Abstract
Even through more sensitive methods for quantifying trace levels of curcumin in plasma were urgently needed, beyond tandem mass spectrometry, the Paul trap MS/MS/MS has never been tested for curcumin quantification. Because of its unique trap function to accumulate target compounds selectively by optimizing multiple stage MS experiments, it showed great potential to remove background issues reported at low concentration ranges. A novel Triple stage Ion Trap Mass Spectrometry coupled with High Performance Liquid Chromatography (HPLC-ITMS/MS/MS) method has been developed and validated as a curcumin quantification method, for the first time. The use of isotope labeled curcumin-d6 as a novel internal standard (IS) is suggested and tested according to FDA validation procedure. A simplified sample preparation is introduced and validated by coupling a novel acetonitrile precipitation with molecular weight cut-off size exclusion method. This method demonstrated excellent recovery rate of 96.69%-109.26% and minimum matrix effect of 95.40%-110.98%. The lower limit of detection (LLOD) and lower limit of quantification (LLOQ) for curcumin in rat plasma were 0.1 ng/ml and 1 ng/ml respectively. The linear calibration curve for quantifying curcumin in rat plasma was 1-3000 ng/ml (r(2) > 0.99) with intra-day and inter-day RSD and accuracy within ±5.11%. Its application in a Pharmacokinetics (PK) study demonstrated detection of curcumin at a very low plasma level (1.0 ng/ml) and it would be applied to larger sample size animal and clinical pharmacokinetic studies. The presented ITMS/MS/MS quantification method has shown its advantages, including better sensitivity, accuracy, precision, wider calibration range and simplicity in sample preparation, when comparing with other curcumin LC/MS analysis methods in the latest 4 years.