A high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) was established to analyze glucose, sucrose, lactose, galactooligotrisaccharide, 1-kestose, galactooligopentosaccharide, nystose and 1F-fructofuranosyl nystose in four commercial brands of infant formula. The spiked recoveries of HPAEC-PAD ranged from 78.0% to 96.8% with relative standard deviation (RSD) of 4% (n = 5). Its limits of detection were between 3.0 and 12.0 mg/100 g. When HPAEC-PAD and the high-performance liquid chromatography (HPLC) specified in the Chinese national standard were applied to detect sucrose, lactose and 1-kestose in real samples, consistent results were obtained. However, the five other sugars were detected by HPAEC-PAD but not by HPLC. Accordingly, compared with HPLC, HPAEC-PAD was more sensitive and useful for the simultaneous determination of multiple sugars in infant formula.

The purpose of this study is to establish a simple, rapid and effective method for the simultaneous analysis of various saccharides (glucose, sucrose, lactose, galactooligotrisaccharide, kestose, galactooligopentasaccharide, nystose and 1F-fructofuranosyl nystose) in infant formula by high performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD). The effect of chromatographic columns, column temperature, detector waveforms, eluent concentration and flow rate on the separation of the 8 saccharides was evaluated. The analysis was performed on a CarboPac PA20 analytical column (3 mm × 150 mm) coupled with a guard column (3 mm × 30 mm) at a 0.30 mL/min flow rate. Column temperature was set as 30 ℃. Efficient separation was achieved using gradient elution. Under the optimal conditions, the detection limit was 3.0–12.0 μg/L for all analytes. The precision, expressed as relative standard deviation (RSD), was less than 3%. The recoveries of the 8 saccharides in spiked soymilk were 78.0%–96.8%, indicating the feasibility of this method.