Analysis of pyridoquinoline derivatives by liquid chromatography/atmospheric pressure chemical ionization mass spectrometry

A method using liquid chromatography/atmospheric pressure chemical ionizati on mass spectrometry (LC/APCI-MS) has been developed for the characterizati on and determination of pyridoquinoline derivatives 4,6-bis(dimethylaminoet hylamino)-2,8,10-trimethylpyrido[3,2-g]quinoline, 4,6-bis (dimethylaminoeth oxy)-2,8,10-trimethylpyrido[3,2-g] quinoline and 4,6-bis[(dimethylamino-eth yl)thio]-2,8,10-trimethylpyrido [3,2-g] quinoline, all with potential antit umor properties. LC separation was performed on a conventional C,g column u sing a binary mobile phase composed of acetonitrile and 50 mM aqueous ammon ium formate at pH 3. The APCI mass spectra obtained showed that proton addi tion giving [M + H](+) was the common mode of ionization to the amino- and thiopyridoquinolines, whereas the alkoxypyridaquinoline was identified by t he main formation of the [M - (C2H3)N(CH3)(2) + H](+), followed by the [M H](+) ion. The LC separation conditions and MS detection parameters were o ptimized for the determination. The analytical method was also applied to t he determination of these pyridoquinoline derivatives in fetal calf serum u sing liquid-liquid extraction with dichloromethane. Acceptable recovery val ues were obtained, ranging between 45 and 98%. Copyright (C) 2001 John Wile y & Sons, Ltd.