A Mid-Infrared Spectroscopy Method to Determine the Glucosamine, Galactosamine, and Muramic Acid Concentrations in Soil Hydrolysates.

Zhang, B., Yang, X.M., Drury, C.F., and Zhang, X.D. (2013). "A Mid-Infrared Spectroscopy Method to Determine the Glucosamine, Galactosamine, and Muramic Acid Concentrations in Soil Hydrolysates.", Soil Science Society of America Journal, 77(3), pp. 842-849. doi : 10.2136/sssaj2012.0359  Access to full text

Abstract

The current method for determining amino sugars in soils involves a derivatization process which is time-consuming and involves working with and disposing of hazardous chemicals. This study aims to evaluate the potential of mid-infrared (MIR) spectroscopy to predict amino sugar concentrations in soil. Two separate sets of the same 60 soil samples were hydrolyzed and purified, and then one set of samples was transformed into amino sugar derivatives for gas chromatography (GC) determination and the other set of samples was used for MIR spectra collection without further processing. The GC-measured concentrations of amino sugars were calibrated, using test-set data set (n} = 20) and leave-one-out data set, against the MIR spectral data with partial least squares (PLS) regression. Based on the values of coefficient of determination (R2) and residual prediction deviation (RPD), the calibration models for amino sugars were good for both data sets, with R2 values ranging from 0.82 to 0.98 and RPD values from 2.38 to 7.76. For test-set validation, predictions were excellent for total amino sugars (R2 = 0.96, RPD = 5.14), glucosamine (R2 = 0.97, RPD = 6.27), galactosamine (R2 = 0.94, RPD = 4.16), and good for muramic acid (R2 = 0.84, RPD = 2.52). For leave-one-out cross-validation, predictions were excellent for glucosamine (R2 = 0.91, RPD = 3.28), good for total amino sugars (R2 = 0.86, RPD = 2.70) and galactosamine (R2 = 0.81, RPD = 2.29), but relatively poor for muramic acid (R2 = 0.61, RPD = 1.61). We concluded that the MIR spectroscopy has high potential to estimate the concentrations of amino sugars in soil with significant savings in time, cost, and chemicals.

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