title: Rapid NMR determination of inorganic cations in food matrices: Application to mineral water.
abstract: A nuclear magnetic resonance (NMR) method was developed to quantify cations in mineral water. The procedure was based on integration of signals from metal-ethylenediaminetetraacetic acid (EDTA) complexes at δ 2.70ppm for Mg2+and δ 2.56ppm for Ca2+. The limits of detection were below 0.5mg/L. Lack of precision did not exceed 5%. Linearity was between 1 and 500mg/L. Correlation between NMR and a reference chromatographic method was significant (p<0.0001, R2=0.99). PLS models were also established to estimate Na+and K+contents. R2was 0.85 and 0.83, respectively. Root mean square errors of cross validation (RMSECV) were 8.0mg/L and 1.9mg/L for Na+and K+, respectively. The method was applied successfully for the analysis of 31 mineral water samples. This method is a useful tool for quantification of important cations in mineral water and might easily be adapted to other food matrices.
authors.affiliation: Spectral Service AG, Emil-Hoffmann-Straße 33, 50996 Köln, Germany; Institute of Chemistry, Saratov State University, Astrakhanskaya Street 83, 410012 Saratov, Russia.
authors.forename: Yulia B
authors.initials: YB
authors.lastname: Monakhova
authors.affiliation: Chemisches und Veterinäruntersuchungsamt (CVUA) Karlsruhe, Weißenburger Straße 3, 76187 Karlsruhe, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Kuballa
authors.affiliation: Chemisches und Veterinäruntersuchungsamt (CVUA) Karlsruhe, Weißenburger Straße 3, 76187 Karlsruhe, Germany.
authors.forename: Christopher
authors.initials: C
authors.lastname: Tschiersch
authors.affiliation: Spectral Service AG, Emil-Hoffmann-Straße 33, 50996 Köln, Germany. Electronic address: diehl@spectralservice.de.
authors.forename: Bernd W K
authors.initials: BWK
authors.lastname: Diehl
mesh_terms: D002118:Calcium / Q000032:analysis; D002412:Cations / Q000032:analysis*; D004492:Edetic Acid / Q000737:chemistry; D005504:Food Analysis; D008274:Magnesium / Q000032:analysis; D009682:Magnetic Resonance Spectroscopy; D008900:Mineral Waters / Q000032:analysis*; D011188:Potassium / Q000032:analysis; D015203:Reproducibility of Results; D012964:Sodium / Q000032:analysis
chemical_list: D002412:Cations; D008900:Mineral Waters; D004492:Edetic Acid; D012964:Sodium; D008274:Magnesium; D011188:Potassium; D002118:Calcium
keywords: Calcium; EDTA complexes; Ethylenediaminetetraacetic acid (PubChem CID: 6049); Magnesium; Mineral water; NMR spectroscopy; PLS regression