LIQUID-CHROMATOGRAPHIC DETERMINATION OF SUGARS IN BEER BY EVAPORATIVELIGHT-SCATTERING DETECTION

A liquid chromatographic method for the determination of mono- and oli gosaccharides in beer was developed using a polymeric NH2 column, a wa ter/acetonitrile gradient and an evaporative light scattering detector (ELSD). The flow rate was 1 ml/min and the column temperature 40-degr ees-C. The optimum settings of the ELSD parameters were: voltage 600 V , temperature 90-degrees-C and nitrogen gas pressure 1.5 bar. The dete ction limit was about 5 mg/l for lower sugars and about 10 mg/l for hi gher ones. The detector response varied among different mono- and olig osaccharides, but it was linear up to a concentration of 0.25 g/l. Owi ng gradient elution, the separation power was much higher than with cl assical liquid chromatographic methods. Reproducibility of the detecto r response was not as good as with refractive index detection. Beer sa mples were prepared by injecting 0.5 ml of beer through a 500 mg C-18 solid-phase extraction tube and flushing the tube with water to make t he final volume of each sample 10 ml. 10 mul of sample was injected in to the liquid chromatograph. Recovery from beer ranged from 78% to 128 % depending on the sugar and its amount added to beer. The highest var iations were observed at low concentrations. Maltotetraose was found t o be the most abundant sugar in beer, its concentration ranging from 0 .7 to 8.4 g/l. The total amount of higher sugars (more than three mono saccharide units) was higher than that of lower ones.