Simultaneous measurement of phosphorus and platinum by Size Exclusion Chromatography coupled to Inductively Coupled Plasma Mass Spectrometry (SEC-ICPMS) using xenon as reactive collision gas for characterization of platinum drug liposomes

Abstract

Liposomes have attracted intensive attention as drug delivery systems in anti-cancer therapy. Since liposomes are constructed by self-assembling of phospholipids, ICP-MS is a suitable method for simultaneous determination of liposomes and encapsulated metallic drug substances such as platinum-based drugs. An efficient method for simultaneous determination of phosphorus and platinum in liposome samples has been established based on the use of xenon as a collision gas in DRC-ICP-MS. Under the optimum conditions with respect to signal to noise ratio, the interferences were suppressed and the detection limits of phosphorus and platinum were 0.3 and 0.05 ng mL⁻¹, respectively. Quality control was performed by using a certified reference material BCR 273 and biological reference materials. For the purpose of investigation of liposome stability and metallo-drug release from liposomes, a hyphenated method based on size exclusion chromatography was developed for separation of free and encapsulated platinum in a model liposome formulation of oxaliplatin. Moreover, an accelerated drug release study was performed by sonication of liposomal samples and using the developed hyphenated method to determine the drug leakage. It has been demonstrated that the SEC-DRC-ICP MS method was an efficient tool in the development and characterization of liposome based formulations of metallic drugs.