Rapid Analysis of α-Tocopherol and Its Oxidation Products Using Supercritical Carbon Dioxide and Proton Transfer Reaction Ionization Mass Spectrometry

Abstract

We have developed a rapid and sensitive analytical method for α-tocopherol and its oxidative products by combining online hyphenation of supercritical fluid extraction-supercritical fluid chromatography (SFC) with proton transfer reaction (PTR) ionization mass spectrometry (MS). α-Tocopherol is a well-known antioxidant that plays a vital role in the antioxidant defense system in plant cells. However, studies on the cellular mechanisms of α-tocopherol have been limited owing to the lack of a rapid analytical method, which limits the comparison of plant cells incubated in various conditions. Additionally, complex sample preparation and long chromatography separation times are required. Moreover, the majority of the involved molecules are a combination of isomers, which must be separated before applying tandem MS. α-Tocopherol produces the α-tocopheroxyl radical in the first step of its antioxidant function; another ion with the same mass may also be generated from the source. SFC separation effectively distinguished the observed ions from their oxidative products in the sample and those produced during the ionization reaction process. This method enabled the measurement of α-tocopherol and its oxidative products such as α-tocopheroxyl radical and αtocopheryl quinone in approximately 3 min per sample, including the time required for sample preparation.

A Method for High Throughput Free Fatty Acids Determination in a Small Section of Bovine Liver Tissue Using Supercritical Fluid Extraction Combined with Supercritical Fluid Chromatography-Medium Vacuum Chemical Ionization Mass Spectrometry

“…Using the previously reported method, the optimum timing (15 s) of switching the sample injection valve was investigated in advance for standard samples and bovine liver samples. 7 , 10) …”

“…MVCI ion source was built in-house, as previously reported. 3 , 7 , 10) Mass calibration was performed using sodium trifluoroacetate, an electrospray ionization (ESI) source, and third-order polynomials for m/z between 159 and 1880. The MVCI ion source was then attached by altering the ESI source.…”

“…SFC carried out with non-modified CO 2 exhibits high column efficiency for a group of molecules such as fat-soluble vitamins and phthalates. 7 , 10) However, a series of free fatty acids (FFAs) exhibits specific interactions with most C18 stationary phases with a non-modified CO 2 mobile phase, degrading column efficiency. Low column efficiency may cause poor peak resolution of isomers on a column, which may interfere with the subsequent tandem mass spectrometry process.…”

Attempts to Detect Lipid Metabolites from a Single Cell Using Proton-Transfer-Reaction Mass Spectrometry Coupled with Micro-Scale Supercritical Fluid Extraction: A Preliminary Study

“…To establish an SFC-PTR MS interface, a study of peak dispersion in the PTR flow tube is mandatory. 17,24)…”