Most cited article - PubMed ID 10544888
Analytical monitoring of the production of biodiesel by high-performance liquid chromatography with various detection methods
Reversed-phase ultrahigh-performance liquid chromatography-mass spectrometry (RP-UHPLC/MS) method was developed with the aim to unambiguously identify a large number of lipid species from multiple lipid classes in human plasma. The optimized RP-UHPLC/MS method employed the C18 column with sub-2-μm particles with the total run time of 25 min. The chromatographic resolution was investigated with 42 standards from 18 lipid classes. The UHPLC system was coupled to high-resolution quadrupole-time-of-flight (QTOF) mass analyzer using electrospray ionization (ESI) measuring full-scan and tandem mass spectra (MS/MS) in positive- and negative-ion modes with high mass accuracy. Our identification approach was based on m/z values measured with mass accuracy within 5 ppm tolerance in the full-scan mode, characteristic fragment ions in MS/MS, and regularity in chromatographic retention dependences for individual lipid species, which provides the highest level of confidence for reported identifications of lipid species including regioisomeric and other isobaric forms. The graphs of dependences of retention times on the carbon number or on the number of double bond(s) in fatty acyl chains were constructed to support the identification of lipid species in homologous lipid series. Our list of identified lipid species is also compared with previous publications investigating human blood samples by various MS-based approaches. In total, we have reported more than 500 lipid species representing 26 polar and nonpolar lipid classes detected in NIST Standard reference material 1950 human plasma.
- Keywords
- Human plasma, Lipidomics, Lipids, Mass spectrometry, Retention behavior, Reversed-phase, Ultrahigh-performance liquid chromatography,
- MeSH
- Chromatography, Liquid methods MeSH
- Mass Spectrometry methods MeSH
- Humans MeSH
- Lipids blood chemistry MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Names of Substances
- Lipids MeSH
We used reversed phase liquid chromatography-electrospray ionization tandem mass spectrometry for direct analysis of mycolic acids (MAs) from four different cultivations of Rhodococcus erythropolis. This technique enabled us to identify and quantify the specific molecular species of MAs directly from lipid extracts of the bacterium, including the determination of their basic characteristics such as retention time and mass spectra. We identified a total of 60 molecular species of MAs by means of LC/MS. In collision-induced dissociation tandem mass spectrometry, the [M-H](-) ions eliminated two residues, i.e., meroaldehyde and carboxylate anions containing α-alkyl chains. The structural information from these fragment ions affords structural assignment of the mycolic acids, including the lengths and number of double bond(s). Two strains, i.e., R. erythropolis CCM 2595 and genetically modified strain CCM 2595 pSRK 21 phe were cultivated on two different substrates (phenol and phenol with addition of humic acids as a sole carbon source). The addition of humic acids showed that there is a marked increase of unsaturated mycolic acids, mostly in the range of 20-100 %. This effect is more pronounced in the R. erythropolis CCM 2595 strain.
- MeSH
- Biotransformation MeSH
- Chromatography, Liquid MeSH
- Phenol metabolism MeSH
- Humic Substances MeSH
- Culture Media chemistry MeSH
- Mycolic Acids chemistry metabolism MeSH
- Rhodococcus chemistry metabolism MeSH
- Tandem Mass Spectrometry MeSH
- Carbon metabolism MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- Phenol MeSH
- Humic Substances MeSH
- Culture Media MeSH
- Mycolic Acids MeSH
- Carbon MeSH