Analysis of the response factors of different quinolones detected by evaporative light-scattering detector

AimTo analyze the response factors of different quinolone antibiotics detected by evaporative light-scattering detector（ELSD）. MethodsThe response factors of five different quinolones (enoxacin， levofloxacin, ciprofloxacin， lomefloxacin and gatifloxacin) detected by ELSD were determined by using a YMC-Pack ODS-AM cloumn （150 mm×4.6 mm ID， 5 μm）as analytical column and 0.5% triethylamine(adjusting pH 2.5 with trifluoroacetic acid)-acetonitrile (48∶12) as mobile phase at a flow rate of 0.6 mL·min^-1, the temprature of the drift tube was set at 117 ℃,and the flow of carrier gas at 3.0 L·min^-1. Detector responses (A) and the amount of injection of each substance (M) were fitted to the logarithmic regression: log A=b log M+log A. ResultsThe linear regression equation obtained were: enoxacin：　Y=1.079　9X+2.761　1, r²=0.999　6; levofloxacin: Y=1.091　3X+2.723　5, r²=0.999　7; ciprofloxacin: Y=1.082　8X+2.752　3, r²=0.999　4; lomefloxacin: Y=1.089　1X+2.739　1, r²=0.999　3; gatifloxacin: Y=1.087　8X+2.739　2, r²=0.999　5. The differences between them were negligible. ConclusionDifferent quinolones can give the same responses with ELSD detection. So, the HPLC-ELSD methods can be applied to the determination of new substances by using another substance as reference.