advancement of trace element analysis in biomedical research and clinical applications.