The analysis of dietary supplements is far less regulated than pharmaceuticals, leading to potential quality issues. Considering their positive effect, many athletes consume supplements containing L-histidine and β-alanine. A new microfluidic method for the determination of L-histidine and β-alanine in dietary supplement formulations has been developed. For the first time, capacitively coupled contactless conductivity detection was employed for the microchip electrophoresis of amino acids in real samples. A linear relationship between detector response and concentration was observed in the range of 10-100 µmol L-1 for L-histidine (R2 = 0.9968) and β-alanine (R2 = 0.9954), while achieved limits of detection (3 × S/N ratio) were 4.2 µmol L-1 and 5.2 µmol L-1, respectively. The accuracy of the method was confirmed using recovery experiments as well as CE-UV-VIS and HPLC-UV-VIS techniques. The developed method allows unambiguous identification of amino acids in native form without chemical derivatization and with the possibility of simultaneous analysis of amino acids with metal cations.
- Klíčová slova
- l-Histidine, Amino acids, Capacitively coupled contactless conductivity detection, Dietary supplements, Microchip electrophoresis, β-Alanine,
- MeSH
- beta-alanin * analýza chemie MeSH
- elektrická vodivost * MeSH
- elektroforéza mikročipová * metody MeSH
- histidin * analýza chemie MeSH
- limita detekce MeSH
- potravní doplňky * analýza MeSH
- sklo chemie MeSH
- technologie zelené chemie metody MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- beta-alanin * MeSH
- histidin * MeSH
Capillary isoelectric focusing hyphenated with mass spectrometry detection, following the sequential injection of the carrier ampholytes and the sample zone, is highly efficient for the characterization of proteins. The main advantage of the sequential injection protocol is that ampholytes, with pH ranges, which are not supposed to cover the isoelectric points of the sample components, can be used for separation. The method then allows online mass spectrometry detection of separated analytes either in the absence (substances that have left the pH gradient) or in the presence of low-level ampholytes (substances that are migrating within the pH gradient). The appearance of the substances within, or outside the pH gradient depends on, e.g., the composition of the ampholytes (broad or narrow pH range) or on the composition of electrolyte solutions. The experiments performed in coated capillaries (with polyvinyl alcohol or with polyacrylamide) show that the amount and the injection length of the ampholytes influence the length of the pH gradient formed in the capillary.
- Klíčová slova
- capillary isoelectric focusing, carrier ampholytes, mass spectrometry, proteins, sequential injection,
- MeSH
- amfolytové směsi MeSH
- elektroforéza kapilární * MeSH
- hmotnostní spektrometrie * MeSH
- isoelektrická fokusace * MeSH
- koncentrace vodíkových iontů MeSH
- proteiny izolace a purifikace MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- amfolytové směsi MeSH
- proteiny MeSH
