Abstract:

A method was established to determine galacto-oligosaccharide (GOS), synthesized with β-galactosidase using
lactose as the precursor, by ion exchange chromatography. The pre-treatment of samples was achieved through volume
dilution instead of gravimetric dilution. CarboPac PA20 anion exchange column and pulsed amperometric detector were
used to determine the contents of GOS. The recovery of the proposed method was 90.58%–99.45% and the relative standard
deviation was 3.54%. The detection limits for gluctose, galactose and lactose were 0.24, 0.59 and 0.75 μg/g, respectively.
The method presented linear correlation coefficients between 0.999 2 and 0.999 9 when the concentrations of gluctose and
galactose were in the range of 0.2–7.0 μg/mL and lactose was 0.6–10 μg/mL. Six GOS samples were determined by this
method to contain galactose, glucose, lactose and GOS in the range of 95.84%–101.19%.

Key words: high performance ion exchange chromatography, galacto-oligosaccharide (GOS), pulsed amperometric detector