Characterization of fuel samples by on‐line LC‐GC with automatic group‐type separation of hydrocarbons

Abstract

SummaryCharacterization of fuels by LC-GC is possible by use of automatic successive transfer (multiple transfer) of HPLC fractions to a GC via an on-column interface. This paper describes the instrumentation and the methodology for the HPLC separation of the hydrocarbons (aliphatic and aromatic) into separate groups and the on-line transfer of these groups to a capillary GC column. Two HPLC methods were used with the same valve configuration: single column (silica) with column back-flush to detector; and double column (silica and amino-bonded silica) with multiple fraction transfer and back-flush. The first method was used for the analysis of total saturated compounds and total aromatic compounds; the second was used for the separation of the one-, two-, three-, and four-ring aromatic compounds present in diesel fuels. Examples are shown of the characterization of diesel fuels, and the repeatability of the data.

Determination of Hydrocarbon Group-Type of Diesel Fuels by Gas Chromatography with Vacuum Ultraviolet Detection

“…Group-type separations of diesel fuels have been performed with gas chromatography (GC), − high-performance liquid chromatography (HPLC), − LC-GC, , SFC-GC, SFC-MS, and recently a number of hyphenated techniques have been reviewed. − Most commonly used HPLC detectors yield a nonuniform response for saturates and aromatics, ,− mandating the use of complex calibrations. However, the use of an FID provides reliable mass quantification of the different hydrocarbon group-types. ,− When more complex hyphenated techniques are used, reliable quantification becomes more difficult, especially when mass spectrometric detectors are used, as they too give nonuniform responses in group-type separations .…”

Phenolic resins for can coatings: II. Resoles based on cresol/phenol mixtures or tert. butyl phenol

“…the components of interest are imbedded in a large amount of matrix material, as often encountered in food extracts. A first fully automated instrument for comprehensive LC Â GC was commercialized in 1989 (Dualchrom 3000 from Thermo Electron, Milan, Italy), where the technique was called ''GC scanning'' of the liquid chromatogram (Trisciani & Munari, 1994). It was brought up again recently (de Koning, Janssen, & Brinkman, 2004).…”

Analysis of PCB by on-line coupled HPLC-HRGC

“…Ethylbenzene (b. p. 136 ~ was selected as the higher-boiling co-solvent added in small amounts to the main solvent. The efficiency of HPLC separation was sufficient to enable the transfer of four fractions of the same HPLC run (fractions 1 4, in Figure 2); this was achieved by interrupting LC flow after transfer of each fraction [31]. At a transfer temperature of 90 ~ loss of volatile compounds is very small and all the peaks are perfect in shape and size.…”