Dried deposits of biological tissues solubilized using formic acid for LA ICP-TOF-MS

Laser ablation of dried deposits of solubilized biological tissues with detection by ICP-TOF-MS was evaluated for trace metal determination. Solubilization was accomplished through simple treatment with formic acid. Aliquots of this solution were dried under a heat lamp, the resulting smooth hard deposit could be easily ablated. The main advantage of the technique is that a uniform solution is produced by the formic acid at which point aqueous internal and calibration standards can be added prior to drying and used for quantitation. This approach addresses the issue of calibration with LA based techniques. Detection limits were 1, 2, 6, 1, 0.2 and 0.05 mg kg−1 for Mn, Cu, Zn, As, Cd, and Pb, respectively. Alternatively, certified reference materials treated in the same manner can also be used for calibration. Linear calibration curves were constructed for the six elements listed using NRCC CRMs TORT-2, DOLT-4, DORM-3 and NIST SRMs 2976, 1566b and RM 8414.