Skip to Content
Merck
  • Selective removal of phosphate for analysis of organic acids in complex samples.

Selective removal of phosphate for analysis of organic acids in complex samples.

Journal of chromatography. A (2015-03-01)
Sandeep Deshmukh, Andrej Frolov, Andrea Marcillo, Claudia Birkemeyer
ABSTRACT

Accurate quantitation of compounds in samples of biological origin is often hampered by matrix interferences one of which occurs in GC-MS analysis from the presence of highly abundant phosphate. Consequently, high concentrations of phosphate need to be removed before sample analysis. Within this context, we screened 17 anion exchange solid-phase extraction (SPE) materials for selective phosphate removal using different protocols to meet the challenge of simultaneous recovery of six common organic acids in aqueous samples prior to derivatization for GC-MS analysis. Up to 75% recovery was achieved for the most organic acids, only the low pKa tartaric and citric acids were badly recovered. Compared to the traditional approach of phosphate removal by precipitation, SPE had a broader compatibility with common detection methods and performed more selectively among the organic acids under investigation. Based on the results of this study, it is recommended that phosphate removal strategies during the analysis of biologically relevant small molecular weight organic acids consider the respective pKa of the anticipated analytes and the detection method of choice.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Sodium phosphate dibasic solution, BioUltra, 0.5 M in H2O
Sigma-Aldrich
Sodium fluoride 0.5 M solution
Sigma-Aldrich
Methanol solution, (Methanol:Dimethyl sulfoxide 1:1 (v/v))
Supelco
Phosphate Standard for IC, TraceCERTĀ®, 1000 mg/L phosphate in water (nominal concentration)
Sigma-Aldrich
Methanol solution, NMR reference standard, 4% in methanol-d4 (99.8 atom % D), NMR tube size 3 mm Ɨ 8 in.
Sigma-Aldrich
D-Mannitol, ā‰„98% (GC)
Sigma-Aldrich
D-Mannitol, ACS reagent
Sigma-Aldrich
D-Mannitol, ā‰„98% (GC), suitable for plant cell culture
Sigma-Aldrich
D-Mannitol, meets EP, FCC, USP testing specifications
Sigma-Aldrich
D-Mannitol, BioXtra, ā‰„98% (HPLC)
Sigma-Aldrich
Potassium chloride solution, 0.075 M, sterile-filtered, BioXtra, suitable for cell culture
Supelco
N-Methyl-bis(trifluoroacetamide), for GC derivatization, LiChropurā„¢, ā‰„97.0% (GC)
Sigma-Aldrich
D-(āˆ’)-Ribose, ā‰„99% (GC)
Sigma-Aldrich
D-(āˆ’)-Ribose, suitable for cell culture, BioReagent
Sigma-Aldrich
Adonitol, ≥99%
Sigma-Aldrich
D-(āˆ’)-Fructose, ā‰„99% (HPLC), BioXtra
Sigma-Aldrich
D-(āˆ’)-Fructose, ā‰„99% (HPLC)
Supelco
D-(āˆ’)-Fructose, analytical standard, analytical standard for fructose assay kit, for use with enzymatic assay kit FA20
Sigma-Aldrich
D-(āˆ’)-Fructose, ā‰„99% (HPLC), BioReagent, suitable for cell culture, suitable for insect cell culture
Sigma-Aldrich
Potassium chloride, BioUltra, for molecular biology, ≥99.5% (AT)
Sigma-Aldrich
Potassium chloride, tested according to Ph. Eur.
Sigma-Aldrich
Methanol, NMR reference standard
Supelco
D-Mannitol, ā‰„99.9999% (metals basis), for boron determination
Supelco
Mannitol, Pharmaceutical Secondary Standard; Certified Reference Material
Mannitol, European Pharmacopoeia (EP) Reference Standard
Fructose, European Pharmacopoeia (EP) Reference Standard
Supelco
Fructose, Pharmaceutical Secondary Standard; Certified Reference Material
Supelco
Methanol, Pharmaceutical Secondary Standard; Certified Reference Material
Supelco
Potassium Chloride, Pharmaceutical Secondary Standard; Certified Reference Material