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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

Methanol, NMR reference standard

Supelco

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

Sigma-Aldrich

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

Supelco

L-Aspartic acid, Pharmaceutical Secondary Standard; Certified Reference Material

Sigma-Aldrich

L-Aspartic acid, reagent grade, ≥98% (HPLC)

Sigma-Aldrich

L-Aspartic acid, BioUltra, ≥99.5% (T)

Supelco

Acetic acid, analytical standard

Sigma-Aldrich

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

Sigma-Aldrich

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

Sigma-Aldrich

Sodium bicarbonate, tested according to Ph. Eur.

Sigma-Aldrich

di-Sodium hydrogen phosphate dihydrate, tested according to Ph. Eur.

Supelco

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

Sigma-Aldrich

Formamide, BioUltra, for molecular biology, ≥99.5% (T)

Sigma-Aldrich

Sodium phosphate monobasic monohydrate, BioXtra, for molecular biology, ≥99.5% (T)

Sigma-Aldrich

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

Sigma-Aldrich

Potassium cyanide, BioUltra, ≥98.0% (AT)

Supelco

Ammonium acetate, LiChropur^™, eluent additive for LC-MS

Sigma-Aldrich

di-Sodium hydrogen phosphate dihydrate, BioXtra, ≥98.0% (T)

Sigma-Aldrich

Acetic acid, for luminescence, BioUltra, ≥99.5% (GC)

Sigma-Aldrich

Potassium fluoride, BioUltra, ≥99.5% (F)

Supelco

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

Sigma-Aldrich

Acetic acid, ≥99.5%, FCC, FG

Sigma-Aldrich

Acetic acid, natural, ≥99.5%, FG

Sigma-Aldrich

Magnesium oxide, nanopowder, ≤50 nm particle size (BET)

Sigma-Aldrich

Magnesium hydroxide, BioUltra, ≥99.0% (KT)

SAFC

L-Aspartic acid

Supelco

Methanol, analytical standard

Sigma-Aldrich

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

Sigma-Aldrich

Ammonium acetate, 99.999% trace metals basis

Sigma-Aldrich

Isopropyl alcohol, ≥99.7%, FCC, FG