Giorgia Purcaro, Sabrina Moret, Lanfranco Conte, Hyphenated liquid chromatography–gas chromatography technique: Recent evolution and applications. Journal of Chromatography A Volume 1255, 14 September 2012, Pages 100–111

Liquid chromatography (LC) hyphenated with gas chromatography (GC) was first presented in 1979. Since then an intensive study has been carried out to explore different types of interfaces both for coupling normal-phase (NP) and reverse-phase (RP) LC with GC. The present review focuses on the technical progress and applications presented in the last decade, and it describes the most used interfaces. In fact, more flexible interfaces have been studied to improve the use of LC–GC, in particular the use of a programmed temperature vaporizer (PTV) injector. An intensive effort has also been devoted to optimizing the coupling of reverse-phase LC for analysis of water-based samples. A brief overview of comprehensive approaches (LC × GC) is discussed along with perspective for further improvement of the technique.



Federica Pellati, Francesco Epifano, Nicoletta Contaldo, Giulia Orlandini, Lisa Cavicchi, Salvatore Genovese, Davide Bertelli, Stefania Benvenuti, Massimo Curini, Assunta Bertaccini, Maria Grazia Bellardi,Chromatographic Methods for Metabolite Profiling of Virus- and
Phytoplasma-Infected Plants of Echinacea purpurea.  J. Agric. Food Chem. 2011; 59: 10425–10434

This study was focused on the effects of virus and phytoplasma infections on the production of Echinacea purpurea (L.) Moench secondary metabolites, such as caffeic acid derivatives, alkamides, and essential oil. The identification of caffeic acid derivatives and alkamides was carried out by means of high-performance liquid chromatography-diode array detection (HPLCDAD), HPLC-electrospray ionization-mass spectrometry (ESI-MS), and MS2. Quantitative analysis of these compounds was carried out using HPLC-DAD. The results indicated that the presence of the two pathogens significantly decreases (< 0.05) the content of cichoric acid, the main caffeic acid derivative. Regarding the main alkamide, dodeca-2E,4E,8Z,10E/Z-tetraenoic acid isobutylamide, a significant decrease (< 0.05) in the content of this secondary metabolite was observed in virus-infected plants in comparison with healthy plants, while in the phytoplasma-infected sample the variation of this secondary metabolite was not appreciable. The % relative area of the E/isomers of this alkamide was also found to change in infected samples. The gas chromatography (GC) and GC-MS analysis of E. purpurea essential oil enabled the identification of 30 compounds. The main significant differences (< 0.05) in the semiquantitative composition were observed for three components: limonene, cis-verbenol, and verbenone. The results indicate that the presence of virus and phytoplasma has an appreciable influence on the content of E. purpurea secondary metabolites, which is an important issue in defining the commercial quality, market value, and therapeutic efficacy of this herbal drug.