A Systematic Approach to Overcome the Matrix Effect during LC-ESI-MS/ MS Analysis by different Sample Extraction Techniques

Abstract

Matrix effect (ME) is a major concern during any LC-ESI-MS/MS analysis. It affects reproducibility, sensitivity and reliability of these analytical techniques. There are, however, no standardized approaches available to overcome the ME related issues. The approach varies from molecule to molecule. Here we examined that sample extraction technique is an approach to overcome the ME during LC-MS/MS bioanalysis. Three types of conventional extraction techniques i.e. protein precipitation, liquid-liquid extraction and solid phase extraction (SPE) were used during extraction of nevirapin from human plasma. It was observed that nevirapin sample when prepared by SPE, eliminates or reduces dramatically the MEs ipso facto. Protein precipitated samples showed highest degree of ME with average matrix factor of 0.30; liquid-liquid extraction had an average matrix factor of 0.80; and the matrix factor obtained by solid phase extraction was 0.99. Different phospholipids were identified by performing the precursor ion scanning at m/z 104 and 184, which interfered with the analyte during chromatographic elution. From the experiment it was observed that long retained phospholipids had significant role on ME. So it is a good practice to observe the phospholipids during precursor scanning for a period which is at least three times of the actual analytical run time. Among all the applied extraction techniques, solid phase extraction produces the cleanest sample, and methanol precipitation produces the dirtiest sample due to high solubility of the phospholipids into it.