Research Article

SPE-UHPLC-FLD Method for the Simultaneous Determination of Five Anthraquinones in Human Urine Using Mixed-Mode Bis(tetraoxacalix[2]arene[2]triazine) Modified Silica as Sorbent

Figure 8

UHPLC-FLD chromatograms of samples and the standard solution: (A) blank urine sample without SPE cleanup; (B) blank urine sample after C18 SPE cleanup; (C) blank urine sample after BTO-SPE SPE cleanup; (D) urine sample spiked with 0.02 μg mL−1 standard solution of five anthraquinones; (E) standard solution of five anthraquinones (0.5 μg mL−1) (peaks: (1) aloe-emodin; (2) rhein; (3) emodin; (4) chrysophanol; (5) physcion).