Cyclobenzaprine Retention with an Inverse Gradient – AppNote

ANP Retention of a Hydrophobic Compound  This Application Note shows an example of a hydrophobic analyte retention in Aqueous Normal Phase (ANP / HILIC Like Gradient) HPLC. Although Cyclobenzaprine has a logP of approximately 4.6–4.9, it is well retained with a Symmetrical Peak Shape. Data from two production lots of Columns is shown to illustrate […]

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Cycloserine LCMS Separation of Impurities and Degradants – AppNote

LCMS Separation of Impurities and Degradants While two major impurities observed in this Cycloserine method were not directly identified, several possibilities can be suggested based on their m/z values in the Mass Spectrum and their relationship to the Serine structure. Serine was also identified but in very low abundance and only after the samples were […]

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Cytarabine Assay with HPLC- AppNote

A Reliable Assay for Detection of a Chemotherapeutic   Cytarabine belongs to the category of chemotherapy called antimetabolites. Antimetabolites are very similar to normal substances within the cell. When these substances are incorporated into the cellular metabolism, they are unable to divide. Antimetabolites are cell-cycle specific and target cells at very specific phases in the […]

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Cytochrome C Analyzed with HPLC – AppNote

From Horse and Bovine Heart Using the simple Reversed Phase HPLC Gradient Method shown in this note, it was possible to separate Horse and Bovine heart Cytochrome C. The Peaks were well separated and symmetrical. A linear detector response was observed over 2 orders of magnitude. Peaks: 1. Cytochrome C from Horse heart 2. Cytochrome […]

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Dantrolene Sodium Analyzed with HPLC with UV – AppNote

Dantrolene Sodium has several amine groups that can interact with lone-silanols causing problematic peak tailing when analyzed with conventional HPLC columns. By utilizing a Bidentate C18™ Column with its Silica Hydride™ surface, challenging compounds like Dantrolene can be readily retained with symmetrical peak shape. Peak:  Dantrolene Sodium Method Conditions: Column: Cogent Bidentate C18™, 4μm, 100Å […]

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Dehydroepiandrosterone (DHEA) Capsule Separation with HPLC – AppNote

Excellent separation from matrix excipients Pharmaceutical formulations may contain a number of excipients that can potentially interfere with a chromatographic analysis. However, using the Cogent Bidentate C8 Column, the DHEA peak is well-resolved from the others, the latter of which all elute as a large peak in the solvent front portion of the run. The […]

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Deoxycholic Acid Analyzed with ELSD- AppNote

An Analysis of a Bile Acid This simple Method shows excellent Peak shape and Reproducibility as shown in the five injection overlay below. As the shape of the molecule is very similar to steroids, the Cogent UDC-Cholesterol™ Column was selected for this Method as it is founded on the ability to retain compounds based on […]

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Deoxycholic Acid Assay Analyzed with HPLC – AppNote

A Reliable Method for a Bile Acid This Deoxycholic Acid Assay produces Run to Run consistency and Precision with Retention Time RSD values of 0.1%. A sensitive HPLC-UV Method that may be used for quantification in raw material and liquid pharmaceutical formulation is presented. Figure 1. Full Chromatogram Figure 2. Magnified Chromatogram to show peak […]

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Desloratadine Assay with HPLC – AppNote

Alternate L1 Column used for HPLC Method of Desloratadine This Desloratadine Assay is easily performed and the five injection overlay below demonstrates Run to Run consistency and Precision. The Peak Efficiency is very good and Peak Tailing guidelines are easily met with RSD values below 0.3%. This demonstrates a good alternate Column for your Desloratadine […]

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Determination of Atropine with HPLC – AppNote

Rugged & Fast Without Paired Ion Reagents Ion-pair Chromatography (IPC) is commonly used in order to retain Atropine on ordinary Reversed Phase HPLC Columns. Beside long equilibration times with these columns, IPC often suffers from poor robustness. Using an isocratic elution with flow rate 1mL / minutes gave symmetrical peak for this Tropane Alkaloid. The […]

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Diazepam Tablet Analyzed with HPLC – AppNote

Excellent Peak Shape and Precision for a Benzodiazepine Compound Valium® This Isocratic Method shows how using 0.1% Trifluoroacetic Acid (TFA) in the Mobile Phase can produce a Peak with excellent Efficiency and Symmetry. In the USP Assay Method, System Suitability requires that a tailing factor of not more than 2.0 be obtained for the API, […]

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Dicloxacillin and Ampicillin, an Antibiotic Mixture Analyzed with HPLC – AppNote

Ampicillin and Dicloxacillin were retained with minimal amounts of buffer concentration and with good run-to-run precision in this HPLC method that can be readily transferred to LCMS. The combination of both drugs presents a mixture of polar and non-polar antibiotics that may incur difficulties to retain on conventional HPLC columns in Reversed Phase. This drug mixture […]

