Cogent UDA HPLC Column Use – Extended AppNote

Ion exchange chromatography can be a useful tool available to the analytical chemist. In this separation mode, an ionized moiety on the stationary phase interacts electrostatically with an oppositely charged analyte. There are several types of ion exchange that can be used, such as strong anion exchange, weak anion exchange, strong cation exchange, and weak […]

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Ethyl Glucuronide Analysis with LCMS – AppNote

Method Optimization in Separation of Ethyl Glucuronide and Ethyl Sulfate Ethyl Glucuronide and Ethyl Sulfate are compounds that are not well-retained or separated using Reversed Phase Columns due to their hydrophilicity thus requiring high water concentrations in the Mobile Phase. To avoid the use of high water content Mobile Phases, HILIC columns were sought as […]

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Separation of Adenine Nucleotides – AppNote

Separation of AMP, ADP, ATP with HPLC The figure shows a separation of three energy nucleotides. All three are baseline separated in order of increasing polarity as is expected when ANP chromatography is used. It is worth noting that the retention of nucleotides increased as the buffer concentration was increased (data not shown). 16.0mM concentration […]

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Separation of Inosine Nucleotides – AppNote

IMP, IDP, and ITP Analyzed with HPLC The figure shows the optimized separation of ITP (Inosine 5’-monophosphate), IDP (Inosine 5’-diphosphate) and IMP (Inosine 5’-triphosphate) in the order of increasing Phosphate content similar to anion exchange. The presence of at least one impurity near ITP and possibly a second near IMP precluded accurate determination of peak […]

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Separation of Nucleotides – AppNote

AMP, NAD, NADP, and GTP on UDA Column Nucleotides are not well retained under Reversed Phase conditions due to their highly polar nature (the presence of one or more Phosphate groups). In this method, weak cation-exchange interactions can provide additional retention/selectivity along with the ANP retention of the Hydride surface. Peaks: 1. AMP – Adenosine […]

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Tobramycin Analyzed with LCMS – AppNote

Retention of Highly Polar, Water Soluble Antibiotic  Tobramycin is a very polar compound that lacks a sufficient chromophore, and therefore is difficult to analyze using Reversed Phase HPLC with UV detection. In this Application Note, the Method below retains Tobramycin and Separates it Uracil which is used as a Solvent Front Marker. Using this Method, […]

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Vardenafil (Levitra®) Analyzed with HPLC – AppNote

LC-MS Compatible Assay Method Vardenafil in a tablet formulation can be readily assayed with this LC-MS compatible gradient method. The peak tailing factor was close to unity. The compound has several amine groups which can produce tailing with ordinary HPLC Columns that have a number of surface Silanols. The MS-compatible Mobile Phase means that the […]

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