[Development of highly sensitive determination of biogenic compounds by high-performance liquid chromatography with...

A sensitive fluorescent labeling reagent, 4-(5,6-dimethoxy-2-phthalimidinyl)-2-methoxyphenylsulfonyl chloride (DMS-Cl), for the determination of amino compounds in HPLC was developed. DMS-Cl reacted with amino compounds in the basic medium to produce the corresponding fluorescent sulfonamides (excition 318 nm, emission 406 nm in aqueous acetonitrile). When amino acids were analyzed using reverse-phase HPLC, the detection limits (signal-to-noise ratio = 3) of almost all amino acids labeled with DMS-Cl were less than 5 fmol/injection. DMS-Cl was utilized for highly sensitive determination of amino compounds in biological samples and HPLC methods for determination of prolyl dipeptides, Pro and Hyp, in serum and urine, pipecolic acid in serum, taurine in plasma, and free and N-acetylated polyamine in urine were established. As these proposed methods are highly sensitive and reproducible and require only a small amount of biological sample, they may be useful for clinical and biochemical research.