Carbohydrates and sugar alcohols

For the analysis of carbohydrates like glucose, fructose and sucrose with CE the charge and the detectability have to be optimized. Therefore diffent methods have proven ist worth in practice: on the one hand it is possible to analyse carbohydrates at a high pH (12,1) with direct UV detection. Under these conditions the carbohydrates are slightly dissociated anions. Unfortunately the resulting detectability is rather low.
Alternatively the samples could be derivatized for example with reductive amination using reagents like aminobenzene acidethylether (ABEE) and 6-aminochinoline (6-AQ). After the derivatization very good detectability and high selectivity can be achieved. The disadvantage of this procedure is the high effort for the sample preparation.
Eventually the carbohydrates can be analysed as anions in a high pH
(12,6) with direct UV detection. For this method a sample preparation is not necessary and the detectability is acceptable.

Hereafter examples for all three different methods are given.

Sugar with indirect detektion

  • Separation: CZE
  • Electrolyte: Basic anion buffer, pH 12,1
  • Capillary: fused silica, 50 µm ID, 114 cm in total
  • Injection: 40 s, 50 mbar
  • Detection: indirect UV, 275 nm
  • Description: The standard solution contains six different carbohydrates: fructose (fruit sugar), mannose (niacinamide, vitamin PP), glucose (dextrose), maltose (malt sugar, maltobiose), lactose (milk sugar, lactobiose) and sucrose (cane sugar, beet sugar) in a concentration of 200 mg/l each. The EOF was reversed using a modifier in the electrolyte.
Zucker_1

Carbohydrates with indirect detection

Download: Zucker_1.pdf

Sugar after derivatization

  • Separation: CZE
  • Electrolyte: Borate
  • Capillary: Bubble cell, fused silica, 50 µm ID, 48 cm in total
  • Injection: 20 s, 50 mbar
  • Detection: direct UV, 250 nm
  • Description: The standard solution with mannose (niacinamide, vitamin PP), glucose (dextrose) and galactose was derivatized with 6-aminochinoline before the determination.
Zucker_2

Carbohydrates after derivatization

Download: Zucker_2.pdf

Sugar in fermentation broth after derivatization

  • Separation: CZE
  • Electrolyte: Borate
  • Capillary: Bubble cell, fused silica, 50 µm ID, 48 cm in total
  • Injection: 20 s, 50 mbar
  • Detection: direct UV, 250 nm
  • Description: Before the determination the fermentation broth was derivatized with 6-aminochinoline. Glucose could be identified and quantified and two other unidentified carbohydrates were determined.
Zucker_3

Carbohydrates in fermentation broth after derivatization

Download: Zucker_3.pdf

Sugar with direct detection at a high pH value

  • Separation: CZE
  • Electrolyte: Phosphate, pH 12,6
  • Capillary: Bubble cell, fused silica, 50 µm ID, 64 cm in total
  • Injection: 6 s, 50 mbar
  • Detection: direct UV, 265 nm
  • Description: The standard solution contains eleven different carbohydrates that can be analysed without sample pretreatment: Xylitol (E967, Pentapentol, birch sugar), trehalose (mykose), sucrose (cane sugar, beet sugar), fucose (methylpentose, desoxy galactose), cellobiose (cellose), galactose, glucose (dextrose), mannose, fructose (fruit sugar), arabinose (pectinose, aloin sugar) and xylose (wood sugar).
Zucker_Standard

Carbohydrates with direct UV-detection

Download: Zucker_Standard.pdf

Determination of sugars in different foods

  • Separation: CZE
  • Electrolyte: Phosphate, pH 12,6
  • Capillary: Bubble cell, fused silica, 50 µm ID, 64 cm in total
  • Injection: 6 s, 50 mbar
  • Detection: direct UV, 265 nm
  • Description: The PDF shows electropherograms of eleven foods like drinks, fruit, vegetables and sausage.
Zucker_Apfelsaft

Carbohydrates in apple juice

Download: Zucker_Anwendungen.pdf

Determination of sugars with a fast screening method

  • Separation: CZE
  • Electrolyte: Phosphate, pH 12,6
  • Capillary: Bubble cell, fused silica, 50 µm ID, 64 cm in total
  • Injection: 6 s, 50 mbar
  • Detection: direct UV, 265 nm
  • Description: All sugars relevant for the determination in foods can also be determined with the fast screening method. The anaylsis of Xylitol (E967, Pentapentol, birch sugar), sucrose (cane sugar, beet sugar), glucose (dextrose), mannose and fructose (fruit sugar) is succesful in less than 10 min.
Zucker_Standard_Screening

Screening of  carbohydrates – standard solution

Download: Zucker_Standard_Screening.pdf

Determination of sugars in beverages with a fast screening method.

  • Separation: CZE
  • Electrolyte: Phosphate, pH 12,6
  • Capillary: Bubble cell, fused silica, 50 µm ID, 64 cm in total
  • Injection: 6 s, 50 mbar
  • Detection: direct UV, 265 nm
  • Description: The PDF shows the analysis of glucose, fructose and sucrose with CE in
Zucker-Apfelsaft

Screening of carbohydrates in beverages

Download: Zucker-Saft-Prosecco.pdf

Determination of sugars in fruit with a fast screening method.

  • Separation: CZE
  • Electrolyte: Phosphate, pH 12,6
  • Capillary: Bubble cell, fused silica, 50 µm ID, 64 cm in total
  • Injection: 6 s, 50 mbar
  • Detection: direct UV, 265 nm
  • Description: The five-sided PDF shows the analysis of glucose, fructose, sucrose, xylitol and sorbitol with CE in several fruit like lemon, pear and raspberries. For sample preparation the fruit were pureed, weigthed and diluted with pure water.
Zucker in Obst

Screening of carbohydrates in fruits

Download: Zucker-Screening-Obst.pdf

Determination of sugars in foods with a fast screening method.

  • Separation: CZE
  • Electrolyte: Phosphate, pH 12,6
  • Capillary: Bubble cell, fused silica, 50 µm ID, 64 cm in total
  • Injection: 6 s, 50 mbar
  • Detection: direct UV, 265 nm
  • Description: All sugars relevant for the determination in foods can be determined with the fast screening method. The anaylsis of sorbitol (E420), sucrose (cane sugar, beet sugar), glucose (dextrose) and fructose (fruit sugar) is succesful in less than 10 min. In total 16 electropherograms are shown of beverages, vegetable and tooth paste for children.
Zucker_Anwendungen_Screening

Screening of carbohydrates in foods

Download: Zucker_Anwendungen_Screening

Analysis of sugar alcohols.

Sugar alcohols have a sweet taste. As their metabolization is indepent of insulin they are widely used as sweeteners in many foods, especially sorbitol.

  • Separation: CZE
  • Electrolyte: Phosphate, pH 12,6
  • Capillary: Bubble cell, fused silica, 50 µm ID, 64 cm in total
  • Injection: 6 s, 50 mbar
  • Detection: direct UV, 265 nm
  • • Description: The standard solution contains sorbitol (E420), mannitol (E421, D-mannite), maltitol (E965, maltit) as well as glucose (dextrose) and fructose (fruit sugar) in a concentration of mg/l each.
Zuckeralkohole

Separation of sugar alcohols

Download: Zuckeralkohole