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Digoxin Analyzed with HPLC – AppNote

Forced Degradation Method Digoxin had several Sugar Residues that can be hydrolyzed in acidic conditions. In this Forced Degradation Method, six degradants are observed. Some of these Peaks are likely the various hydrolyzed forms, including the Aglycone Digoxigenin. The Method is capable of Separating a wide variety of Degradants. Figure A shows the Chromatogram of […]

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Dimethylolpropionic Acid – AppNote

Hydrophilic acid retention on the Cogent Diamond Hydride™  Dimethylolpropionic Acid is a unique diol molecule with both hydroxyl and carboxyl functionality and presents several challenges in chromatographic analysis. Traditional reversed phase mode may not be viable due to the high hydrophilicity of this organic acid. Also, by lacking chromophores it can be difficult to detect […]

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Diphenhydramine HCL Analyzed with LCMS – AppNote

Online SPE with a Simple Mobile Phase Step Gradient When a Mobile Phase containing 80% Solvent B (with 10mM Pyridine in Solvent A and B) is used Diphenhydramine Hydrochloride (DPH) is fully retained on the Column, meaning it does not elute and continues to be retained until it would overload the Column if injections were […]

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Diphenhydramine HCL Capsule Analyzed with HPLC – AppNote

Assay Method for Diphenhydramine HCL without Ion Pairing Agents Diphenhydramine has a tertiary amine functional group that can produce tailing with conventional Columns in Reversed Phase HPLC. The USP Method features a Triethylamine additive in the Mobile Phase for this reason. These additives often take a significant time to completely load onto the Column and […]

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Dipyridamole Analyzed with HPLC – AppNote

Several Tertiary Amines on a Molecule that is Easily Retained This Method for the Analysis of Dipyridamole USP Tablet Formulation is easy to do. Note the excellent Resolution from capsule excipients, along with the excellent Peak shape for this complex, difficult molecule.   Peaks: 1. Dipyridamole 2. Tablet Excipients Method Conditions Column: Cogent Bidentate C18™, 4μm, […]

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DMAP, 4-Dimethylaminopyridine Analyzed with HPLC – AppNote

Analyzing the Catalyst, DMAP, 4-Dimethylaminopyridine with HPLC This AppNote shows a rapid, reliable, Isocratic Reversed Phase, HPLC Method that was developed for the Analysis of an important Catalyst for many applications and industries: 4-Dimethylaminopyridine (DMAP). Peak: DMAP Method Conditions Column: Cogent Diamond Hydride™, 4μm, 100Å Catalog No.: 70000-7.5P Dimensions: 4.6 x 75mm Mobile Phase: —90:10 Solvent A / […]

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Docusate Sodium Analyzed with HPLC – AppNote

A Simple Gradient with Good Separation    The official USP assay method for Docusate Sodium tablets calls for a Mobile Phase of 50% 7mM Ammonium Acetate / 50% Acetonitrile at 40°C. However, retention for the API and the System Suitability compound Methyl Paraben were found to be low using these conditions. This Method not only […]

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Domoic Acid Analyzed by LCMS – AppNote

Determination without Derivatization To date, several analytical methods have been developed for the quantitative determination of Domoic Acid (DA). However, many of the methods require tedious and labor intensive derivatization of this compound in order to detect it. A new method based on HPLC and MS detection which does not require derivatization has been developed. […]

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Domoic Acid in Seafood Samples Analyzed by LCMS – AppNote

Domoic Acid (DA) From Seafood Without Derivatization Several Seafood and Plankton samples were tested for Domoic Acid (DA) which, as a highly polar compound, is poorly Retained on most Reversed Phase Columns. This developed Method based on HPLC and MS detection does not require derivatization of Domoic Acid. The concentration of this potent toxin varied […]

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Domoic Acid Separation with LCMS without Derivatization – AppNote

Several analytical methods have been developed for the quantitative determination of Domoic Acid (DA). However, many of the methods require tedious and labor-intensive derivatization of this compound in order to detect it. A new method based on HPLC and MS detection which does not require derivatization has been developed. A simple linear gradient and typical […]

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Domoic Acid, Amino Acids, & Ornithine Analyzed with LCMS – AppNote

LC-MS Analysis without Analyte Derivatization The potent toxin, Domoic Acid is a highly polar compound which is poorly retained on most Reversed Phase Columns. In this Method , not only was Domoic Acid well Retained but also two isobaric compounds (L-Asparagine and Ornithine) were Retained and Separated. In addition, the Peak obtained for Aspartic Acid […]

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Doxapram HCL Analyzed with HPLC – AppNote

