Abstract:Four amino sugars, namely, muramic acid (MurN), mannosamine (ManN), galactosamine (GalN) and glucosamine (GluN), in soil were determined by ortho-phthalaldehyde (OPA) pre-column derivatisation-high performance liquid chromatography (HPLC). The sensitivity, precision and accuracy of the instrument and method were tested from chromatographic peaks, theoretical plates, signal-noise (S/N) ratio, limits of detection and quantification, sample content repeatability, standard linearity, and recovery. The results showed that the chromatographic peak orders of the four amino sugars were MurN, ManN, GalN and GluN. The chromatographic peak shapes were good and the resolutions of each two adjacent peaks were >1.5, indicating that the two adjacent peaks were completely separated. Theoretical plates were >2 000, indicating high chromatographic column efficiency. The instrument detection limits of MurN, ManN, GalN and GluN were 0.030, 0.300, 0.150 and 0.150 μmol/L, the instrument quantitative limits were 0.100, 1.000, 0.500 and 0.500 μmol/L, the method detection limits were 0.010, 1.500, 0.100 and 0.100 μmol/L, and the method quantitative limits were 0.030, 5.000, 0.300 and 0.300 μmol/L, respectively. In addition to ManN in the soil below 10 cm, S/N ratios of the amino sugars amount were all >10, indicating high sensitivity of the instrument and method. The relative standard deviations of the amino sugar amount in the parallel standard samples, parallel soil samples and repeated soil samples were all <5%, indicating high precision of the instrument and method. The R2 values of the standard curve were >0.997 0, and the recovery rates of blank and soil substrate were between 80% and 94%, indicating high accuracy of the instrument and method. In conclusion, the method for the determination of soil amino sugar content by OPA pre-column derivatisation-HPLC, which is simple in operation and high in sensitivity, could accurately determine the contents of amino sugar in soils.