Thermal stability of glucose and other sugar aldoses in normal phase high performance liquid chromatography

Analysis of glucose and other simple sugars are often performed by use of normal phase HPLC methods with acetonitrile as major eluent. The present results clearly show that column temperature plays an important role with respect to chromatographic performance and detection limits of glucose when using a specific carbohydrate column. A change in column temperature from 25 to 45 °C reduced the detection of glucose (with ELSD) by more than 41%, whereas the detection of other sugar aldoses (galactose, xylose and rhamnose) were suppressed even more. By increase of column temperature to 70 °C the detector signal of glucose was found to be less than 2% compared to that obtained at 20 °C. Neither fructose nor sucrose showed similar correlation between column temperature and detection. The rate of decreased response is not dependent on sample concentration or the ELSD settings. The results express the importance of accurate temperature control in the analysis of sugar aldoses, and also values low column temperatures for samples with low concentrations of sugar aldoses in order to improve detection.