Easy, Rapid Isocratic Assay of A Polar Compound Automating a Method is a distinct advantage over the official USP Method for Doxapram which is by Titration. Not only will this Method save time and money, but will reduce errors. Simple to perform, the Mobile Phase can be quickly prepared without errors. A highly Symmetrical Peak […]

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Doxycycline Analyzed with HPLC – AppNote

Forced Degradation Method Using Shape Selectivity Doxycycline is known to epimerize at the C4 and C6 positions in acid conditions. Epimers can be difficult to separate in Reversed Phase due to subtle differences in hydrophobicity. However, this Method differentiates based on shape as well as hydrophobicity and is therefore well suited to this Isomer separation. […]

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Doxycycline and Methacycline Analyzed with HPLC – AppNote

Simple Isocratic Method for API and Main Impurity Formulations of Doxycycline may contain a Methacycline Impurity.  As such, it is crucial for analytical methods to be able to separate these two peaks. Using this simple isocratic Method, the baseline resolution is obtained for this pair. Peaks: 1. Methacycline 2. Doxycycline * Impurities in doxycycline standard […]

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Doxylamine Succinate Tablet Analyzed with HPLC – AppNote

Shorter Run Time than USP Method The USP Assay Method for Doxylamine Succinate tablets uses Triethylamine and Sodium Lauryl Sulfate in the Mobile Phase. These reagents are slow to fully load onto the Column, resulting in long run times and poor Robustness. This Method uses Trifluoroacetic Acid to get an excellent Peak Shape. An overlay […]

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Dyclonine HCL Analyzed with HPLC – AppNote

A Reproducible Method for Detection of Dyclonine Hydrochloride A rapid, sensitive, and reproducible Method has been developed for detection of Dyclonine HCL. The data below, (overlay of 20 chromatograms ) illustrates how the compound can be adequately Retained and detected using HPLC, with both excellent Peak Shape and run-to-run precision. Using a simple Gradient in […]

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EDTA Analysis with HPLC – AppNote

EDTA does not have a significant Chromophore, so to achieve UV Detection, in the Method shown below we used a pre-Column reaction of a Solution of Ferric Chloride with the Sample. The resulting EDTA/Fe3+ has significant UV Absorbance making this a very Sensitive Method. Ethylenediaminetetraacetic acid is extremely difficult to analyze by itself however in […]

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EDTA Analyzed with HPLC – AppNote

Very Sensitive Method for Measuring Ethylenediaminetetraacetic Acid EDTA does not have a significant Chromophore, so to achieve UV Detection, this Method uses a Pre-Column reaction of a solution of Ferric Chloride with the sample. The resulting EDTA / Fe3+ has significant UV Absorbance making this a very sensitive Method. With this Method, Peak Shapes and […]

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Effect of Sodium Acetate for Glucose Ionization in LCMS – AppNote

Improved Signal to Noise for Glucose with LCMS Glucose, a simple monosaccharide, was analyzed by LCMS and the peak is very symmetrical and easy to integrate. This application note illustrates the importance in the addition of Micro Molar amount of Sodium to the Mobile Phase when sugars are analyzed. Sodium adducts of sugars produce much […]

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Effexor Capsule Analyzed with HPLC- AppNote

Reducing Tailing for Venlafaxine with HPLC The USP assay Method for Venlafaxine capsules uses Triethylamine and Phosphoric Acid in the Mobile Phase, both of which are incompatible with LC-MS. The system suitability for Venlafaxine tailing factor is 2.0, indicating the compound has a tendency for tailing. Here a sharp symmetrical peak is observed using Formic […]

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Efficiency of ANP Measured – AppNote

Aqueous Normal Phase (ANP) Efficiency Measured with Sorbitol, Glucose & Uracil Figure A is an excerpt from a study that investigated analyses of Glucose and Sorbitol on TYPE-C Silica based HPLC Columns and found that the efficiency of ANP is better than observed with HILIC. A Cogent Diamond Hydride Column (2.1 x 150mm with a […]

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Epigallocatechin Gallate Analyzed with HPLC – AppNote

A Reliable Method for a EGCG Analysis This Epigallocatechin Gallate (EGCG) Assay produces Run to Run consistency and Precision with Retention Time RSD values of 0.02%.  This is a sensitive HPLC-UV Method that may be used for quantification of EGCG in food and beverage formulations. Peak: Epigallocatechin Gallate  Method Conditions: Column: Cogent Zx Similars C18, […]

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Ethambutol Analyzed with LCMS- AppNote

Retention of Hydrophilic Analyte in a Drug Product When Ethambutol is analyzed on many C18 Columns, it strongly interacts with residual Silanol groups in the Stationary Phase. These interactions normally cause excessive Retention and severe Peak broadening. In this LCMS Method, Formic Acid is all that is required for the analysis of charged drugs like […]

