lec_2.pdf

Spectrophotometer What is UV-Vis ———————- spectrophotometer ? ——————————— UV-Vis spectrophotometry is an analytical technique that measures the amount of discrete wavelengths of UV or visible light that are absorbed by or transmitted through a sample. A blank and a standard are necessary...

Spectrophotometer What is UV-Vis ———————- spectrophotometer ? ——————————— UV-Vis spectrophotometry is an analytical technique that measures the amount of discrete wavelengths of UV or visible light that are absorbed by or transmitted through a sample. A blank and a standard are necessary. This process helps to calculate the concentration of analyte. The spectrophotometer ———————————————is an instrument which measures the amount of light that a sample absorbs. The spectrophotometer works by passing a light beam through a sample to measure the light absorbtivity of it. What is absorbance? Absorbance (A), also known as optical density (OD), is the quantity of light absorbed by a solution. A spectrophotometer is used to know the concentration of solutes in solution colorless or coloured. It is used for the determination of the rate of reaction ( reaction rate analyzers) where the cuvette is kept at 37c degrees What is absorbance? Absorbance (A), also known as optical density (OD), is the quantity of light absorbed by a solution. Transmittance T is the quantity of light that comes out. The spectrophotometer instrument consists of a light source, a digital display, a monochromator, a wavelength selecter to transmit a selected wavelength, photoelectric detector and a cuvette to place a sample. Why is a glass cuvette not suitable for UV? Because glass and most plastics absorb ultraviolet light, reusable quartz cuvettes were formerly required for measurements in the ultraviolet range. The water bath of the ———————spectrophotometer: ——————————- A small water bath is built in here with a space for the cuvette holder. The only purpose is to carry enzyme reaction at 37 C eg AST, ALT, CK. Thes take incubation of 5 minute at 37 without any color development. Is called reaction rate analysis. Wavelength is UV at 340 nm