Category: HPLC Tips and 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 HPLC columns that could be used to separate both polar and nonpolar compounds in a single run - 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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Avoid loss of concentration of heparin with HPLC when using syringe filters - Tips & Suggestions
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Biological extracts Diamond Hydride columns and LCMS ion source diminished peak height problem - FAQ
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Blocked HPLC column from proteins from the sample matrix can be recovered - Tips & Suggestions
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Buffer concentration can affect ANP retention of acids in HPLC Analyses - Tips & Suggestions
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Can amber or clear polypropylene vials be sterilized with autoclaving or ethylene oxide - FAQ
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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 use a silica or Silica-C guard column with an analytical column of a different phase - FAQ
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Can I use phosphoric acid or sodium phosphate with the Cogent Diamond Hydride HPLC column - FAQ
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Can I use the certified HPLC column supplied in the HSQ Kit for UHPLC performance qualification - 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 I use the holmium oxide solution in a UV instrument that calls for Starna or NIST cuvettes - FAQ
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Can I use trifluoroacetic acid TFA to improve the chromatographic performance in LCMS - 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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Causes of high baseline noise with Cogent Diamond Hydride HPLC column - Tips & Suggestions
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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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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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For the separation of polar intermediates in reversed phase HPLC which C18 column do you recommend - FAQ
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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 Cogent TYPE-C HPLC columns offer faster results compared to other type of silica based columns - FAQ
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How can I fix poor peak shape for phosphorylated compounds in aqueous normal phase ANP methods - FAQ
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How can I improve accuracy and precision when separating polar compounds by HPLC using Aqueous Normal Phase ANP - 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 does ammonium fluoride affect HPLC and LCMS data if using Aqueous Normal Phase ANP methods - FAQ
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How long will it take for chloroform to degrade the plastic safety coating on the mobile phase bottles if the bottle is broken during a fall - FAQ
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How often do I need to do the conditioning procedure for a new Diamond Hydride column - 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 calibrate UV-vis and HPLC detectors with NIST traceable solutions below 230nm - Tips & Suggestions
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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 define custom plate measurements for the U-2D Micro-Sample Management System in the Waters Acquity console software - How to
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How to determine concentration of an impurity in HPLC with the relative response factor RRF - How to
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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 handle sparging stones to avoid contamination of mobile phases - 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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How to prepare 10mM ammonium acetate buffer 90:10 in acetonitrile for HPLC and LCMS - Tips & Suggestions
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How to prepare 16mM ammonium acetate buffer 90:10 in acetonitrile for HPLC - 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 heard that there is not a good alternative to HILIC to achieve sufficient retention for some compounds - FAQ
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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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Identify used U-2D inserts for multiple projects or in small sample sets - 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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Injection Technique for Aqueous Samples using Cogent TYPE-C Columns in ANP - Tips & Suggestions
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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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Is there a difference in the properties of different colors of rubber in vial cap septa - 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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LFER studies compared to Log D data in describing the Aqueous Normal Phase ANP retention - Tips & Suggestions
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Lower retention is observed when functional group in a compound is ionized - Tips & Suggestions
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Metal free stainless steel HPLC columns comparison to PEEK column performance - Tips & Suggestions
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Mobile Phase recommendation Cogent Diamond Hydride columns for use with serum samples in Aqueous Normal Phase LCMS - 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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My retention times are changing after storing my buffer and what could be causing this and tips to help avoid issues - FAQ
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Peaks are broad and non symmetrical in LCMS method using Reversed Phase columns - 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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Should I use methanol as the organic solvent in HPLC when using Aqueous Normal Phase ANP - FAQ
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Silicone rubber in septa for autosampler vials vary in the way it is made - Tech Information
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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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Solving baseline problems in ANP methods with the Cogent Diamond Hydride column - Tips & Suggestions
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Spurious peaks from nylon syringe filters with DI water using electrochemical detection can be avoided - Tips & Suggestions
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Suggestion for separation of phenylephrine HCl acetaminophen and dextromethorphan - Tips & Suggestions
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The best way to avoid with ion suppression issues in LCMS if you need to use an ion-pair agent - Primer
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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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Two gradients to use for analysis of hydrophilic and or hydrophobic molecules in the same Aqueous Normal Phase ANP method - 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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Use a low concentration of salt in your mobile phase to avoid ion suppression and build up on your inlet source - 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 ammonium acetate or formate in an acetonitrile based HPLC mobile phase for Aqueous Normal Phase ANP - 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 temperature changes for separations of terpenoids with the Cogent Bidentate C18 and UDC-Cholesterol HPLC columns - 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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Using triethylamine TEA in Aqueous Normal Phase ANP methods for simple sugars - Tips & Suggestions
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Using two HPLC columns together in a tandem separation for polar and non polar retention - 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 are some of the advantages of using Cogent TYPE-C prep and semi-prep HPLC columns - FAQ
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What are the typical flow rates recommended by HPLC column companies to start with for various column ID - Primer
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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 compatibility of Cogent TYPE-C Silica HPLC columns with UHPLC instruments - FAQ
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What is the difference between related compounds and related substances in pharmaceutical HPLC - FAQ
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What is the difference between weak and strong cation exchange for Ion Exchange columns - FAQ
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What is the durability of the SOLVFIL when used with standard mobile phases and buffered mobile phases - 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 loading capacity mass injection volume that can be used for a semi prep Cogent TYPE-C HPLC column - FAQ
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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 pilot length or dimension X depth for end fittings uses to connect HPLC columns - FAQ
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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 special care should I take to protect my HPLC columns when I am equilibrating them - 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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Which acid or base additive should I choose for positive or negative ion mode in LC-MS - FAQ
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Which column do you suggest for Cocaine & metabolite Ecognin separation - Tips & Suggestions
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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 ionized polar compounds generally better retained in Aqueous Normal Phase ANP HPLC - 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 see large intermittent pressure spikes in HPLC runs and can it be a defective column - FAQ
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Why does the metal content of a silica particle contribute to the peak shape of my chromatogram in HPLC - 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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