Patent ID: 6342948
Filing Date: 2002-01-29
Classification: G01N

Abstract:
An absorbance detector apparatus, comprising:a flow cell having a chamber receiving a sample, said chamber being configured to provide at least a first light path through said sample and a second light path through said sample, said first light path being longer than said second light path; a light source directing light into said flow cell and into said at least said first light path through said sample and said second light path through said sample; and a single photo detector or single photodetector array receiving light exiting from said at least said first light path through said sample and said second light path through said sample; wherein concentration of the sample relates to the measured absorbance by the equation set forth below: A=log(Im/I)=log[(X.10âˆ’Am+(1âˆ’X).10âˆ’jAm+k)/(X.10âˆ’Am.eâˆ’&agr;bc+(1âˆ’X).10âˆ’jAm.câˆ’&agr;jbc+k)]â€ƒand the letters and symbols have the following meanings: A represents absorbance of the analyte; Im represents the signal of a detector relating to the light transmitted through the mobile phase, I represents the signal or a detector relating to light transmitted in the presence of analyte; X represents the fraction of light passed by the first light path absent mobile phase and analyte absorbtion; (1âˆ’X) represents the fraction of light passed by the second light path absent mobile phase and analyte absorbtion; b represents the length of the first light path; jb represents the length of the second light path; Am represents the absorbance of the mobile phase; k represents a constant relating to stray light; &agr; represents the absorbtion coefficient of the an analyte; c represents the concentration of the analyte; and, c represents the base of natural logarithms.