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Determination of calcium in complex samples using functional magnetic beads combined with electrodeless/sheathless electrospray ionization mass spectrometry
Author(s) -
Wu YiTing,
Chen YuChie
Publication year - 2006
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.2548
Subject(s) - chemistry , nitrilotriacetic acid , ethylenediaminetetraacetic acid , metal ions in aqueous solution , mass spectrometry , elution , electrospray ionization , metal , chromatography , analytical chemistry (journal) , ion , chelation , inorganic chemistry , organic chemistry
Conventionally, electrospray ionization ion trap mass spectrometry (ESI‐ITMS) is not used for the analysis of metal ions because metal ions may be of too low mass to be trapped by the mass analyzer. Furthermore, metal ions can easily precipitate during ESI processes because of their poor volatilities. We present an approach for solving these two problems using milk as the sample to demonstrate the feasibility of using ESI‐ITMS as the detection method for metal ions. Iron oxide magnetic beads with nitrilotriacetic acid (NTA) immobilized on their surface were used as affinity probes for calcium ions from dairy drinks. Ethylenediaminetetraacetic acid (EDTA) was used for the elution of the metal ions chelated by NTA on the beads. The EDTA eluent was analyzed by electrodeless/sheathless ESI‐ITMS. The use of functional magnetic beads to trap metal ions from complex samples can effectively reduce the interference from sample matrix. Using the EDTA eluent as the sample avoids the problem of the low volatility of metal ions during ESI‐ITMS analysis. This method gives measurements of calcium ions in dairy drinks quantitatively very close to the true values (<4% error). Copyright © 2006 John Wiley & Sons, Ltd.