Explanation of the selectivity differences between reversed-phase ion-pair chromatographic systems containing trifluoroacetate or heptafluorobutyrate as pairing ion

Selenium speciation in enriched and natural samples by HPLC-ICP-MS and HPLC-ESI-MS with perfluorinated carboxylic acid ion-pairing agents

“…8 The spray chamber had a path length of 8.4 cm and a volume of 14 mL. Instrumental conditions were as follows: rf forward power, 1100 W; plasma flow rate, 15.0 L min 21 ; auxiliary flow rate, 0.8 L min 21 ; nebulizer flow rate, 0.80-0.95 L min 21 ; resolution, normal; scanning mode, peak hop; dwell time, 500 or 1000 ms; and isotope monitored, mass 82.…”

“…6,7,19,20 The ion-pairing role of trifluoroacetic acid (TFA) and other perfluorinated carboxylic acids for the separation of common amino acids has been evaluated. [21][22][23] Casiot et al 20 identified Se-adenosylselenohomocysteine in a yeast extract with off-line ESI-MS detection. We independently reported this finding and the identification of selenomethionine in yeast by on-line HPLC-ESI-MS. 19 Identification of gglutamyl-Se-methylselenocysteine and possibly g-glutamyl-Seselenomethionine in garlic were also made in the same publication.…”

High-performance liquid chromatography of selenium compounds utilizing perfluorinated carboxylic acid ion-pairing agents and inductively coupled plasma and electrospray ionization mass spectrometric detection

“…Uden) dietary supplementation with selenium-enriched yeast decreased cancer incidence and mortality rates carboxylic acids for the separation of amino acids by almost 50%. Increase in selenium intake by has been evaluated [32][33][34]. consuming a diet with natural selenium levels is Other nonvolatile organic selenium species, which problematic due to the low abundance of selenium in may be present in natural samples, are the selenoxcommon food [2].…”

Purification of Recombinant Brain Derived Neurotrophic Factor Using Reversed Phase Displacement Chromatography

“…In developing a protocol for RPLC displacement of this basic neurotrophin, it was observed that the percentage of TFA in the buffer played an important role in improving the process yield. Although the importance of TFA for the separation of basic small molecules, peptides and proteins has been documented in the literature (Cai and Li, 1999; Guo et al, 1987; Patthy, 1994), more work is needed to elucidate how the ion‐pairing agent improves the resolution of this basic neurotrophin (note pI of rHu‐BDNF: 10.3). This work has also highlighted the importance of resin properties (such as surface area and carbon load) and resin particle size in influencing the yield of the displacement process.…”