US 5,596,135 AGranted

Apparatus for and method of determining purity of a peak of a peak of a chromatogram

AssigneeShimadzu Corporation

InventorsYasuhiro Mito, Hideki Minegishi

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Abstract

It is judged whether a part of a peak section of a chromatogram corresponding to a component of a sample is pure by comparing a similarity value of the absorbance spectrum of the part to a threshold value. The similarity value r and the threshold value t are calculated as follows. a) A series of absorbance spectra of a sample effluent from a column of the chromatograph are obtained repeatedly at a plurality of time points of short intervals. An absorbance spectrum is composed of a set of absorbance data with respect to wavelengths of light passing through the sample. b) A chromatogram of the sample is constructed using the series of absorbance spectra. c) A peak section including an object component of the sample is detected in the chromatogram. d) A similarity value is then calculated as a cosine of the angle between an absorbance spectrum vector and a standard spectrum vector. e) The threshold value is calculated by a cosine of the angle between two outermost tangential lines of an n-dimensional sphere centering an end of the absorbance spectrum vector and another n-dimensional sphere centering an end of the standard spectrum vector.

Claims18

Dependent claims

A detector for a chromatograph comprising:

a) means for obtaining a series of absorbance spectra of a sample effluent from a column of the chromatograph repeatedly obtained at a plurality of time points separated by short intervals during a retention time of the sample effluent, each absorbance spectrum of the series of absorbance spectra being composed of a set of absorbance data with respect to wavelengths of light passing through the sample effluent;
b) means for constructing a chromatogram of the sample using the series of absorbance spectra;
c) means for detecting a peak section including an object component of the sample effluent in the chromatogram in real time;
d) means for calculating a similarity value between an absorbance spectrum of each of the plurality of time points and a standard absorbance spectrum of the object component, wherein the similarity calculating means calculates the similarity value based on an angle between an absorbance spectrum vector corresponding to the absorbance spectrum and a standard spectrum vector corresponding to the standard absorbance spectrum in real time;
e) means for calculating a threshold value using the absorbance spectrum of said each of the plurality of time points, the standard absorbance spectrum and a noise level value of the chromatograph in real time;
and
f) means for determining whether the absorbance spectrum is similar to the standard absorbance spectrum by comparing the similarity value to the threshold value in real time.

4 more elements

A method of determining purity of a peak of a chromatogram comprising the steps of:

a) obtaining a series of absorbance spectra of a sample effluent from a column of the chromatograph repeatedly at a plurality of time points separated by short intervals during a retention time of the sample effluent, each absorbance spectrum of the series of absorbance spectra being composed of a set of absorbance data with respect to wavelengths of light passing through the sample;
b) constructing a chromatogram of the sample using the series of absorbance spectra;
c) detecting a peak section including an object component of the sample effluent in the chromatogram in real time;
d) calculating a similarity value between an absorbance spectrum of each of the plurality of time points and a standard absorbance spectrum of the object component in real time, wherein the similarity value is calculated in the similarity calculating step based on an angle between an absorbance spectrum vector corresponding to the absorbance spectrum and a standard spectrum vector corresponding to the standard absorbance spectrum;
e) calculating a threshold value using the absorbance spectrum of each of the plurality of time points, the standard absorbance spectrum and a noise level value of the chromatograph in real time;
and
f) determining whether a part of the peak section is pure by comparing the similarity value of the absorbance spectrum of the part of the peak section to the threshold value in real time.

4 more elements

Dependencies are inferred from the claim text.