Category: Trouble Shooting Suggestions
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Add 10 micro molar EDTA or medronic acid to mobile phase for better peak shapes - Tips & Suggestions
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Analyte retention decreases with mobile phase water content using the Cogent Bidentate C18 HPLC column has anything happened to the column - Tech Information
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Analyze phosphorylated compounds with the Cogent Diamond Hydride column - Tips & Suggestions
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Analyzing metformin in plasma samples how do I obtain reproducible results and peak shapes - FAQ
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Aqueous Normal Phase ANP ballistic gradients compared to same in HILIC - Tips & Suggestions
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Aqueous Normal Phase ANP defined & compared to Reversed Phase & Normal Phase definitions HPLC
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Are there any solvents that I cannot use with the knitted reactor coils KRC and knitted delay tubes KDT - FAQ
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Assuring retention of polar compounds in an Aqueous Normal Phase ANP gradient in positive ion mode LCMS - Tips & Suggestions
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Biological extracts Diamond Hydride columns and LCMS ion source diminished peak height problem - FAQ
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Buffer concentration can affect ANP retention of acids in HPLC Analyses - Tips & Suggestions
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Can I choose HPLC mobile phase percentages other than those used in the HSQ Spreadsheet - FAQ
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Can I expect a more predictable retention time with Silica-C columns than with ordinary silica - FAQ
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Can I use the Cogent Diamond Hydride column without mobile phase additives like formic acid - FAQ
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Can the HSQ or PQ qualification kits be used with Waters equipment and Empower chromatography data software - FAQ
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Changing retention times of amino acids in biological extracts using ammonium acetate in HPLC methods. - Troubleshooting.
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Citric acid retention and peak shape has changed compared to data from a previous run what happened - FAQ
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Determining Efficiency of HPLC methods comparing 4um v 2.o HPLC columns - Tips & Suggestions
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Difficulties with wavelength accuracy readings while performing a PQ of an HPLC - Tips & Suggestions
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Do different retention times for peaks in the Resolution Test Mixture on different systems impact the integrity of my data - FAQ
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Do Tanaka Plots for HPLC apply to columns used with Aqueous Normal Phase ANP methods - FAQ
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Does deactivation process of RSA-Pro X autosampler vials add any chlorides to the glass surface - FAQ
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Eliminate broad split peaks in Aqueous Normal Phase ANP methods and a methanol diluent- Tips & Suggestions
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Eliminating shoulder peaks in an HPLC method using Cogent RP C18 columns - Tips & Suggestions
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For sugars analyzed by LCMS sodium acetate is recommended for sensitivity of Na adducts - Tips & Suggestions
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Ghost peaks appearing in results using a gradient with TFA which can degrade with time - Tips & Suggestions
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Glucose pyruvate taurocholic acid gamma glutamylcysteine and other analysis - Tips & Suggestions
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High molecular weight compounds that won't retain on Cogent Diamond Hydride column try Cogent Bidentate C8 300 - Tips & Suggestions
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High pressure develops after flushing a Cogent Diamond Hydride column with acetonitrile cause and solution - FAQ
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How can I make changes to locked cells in the Excel spreadsheet that comes with the HSQ qualification kit - FAQ
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How can I restore my Diamond Hydride HPLC column after I ran out of mobile phase and air was accidently introduced into it - FAQ
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How do I avoid distorted peak shapes when using a basic mobile phase pH for the analysis of a lipophilic amine - FAQ
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How do RSA autosampler vials compare against silanized vials for pharma applications - FAQ
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How similar fittings for chromatography can differ from different brands in HPLC - Tech Information
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How tight should an autosampler vial cap be to prevent push through of the septa during injection - FAQ
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How to choose a suitable mobile phase additive for negative ionization mode LCMS - Tips & Suggestions
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How to eliminate retention time drift in LCMS with Aqueous Normal Phase ANP methods - Tips & Suggestions
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How to get improved retention and peak shape for glutamine glutamic acid and aspartic acid - Tips & Suggestions
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How to improve peak shapes, retention & carryover for polar compounds with the Cogent Diamond Hydride™ column - Tips & Suggestions
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How to keep the Cogent Diamond Hydride column clean when using blood as a sample - Tips & Suggestions
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I am not observing any peaks for succinic acid or alpha-ketoglutarate with the Cogent Diamond Hydride column - Tips & Suggestions
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I see a strange saw tooth type of pattern in the UV baseline using my Cogent HPLC column what is it and how can I fix it - FAQ
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I see extra peaks in my chromatography when I am not using the same filter - Tips & Suggestions
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If an analyte is only soluble at basic pH can you use a basic mobile phase for my method - FAQ
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If I use a buffer at pH 9 at 30 to 35C with the Zero Flow capillaries what lifetime should I expect from them - FAQ
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Is TFA or formic acid better as an acidic mobile phase additive for Cogent TYPE-C columns - FAQ
