Equivalency of near infrared transmission instruments for grain analyzers

Abstract

<p>The Grain Inspection Packers and Stockyard Administration (GIPSA) has one approved near infrared transmission (NIRT) instrument for the official inspection of grains. This is believed to be more accurate multiple makes and models used. This study focused on determining if more than one make and model of transmission instruments can be used. Three National Type Evaluation Program (NTEP) approved NIRT instruments coded A, B, and C were evaluated for equivalence. To be equivalent, the variation of results of all the instruments would be less than or equal to that of one instrument make and model on a population of samples. The study used 5 copies of each instrument, for a total of 15 machines. The number of samples used were, 250 wheat, 100 barley, 145 soybeans, and 149 corn. The samples were passed through all 15 machines three times each. Results for wheat (protein), barley (protein), soybean (protein and oil), and corn (protein and oil) were collected using the NTEP approved calibrations for each unit, with and without slope-bias standardization. A least mean squares analysis partitioned the variance by A-A, A-B, B-B, B-C, and C-C. The instruments as set up were not equivalent because A-B, A-C, and B-C were significantly larger than the within brand comparisons A-A, B-B, and C-C (p<0.0001).</p>