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Ethanolamine Analyzed with LCMS – AppNote

Retention & Analysis of Hydrophilic, Ethanolamine from Plasma In this Application Note, the Chromatograms show Ethanolamine sufficiently retained using either the Gradient or Isocratic Methods. The advantages of using these Methods are fast equilibration between runs when Gradient analysis is required and due to the high organic content of the Mobile Phase, the Ionization efficiency […]

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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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Etodolac Tablet Analyzed with HPLC – AppNote

An Assay Method for Etodolac Tablets The USP Assay Method for  Etodolac tablets uses a Phosphoric Acid based Mobile Phase which is not LCMS compatible. The Method in this Application Note is more versatile since it can be used for HPLC or LCMS. The Gradient can be adjusted if lower Retention is required. Data from […]

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Famotidine Tablet Analyzed with HPLC – AppNote

API Separation from Matrix Component This Method for Analysis of Famotidine Tablets is easy to perform and produces a Symmetrical Peak Shape for the API. This compound has numerous amines which can be problematic in terms of Peak Shape with conventional Columns. Separation from a component from the tablet extract matrix is obtained as well, […]

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Felodipine Extended-Release Tablets USP Assay – AppNote

USP Method for Felodipine ER Tablets This method presents the USP Felodipine Extended-Release Tablet assay using the Cogent RP C18. As shown in the chromatogram with a five injection overlay, the peak efficiency is superb and USP peak tailing guidelines are easily met with the Cogent RP C18™ column.  This demonstrates a great alternative Column […]

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Fenfluramine & Phentermine Analyzed with HPLC – AppNote

Assay for Anti-Obesity Combination Capsule & Tablet This Application  Note illustrates Separation of similar compounds in the Phenethylamine class of compounds; Fenfluramine & Phentermine. These two compounds in particular were once used as APIs in the same formulation. The data shows how these Phenethylamines can be easily Retained and Separated with an Isocratic Mobile Phase […]

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Fenofibric Acid Capsule Analyzed with HPLC – AppNote

Simple Isocratic LCMS Compatible Assay Method The USP Assay Method for Fenofibric Acid uses a Phosphate buffer which is incompatible with MS detection. In this isocratic Method, only Formic Acid is needed in the Mobile Phase. The Peak Efficiency and Symmetry are excellent and the run-to-run precision is reliable and robust, as the 10 Chromatograms […]

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Fexofenadine Analyzed with HPLC – AppNote

Simple Isocratic Assay Method without Amine Additives Fexofenadine, antihistamine, has a number of aromatic moieties and the tertiary amine in its chemical structure that can cause Peak tailing issues when using most L11 Columns for Analysis. The USP Assay Monograph for Fexofenadine Tablets uses Triethylamine to reduce tailing. With this Method, Trifluoroacetic Acid is used […]

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Fioricet Analyzed with HPLC – AppNote

Gradient Separation of Acetaminophen, Caffeine, and Butalbital In this Method, a simple Reversed Phase gradient is used to separate the three components of a Fioricet tablet. Figure A shows the five-run overlay obtained from the gradient. Figure B shows a “zoomed in view” so that the Butalbital Peak can be seen clearly. Peaks: 1. Acetaminophen […]

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Fluconazole Tablet Analyzed with HPLC – AppNote

Assay Method for Amine Containing API This Application Note shows a simple Gradient Method for Assay of Fluconazole Tablets. In Reversed Phase HPLC, notable tailing was observed due to the two heterocyclic amine groups. Use of Aqueous Normal Phase (ANP) HPLC produced a sharp Peak for this API. Data from three different Column lots is […]

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Fluorouracil Assay Analyzed with HPLC – AppNote

A Reliable Method for a Chemotherapeutic Drug This Fluorouracil Assay is easily performed and demonstrates Run to Run consistency and Precision with Retention Time RSD values below 0.1%. This Method shows reliability for analysis of this Pyrimidine Analog that is an anti-neoplastic anti-metabolite. Peak: Fluorouracil Method Conditions: Column: Cogent RP C18™, 5um, 100Å Catalog No.: […]

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Fluoxetine (Prozac®) – AppNote

Excellent Retention and Peak Shape with Amide Column Fluoxetine can have a tendency to tail in some HPLC methods due to its secondary amine group. However, peak shape with the Cogent Amide Column was found to be highly symmetrical without the aid of ion pairing agents. This allows the method conditions to be adapted to […]

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Fluoxetine Orthogonal Assay Method – AppNote

Simple Methods Without the Use of Ion-Pairing Agents Unlike the USP assay method, Ion Pair Agents are not needed in this application. Both figures show how good Peak symmetry can be achieved either in the Reversed Phase (RP, Figure A) or Aqueous Normal Phase (ANP, Figure B) mode with only Formic Acid as the Mobile […]

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