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[Simultaneous determination of four Sudan dyes in blood by solid-phase extraction combined with ultra-fast liquid chromatography-tandem mass spectrometry].

A method for the simultaneous determination of Sudan I, II, III, and IV in blood samples by solid-phase extraction (SPE) combined with ultra-fast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) has been established. The samples were extracted with acetonitrile by vortex and vibrate technique, and then the supernatant was diluted with equal volume of water and cleaned up by a C18 SPE column. The separation was performed on an Agilent Eclipse Plus C18 column (100 mm x 2.1 mm, 1.8 microm) by gradient elution with acetonitrile containing 0.1% (v/v) formic acid and 0.1% (v/v) formic acid aqueous solution as the mobile phases. The electrospray ionization (ESI) source in the positive mode and multiple reaction monitoring (MRM) mode were used for the quantitative analysis. In addition, the phenomenon of E-Z optical isomer occurred by the azo group from Sudan III and IV was found, and the influencing factors were discussed. The results showed that the calibration curves were in good linearity for the four Sudan dyes ranged from 0.1 to 20.0 microg/L with the correlation coefficients of more than 0.999. The average recoveries were from 93.0% to 108.2% with the relative standard deviations (RSDs) from 4.8% to 9.5%. The limits of detection (LODs) and the limits of quantification (LOQs) were 0.06 microg/L and 0.2 microg/L for the four analytes, respectively. The developed method is simple, rapid, and highly sensitive. It can be used for the determination of trace Sudan dyes in blood samples.