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.

This paper reviews the progress in the application of gas and liquid chromatographies, ion chromatography and liquid chromatography-mass spectrometry for the detection of carbohydrates in milk powder. It points out the advantages and disadvantages of these methods. While ion chromatography is nowadays the most used technique to detect carbohydrates in milk powder, ion chromatography will be an important trend in this field owing to its distinct advantages in terms of sensitivity and anti-interference ability.