Browsing by Subject "bioanalyysi"

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  • Lindfors, Pia (Helsingfors universitet, 2010)
    The most important part in bioanalysis is the sample cleanup process which is usually the most laborious and time consuming part of the analysis and very susceptible to errors. A functional bioanalysis has to be quick, easily automated, sensitive, selective and stable. It also needs to be suitable for high throughput analysis. Desorption atmospheric pressure photoionization (DAPPI) is a novel direct desorption/ionization technique for mass spectrometry that enables direct analysis of solids from surfaces or liquid samples from a suitable sample plate often without any sample preparation. The suitability of DAPPI-MS for biological samples was investigated by measuring the limits of detection for selected opioids and benzodiazepines and screening them from authentic urine samples. Limits of detection were measured for standard solutions and spiked urine. Opioids and benzodiazepines were analyzed from post mortem urine samples with an optimized DAPPI-MS method. Post mortem urine samples were analyzed with and without sample preparation. Sample preparation improved the sensitivity of the method remarkably. About 50 % of the analytes were detected without sample preparation and almost 100 % after sample cleanup. It is however difficult to estimate the suitability of DAPPI-MS as a screening method because not all analyte concentrations of the urine samples were known. Therefore we cannot be certain weither the results obtained without sample preparation are caused by the suppression of the urine matrix or if the concentrations of the analytes are below the limits of detection. The reliability of the method can further be improved by investigating the metabolites of the analytes and improving the system towards automation. On grounds of this research DAPPI-MS should be used cautiously as a screening method for urine samples without sample preparation and with only high enough analyte concentrations. DAPPI-MS shows promise as a screening method for opioids and benzodiazepines from urine when the sample cleanup is used before the analysis.