Determination of Cu in blood: Via direct analysis of dried blood spots using high-resolution continuum source graphite furnace atomic absorption spectrometry

The performance of state-of-the-art high-resolution continuum source graphite furnace atomic absorption spectrometry (HR CS GFAAS) instrumentation and four novel devices to produce dried blood spots of perfectly defined volumes is evaluated with the aim of developing a simple, direct method for the determination of Cu in blood samples. In all cases, it is feasible to obtain accurate quantitative information using any of the four devices tested (Mitra, HemaXis DB10, Capitainer qDBS and HemaPEN) via simple external calibration with aqueous standards. One of the main differences in the performance of such devices is related to the blanks obtained, such that HemaXis DB10 and HemaPEN are preferred when abnormally low Cu levels (500 µg L-1 or lower), associated with some diseases, need to be determined. The results prove that accurate values with RSD values below 10% can be achieved for these devices even for such Cu levels, while for Capitainer qDBS and, to a higher extent, for Mitra, blank variations will ultimately increase the uncertainty. It is important to stress that analysis of four real samples using both venipuncture and all the DBS specimens showed a very good agreement. Thus, the approach proposed could be readily applied, such that patients with disorders requiring Cu control can prepare their own samples and submit them via postal mail to labs for HR CS GFAAS direct and fast analysis. © The Royal Society of Chemistry