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Method and apparatus for spectroscopic comparison of compositions

  • US 5,046,846 A
  • Filed: 03/22/1989
  • Issued: 09/10/1991
  • Est. Priority Date: 03/22/1989
  • Status: Expired due to Fees
First Claim
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1. A method of analysis, comprising the steps of:

  • (A) examining at least one characteristic of a sample as a function of a variable parameter to obtain data,(B) normalizing the sample data with respect to a model by;

    (1) establishing a plurality of data pairs which are characteristic values for the sample and a reference, both established at a single value of the variable parameter;

    (2) performing a regression analysis with the data pairs to obtain normalization parameters by;

    (a) performing a first regression, using all data pairs, to obtain a set of regression parameters;

    (b) determining acceptability of the regression parameters by comparing variability of the data pairs around the model to predetermined variability limits;

    (c) if the regression parameters are not acceptable, excluding data pairs which do not fall within a predetermined statistical limit around the model, and performing a further regression using a diminished set of data pairs to obtain further regression parameters; and

    (d) repeating steps (b) and (c) in an iterative manner until acceptable regression parameters are obtained, or until a predetermined number of iterations are completed, whichever first occurs; and

    (3) using the normalization parameters to normalize characteristic sample values to reference values,(C) making a comparison of the normalized sample data with reference data, and(D) determining from the comparison quality of the sample.

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