UPLC-DAD-MS/MS Method for Analysis of PQQ in Fermentation Broth

Pyrroloquinoline quinone (PQQ) is an important biofactor which can be synthesized by several bacteria. To determine the level of PQQ in a fermentation broth, a rapid and reliable UPLC-DAD-MS/MS method was developed. In this method, solid phase extraction allowed for excellent recoveries (>90 %) and eliminated interference at the same time. The pretreated sample was separated on a Waters Acquity BEH C18 column (2.1 × 100 mm, 1.7 μm) and detected using an ESI tandem mass spectrometer operated in negative-ion mode at a m/z range between 90.0 and 1000.0 and a DAD detector in the range from 200 to 400 nm. PQQ was observed to separate absolutely from the other components using gradient elution with water and acetonitrile. This separation also reduced the matrix effects. The assay range is 200–500 µg/mL and proved to be linear (R2 > 0.996), accurate (≤10 % deviation), and precise (CV < 15 %). The retention time for PQQ in the column was almost 1 min due to the high column efficiency on the UPLC system. Therefore, this work provides a rapid and reliable method to quantitate the PQQ level in a fermentation broth.