Mass Spectrometric Applications for the Quantitative Analysis of Dried Blood Spot and Capillary Micro-Sampling Techniques

A reversed phase UHPLC-MS/MS method for the quantitative analysis of pioglitazone in dried blood spots (DBS) has been used to validate two new novel techniques to analyse sample concentrations that lie above a particular calibration range. The first of the two techniques is mass spectrometer signal dilution (MSSD) which consists of lowering the signal which reaches the detector, which is achieved by lowering the collision energy applied in the collision cell. The second technique designated isotope signal ratio monitoring (ISRM) looks at [M+2]+1 ions (caused by natural occurring isotopes) for samples above the limit of quantification. For both techniques the requirements for reanalysis of above range samples can be eliminated. A reversed phase UHPLC-MS/MS method for the quantitative analysis of a phosphorothioate oligonucleotide in human plasma capillary micro-sampling samples has been developed and validated, to demonstrate the compatibility of capillary micro-sampling (CMS) with an analytically challenging class of compounds.