Anthocyanin determination in black raspberry (Rubus occidentalis) and biological specimens using liquid chromatography-electrospray ionization tandem mass spectrometry

The capabilities of mass spectrometry for microscale determination of anthocyanins were investigated using high-performance liquid chromatography electrospray ionization mass spectrometry (LC-ESI/ MS) and tandem mass spectrometry (MS-MS). Four anthocyanins [cyanidin 3-glucoside, cyanidin 3-sambubioside, cyanidin 3-(2(G)-xylosylrutinoside) and cyanidin 3-rutinoside] were characterized in black raspberry samples by LC-ESI/MS-MS using both positive and negative ion analyses. Quantification of anthocyanins was conducted using ESI/MS-MS with selected reaction monitoring (SRM). Linear responses of several anthocyanins were determined during MS-MS analyses. Detection limits as low as 1 femtomol for most anthocyanins were obtained during ESI/MS-MS. Compared with other quantitative procedures such as high-performance liquid chromatography (HPLC) and ultraviolet/visible spectrophotometry, the current method provides an improved sensitive, specific technique for direct determination of intact anthocyanins. The developed methodology was successfully applied to analysis of trace levels of anthocyanins in human plasma and epithelial cells.