Evaluation of enantiomeric purity of magnesium-L-aspartate dihydrate.

Evaluation of enantiomeric purity of magnesium-L-aspartate dihydrate.

Journal of pharmaceutical and biomedical analysis (2014-09-30)

Oliver Wahl, Ulrike Holzgrabe

ABSTRACT

Magnesium supplementation in form of organic magnesium salts is a very popular practice. We examined the enantiomeric purity of "Magnesium aspartate dihydrate" monographed in the European Pharmacopeia. A chiral capillary zone electrophoresis using (2-hydroxypropyl)-β-cyclodextrin coupled to laser induced fluorescence detection and a HPLC-fluorescence method with chiral derivatization using o-phthaldialdehyde and N-acetyl-L-cysteine as an orthogonal method were developed and validated. Two batch samples of this substance and three drug products containing the salt were analyzed by means of both methods. The concentration of the D-enantiomer of aspartic acid ranged from 0.03 to 0.12%. Simulations of the synthesis revealed that the d-aspartic acid content is elevated if the dissolution of L-aspartic acid was performed at acidic pH values.

MATERIALS

Product Number

Brand

Product Description

94563

Supelco

Dimethyl sulfoxide, analytical standard

295426

Sigma-Aldrich

Hydrogen chloride, ReagentPlus^®, ≥99%

B3545

Sigma-Aldrich

Sodium tetraborate decahydrate, BioXtra, ≥99.5%

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Sigma-Aldrich

Dimethyl sulfoxide, Vetec^™, reagent grade, 99%

1424109

USP

Methyl alcohol, United States Pharmacopeia (USP) Reference Standard

632546

Supelco

Methanol solution, contains 0.10 % (v/v) formic acid, UHPLC, suitable for mass spectrometry (MS), ≥99.5%

95436

Supelco

L-Glutamic acid, certified reference material, TraceCERT^®, Manufactured by: Sigma-Aldrich Production GmbH, Switzerland

PHR1098

Supelco

N-Acetyl-L-cysteine, Pharmaceutical Secondary Standard; Certified Reference Material

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Sigma-Aldrich

Methanol solution, NMR reference standard, 4% in methanol-d₄ (99.8 atom % D), NMR tube size 3 mm × 8 in.

673773

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2-Propanol, ACS reagent, ≥99.5%

109827

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2-Propanol, Laboratory Reagent, ≥99.5%

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190764

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