Glycine

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Hydroxyproline seems to be the most promising amino acid used in carbon dating when isolated from bone collagen. Separation of amino acids is challenging, especially without the use of ions or inorganic buffers that can interfere with Mass spectrometer (MS) or contaminate the sample with modern carbon. Amino acids are also not retained in reverse-phase chromatography. The ideal solution would be using water only to separate the amino acids. This would allow a direct coupling to MS. We were able to separate hydroxyproline from proline and other simple amino acids like glycine and alanine in HPLC on Newcrom AH column using water only as a mobile phase. Using water also allowed UV detection at 205 nm which can’t be done if using a buffer based on acetic or formic acid.
See more information on radiocarbon dating here.
The same method can be modified to get symmetrical peaks and higher efficiency if a mobile phase with ionic modifier such as formic acid is used.

Application Notes: Amino acids are polar ionic compounds which are not retained on reversed-phase column without ion-pairing reagent. In our application, lysine and arginine can be separated from other amino acids. Amino acids with a pH between 3 and 5 and with one basic and one acidic group become very polar. Therefore these amino acids don’t have strong ion-exchange interaction with Primesep C stationary phase. Amino acids with two amino groups still carry positive net charge and can interact with stationary phase by cations-exchange mechanism. pH variation of the mobile phase can be an effective tool to adjust selectivity of separation for zwitter-ionic, basic and acidic compounds. This method can be used for separation of mono-charged compounds from compounds having an extra charge.

Application Columns: Primesep C
Application compounds: Aspartic acid, Glutamic acid, Aspargine, Glycine, Proline, Alanine, Phenylalanine, Tyrosine, Leucine, Lysine, Arginine
Detection technique: UV, LC/MS, ELSD/CAD

Polysorbates are a class of emulsifiers used in some pharmaceuticals and food preparation. They are often used in cosmetics to solubilize essential oils into water-based products. Polysorbates are oily liquids derived from PEG-ylated sorbitan (a derivative of sorbitol) esterified with fatty acids. Surfactants that are esters of plain (non-PEG-ylated) sorbitan with fatty acids are usually referred to by the name Span. It is often required to quantitate Polysorbate (Polysorbate/Tween 20, Polysorbate/Tween 40, Polysorbate 60/Tween 60 and Polysorbate 80) by HPLC in various formulations. Polysorbates exist in form of oligomers.

Dimethyl sulfoxide is important polar aprotic solvent, which is frequently used in pharmaceutical drug manufacturing, desolution, etc. DMSO is used as one of the solvents on protein chemistry due to universal ability to dissolve small molecules like amino acids. Amino acids and DMSO are very polar and have no retention on reversed-phase columns. In this HPLC application DMSO and glycine are separated on Primesep 100 mixed-mode column. DMSO is retained by weak reversed-phase mechanism and very low organic concentration is required in order to achieve any retention. Glycine, like any other underivatized amino acid, is retained by weak reversed-phase and moderate cation-exchange mechanism. Method uses acetonitrile/water/TFA gradient and UV detection.