Selective removal of phosphate for analysis of organic acids in complex samples.
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.
Institute of Analytical Chemistry, University of Leipzig, Linnéstr. 3, 04103 Leipzig, Germany.
Sandeep
S
Deshmukh
Institute of Bioanalytical Chemistry, University of Leipzig, Deutscher Platz 5, 04103 Leipzig, Germany.
Andrej
A
Frolov
Institute of Analytical Chemistry, University of Leipzig, Linnéstr. 3, 04103 Leipzig, Germany.
Andrea
A
Marcillo
Institute of Analytical Chemistry, University of Leipzig, Linnéstr. 3, 04103 Leipzig, Germany. Electronic address: birkemeyer@chemie.uni-leipzig.de.
Claudia
C
Birkemeyer
D000143:Acids / Q000032:analysis*; D002241:Carbohydrates / Q000032:analysis; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D009930:Organic Chemicals / Q000032:analysis*; D010710:Phosphates / Q000302:isolation & purification*; D011108:Polymers / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry; D052616:Solid Phase Extraction / Q000379:methods*
D000143:Acids; D002241:Carbohydrates; D009930:Organic Chemicals; D010710:Phosphates; D011108:Polymers; D012822:Silicon Dioxide
Anion exchange solid-phase extraction; Carbohydrates; Gas chromatography–mass spectrometry; Organic acids; Phosphate removal; matrix effects