Quantification of tocopherols and tocotrienols in soybean oil by supercritical-fluid chromatography coupled to high-resolution mass spectrometry.

For the most effective analytical strategies, development and validation include optimization of such analytical variables as resolution, detectability, sensitivity, simplicity, cost effectiveness, flexibility, and speed. However, other aspects concerning operator safety and environmental impact are not considered at the same level. The result has been many unintended negative effects of analytical methods developed to investigate different kinds of sample, especially hydrophobic compounds that generate a large amount of chemical waste and have a strong negative environmental impact. In this context, quantification of tocopherols and tocotrienols, i.e. the vitamin E family, is usually achieved by normal-phase liquid chromatography using large volumes of toxic organic solvents, or reversed-phase liquid chromatography using a high percentage of methanol for elution. We propose here a "greener" analytical strategy, including the hyphenation of supercritical-fluid chromatography, using CO2 and ethanol as mobile phase, NH2 as stationary phase, and mass spectrometry for the detection and quantification of vitamin E congeners in soybean oil. An atmospheric-pressure photoionization (APPI) source seemed significantly more sensitive and robust than electrospray or atmospheric-pressure chemical ionization (APCI). This method led to shortened analysis time (less than 5 min) and was revealed to be as sensitive as more traditional approaches, with limits of detection and quantification in the tens of µg L(-1).

Determination of ionization energies of a monoterpene series by atmospheric pressure photoionization using tunable vacuum ultraviolet synchrotron radiation.

Monoterpenes are the main class of biogenic volatile organic compounds. They promptly react with oxygen and nitrogen species, leading to the formation of secondary aerosols. The determination of their physicochemical properties, such as their ionization energies (IEs), is crucial to understand better their reactivity. We previously introduced a modified atmospheric pressure photoionization source coupled to a tunable vacuum ultraviolet source at the SOLEIL synchrotron radiation facility. Here, this set-up is employed to determine IEs of ten monoterpenes with a good precision (±50 meV) and a small sample consumption limited to 10 µg.

Supercritical fluid chromatography coupled to mass spectrometry for lipidomics.

Supercritical fluid chromatography (SFC) has experienced a particular revival in recent years thanks to the development of robust and efficient commercial systems. Because of its physico-chemical properties, supercritical carbon dioxide (CO2 ) mixed with cosolvents and additives is particularly suitable for SFC to allow the elution of compounds of different polarities and more particularly complex lipids. Hyphenation with mass spectrometry (MS) is increasingly described in the literature but still requires many further developments in order to be as user-friendly as coupling with liquid chromatography. The basic concepts of SFC and MS hyphenation will be first considered. Then a representative example of method development in lipidomics will be introduced. In conclusion, the challenges and future needs in this field of research will be discussed.