Liquid Glucose

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

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CAS RN^®: 8027-56-3.

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1 DEFINITION

Liquid Glucose is a product obtained by the incomplete hydrolysis of starch. It consists chiefly of dextrose, dextrins, maltose, and water. The dextrose equivalent (DE) of Liquid Glucose is NLT 20 and NMT 100 and 90.0%-110.0% of the labeled value. (NF 1-Aug-2024)

2 IDENTIFICATION

A. It meets the requirements in the Assay for Reducing Sugars (Dextrose Equivalent).

3 ASSAY

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REDUCING SUGARS (DEXTROSE EQUIVALENT)

Mobile phase: Water

Standard solution A: Prepare a solution in Mobile phase, containing a total of 2% of dextrose and 1.5% of maltose, using USP Dextrose RS and USP Maltose Monohydrate RS.

Standard solution B: Prepare a solution in Mobile phase, containing a total of 10% (w/v) of saccharide solids, by diluting USP Corn Syrup DE 42 RS with Mobile phase.

Sample solution: Dilute a known weight of Liquid Glucose, determined from the result of the test for Water Determination, with Mobile phase to have 10% (w/v) of solids.

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: Refractive index

Columns

Guard: 4.6-mm x 3-cm ¹

Analytical: 7.8-mm x 30-cm; two analytical columns, 25-µm packing L124 ²

Temperatures

Column: 85°

[NOTE-For high-maltose corn syrup made by enzyme hydrolysis, a column temperature of 60 ± 1° may be needed. Column and detector temperatures (±1°) will help achieve system suitability requirements.]

Detector: 45°

Flow rate: 0.4 mL/min

Injection volume: 20 µL

Run time: 60 min

System suitability

Samples: Standard solution A and Standard solution B

[NOTE-See Table 1 for the relative retention times.]

Table 1

^a DP₁, monosaccharides, primarily dextrose, in liquid glucose or corn syrup; DP₂, disaccharides, primarily maltose; DP₃, trisaccharides, primarily maltotriose; DP₄, maltotetraose; DP₅₊, oligosaccharides and polysaccharides.

Suitability requirement

Resolution: NLT 2.0 between the dextrose and maltose peaks using vertical drop-down integration, Standard solution A; NLT 0.2 between DP₉ and DP₁₀ using vertical drop-down integration, Standard solution B

Analysis

Samples: Standard solution A, Standard solution B, and Sample solution

Identify each saccharide peak in the Sample solution based on that in Standard solution A and Standard solution B using vertical drop-down integration.

Calculate the percentage of each saccharide (S_X) in the portion of Liquid Glucose taken:

Result = (r_A/r_B) x 100

r_A = peak response of each saccharide from the Sample solution

r_B = sum of all of the peak responses, excluding peak responses due to solvent from the Sample solution

The expected DE values for each component are listed in Table 2.

Table 2

Due to the fact that the HPLC analysis using two analytical columns cannot further distinguish polysaccharides greater than DP₂₁, the value for DP₂₁₊ was estimated as the average of the expected DE values for DP₂₁-DP₅₀. Typically, there is too much overlap for distinct peaks to be observed for DP₁₂-DP₂₀ due to their low amounts, whereas DP₁₁ is a distinct peak roughly half of the time; the analysis includes all of these overlapped peak areas into a single peak labeled DP_11-20. If DP₁₁ is distinguished, then use the expected DE for DP₁₁ for this calculation; if DP₁₁ is not distinguished, use the expected DE for DP_11-20 instead.

Calculate the DE:

DE = Σ[(E_DE)_DPX x (S_X/100)_DPX]

E_DE = expected DE as defined in Table 2

S_X = calculated above

Acceptance criteria: The DE of Liquid Glucose is NLT 20 and NMT 100 and 90.0%-110.0% of the labeled value. (NF 1-Aug-2024)

4 IMPURITIES

4.1 RESIDUE ON IGNITION (281)

NMT 0.5%

4.2 SULFITE

Sample solution: 5 g in 50 mL of water

Analysis: To the Sample solution add 0.2 mL of 0.1 N iodine, then add 0.5 mL of starch TS.

Acceptance criteria: A blue color is produced.

4.3 STARCH

Sample solution: 5 g in 50 mL of water

Analysis: Boil the Sample solution for 1 min, cool, and add 0.2 mL of 0.1 N iodine.

Acceptance criteria: No blue color is produced.

5 SPECIFIC TESTS

5.1 ACIDITY

Sample solution: 5.0 g in 15 mL of water

Analysis: To the Sample solution add 5 drops of phenolphthalein TS, and titrate with 0.10 N sodium hydroxide.

Acceptance criteria: NMT 0.60 mL of 0.10 N sodium hydroxide is required to produce a pink color.

5.2 WATER DETERMINATION (921), Method I, Method la

Sample: 100 mg

Acceptance criteria: NMT 21.0%

6 ADDITIONAL REQUIREMENTS

6.1 PACKAGING AND STORAGE

Preserve in tightly closed containers. No storage requirements specified.

6.2 LABELING

Label it to indicate the natural source of starch. Label it to indicate its nominal dextrose equivalent.

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6.3 USP REFERENCE STANDARDS (11)

USP Corn Syrup DE 42 RSA (NF 1-Aug-2024)

USP Dextrose RS

USP Maltose Monohydrate RS (NF 1-Aug-2024)

¹ Suitable microguard de-ashing refill cartridges #1250118, H⁺ (cation) and CO₃^- (anion) form, (H⁺ first and then CO₃^-, in series using de-ashing cartridge holder #1250139), can be found at www.bio-rad.com.

² A suitable column is available from www.bio-rad.com, Aminex HPX-42A.