Radiant energy – Invisible radiant energy responsive electric signalling – Infrared responsive
Patent
1996-04-23
1998-06-09
Hannaher, Constantine
Radiant energy
Invisible radiant energy responsive electric signalling
Infrared responsive
25033912, 2503418, G01N 2103, G01N 2111
Patent
active
057638845
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD & BACKGROUND ART
The present invention relates to spectrophotometric analysis and is particularly concerned with a method of, and apparatus for, such analysis of a material in powder form by reflectance measurements of a beam of electromagnetic radiation (usually near infrared) through the material.
Scanning spectrophotometers are well known to provide quantitative and qualitative analysis of organic and biological substances and materials and especially pharmaceutical materials in powder form. Typical near infrared scanning spectrophotometers are sold under the Trade Marks "COMPSCAN" by the Gardner Neotech Division of Pacific Scientific and "Model 6500" by NIR Systems Inc., and an example of such a spectrophotometer is disclosed in U.S. Pat. No. 4,692,620. Generally such known spectrophotometers comprise a cell within which a sample of the material for analysis is retained, a beam of electromagnetic radiation, usually near infrared as previously mentioned, which scans the material in the cell, and sensors which are responsive to reflections from the material and provide an output from which the analysis is effected. An example of a spectrophotometric cell which compresses the material contained therein is disclosed in Patent NL-A-8700709. Usually the spectrophotometer is coupled to a computer by which the scanning is controlled and which provides a required analysis of the output from the sensors.
Spectrophotometers of the kind discussed above are employed in the pharmaceutical industry for analysis of pharmaceutical materials in powder form, typically for carrying out random tests on samples of a pharmaceutical (which may be in, or rendered to, powder form) and as is intended to be marketed. These tests are principally to ensure that the material has the required chemical constituents, that the proportions of the required chemical constituents are correct and that the chemical constituents are dispersed uniformly throughout the material. The necessity to ensure that a pharmaceutical material has the correct chemical constituents in the required proportions is an understandable requirement. The requirement to ensure that the chemical constituents are uniformly distributed throughout the material is now called for by many regulatory authorities, such as the Medicines Control Agency in the United Kingdom, the U.S. Federal Drug Administration and the European Medical Commission. Many pharmaceuticals as supplied for use in a predetermined dosage weight, either in powder (for example capsule) or tablet form, contain a significant proportion of an inactive carrier substance or placebo through which the active chemical constituents are distributed. It is a requirement that the active chemical constituents are uniformly and evenly distributed throughout the carrier substance for each intended dose. With the aforementioned spectrophotometric random testing, spectral analysis of a pharmaceutical sample by conventional techniques has, on occasion, found to be unreliable in determining the distribution of the active chemical constituents; for example such tests may provide a false indication of the distribution when related to a dose weight of the pharmaceutical product as it is intended to be marketed or may be unacceptable to the regulatory authorities as having been carried out on an unrepresentative sample of the product when related to the intended dose weight. It is an object of the present invention to provide a method of and apparatus for spectrophotometric analysis of a material in powder form by reflectance measurements which is an improvement in known spectrophotometric apparatus and methods of analysis and may be used to alleviate the aforementioned problem in determining the distribution of the chemical constituents in the material so that such determination is consistent with a predetermined or intended dose by weight of the material.
STATEMENTS OF INVENTION & ADVANTAGES
According to the present invention there is provided a method of spectrophotometric analysis of a material by refl
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Hammond Stephen Victor
Romans David Grant
Wakeman John Stephen
Benson Gregg C.
Hannaher Constantine
Pfizer Inc.
Richardson Peter C.
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