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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

Sigma-Aldrich

Acetic acid-¹²C₂, 99.9 atom % ¹²C

Supelco

Acetic acid, analytical standard

Sigma-Aldrich

Hydrochloric acid solution, ~6 M in H₂O, for amino acid analysis

Supelco

Hydrogen chloride – 2-propanol solution, ~1.25 M HCl (T), for GC derivatization, LiChropur^™

Sigma-Aldrich

Magnesium oxide, tested according to Ph. Eur., heavy

Supelco

Methanol, analytical standard

Sigma-Aldrich

Ammonium acetate solution, BioUltra, for molecular biology, ~5 M in H₂O

Sigma-Aldrich

Ammonium acetate, BioUltra, for molecular biology, ≥99.0%

Sigma-Aldrich

L-Aspartic acid, BioUltra, ≥99.5% (T)

Sigma-Aldrich

Magnesium hydroxide, BioUltra, ≥99.0% (KT)

Sigma-Aldrich

Magnesium oxide, BioUltra, ≥97.0% (calcined substance, KT)

Sigma-Aldrich

Sodium bicarbonate, tested according to Ph. Eur.

Supelco

Hydrogen chloride – ethanol solution, ~1.25 M HCl, for GC derivatization, LiChropur^™

Supelco

Hydrogen chloride – methanol solution, ~1.25 m HCl (T), for GC derivatization, LiChropur^™

Sigma-Aldrich

Acetonitrile solution, contains 0.1 % (v/v) trifluoroacetic acid, suitable for HPLC

Sigma-Aldrich

Methanol, anhydrous, 99.8%

Sigma-Aldrich

Magnesium oxide, 99.99% trace metals basis

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Isopropyl alcohol, ≥99.7%, FCC, FG

Sigma-Aldrich

Ammonium acetate, 99.999% trace metals basis

Sigma-Aldrich

Acetic acid, ≥99.5%, FCC, FG

Sigma-Aldrich

Acetic acid, natural, ≥99.5%, FG

Sigma-Aldrich

Hydrogen chloride solution, 3 M in cyclopentyl methyl ether (CPME)

Sigma-Aldrich

Sodium phosphate dibasic dihydrate, tested according to Ph. Eur.

Supelco

Dimethyl sulfoxide, analytical standard

Sigma-Aldrich

Dimethyl sulfoxide, for molecular biology

Sigma-Aldrich

N-Acetyl-L-cysteine, suitable for cell culture, BioReagent

Sigma-Aldrich

Dimethyl sulfoxide, PCR Reagent

Sigma-Aldrich

Dimethyl sulfoxide, ≥99.5% (GC), suitable for plant cell culture

Sigma-Aldrich

Dimethyl sulfoxide, Hybri-Max^™, sterile-filtered, BioReagent, suitable for hybridoma, ≥99.7%