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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

Acetonitrile, AR, ≥99.5%

Dimethyl sulfoxide, European Pharmacopoeia (EP) Reference Standard

Magnesium aspartate dihydrate, European Pharmacopoeia (EP) Reference Standard

USP

Residual Solvent Class 2 - Acetonitrile, United States Pharmacopeia (USP) Reference Standard

USP

Glacial acetic acid, United States Pharmacopeia (USP) Reference Standard

USP

Methyl alcohol, United States Pharmacopeia (USP) Reference Standard

Sigma-Aldrich

Acetonitrile, suitable for HPLC, gradient grade, ≥99.9%

Sigma-Aldrich

2-Propanol, suitable for HPLC, 99.9%

Sigma-Aldrich

Acetonitrile, suitable for HPLC-GC, ≥99.8% (GC)

Sigma-Aldrich

Dimethyl sulfoxide, suitable for HPLC, ≥99.7%

Sigma-Aldrich

2-Propanol, HPLC Plus, for HPLC, GC, and residue analysis, 99.9%

Sigma-Aldrich

Acetonitrile, ≥99.9% (GC)

Sigma-Aldrich

Acetonitrile, HPLC Plus, ≥99.9%

Sigma-Aldrich

Acetonitrile, suitable for HPLC, gradient grade, ≥99.9%

USP

Dimethyl sulfoxide, United States Pharmacopeia (USP) Reference Standard

Sigma-Aldrich

Dimethyl sulfoxide, ReagentPlus^®, ≥99.5%

Sigma-Aldrich

Sodium tetraborate decahydrate, ACS reagent, ≥99.5%

Sigma-Aldrich

2-Propanol, ACS reagent, ≥99.5%

Sigma-Aldrich

Dimethyl sulfoxide, ACS reagent, ≥99.9%

Sigma-Aldrich

2-Propanol, puriss. p.a., ACS reagent, ≥99.8% (GC)

Sigma-Aldrich

Sodium tetraborate decahydrate, puriss. p.a., ACS reagent, reag. ISO, buffer substance, ≥99.5%

Sigma-Aldrich

Dimethyl sulfoxide, puriss. p.a., dried, ≤0.02% water

Supelco

2-Propanol, Pharmaceutical Secondary Standard; Certified Reference Material

Supelco

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

Sigma-Aldrich

L-Glutamic acid, FCC

Sigma-Aldrich

2-Propanol, anhydrous, 99.5%

Supelco

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

Sigma-Aldrich

Sodium bicarbonate-¹²C, 99.9 atom % ¹²C

Sigma-Aldrich

Dimethyl sulfoxide, anhydrous, ≥99.9%

Sigma-Aldrich

Acetonitrile, anhydrous, 99.8%