On April 9, 2014, in collaboration with The Chromatographic Society (ChromSoc), Syngenta Research Labs will host “Separating the Wheat from the Chaff; Advances in Natural Product Analysis” at their Jealotts Hill Research Centre in Bracknell, Berkshire, UK. The focus of this conference is the chromatographic and mass spectrometric analysis of foods, vegetables, and natural products. Restek’s International GC Specialist Jaap de Zeeuw will join Professor Pat Sandra (Gent), Dr. Paul Russell (Unilever), Dr. Robin Clery (Givaudan), Dr. Geoffrey Kite (Kew), and other noted industry experts in a full day of valuable presentations.
Considerations for Improved Measurement of Traces in Food Matrices by Minimizing the Injection Bandwidth Using Normal and Large Volume Splitless Injection
Jaap de Zeeuw (presenter)
Abstract: In GC, the efficiency of a capillary can only be exploited if the analytes injected are focused as a narrow band. Using a split injection, this is relatively easy as the injection is fast. If trace analysis is required, a bigger sample volume has to be injected. To inject a larger sample, one needs to eliminate the impact of the solvent.
It is possible to remove the solvent via concentration techniques, but this will cause extra sample preparation time. Easier is to inject a larger amount onto the column. Special injection techniques have been developed to introduce larger sample volumes. One of the most used techniques is the splitless technique. In this technique, the sample is introduced in a hot liner with the split line closed. The whole content of the liner is transferred into the column, which takes between 20 and 60 seconds. To get a focused band, one uses the solvent effect by setting the oven temperature about 20 °C below the BP of the solvent. Components will focus here and a narrow band is created.
The focusing will only happen if the solvent used is compatible with the surface polarity of the stationary phase. If there is no compatibility, the solvent will form droplets and multiple injection bands can be formed. The same challenge is observed when larger volumes are introduced. The use of a retention gap helps for generating a focused band, not only when solvent is entering the column, but also when solvent and column phase are not compatible. The retention gap was found to be extremely helpful in operating the large volume splitless injection technique known as CSR-LVSI. This acronym stands for “concurrent solvent recondensation – large volume splitless injection.” With this technique, it is possible to get a focused band while injecting volumes up to 100 µL in standard split/splitless injection systems.
Standard split/splitless systems for injection of larger volumes, avoiding the use of (expensive) PTV-type injection systems and methods, are relatively easy to set up once the process of band-focusing is understood.
Restek has been a leader in the chromatographic analysis of food for over 25 years, so we are proud to be a participant in what is sure to be an informative and worthwhile event. In addition to the long list of distinguished speakers, attendees will also have access to an exhibition of leading manufacturers and suppliers, including Thames Restek UK.
To view the schedule of talks and to register, visit www.chromsoc.com/ChromsocEvents.aspx today.