A method was developed for the determination of V and Ni as tetrapyrroles by High Performance Liquid Chromatography hyphenated to Inductively Coupled Plasma Mass Spectrometry (HPLC-ICP-MS) using reversed phase and elution gradient. Chlorinated solvents and tetrahydrofuran were investigated as regard to separation time and ICP-MS detection efficiencies The final elution gradient program started from pure methanol to a
mixture of 20:80 (v/v) chloroform:methanol. External quantification of V and Ni with inorganic standards byflow
injection ICP-MS, used online with HPLC, resulted in 95% of recoveries. The Limits of Detection for V during
methanol elution and for Ni during the 20% chloroform gradient elution were evaluated by their minimum
detectable concentrations, which were, respectively