For optimal results in HPLC analysis, it is recommended to measure absorbance at a wavelength that matches the absorption maximum of the compound(s) being analyzed. The UV spectrum shown can assist in selecting an appropriate wavelength for your analysis. Please note that certain mobile phases and buffers may block wavelengths below 230 nm, rendering absorbance measurement at these wavelengths ineffective. If detection below 230 nm is required, it is recommended to use acetonitrile and water as low UV-transparent mobile phases, with phosphoric acid and its salts, sulfuric acid, and TFA as buffers.
For some compounds, the UV-Vis Spectrum is affected by the pH of the mobile phase. The spectra presented here are measured with an acidic mobile phase that has a pH of 3 or lower.

Separation type: Liquid Chromatography Mixed-mode

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Catecholamines are neurotransmitters that generate the ‘fight-or-flight’ responsein the body. The 3 main catecholamines are epinephrine (also known as adrenaline), norepinephrine, and dopamine, and they are produced by the adrenal glands.
These 3 catecholamines can be detected in the low UV regime. Using a Newcrom AH mixed-mode column and a mobile phase consisting of almost entirely water with either a phosphoric (H3PO4) acid or ammonium formate (AmFm) buffer, the catecholamines can be retained, separated, and measured. This analysis method can be UV detected at 275 nm with high resolution. The latter mobile phase (utilizing AmFm) is compatible with Mass Spectrometry.

Application Notes: Norepinephrine is a naturally occurring hormone and neurotransmitter. The USP HPLC method for the separation of norepinephrine was developed on Legacy L1 column according to the US Pharmacopeia methodology. L1 classification is assigned to reversed-phase HPLC column containing C18 ligand. Support for the material is spherical silica gel with particles size 3-10 um and pore size of 100-120A. Resolution between critical pairs corresponds to rules and specifications of UPS.  

Application Columns: Legacy L1 C18 HPLC column

Application compounds: Norepinephrine

Mobile phase: Sodium heptanesulfonate/H2O/MeOH 0.22/160/40  pH 3.0

Detection technique: UV

Reference: USP35: NF30

The catecholamine neurotransmitters are amino-acid derivatives of tyrosine. DOPA, tyrosine, phenylalanine, norepinephrine, epinephrine, and dopamine and baseline are resolved on a Primesep 100 column with UV-transparent phosphate buffer. This method can be used for analysis of catecholamines and related impurities in various matrices. Peak order and retention time can be changed by changing the amount of ACN, buffer concentration and buffer pH. Various buffers can be used to accommodate desired detection technique. Primesep 100 is a reversed-phase cation-exchange mixed-mode column that can be used for analysis of polar neutral, polar ionizable, polar zwitter-ionic, hydrophobic neutral, and hydrophobic ionic compounds in the same run. Column can be operated in reverse-phase, cation-exchange, anion-exclusion, HILIC and mixed-modes depending on the mobile phase selection and nature of analytes. Column is compatible with LC/MS and does not require use of ion-pairing reagents.

The separation of amino acids, the building blocks of proteins, can be challenging to separate on a reverse-phase column due to their high polarity. Using a mixed-mode HPLC column, allows the separation of amino acids by cation-exchange and ion-exclusion mechanisms as well as hydrophobicity. Fine tuning of separation can be achieved with changes in organic concentration of the mobile phase as well as choice of buffer and pH.

Catecholamines are chemical compounds derived from the amino acid tyrosine containing catechol and amine groups. Some of them are biogenic amines. Retention of compounds of the catecholamine pathway is achieved on Obelisc N column. All polar compounds are well retained by combination of HILIC and ion-exchange mechanisms. Obelisc N columns produce very good peak shapes for all analytes. The method is very sensitive to amount of ACN, buffer and buffer pH. The retention time changes with variation of the main parameters. This method can be used for quantitation of biogenic amines and related compounds (homovanillic acid, dihydroxyphenyl acetic acid, serotonin, dopamine, epinephrine, hydroxytryptophan, epinephrine and DOPA) in urine, blood and other biological fluids. Further optimization of this HPLC method can be used during screening and validation. Amines and acids can be analyzed in the same run and retained by a combination of polar organic mode, cation-exchange and anion-exchange modes. Various buffers within specified pH can be employed (ammonium formate, ammonium acetate, sodium phosphate, etc.).

Epinephrine and norepinephrine (adrenaline and noradrenaline) are hormones and neurotransmitters. Epinephrine is synthesized from norepinephrine in a synthetic pathway shared by all catecholamines, including L-dopa, dopamine, norepinephrine, and epinephrine. Phenylephrine is used as a decongestant, available as an oral medicine or as a nasal spray. Phenylephrine is now the most common over-the-counter (OTC) decongestant. All three compounds are used in various drug compositions. Separation of epinephrine and norepinephrine is a challenging task due to polarity and close properties of two compounds. Epinephrine, norepinephrine and phenylephrine are separated in this method on Obelisc R mixed-mode HPLC columns. The method is very sensitive to variation of pH and pH adjustment can be used to achieve desired selectivity and retention time. Other catecholamines can be analyzed using this HPLC method. The method can be used as a stability indicating or a impurity profiling approach to the analysis of neurotransmitters in drug formulation, blood, serum and urine.

Primesep 200 separates the catecholamines, norepinephrine and epinephrine, less than 8 minutes. Norepinephrine and epinephrine are baseline resolved by a combination of reversed-phase, and ion-exchange mechanisms. Excellent peak shape results with a mass spec compatible mobile phase of water, acetonitrile (MeCN, ACN) and trifluoroacetic acid (TFA) with UV detection at 210 nm.