A new liquid chromatography method for the simultaneous and sensitive quantification of lactose and lactulose in milk

Abstract

The disaccharide lactulose is known to have a large influence on human digestion, the effects of which range from prebiotic to laxative action. Lactulose can be derived from lactose by either alkaline isomerization or enzymatic transgalactosylation of fructose. The aim of this study was to establish a new analytical method for the quantification of both disaccharides lactose and lactulose using high performance liquid chromatography (HPLC) and evaporative light scattering detection (ELSD). The new method needs to provide good chromatographic separation of lactose and lactulose while being fast and reliable. Therefore, four analytical methods using different HPLC columns were developed and compared. A HPLC column with an amino-bonded polymeric matrix yielded better results compared to amino-bonded silica-phase resin or cation-exchange resin. The new method had detection limits for lactose and lactulose of 3.8 and 2.5 mg L −1 and was successfully applied to the quantification of lactulose and lactose in commercial milk products.

Carbohydrate analysis: From sample preparation to HPLC on different stationary phases coupled with evaporative light‐scattering detection

“…A Rezex RCM‐Monosaccharide Ca 2+ ion‐exclusion column including sulfonated cross linked styrene divinylbenzene copolymer with calcium counterions was applied in a study by Schuster‐Wolff‐Bühring , who attempted to identify the best separation conditions for the determination of disaccharides using various HPLC columns with different stationary phases and ELSD. The Rezex column eluted disaccharides prior to monosaccharides, which could be explained by the size‐exclusion effect of cationic resins.…”

“…However, the best results in carbohydrate analysis in plants and other natural materials have been achieved by HPLC . HPLC analysis of carbohydrates has been applied on different stationary phases using either cation‐exchange resins , an anion‐exchange column , or bonded‐phase columns. For these systems, an amine‐bonded silica gel column is the one mostly used .…”

NMR spectroscopy as a screening tool to validate nutrition labeling of milk, lactose-free milk, and milk substitutes based on soy and grains

“…The most frequently used technique for lactose determination in milk and dairy products is an enzymatic assay based on spectrophotometric measurement, which is also the German reference method (Amtliche Sammlung von Untersuchungsverfahren 2010). Other approaches include biosensors (Ammam and Fransaer 2010), colorimetry (Bakos et al 2002), near-infrared (NIR) spectroscopy (Kawasaki et al 2008;Woo et al 2002), Fourier transform infrared spectroscopy (Lefier et al 1996), or chromatographic techniques (Eadala et al 2009;Paredes et al 2006;Schuster-Wolff-Bühring et al 2011). Besides being comparably time-consuming, none of these methods appear to be appropriate for our purpose to provide a rapid screening of nutrition parameters.…”

Advances in Fractionation and Analysis of Milk Carbohydrates

“…Recently, Schuster-Wolff-Bühring et al [64] developed a sensitive and reliable method for simultaneous detection and quantification of lactose and lactulose in milk-based products using HPLC with ELSD and also compared four analytical methods using different HPLC columns. A HPLC column with an amino-bonded polymeric matrix yielded better results compared to amino-bonded silica-phase resin or cation-exchange resin.…”