title: A modified system for thiazolinone conversion to thiohydantoin derivatives and their separation by high-pressure liquid chromatography.
abstract: An improved and very simple procedure for thiazolinone conversion to thiohydantoin derivatives and their separation by reverse-phase high-pressure liquid chromatography is described. Trifluoroacetic acid (10%) in ethyl acetate has been employed as a conversion reagent to circumvent the deamidation of acid amides and methylation of acidic amino acids, with a concomitant increase in the detection limits of these residues. Additionally, a very simple procedure has been developed for the separation of phenylthiohydantoin (PTH) derivatives of amino acids. The system takes advantage of the computer-controlled precise mixing of the solvents A and B to achieve accurate pH and thus avoid the necessity of pH adjustment of a buffer. The procedure is simple and highly reproducible, and separates all the 20 known PTH amino acids. The efficiency of the method has been examined on synthetic and natural proteins/peptides, in manual and autoconversion systems, over a period of more than 18 months.
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D055598:Chemical Phenomena; D002621:Chemistry; D002851:Chromatography, High Pressure Liquid; D006827:Hydantoins / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D012997:Solvents; D013844:Thiazoles; D013867:Thiohydantoins / Q000302:isolation & purification*
chemical_list: D000596:Amino Acids; D006827:Hydantoins; D012997:Solvents; D013844:Thiazoles; D013867:Thiohydantoins