A determination of sterols is essential for the control of purity and quality of for example edible oils. According to the ISO 12228 method, the sample first is saponified and then purified by solid phase extraction.
After neutralization and restriction, the obtained analytes are further purified by means of preparative thin-layer chromatography. Next, the manual removal of the fraction from the TLC plate is necessary. Then, the fraction is derivatized and chromatographically analyzed by GC-FID. Due to numerous manual steps during this procedure, the method is highly time-consuming and error-prone.
Axel Semrau® provides a solution for this kind of analysis. It is based on a LC-GC technology which is also used within the MOSH/MOAH system and is in routine use in several laboratories. Saponification of the sample and many further preparative steps are fully automated. For this purpose, a DualPAL (CTC Analytics) is applied. The DualPAL includes two syringes: One syringe is used to meter the required reagents for saponification, the second smaller syringe is used to perform the injection into the HPLC. Subsequently, purification is carried out through HPLC, which is directly connected to the GC-FID detection.
The sterol-containing HPLC fractions are specifically selected and directly transferred to the GC system. Disturbing components are eliminated by this method. By performing LC first, a preparative thin-layer chromatography is not required anymore. Thus, manual steps are limited to the weighing and positioning of the sample within the autosampler. This great level of automation is achieved through the DualPAL concept with two different syringes and the use of LC for purification in the GC.
An extensive validation of this method in customers laboratories was performed. Therefore, numerous samples containing different known concentrations and distributions of sterols were analyzed. The results verified that the presented method is precise and provides reproducible results. Concerning analytical parameters, this method is equally good or even better than the required ISO values.
The entire control of the system is provided through the user-friendly software CHRONOS, which simplifies complex methods.
The illustrations below show exemplary chromatograms.
The LC-GC coupling provides two chromatograms simultaneously:
Signal of the UV detector from the HPLC
FID signal of the sterols
At Kovalent we strive to establish and develop long-term partnerships with our customers. When we use the word “partnership” we mean that Kovalent becomes an integral part of our customers’ projects, where we are expected to fully understand their application needs. We aim to make Kovalent our customers’ first and natural choice, and this ambition permeates our entire organisation from initial contact to finished and delivered product.
Genetec is a member of the same family of companies as Kovalent. Both companies share the same set of values and are in many ways integrated with each other. The main difference between the two companies are their products. Kovalent is involved in system solutions including instrumentation and Genetec is mainly working with consumables. The focus of Genetec is chromatography accessories. You are welcome to visit their state of the art web shop: genetec.se