Valine

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Essential amino acids cannot be made by the body. As a result, they must come from food.
The 9 essential amino acids are: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.

Essential and non-essential amino acids can be retained and separated in zero-organic mode on Primesep mixed-mode HPLC columns. Zero-organic mode is required to monitor isotopes of carbon. Amino acids are retained by combination of reversed-phase and cation-exchange mechanisms. At lower pH, some of the amino acids are more hydrophobic. Buffer pH will affect ionization state of amino acids, and at higher pH (above 2.5), the amino acids will be less hydrophobic and retentive in zero-organic mode. Amino acids can be monitored by low UV. Method can be used in archeological research for analysis of various molecules where presence of organic component of the mobile phase interferes with analysis.

11 underivatized amino acids (aspartic acid, glutamic acid, alanine, valine, methionine, isoleucine, cysteine, phenylalanine, histidine, lysine, and arginine) are separated by a Primesep 100 HPLC column by reversed-phase and ion-exchange mechanisms with LC/MS compatible conditions without the use of ion-pair reagents. The HPLC separation uses a TFA (trifluoroacetic acid) gradient in a mobile phase of water acetonitrile (MeCN, ACN with evaporative light scattering detection (ELSD).

Glutamine, valine, isoleucine, and leucine are baseline resolved in a dietary supplement with a mobile phase of acetonitrile, water, and sulfuric acid with ultraviolet (UV) detection at 210 nm on a Primesep 100 column. Increasing the sulfuric acid concentration allows elution of arginine. Primesep 100 separates underivatized amino acids and amines by combining reversed-phase and ion-exchange mechanisms. The HPLC separation uses a mobile phase of water, acetonitrile (MeCN, ACN), and sulfuric acid with ultraviolet (UV) detection at 210 nm.

Adding on to the previous HPLC separation of amino acids using Bufferless Ion Separation (BLIS) Chromatography; here we have additional amino acids separated on Primesep 200 column using only water and acetonitrile (MeCN, ACN) in the mobile phase.  Primesep 200 is a reverse-phase (RP) column with weak acidic ion-pairing groups embedded. With no buffer present in the mobile phase, detection can be achieved with UV, mass spectrometry (MS), evaporative light scattering detection (ELSD).