Determination of gadolinium in biological materials using graphite furnace atomic absorption spectrometry with a tantalum boat after solvent extraction

A method was developed for the determination of gadolinium (Gd) in biological material using graphite furnace atomic absorption spectrometry (GFAAS). The element is first extracted into methyl isobutyl ketone and then reextracted into hydrochloric acid. Factors influencing the recovery of extraction such as pH, choice of chelating agents, and hydrochloric acid concentration have been investigated. The element is determined under STPF (stabilized temperature platform furnace) conditions with atomization from a tantalum boat. Under optimized furnace conditions, the use of the tantalum boat improved sensitivity substantially compared to the use of pyrolytically coated graphite tubes. Around 150 measurements could be performed with 1 boat. Memory effects, being a common problem in the GFAAS determination of lanthanoids, were no longer observed after insertion of the boat. The characteristic mass and detection limit (2SD; SD = standard deviation) of the Gd determination are 1000 and 2060 pg, respectively. The precision evaluated as the relative standard deviation (RSD) of six analyses was below 10% for tissue Gd concentrations ranging from 0.92 to 72.0 micrograms g-1. The recovery of added analyte ranged between 92.0% and 99.3%. The method was found to be suitable for studying the pharmacokinetics and biodistribution of Gd in rats.