Automatic photometric titrator
First Claim
1. A method for detection of end-point in acid-base titration reactions to determine acid in an acid-containing material, said method comprising placing a quantity of a chemiluminescent indicator together with a sample of the acid-containing material to be analyzed into a vessel, gradually adding a suitable basic titrant to the vessel whilst monitoring by means of a light detector the intensity of light emission from the indicator, obtaining the first derivative with respect to time of the output signal of the light detector and detecting when the first derivative of the output signal reaches an amplitude level indicative of the acid-base reaction end-point.
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Abstract
An alkaline-acid end point detector for titration reactions in which the phenomenon of chemiluminescence is used to detect the end point by monitoring, by means of an electronic light detector, the light output of the reaction materials in a light-tight vessel. The output from the detector is differentiated to detect the maximum output which corresponds to the reaction end point. The detector is useful in the determination of acid numbers in oils and greases.
14 Citations
12 Claims
- 1. A method for detection of end-point in acid-base titration reactions to determine acid in an acid-containing material, said method comprising placing a quantity of a chemiluminescent indicator together with a sample of the acid-containing material to be analyzed into a vessel, gradually adding a suitable basic titrant to the vessel whilst monitoring by means of a light detector the intensity of light emission from the indicator, obtaining the first derivative with respect to time of the output signal of the light detector and detecting when the first derivative of the output signal reaches an amplitude level indicative of the acid-base reaction end-point.
- 5. Apparatus for detecting end-point in titration to determine acid in acid-containing material by mixing a chemiluminescent indicator with the material, adding a basic titrant at a constant rate which is capable of causing light emission by the indicator and in accordance with said addition of titrant, and determining when the first derivative with respect to time, of change in said light emission, indicates that the light emission has reached a value indicative of said end-point, comprising a vessel into which the chemiluminescent indicator and the sample of material to be analyzed may be placed, means for feeding titrant at a constant rate into the vessel, a light detector for detecting the intensity of light emission by the indicator, a differentiating circuit for obtaining the first derivative with respect to time of the output signal of said light detector and a comparator circuit for providing an output signal indicative of when the first derivative of the output signal of said light detector has reached a level representing said end-point value.
Specification