The addition of salts, specifically sodium perchlorate (NaClO4), to mobile phases at acidic pH as ion-pairing reagents for reversed-phase high-performance liquid chromatography (RP-HPLC) has been generally overlooked. To demonstrate the potential of NaClO4 as an effective anionic ion-pairing reagent, we applied RP-HPLC in the presence of 0-100 mM sodium chloride (NaCl), sodium trifluoroacetate (NaTFA) or NaClO4 to two mixtures of synthetic 18-residue peptides: a mixture of peptides with the same net positive charge (+4) and a mixture of four peptides of +1, +2, +3 and +4 net charge. Interestingly, the effect of increasing NaClO4 concentration on increasing peptide retention times and selectivity changes was more dramatic than that of either NaCl or NaTFA, with the order of increasing anion effectiveness being Cl- << TFA- < C104-. Such effects were more marked when salt addition was applied to eluents containing 10 mM phosphoric acid (H3PO4) compared to 10 mM trifluoroacetic acid (TFA) due to the lesser starting anion hydrophobicity of the former mobile phase (containing the phosphate ion) compared to the latter (containing the TFA- ion).
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http://dx.doi.org/10.1016/j.chroma.2005.02.063 | DOI Listing |
J Chromatogr Sci
January 2025
Division of Chemical and Material Metrology, Korea Research Institute of Standards and Science, 267, Gajeong-ro, Yuseong-gu, Daejeon, 34113Republic of Korea.
We developed a reversed-phased high-performance liquid chromatographic method combining ultraviolet detection and integrated pulsed amperometric detection for the simultaneous quantification of dopamine, 5-hydroxyindolacetic acid, homovanillic acid, serotonin, 3,4-dihydroxyphenylacetic acid, norepinephrine and epinephrine. All target components were completely separated in a C18 column with isocratic elution of 5% acetonitrile solution containing 8 mM HClO4 and 0.20 mM 1-octanesulfonic acid as an ion pairing reagent.
View Article and Find Full Text PDFAnal Chim Acta
January 2025
HAB Monitoring & Reference Branch, Stressor Detection and Impacts Division, National Centers for Coastal Ocean Science, NOAA National Ocean Service, 331 Fort Johnson Road, Charleston, SC, 29412, USA.
Background: Microcystins (MCs) and nodularins (NODs) produced by cyanobacteria occur in ambient freshwaters and across the freshwater-marine continuum, and pose health threats through drinking and recreational waters, as well as food resources. Approximately 300 MC and NOD toxins have been published, but less than 15 of them are commercially available as toxin standards. Our aim herein was to rapidly identify and quantify all toxin congeners, including those without standards, in water samples even at low abundance by reversed-phase solid phase extraction (SPE)-liquid chromatography-tandem mass spectrometry (LC-MS/MS) to provide insights into toxin levels and potential toxicity.
View Article and Find Full Text PDFLuminescence
October 2024
Pharmaceutical Chemistry Department, Faculty of Pharmacy, Deraya University, New Minia, Egypt.
Using spectroscopy, two quick and sensitive analytical methods based on eosin Y ion pairing were developed and assessed in order to determine capivasertib and futibatinib with high selectivity and sensitivity. The quenching impact of futibatinib or capivasertib on the eosin Y's fluorescence at a pH 3.8 and 3.
View Article and Find Full Text PDFAAPS PharmSciTech
October 2024
Pharmacokinetics, Dynamics, Metabolism, and Bioanalytics, Merck & Co., Inc., Boston, Massachusetts, 02115, USA.
J Pharm Biomed Anal
January 2025
Section of Nutrition, Division of Digestive Diseases, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, Hammersmith Campus, Commonwealth Building, Du Cane Road, London W12 0NN, United Kingdom. Electronic address:
Trimethylamine (TMA) and trimethylamine-N-oxide (TMAO) play a crucial role in many biochemical processes within diverse organisms including animals, plants, fungi and bacteria. Studies have linked these metabolites with cardiovascular and kidney diseases; however, emerging evidence demonstrates their protective properties. Owing to these controversies and co-existence of these metabolites in biological samples, it is crucial to accurately quantify these metabolites to associate their concentrations with various physiological and pathophysiological conditions to elucidate their potential roles.
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