DOPA (3,4-dihydroxy-L-phenylalanine)

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.

The neurotransmitters dl-DOPA, creatinine, hydroxytryptophan (5-HTP), and serotonin are separated in less than 4 minutes on a short 50 mm Primesep 200 column. The HPLC separation uses a mobile phase of water, acetonitrile (MeCN, ACN) and trifluoroacetic acid (TFA) and UV detection at 250 nm. Ion-pair reagents were not needed for retention of these polar, hydrophilic compounds, instead, a combination of ion-exchange and reversed-phase interactions were used.

Amino acids can be retained and separated on a Primesep S2 column in HILIC/cation-exchange mode.

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.

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.).

The catecholamine neurotransmitters are amino-acid derivatives of tyrosine. DOPA, tyrosine, phenylalanine, norepinephrine, epinephrine, and dopamine and baseline are resolved on a
Primesep 200 column with UV-transparent phosphate buffer. This method can be used for the analysis of catecholamines and related impurities in various matrices. The 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 the desired detection technique. Primesep 200 is a reversed-phase cation-exchange mixed-mode column that can be used for analysis of polar neutral, polar ionizable, polar zwitterionic, 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 the nature of the analytes. The column is compatible with LC/MS and does not require the use of ion-pairing reagents.

Amino acids are the building blocks of proteins and are widely used as supplements.  Amino acids can exist in acidic, basic or zwitterionic form depending on the pH of their environment (mobile phase in this case).  Primesep 200 is a reverse-phase column with embedded weak acidic ion-pairing groups which allows for retention and separation of amino acids without requiring a buffer making it ideal for use with UV detection, mass spectrometry (MS), evaporative light scattering detection (ELSD).

Primesep 200 separates catecholamines in the catecholamine pathway in 10 minutes. Phenylalanine, tyrosine, DOPA, dopamine, norepinephrine, and epinephrine are baseline resolved by a combination of reversed-phase, ion-exchange, and ion-exclusion mechanisms. Excellent peak shape results with a mass spec compatible mobile phase of water, acetonitrile (MeCN, ACN) and trifluoracetic acid (TFA) with UV detection at 210 nm.