Simple, Rapid and Sensitive Method for Determination of Tacrolimus in Human Blood by using Liquid Chromatography/Tandem Mass Spectrometry

A simple, rapid and sensitive method using an isocratic Liquid chromatography coupled with Tandem mass spectrometry was developed and validated for the assay of Tacrolimus in the Human Blood. The Mass transition of Tacrolimus and Sirolimus (Internal standard) were M/z 821.7/768.7 and M/Z 931.6/864.6 in ESI Negative ionization. Linearity was observed between the Tacrolimus concentration and the peak area ratio from 0.52 to 61.00 ng/mL with r2 value of 0.99. Blood samples containing Tacrolimus were extracted with Zinc sulphate and methanol to precipitate proteins followed by SPE. The observed recovery of Tacrolimus was 66.7%. The intra-day and inter-day accuracy ranged from 91.3 - 110.5% and from 93.9 - 100.6% respectively, at Low, middle and high level concentrations. The method will be used in the determination of the pharmacokinetic parameters of Tacrolimus after oral administration of Tacrolimus formulation in human blood.