posted on 2017-08-29, 00:00authored byFahmida Jabeen, Muhammad Najam-ul-Haq, Matthias Rainer, Christian W. Huck, Guenther K. Bonn
Polymeric monoliths
fabricated in tips with embedded materials
of choice are important in separation science. Polymeric backbone
however interferes in the enrichment and thus affects efficiency.
This work focuses on the in-tip fabrication of lanthanum oxide porous
monolith and its application in the enrichment of phosphorylated peptides
and lipids. Polycondensation reaction uses an aqueous solution of
LaCl3·7H2O with N-methyl
formamide as porogen and propylene oxide as initiator. The aging time
of monolith and temperature condition for the reaction are optimized
to attain porous monolithic tip. A comparison of (i) solid phase batch
extraction using La2O3, (ii) La2O3 embedded in poly(glycidyl methacrylate (GMA)/divinylbenzene
(DVB)) tip, and (iii) pure La2O3 monolithic
tip shows improved enrichment efficiency in the case of pure La2O3 monolithic tip. The monolithic tip achieves
selectivity of 1:4500 as compared to solid phase extraction (SPE)(1:3500)
and limit of detection down to 0.25 fmol. The in-tip La2O3 monolith strategy has better batch to batch reproducibility,
reduced time of enrichment, and ease of operation in comparison to
solid phase batch extraction. The developed strategy enriches phospho-
content from biological samples like phosvitin and lipovitellin from
egg yolk and phospholipids/phosphopeptides from human serum. The enriched
phospho- moieties are analyzed by matrix-assisted laser desorption
ionization-mass spectrometry (MALDI-MS) except the phospholipids where
laser desorption ionization (LDI)-MS is employed.