Agilent hp1200 liquid chromatography system

The Agilent HP1200 liquid chromatography system (Agilent Technology Inc., CA, USA) and API 3200 triple-quadrupole mass spectrometer (Applied Biosystems, CA, USA) operated with a TurboIon spray interface in positive ion mode were used for LC-MS/MS analysis. Chromatographic separation was performed on an Eclipse XDB-C₈ column (150 mm × 4.6 mm, 5 µm; Agilent Technology Inc., CA, USA) at ambient temperature. The mobile phase consisted of acetonitrile and water with 0.1% (v/v) formic acid (40:60, v/v) at a flow rate of 0.5 ml/min. The parameters of the ESI source were optimised under the actual chromatographic conditions. Multiple reactions monitoring (MRM) mode was used to detect the compound of interest. The selected transitions of m/z were m/z 300.10→126.10 for imipenem, m/z 359.20→97.40 for cilastatin, m/z 193.00→149.00 for PAH, and m/z 348.90→268.90 for ES. Data acquisition and analysis were performed with Analyst software (version 1.4.1).

An Agilent HP1200 liquid chromatography system (Agilent Technology Inc., USA) was used. Mass spectrometric detection was performed on an API 3200 triple-quadrupole mass spectrometer (Applied Biosystems, USA). The analysis condition was described separately as follows: