Chemical apparatus and process disinfecting – deodorizing – preser – Analyzer – structured indicator – or manipulative laboratory... – Means for analyzing liquid or solid sample
Reexamination Certificate
1998-01-16
2001-11-13
Wallenhorst, Maureen M. (Department: 1743)
Chemical apparatus and process disinfecting, deodorizing, preser
Analyzer, structured indicator, or manipulative laboratory...
Means for analyzing liquid or solid sample
C422S082050, C422S082090, C436S164000, C356S317000, C356S337000, C356S338000, C356S340000, C356S343000, C356S432000, C356S435000, C356S436000, C356S441000, C356S442000
Reexamination Certificate
active
06315955
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to a method and apparatus for the quantitative determination of particles in fluids. The preferred embodiments will find use for quantitative analysis of fat in milk and other dairy fluids.
2. Description of the Prior Art
The present invention is directed to the field of quantitative determination of particles in fluids. The term particle shall be used in its broadest sense and shall typically not only be restricted to mean pieces of solid matter in another phase, but also include the situation of small volumes of liquid in another liquid phase—an example would be micelles or small globules dispersed in a bulk liquid phase such as in an emulsion, or fat globules in a liquid such as milk.
In addition, the term ‘fluid’ shall also be taken to include the gaseous phase though it is envisaged that most embodiments will be used in applications where the fluid is a liquid.
Most apparatus which is currently used for the quantitative determination of particles in a fluid are relatively complex in nature. Their degree of complexity is at least partially a cause for several disadvantages:
they are relatively expensive;
they are often relatively delicate and generally unsuitable for use in the field or in normal manufacturing and processing environments;
they are generally specific in purpose and often cannot be readily adapted for other applications;
they are often unable to be used for monitoring an in-line sample arrangement—most embodiments require samples to be removed from the production line and placed in the apparatus for analysis.
Much of the art relies on spectroscopic techniques for quantitative determination of particle presence in a fluid. Most of these techniques are based on infrared spectroscopy and are only useful in many cases for detecting and quantitatively determining organic or organometallic particles in the fluid. An example is the subject matter of NZ Patent No. 192325 which describes a method of quantitative measurement of fat in a sample by using an infrared absorption technique and evaluating the infrared absorption characteristic of saturated carbon-hydrogen bond stretching. However this and corresponding methods are generally specific to the quantitative analysis of particular categories of compounds and could be influenced by the presence of substances other than those of interest which are also present in the sample.
International Patent Appln No. WO 92/17767 is directed to a similar method of quantitative fat determination in an emulsion and also takes into account infrared absorption peaks due to other (than C—H bond excitation) as well. While this technique would also appear to improve selectivity (and thus have the potential to eliminate interference from other substances present in the sample) it also claimed that more accurate determinations can be carried out directly from full milk, without a preceding homogenisation treatment. However the invention described in this specification also possesses many of the general disadvantages described above.
French Patent No. FR 2050525 describes a method where an infrared beam is reflected off parallel transparent walls bounded on the outside by the sample fluid. Here only part of the beam will be reflected (and some absorbed or transmitted through the sample liquid) to be measured as it exits the chamber. The intensity of the reflected beams reflects particle content, supposedly. However this method will have limitations in the number and type of different fluids with which it may be used.
Russian Patents Nos. SU 983538 and SU 1748058 are also directed to methods of particle determination in fluids though rely upon the use of expensive or complex equipment; one of which prefers the use of a maser which is not an off-the-shelf item in most countries.
In general the bulk of the prior art does not allow for the continuous or in-line monitoring of sample fluid and are generally and relatively inflexible in how they may be used or applied.
It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.
Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.
SUMMARY OF THE INVENTION
According to one aspect of the present invention there is provided apparatus for quantitative particle determination in fluids, said apparatus comprising:
an emitter set comprising one or more light emitters in turn providing one or more sample light signals;
a detector set comprising one or more light detectors sensitive to the output of the light emitters,
the arrangement being characterised such that the sample light signals from a plurality of sample light signal paths between the emitter and detector sets are received by the detector set during analysis of a sample;
the detector providing output values which can be evaluated by processing means for providing a value indicative of the fluid particle content.
According to another aspect of the present invention there is provided apparatus, substantially as described above, in which the detector set is arranged to detect at least one set of scattered or reflected light signals due to reflectance by particles present within the fluid.
According to another aspect of the present invention there is provided apparatus, substantially as described above, which includes optical feedback means comprising a feedback detector whose output provides for at least one of:
influencing either or both the voltage and current of at least one light emitter to maintain light output at a predetermined level;
influencing the sensitivity of at least one light detector to match the light output of at least one light emitter, and
providing a signal available to processing means for use in correction when providing a value indicative of particle content.
According to another aspect of the present invention there is provided apparatus, substantially as described above, in which said sample light signal paths differ from each other by at least one of:
their path length through the fluid sample being analysed, and
their relative path angle through the fluid sample being analysed.
According to another aspect of the present invention there is provided apparatus, substantially as described above, comprising an emitter set comprising a plurality of light emitters at different positions along the wall or walls of a sample cell, or positioned to be present along the wall or walls of an inserted sample cell; the output of said emitters directed to provide a plurality of substantially direct signal paths to one or more light detectors of the detector set.
According to another aspect of the present invention there is provided apparatus, substantially as described above, comprising a plurality of pulsed light emitters, and in which the detector set, or an individual detector of the detector set, detects substantially the output of a single light emitter, or combination thereof, at a time during analysis of a sample; the pulsing of said light emitters being synchronised to allow the detection of the output of individual light emitters, or groups thereof.
According to another aspect of the present invention there is provided apparatus, substantially as described above, which includes processing means which compares values produced by the detector set with stored calibration reference values, the comparison producing values indicative of the presence of one or more different types of particles within a sample fluid.
According to a further aspect of the present invention there is provided a method for the quantitative determination of the levels of one or more different particles in a fluid comprising transmitting one or more light signals into a fluid sample, detecting the sample light signals from a plurality of sample light signal paths, and making the detected output available for subsequent evaluation by processing means.
According to another aspect of the present invention there is
DeLaval International A.B.
Hovey Williams Timmons & Collins
Wallenhorst Maureen M.
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