Sophisticated statistical tools are required to extract the full analytical power from high-performance thin-layer chromatography (HPTLC). Especially, the combination of HPTLC fingerprints (image) with chemometrics is rarely used so far. Also, the newly developed, instantaneous direct analysis in real time mass spectrometry (DART-MS) method is perspective for sample characterization and differentiation by multivariate data analysis. This is a first novel study on the differentiation of natural products using a combination of fast fingerprint techniques, like HPTLC and DART-MS, for multivariate data analysis. The results obtained by the chemometric evaluation of HPTLC and DART-MS data provided complementary information. The complexity, expense, and analysis time were significantly reduced due to the use of statistical tools for evaluation of fingerprints. The approach allowed categorizing 91 propolis samples from Germany and other locations based on their phenolic compound profile. A high level of confidence was obtained when combining orthogonal approaches (HPTLC and DART-MS) for ultrafast sample characterization. HPTLC with selective post-chromatographic derivatization provided information on polarity, functional groups and spectral properties of marker compounds, while information on possible elemental formulae of principal components (phenolic markers) was obtained by DART-MS.
Direct analysis in real time (DART), a relatively new ionization source for mass spectrometry, ionizes small-molecule components from different kinds of samples without any sample preparation and chromatographic separation. The current paper reviews the published data available on the determination of drugs and drug-like compounds in different matrices with DART-MS, including identification and quantitation issues. Parameters that affect ionization efficiency and mass spectra composition are also discussed.
Three derivatization agents used in GC analysis of amino acids were compared: N,O‐bis(trimethylsilyl)trifluoroacetamide, (BSTFA), N‐methyl‐N‐(tert‐butyldimethylsilyl)trifluoroacetamide (MTBSTFA), and isobutyl chloroformate (iBuCF). It was shown that the analytical characteristics achieved in the case of silylation with MTBSTFA are comparable to those obtained for esterification/acylation. However, since the former approach requires laborious sample preparation to isolate the compounds in question prior to derivatization, determination of amino acids as N(O,S)‐alkoxycarbonyl alkyl esters seems to be preferable in many cases. Application of the esterification/acylation procedure to analysis of lyophilized E. coli microbial culture was demonstrated.
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