Abstract:

The two-dimensional ultra performance liquid chromatography-triple quadrupole/linear ion trap mass spectrometry (2D-UPLC-QTRAP MS) method has been developed for the determination of rotenone in whole blood and urine. This method is based on the use of two columns of different stationary phases (Kinetex Biphenyl and Acquity BEH C₈) connected through two six-port two-position switching valves. Urine samples were diluted with equal quantity of water and then directly injected into the separation system. Blood samples were prepared by precipitation of proteins with acetonitrile, and then the supernatants were diluted with water and injected into the system. The samples were loaded onto the Cyclone column at high flow-rates, allowing the excluded proteinaceous material to flow through to waste. Then the retained rotenone was eluted into the Kinetex Biphenyl column, and the first dimension separation was completed. The fraction containing rotenone was switched into a trap column (XBridge C₈ Direct Connect HP). After the rotenone was retained completely by trap column, the valve switched it into the stream of the second dimension. The rotenone was separated on the Acquity BEH C₈ column with gradient elution of mobile phases of acetonitrile-H₂O containing 0.2% (v/v) formic acid, detected by positive electrospray ionization tandem mass spectrometry in the multiple reaction monitoring-information-dependent acquisition-enhanced product ion (MRM-IDA-EPI) mode, and quantified by solvent standard solutions. The average recoveries were 84.6%-94.3% and 88.4%-95.7% for rotenone in blood and urine with relative standard deviations of 2.6%-7.3% and 2.8%-6.8% (n=6). The limits of detection were 0.2 and 0.03 μg/L for blood and urine, respectively. The method is sensitive, selective, and has been successfully applied to the detection of rotenone in the samples resulting in food poisoning.

Key words: heart-cutting, rotenone, triple quadrupole/linear ion trap mass spectrometry (QTRAP MS), two-dimensional ultra-performance liquid chromatography (2D-UPLC), urine, whole blood