Chromatographic behavior of ionizable compounds in liquid chromatography. Part 2. Standardization of potentiometric sensors and effect of pH and ionic strength on the retention of analytes using acetonitrile–water mobile phases

1999 ◽  
Vol 389 (1-3) ◽  
pp. 43-52 ◽  
Author(s):  
J Barbosa ◽  
R Bergés ◽  
V Sanz-Nebot ◽  
I Toro
Keyword(s):  
Liquid Chromatography ◽  
Ionic Strength ◽  
Potentiometric Sensors ◽  
Chromatographic Behavior ◽  
Effect Of Ph ◽  
Mobile Phases ◽  
Ionizable Compounds

Retention of Ionizable Compounds on HPLC. 2. Effect of pH, Ionic Strength, and Mobile Phase Composition on the Retention of Weak Acids

1996 ◽  
Vol 68 (23) ◽  
pp. 4094-4100 ◽  
Author(s):  
Martí Rosés ◽  
Immaculada Canals ◽  
Hille Allemann ◽  
Katrin Siigur ◽  
Elisabeth Bosch
Keyword(s):  
Phase Composition ◽  
Ionic Strength ◽  
Mobile Phase ◽  
Weak Acids ◽  
Mobile Phase Composition ◽  
Effect Of Ph ◽  
Ionizable Compounds

scholarly journals The analysis of chromatographic behavior of homoandrostane derivatives in reversed-phase ultra-high performance liquid chromatography

2021 ◽  
pp. 147-158
Author(s):  
Strahinja Kovacevic ◽  
Milica Karadzic-Banjac ◽  
Jasmina Anojcic ◽  
Lidija Jevric ◽  
Sanja Podunavac-Kuzmanovic ◽  
...  
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
In Silico ◽  
High Performance ◽  
Hierarchical Cluster ◽  
Reversed Phase ◽  
Chromatographic Behavior ◽  
Heat Map ◽  
Mobile Phases ◽  
Sum Of Ranking Differences

Homoandrostane derivatives, as compounds with significant bioactivity, were studied in terms of their chromatographic behavior in reversed-phase ultra-high performance liquid chromatography (RP-UHPLC). In the present study, five androstane derivatives from the series of homoandrostanes were analyzed, including: 3?-hydroxy-17-oxa-17a-homoandrost-5-en-16-one, 3?,5?-dihydroxy-17- oxa-17a-homoandrostane-6,16-dione, 17-oxa-5?,6?-epoxy-17a-homoandrostane-3,16-dione, 5?-hydroxy- 17-oxa-17a-homoandrostane-6,16-dione-3?-yl acetate and 3?-hydroxy-17-oxa-5?,6?-epoxy-Dhomoandrostan- 16-one. The compounds were analyzed by applying methanol-water mobile phases with different volume fractions of methanol, as a polar protic solvent, and logk0 parameters of each compound were determined. The outstanding correlations between in silico logP descriptors and logk0 parameters were obtained, as well as between in silico logD descriptors and logk0 parameters. The logk0 parameters are very well correlated with polar surface area (PSA) descriptor as well. The studied compounds and lipophilicity descriptors (including the chromatographic lipophilicity parameters - logk0) were clustered applying hierarchical cluster analysis (HCA) in the form of clustered heat map known as double dendrogram. Furthermore, the sum of ranking differences (SRD) method was used for the ranking of the lipophilicity measures of the analyzed homoandrostane derivatives so the most suitable lipophilicity measures of this series of compounds can be selected.

Vitamin D analyses in veterinary feeds by gas chromatography-tandem mass spectrometry

2021 ◽  
pp. 146906672110002
Author(s):  
Andreas Lehner ◽  
Margaret Johnson ◽  
Alan Zimmerman ◽  
Justin Zyskowski ◽  
John Buchweitz
Keyword(s):  
Mass Spectrometry ◽  
Vitamin D ◽  
Gas Chromatography ◽  
Liquid Chromatography ◽  
Tandem Mass Spectrometry ◽  
Vitamin D3 ◽  
Mass Spectrometric ◽  
Chromatographic Behavior ◽  
Tandem Mass ◽  
Chromatography Tandem Mass Spectrometry

This report examines the feasibility of determination of Vitamin D3, D2 and their 25-hydroxy metabolites utilizing Gas Chromatography Tandem Mass Spectrometry (GC/MS/MS) as a potential alternative to popular Liquid Chromatography Tandem Mass Spectrometric (LC/MS/MS) methodologies. The GC/MS/MS approach was found to operate reasonably well despite long-standing concerns that gas-liquid chromatography of vitamin D compounds invoke thermal rearrangements owing to the relatively high inlet and capillary column temperatures used. The workup procedure involved incubation of feed samples with concentrated potassium hydroxide for overnight fat saponification, extraction of D Vitamins in n-hexane and reaction with N,O-bis(trimethylsilyl)trifluoroacetamide at 70 °C for 30 mins. In addition to parent compounds, small amounts of pyro-, isopyro-, and iso-vitamin D and isotachysterol3 variants were obtained from each Vitamin D-related compound upon extraction and GC/MS/MS analysis. Mass spectral and chromatographic behavior of these compounds are herein described and interpreted. Multiple Reaction Monitoring settings on GC/MS/MS included m/z 456→351 for Vitamin D3 and m/z 486→363 for Vitamin D2. Trimethylsilylation enabled single predominant peaks for Vitamins D3 and D2, and sample workup in the presence of deuterated Vitamin D analogs enabled accurate and precise sensitivity to 1 ppb (ng/g) in feeds. The method could be extended with reasonable accuracy to 25-hydroxy (25OH) compounds, but accuracies would be significantly improved by inclusion of respective 25OH-specific deuterated internal standards. The method was applied to 27 submissions of suspect dog foods of which 22% were discovered elevated and 44% were discovered to contain toxic levels of Vitamin D3. The described method was thus discovered to provide a suitable mass spectrometric approach for Vitamin D, proving itself here specifically of value in detection of ergocalciferol and cholecalciferol in animal feeds. The specificity and sensitivity of the tandem quadrupole approach can enable suitable applicability to serum determination if desired.

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