A Novel Analytical Method of Cisplatin Using the HPLC with a Naphthylethyl Group Bonded with Silica Gel (πNAP) Column

Cisplatin is the most widely used anticancer drug in the world. Mono-chloro and none-chloro complexes of cisplatin may be believed to be the activated compounds. The separation of these compounds using octa decyl silyl column or aminopropylsilyl silica gel column is difficult because of high-reactivity and structural similarity. In this study, cisplatin, hydroxo complexes, and OH-dimer were determined by HPLC using a naphthylethyl group bonded with silica gel (πNAP) column. The analytical conditions of HPLC were as follows: analytical column, πNAP column; wave length, 225 nm; column temperature, 40°C; mobile phase, 0.1 M sodium perchlorate, acetonitrile, and perchloric acid (290 : 10 : 3), flow rate, 1.0 mL/min. Sample (20 µL) was injected onto the HPLC system. Retention time of cisplatin, mono-chloride, OH-dimer, and none-chloride was 3.2, 3.4, 3.6, and, 4.3-6.6 min, respectively. Measurable ranges with this method were 1×10^-5 to 4×10^-3 M for cisplatin. Correlation coefficient of the calibration curves of cisplatin was 0.999 (p<0.01). The within- and between-day variations of coefficient of variation (CV) were 5% or lower. In this study, injectable formulations in physiological saline solution, water for injection, 5% glucose solution, and 7% sodium bicarbonate precisely were measured the stability and compositional changes upon mixing by πNAP column rather than C18 column. We successfully determined cisplatin, hydroxo complexes, and OH-dimer by HPLC using a πNAP column. Thus the measurement of cisplatin (cis-diamminedichloro-platinum(II), cis-[PtCl₂(NH₃)₂]) (CDDP) should be done using a πNAP column rather than a C18 column or aminopropylsilyl silica gel column.