HPLC-HRGC

Figure 2.6 Gas cluotnatograni of a 10 ml test sample containing C I4 C26 alkanes in -hexane (about 1 ppb each) the earner gas (H2) inlet pressure was 2.5 bar for a 22 m X 0.32 mm id separation column coupled with a 2 m X 0.32 mm id uncoated precolumn (no vapour exit). Reprinted from Journal of High Resolution Chromatography, 9, K. Grob et al., Concunent solvent evaporation for on-line coupled HPLC-HRGC , pp. 95-101, 1986, with peimission from Wiley-VCH.

K. Grob, C. Walder and B. Schilling, Concuirent solvent evaporation for on-line coupled HPLC-HRGC , 7. High Resolut. Chromatogr. Chromatogr. Commun. 9 95-101 (1986). 

J. Beens and R. Tijssen, An on-line coupled HPLC-HRGC system for the quantitative chai acterization of oil fractions in the middle distillate range , J. Microcolumn Sep. 7 345-354(1995). 

In 1996, Mondello et al. (48) published a review article on the applications of HPLC-HRGC developed for food and water analysis over the period from 1986 to 1995. These authors cited 98 references, grouped by following a chronological order and by the subject of the application, as follows ... 

The analysis of sterols, sterols esters, erythrodiol and uvaol, and other minor components of oils and fats, is usually carried out by normal-phase HPLC-HRGC by using a loop-type interface and the concurrent eluent evaporation technique, as reported in the papers cited by Mondello et al. (48) (up to 1995) and in more recent papers (49, 50). More recently, reversed-phase LC-GC methods have been... 

Mondello et al. (54) have developed some applications of on-line HPLC-HRGC and HPLC-HRGC/MS in the analysis of citrus essential oils. In particular, they used LC-GC to determine the enantiomeric ratios of monoterpene alcohols in lemon, mandarin, bitter orange and sweet orange oils. LC-GC/MS was used to study the composition of the most common citrus peel, citrus leaf (petitgrain) and flower (neroli) oils. The oils were separated into two fractions, i.e. mono- and sesquiterpene... 

Figure 10.11 Comparison of the mass spectra of a neroli oil peak (camphene) obtained by HPLC-HRGC-MS (a) and GC-MS (b) with a library specti um of the same compound (c). Reprinted from Perfumer and Flavorist, 21, L. Mondello et al., On-line HPLC- HRGC in the analytical chemistiy of citms essential oils , pp. 25-49, 1996, with permission from Allured Publishing Coip.

Analogous to HPLC-HRGC, the combination of packed column SEC and capillary column GC can be used for the analysis of complex samples. The advantage of SEC/GC with respect to HPLC/GC is the absence of problems associated with the evaporation of the HPLC mobile phase prior to the GC analysis. 

R Lanuzza, G. Micali and G. Calabro, On-line HPLC-HRGC coupling and simultaneous transfer of two different LC fractions determination of aliphatic alcohols and sterols in olive oil , 7. High Resolut. Chromatogr. 19 444-448 (1996). 

F. Munari and K. Grob, Automated on-line HPLC-HRGC instnimental aspects and application for the determination of heroin metabolites in urine , J. High. Resolut. Chromatogr. Chromatogr. Commun. 11 172-176(1988). 

There are cases where HPLC separation is performed not in order to quantify the alcohols but as a technique for the purification of the analytes to be subjected to further instrumental analysis. This is the case, for example, with the identification and determination of the structure of an abscisic acid in starfruit extract (Averrhoa carambola L.). The separation and purification of the analytes was carried out also with HPLC using a mobile phase of diethyl ether, whereas the structure was elucidated by H and UC-NMR (6). In a similar way, to separate the sterols and alkanols from the unsaponifiable matter from olive oils on a silica column, a gradient composed of hexane/diethyl ether was chosen in an offline system (7), whereas an online HPLC-HRGC system uses as its mobile phase hexane/isopropanol (8). 

L. Mondello, G. Dugo, P. Dugo and K. Bartle, On-line HPLC-HRGC in the analytical chemistry of citrus essential oils , Perfumer Flavorist 21 25 -49 (1996). 

G. Full, G. Krammer and P. Schreier, On-line coupled HPLC-HRGC A powerful tool for vapor phase FTIR analysis (LC-GC-FTIR) , J. High Resolut. Chromatogr. 14 160-163 (1991). 

HPLC-HRGC coupling 235-243 MDGC 217-231, 422 TLC 242-245 Food packaging 305-306 Forensic applications 407-429 see also biomedical applications Fragrance analysis see food analysis... 

Hyphenated chromatographic techniques of various types (e.g., HRGC/HRGC and HPLC/HRGC) are being used in conjunction with a variety of detectors to improve detectability, increase specificity, and reduce cleanup costs for routine analysis. Vuruls et al. (1992) reported ng/L quantitation for aqueous atrazine samples by LC/GC/MS. 

Drinking water (CDDs) Addition of 13C-labeled CDD internal standards extraction with organic solvent volume reduction clean-up on multiple columns of silica gel/basic silica/acidic silica, AgN03-siiica/basic alumina, and HPLC HRGC/LRMS (SIM) HRGC/MS/MS (SIM) No data No data McCurvin et al. 1989... 

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