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Issues arising from changes in mobile phase with acids to one with ammonium salts. Tips & Suggestions
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Lower retention is observed when functional group in a compound is ionized - Tips & Suggestions
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Modify selectivity in an ANP method of HPLC using different mobile phase pH - Tips & Suggestions
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My LCMS source was getting white film on it and at the same time the background noise was very low so is my Diamond Hydride column bleeding packing material - FAQ
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Peaks are broad and non symmetrical in LCMS method using Reversed Phase columns - Tips & Suggestions
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Protecting HPLC analytical columns and when to use guard columns vs Cogent Column Filters - Tips & Suggestions
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Restoring the initial results with a method for analyzing AMP ADP ATP UDP and GPT in biological extracts - Tips & Suggestions
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Retention and or peak shape for citric acid has changed compared to data from a previous HPLC run - Tips & Suggestions
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Since Cogent TYPE-C columns can be used in Reversed Phase or Normal Phase what do you suggest to switch these solvent systems which are not miscible - FAQ
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Since Cogent TYPE-C Silica columns use a transition metal catalyst in production what is the presence of any trace quantity on the surface of the stationary phase- FAQ
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Solvents and solutions that should be avoided when using PEEK filters fittings or tubing - Tech Information
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Suggestion for separation of phenylephrine HCl acetaminophen and dextromethorphan - Tips & Suggestions
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The effect of ionic strength of the mobile phase additive for HPLC columns in Aqueous Normal Phase - Tips & Suggestions
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To obtain greater sensitivity than Na adducts for sugars could you add ammonia NH4 instead - FAQ
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Troubleshooting problems with poor HPLC runs before the examining the column - Tips & Suggestions
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Type of gradient to use for analysis of hydrophilic and hydrophobic molecules in the same HPLC or LCMS run - Tips & Suggestions
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Using a Constant Pressure Method on two Instruments Producing Different Flow Rates- Tips & Suggestions
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Using an Aqueous Normal Phase ANP method will sodium ions interfere with succinate when analyzing sodium succinate - FAQ
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Using methanol instead of acetonitrile in an HPLC method should be done with caution - Tips & Suggestions
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Using the wavelength calibration solution holmium oxide for HPLC UV detector performance qualification - Tips & Suggestions
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What are some common sources of variance during sample preparation in an analytical application - FAQ
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What can cause changing retention times and a peak showing up in my blank with a Silica-C column - FAQ
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What effect does high injection volume have on column performance in Aqueous Normal Phase ANP HPLC- FAQ
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What is the effect of extra column volume for different HPLC instruments on the same method - FAQ
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What is the maximum concentration of ammonium fluoride to use in a mobile phase to avoid column damage - Tips & Suggestions
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What is the maximum salt concentration to use with Cogent TYPE-C HPLC columns with HPLC or LCMS - FAQ
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What is the most effective way to clean HPLC columns after or before use - Tips & Suggestions
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What is the purpose of using isopropanol IPA as part of the mobile phase solvent in ANP methods - FAQ
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What problems can occur when using a dedicated Reversed Phase HPLC instrument for an Aqueous Normal Phase ANP method for the first time - FAQ
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What type of tubing do I use to connect the guard column holder to analytical columns - FAQ
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What will the pressure be with a mobile phase of 90% methanol and 10% DI water with a 4.6 x 250mm Cogent TYPE-C HPLC column - FAQ
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When I run gradients on my HPLC and switch from one gradient to another my baseline shows as negative and if I auto zero it becomes positive for the remainder of the run but when I start again it is negative - Primer
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Why am I observing broad split peaks in Aqueous Normal Phase ANP when using acetonitrile and methanol diluents - FAQ
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Why are environmental conditions such as temperature relative humidity that are not specified on the CofA for the UV Calibration Kit - FAQ
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Why are pipettors not recommended for dispensing non aqueous liquids accurately and precisely - FAQ
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Why do I have lower than normal back pressure with Cogent Diamond Hydride HPLC columns - FAQ
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Why do I see large intermittent pressure spikes in HPLC runs and can it be a defective column - FAQ
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Why does the color of the Holmium Oxide solution for HPLC performance qualification look different than before - FAQ
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Why you should use temperature control with the UDC-Cholesterol column - Tips & Suggestions
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Will a different guard column hardware system different from the Cogent system affect my results when using a Cogent column - FAQ
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Will different guard columns packed by different column packers be equivalent - INTERNAL ONLY
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Will I protect HPLC columns from samples that get permanently adsorbed to the column by using a syringe filter - FAQ
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