Total Alkaloid Determinations in Larkspur and Lupine with near Infrared Reflectance Spectroscopy1
- D. H. Clark,
- M. H. Ralphs and
- R. C. Lamb2
Near infrared reflectance spectroscopy (NIRS) is used for quality component determinations in forages and grains. However, the use of NIRS to determine antiquality factors in forages has not been reported. Therefore, NIRS spectra were collected on leaf, stem, and head fractions to total 273 tall larkspur (Delphinium occidentale Muth.) and 246 velvet lupine (Lupinus leucophyllus Dougl.) samples. Total alkaloid concentrations (TAG) were determined through extraction and titration, and regressed against NIRS reflectance values from 1100 to 2500 nm. Three NIRS equations were developed to determine TAC: one each for larkspur and lupine, and one for a combination of larkspur and lupine. Of the total, 136 larkspur, 82 lupine, and 260 larkspur plus lupine samples were held from regression analysis and used for testing the equations. Standard errors of calibration for TAC were lowest for lupine, followed by larkspur and larkspur plus lupine (0.04, 0.10, and 0.10 dag kg−1, respectively). Standard errors of analysis for TAC were lowest for larkspur, followed by lupine and larkspur plus lupine (0.01, 0.05, and 0.10 dag kg−1, respectively). Relationships between NIRS and wet laboratory determined values were equal for larkspur and larkspur plus lupine (r2=0.93) and slightly lower for lupine (r2=0.90). Spectral comparisons of plant material and alkaloids showed strong relationships between the wavelengths used in the equations and alkaloid peaks. Total alkaloid concentrations in larkspur and lupine can be accurately analyzed by NIRS.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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