Patent ID: 6448067
Filing Date: 2002-09-10
Classification: G01N

Abstract:
An apparatus for determining a chemical component from a sample of matter, the apparatus comprising:a sample holder for accommodating a test strip, the test strip being configured to receive the sample on one side of the test strip, the test strip including a reagent, the reagent being configured to cause a color reaction, directly or through an intermediate reaction, with the chemical component, and the test strip being further configured such that components of the sample penetrate the test strip and start the color reaction at an opposing side of the test strip; a light source for illuminating the sample placed into the sample holder; a measuring circuit for measuring the intensity of the light reflected from the sample and generating an output signal corresponding to the intensity of the light; a controller and analyzer circuit for receiving the output signal from the measuring circuit, where the controller and analyzer circuit is configured to determine the chemical component of the sample by: illuminating the sample and measuring a reflection R from the test strip and recording a reflection function R(t), detecting a wetting through of the sample, determining a starting time T0, where the starting time T0 is not earlier than the time of detection of wetting through of the sample, generating from the starting time T0, a function R(t)+L(t), where L(t) is a predetermined function that is independent of the measured reflection, monitoring and storing an extreme value ext[R(t)+l(T)] of the R(t)+L(t) function, generating a function R(t)+L(t)âˆ’ext[R(t)+L(t)] from the time of reaching at least one value for extreme value ext[R(t)+L(t)], where the R(t)+L(t)âˆ’ext[R(t)+L(t)] function reaches a predetermined C(t) value, determining a Tm measuring time, C(t) being a predetermined function independent of the measured reflection, and determining from the R reflection value measured at the Tm measuring time an amount of the chemical component in the sample.