[Determination of fructooligosaccharides in milk powder using high performance anion-exchange chromatography coupled with pulsed amperometric detection].

Fructooligosaccharides(FOS)are usually added in milk powder as a kind of prebi otic. Thus,quantitative analysis of the FOS is very important for the quality control of milk powder. In this study,a simple method for the simultaneous determination of three FOS com ponents with degrees of polymerization(DP)3- 5 in milk powder was developed by high per formance anion exchange chromatography coupled with pulsed amperometric detection(HPAEC PAD). The samples were extracted with 50%(v/ v)ethanol aqueous solution and defatted by an On Guard RP pretreatment column. The separation was performed on a Car boPac PA200 column by gradient elution using deionized water,0. 2 mol / L NaOH solution and0. 4 mol / L NaAc solution as the mobile phases. The flow rate was 0. 4 mL / min. The column temperature was 30 ℃; and the injection volume was 25 μL. Good linear response was observed in the concentration range of 0. 05- 10 mg / L(r2 0. 999 3). The limits of quantifica tion were 0. 02,0. 005 and 0. 02 mg / L for 1 kestose,nystose and fructofuranosyl nystose,re spectively. The mean recoveries varied from 86. 0% to 114. 0% at three spiked levels of 0. 5,1. 0 and 5. 0 mg / L. The short chain fructooligosaccharides from inulooligosaccharides(IOS)were successfully separated by the developed HPAEC PAD method. The method is simple,ac curate,sensitive,and helpful for the quality control of milk powder.