Direct analysis from dried blood spot card surfaces with direct probe mass spectrometry - Evaluation study.

RATIONALE: The Direct Probe Mass Spectrometry (DIPMS) method allows successful analysis of powders, solid and liquid samples. The potential of direct surface analysis could find further application in the examination of surfaces with good absorption properties such as Dried Blood Spot (DBS) cards that constitute a great alternative to the classical blood collection method directly from veins. METHODS: DIPMS was performed with the ionization carried out under atmospheric pressure in an Atmospheric Pressure Chemical Ionization source. Direct analysis of diazepam solutions in methanol and after their deposition onto a DBS card was conducted. Subsequently, images of the DBS cards with and without blood samples were acquired using Scanning Electron Microscopy (SEM). RESULTS: Direct quantitative analysis of diazepam liquid samples by DIPMS was successfully performed. Linear correlation between the concentration of diazepam and the peak intensity with a R2 coefficient of 0.937 was obtained. However, the method failed when the analysis was conducted directly from the surface of the DBS cards and no diazepam peak was observed in the mass spectrum. The SEM images confirmed the good absorption properties of DBS cards and the absence of blood components on the surface. CONCLUSIONS: DIPMS is an excellent technique for the rapid, direct analysis of powders, solid and liquid samples; however, the potential of the method is limited when samples are deposited on surfaces with good absorption properties such as DBS cards.