Spectrophotometers and microplate readers are both commonly used analytical measurement tools in laboratories. Their measurement principles are the same, both use the Lambert-Beer law, and both measure the absorbance of samples.

As instruments for measuring absorbance in the laboratory, there are some differences between laboratory spectrophotometer and microplate reader. The specific differences are as follows:

1. Container for the solution to be tested

The spectrophotometer uses a cuvette, and the microplate reader uses a plastic microplate (ELISA plate). The cuvette can only hold the solution, and each cuvette can only hold one solution at a time. As a solid phase carrier, the ELISA plate is usually 48 or 96 wells, and each microwell can hold a different solution.

2. Direction of the light path

The spectrophotometer is a horizontal light path, while the microplate reader is a vertical light path. Since the plastic microplate containing the sample of the ELISA plate has multiple rows of holes, the light can only pass through vertically, so the light beam of the ELISA reader passes vertically through the solution to be tested and the microplate, and the light beam can pass through the colorimetric solution from top to bottom or from bottom to top.

3. Length of the optical path

The width of the cuvette used in the digital spectrophotometer is usually 1 cm, so the optical path length is fixed at 1 cm. Therefore, the data measured by different instruments and different batches are equally comparable. The microplate reader uses a vertical optical path, so the length of the optical path should be the height of the liquid surface. Therefore, the measured value is affected by the volume of the sample.