Measurement of free amino acids in soil and fertilizer samples using high performance liquid chromatography equipped with ultraviolet detector

Abstract

In this study, the concentration of effective amino acids in plant metabolism was measured in different soil and fertilizer samples by high performance liquid chromatography. First, the amino acids of the sample were extracted with 0.1 N hydrochloric acid. Then they were derivatized with phenyl isothiocyanate (PITC). Finally, the phenylthiocarbamyl-amino acid derivatives were isolated in the reverse phase column using gradient elution with sodium acetate trihydrate and acetonitrile-water (40:60), and detected by a UV detector at 254 nm. Several parameters related to the separation of amino acid peaks, including pH and temperature of the mobile phase, buffer concentration and modifier (triethylamine) in the mobile phase were studied. By changing each of the existing conditions, the amount of resolution for amino acid peaks was optimized. Under optimal conditions, a good linear range (0.0312-0.125 µmol / ml) was obtained for 17 amino acids with a detection limit of 0.0094 µmol / ml and acceptable reproducibility for each amino acid (RSD ≤6.1%). Finally, the percentage of free amino acids was measured in different soil and fertilizer samples by this method.

Keywords

• "free amino acids"
• "hplc"
• "phenyl isothiocyanate"
• "soil"
• "fertilizer"