Deproteination of whole blood for LC-MS/MS using paramagnetic micro-particles

Liquid chromatography tandem mass spectrometry has become increasingly popular in clinical laboratories over the last decade due to the inherent sensitivity and specificity of the technology. Nevertheless, full automation and hence application in routine laboratories is still hampered by laborious and difficult-to-automate sample pre-treatment protocols. Functionalized paramagnetic micro-particles could simplify sample pre-treatment and ease automation. We evaluated the applicability of a pre-commercial, straightforward paramagnetic micro-particle based kit for the lysis and deproteination of whole blood for the LC-MS/MS analysis of everolimus and compared the performance to our routine protein precipitation method.

Samples were prepared for LC-MS/MS everolimus analysis on an Acquity UPLC chromatographic system coupled to a TQD mass spectrometer (both Waters Ltd.) using a pre-commercial MagSi-TDMprep kit and a routine protein precipitation respectively. Both pre-treatment methods were validated for imprecision, accuracy, linearity, limit of quantification, matrix effect, recovery and process efficiency. A method comparison (n=63) between both pre-treatment methods was performed.

Imprecision and bias were within pre-defined criteria (15%) for both pre-treatment methods. Both methods were linear from 1.2 to 14.8μg/L with a limit of quantification of 0.6μg/L. Process efficiency was on average 65% for protein precipitation pre-treatment and was substantially higher for the MagSi-TDMprep method (85%). A Passing-Bablok regression showed no significant difference between the two pre-treatment methods.

For everolimus in whole blood, the MagSi-TDMprep sample pre-treatment was applicable and comparable to protein precipitation for LC-MS/MS with the possible advantage of easier automation.