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Colorimetric assays use reagents that undergo a measurable color change in the presence of the analyte. They are widely used in biochemistry to test for the presence of enzymes, specific compounds, antibodies, hormones and many more analytes. For example, para-Nitrophenylphosphate is converted into a yellow product by alkaline phosphatase enzyme.
The equipment required is a colorimeter, some cuvettes and a suitable color reagent. The process may be automated, e.g. by the use of an AutoAnalyzer or by flow injection analysis . Recently, colorimetric analyses developed for colorimeters have been adapted for use with plate readers to speed up analysis and reduce the waste stream.
Indicator: A substance that changes color in response to a chemical change. An acid–base indicator (e.g., phenolphthalein) changes color depending on the pH. Redox indicators are also used. A drop of indicator solution is added to the titration at the beginning; the endpoint has been reached when the color changes.
Colorimetry is "the science and technology used to quantify and describe physically the human color perception". [1] It is similar to spectrophotometry, but is distinguished by its interest in reducing spectra to the physical correlates of color perception, most often the CIE 1931 XYZ color space tristimulus values and related quantities.
A limiting factor in using Coomassie-based protein determination dyes stems from the significant variation in color yield observed across different proteins [19] This limiting factor is notably evident in collagen-rich protein samples, like pancreatic extracts, where both the Lowry and Bradford methods tend to underestimate protein content.
A forensic pathologist with the city medical examiner's office at the time, Dr. Marlon Osbourne, initially ruled Greenberg's death a homicide, according to court documents.
pH indicators: a graphic view. A pH indicator is a halochromic chemical compound added in small amounts to a solution so the pH (acidity or basicity) of the solution can be determined visually or spectroscopically by changes in absorption and/or emission properties. [1]
A pregnant woman is recovering in the hospital after she was stabbed multiple times by a pizza delivery driver over the size of her tip, according to reports.