Elemental labelling combined with liquid chromatography inductively coupled plasma mass spectrometry for quantification of biomolecules: a review.
Bottom Line: Fundamental methodology of elemental labelling will be highlighted and analytical, as well as biomedical applications will be presented.A special focus will lie on established applications underlining benefits and bottlenecks of such approaches for the implementation in real life analysis.Key research made in this field will be summarized and a perspective for future developments including sophisticated and innovative applications will given.
Affiliation: University of Natural Resources and Life Sciences, BOKU Vienna, Department of Chemistry, Division of Analytical Chemistry, Muthgasse 18, A-1190 Vienna, Austria.Show MeSH
Mentions: Zheng et al.  performed relative quantification of protein mixtures containing RNase, cytochrome c and lysozyme utilizing lanthanide labelling of the amine groups with Ce and Sm coordinated to DTPAA (diethylenetriamine-N,N,N′,N″,N″-pentaacetic dianhydride). For this study a cation exchange column (TSK GEL SP-5PW 7.5 mm × 75 mm, 70 μm) operated at 0.8 mL min−1 was coupled to an ICP-MS instrument (see Fig. 4). Gradient elution with 20 mM sodium phosphate buffer as eluent A (pH 6.5), and 500 mM ammonia chloride and 20 mM sodium phosphate buffer as eluent B (pH 6.5) was applied using an injection volume of 100 μL. 140Ce and 152Sm were used as analytes and signal intensities were compared. Multi element capabilities were emphasized since labelling with different lanthanides is possible providing the conditions for high throughput and top-down proteomics. Labelling was optimized with highest yields at a 10-fold molar excess of DTPAA compared to the proteins and a 2-fold molar excess of Ce and Sm compared to DTPAA-protein. In a first step the proteins were labelled with the chelator DTPAA (2 h, 37 °C) and in a second step the lanthanides were coordinated which was rapid and complete after 2 h at 37 °C. The presented approach revealed LODs between 0.2 and 7 pmol for the investigated proteins with good precision (RSD of 5%). No considerations about unspecific interactions due to the sequence of the labelling procedure were reported. In the work of Waentig et al. higher lanthanide background levels were observed when the lanthanide was attached after the chelator was linked to the biomolecule .
Affiliation: University of Natural Resources and Life Sciences, BOKU Vienna, Department of Chemistry, Division of Analytical Chemistry, Muthgasse 18, A-1190 Vienna, Austria.