3.1 UPLC-MS/MS analytical conditions
TGC is a novel glycyclcycline, which belongs to third generation
tetracycline. Due to high hydrophilic property (Log P=-1.30) of TGC,
hydrophilic columns, such as HILIC and T3 column, were firstly tried to
perform the separation. However, the peak shape of TGC provided by
hydrophilic columns could not meet our expectation. Waters XBridge® BEH
Shield RP18 column (3.0×50mm, 2.5μm) could perform the separation with
100% aqueous phase. The 100% aqueous phase was chosen for the
retention of TGC according to the high hydrophilic property of TGC, and
TGC could achieve symmetric and sharp peak shapes in this
chromatographic condition (Figure 1). Quantification of TGC was
performed by MRM in positive mode. Therefore, formic acid was added in
the aqueous phase to enhance signal response. And ammonium formate was
utilized to achieve sharp peak of analyte without tailing. TGC-d9 was
used as IS to decrease the effect of matrix.