Spectrophotometer Applications: 

Spectrophotometers have become routine instruments in modern molecular biology laboratories. Commonly used in nucleic acid, protein, substance concentration, enzyme activity, and quantification of bacterial growth concentration.

The essential components of spectrophotometer instrumentation include:

1. Light source

Sources of Ultraviolet radiation: Most commonly used source of UV radiation is a deuterium lamp. Xenon lamps may also be used for UV radiation. 

Sources of Visible Radiation: “Tungsten filament” lamp is the most commonly used source of visible radiation. It is inexpensive and emits continuous radiation in the range between 340 and 2500nm.

2. Monochromator

A monochromator resolves polychromatic radiation into its individual wavelengths and isolates these wavelengths into very narrow bands.

3. Sample containers

Cell holder: Manual 4 position(1, 5, 10cm)

Automatic 8-position cell changer

Tube rack, micro-volume cell holder

Cuvettes: Glass(visible range), Quartz(UV range)

4. Detector

Most detectors depend on the photoelectric effect. The current is then proportional to the light intensity and therefore a measure of it.

5. Display

Radiation detectors generate electronic signals which are proportional to the transmitted light

These signals need to be translated into a form easy to interpret.

• 70*40mm backlit LCD screen

• 7-inch TFT color screen

•  7-inch capacitive touchscreen

Basic Principle:

Definition: A spectrophotometer is commonly used for the measurement of transmittance or reflectance of solutions, transparent or opaque solids, such as polished glass

Beer-Lambert’s Law 

When a beam of parallel monochromatic light is going through a dilute, uniform, and transparent

solution (light-absorbing material) vertically, the light absorption is proportional to the

concentration and thickness (length, optical path) of the solution.

Equation: A＝kcl

A = Absorbance(optical density of solution)

K = Constant(absorption coecient)

C = Concentration of solution

L = Path length