Microplate ReaderIt is a device which used to read the result of

ELISA test utilizing theory of spectrophotometer.ELISA-(Enzyme-Linked Immunosorbent Assay) Biochemical technique used mainly in Immunology to detect the presence of an antibody or an antigen in a sample.Also called  Photometric Microplate reader, ELISA reader

Theory of operation Microplate reader is specialized spectrophotometer which

facilitates readings on a wide range of wavelengths, generally between 400 to 750 nm.

Beer Lambert law, A = absorption ε = absorption coefficient l = path length c = concentration I0 = reference light intensity I = light intensity

A light beam, passing through the sample has a diameter ranging between 1 to 3 mm.

Then detection system detects the light coming from the sample, amplifies the signal and determines the sample’s absorbance.

l

c

Theory of operation

Internal Parts

Power supply

ELISA Plate

Light Source

InstallationA clean, dust free environment.A stable work table away from equipment

that vibrates (centrifuges, agitators).

calibration Calibration plates are equipped with at least three

predetermined optic density values within the measurement ranges; low, medium, and high value.

Place the calibration plate on the equipment and carry out a complete reading.

Verify if there are differences in the readings obtained from well to well. If this is the case, invert the plate (180°) and repeat the reading to rule out that differences are attributed to the plate itself. 

Identify the reader requires calibration. If so, proceed with the calibration according to manufacturer.

MaintenanceBasic : Daily  Preventive : Quarterly1. Review that optical sensors of

each channel are clean.2. If dirt is detected, clean the

light emitters and the sensors with a small brush.

3. When the daily operations begin, let the reader warm up for 30 minutes. Next, do a blank reading and then read a full plate of substrate. The readings must be identical.

4. Examine the automatic drawer sliding system. It must be smooth and constant.

1. Verify the stability of the lamp. Use the calibration plate conducting readings with intervals of 30 minutes with the same plate. Compare readings. There must be no differences.

2. Clean the detectors’ optical systems and the lighting systems.

3. Clean the plate drawer.4. Verify the alignment of each

well with the light emission and detection systems.

Basic fault Identification1. The reader gives a reading that

does not make sense 2. The reader’s readings vary from

row to row. 3. The reader displays unexpected

variation in the optical density readings.

4. The reader displays a gradual increase or decrease from column to column.

5. Low reproducibility.

6. Misaligned light beam.

1.0 The reader gives a reading that does not make sense …?

The illumination lamp is out of service.

Replace the lamp with one with the same characteristics as the original.

2.0 The reader’s readings vary from row to row.

• Dirty optical sensors. 

• The illumination system’s lenses or parts are dirty.

• Lack of calibration in one or more channels.

Clean the sensors.

Clean the lighting system’s lenses.

Verify the calibration of each one of the channels.

3.0 The reader displays unexpected variation with different wavelengths.

The reader’s lamp is unstable.

Replace the lamp with one that has similar characteristics as the original.

4.0 The reader displays a gradual increase or decrease from column to column.Inappropriate calibration of the plate’s controlling motor.

Calibrate the plate’s controlling system so that at each step the wells remain exactly aligned with the lighting system.

5.0 Low reproducibility.

• Sample homogeneity.

•Incorrect pipetting procedure.

•Reader not calibrated.

•Reading without sufficient warm up time.

•Expired reagents.

•Insufficient or Inefficient washing

Mix the reagents before use. Allow these to equilibrate to room temperature.

Ensure pipette’s tips are changed between samples and that excessive liquid inside is removed

Check the calibration.

Wait until the reader has warmed up to its operating temperature.

6.0 Misaligned light beam.

•The reader was transferred or moved without using the necessary precautions.

•The light source has been changed and the replacement has not been installed or aligned incorrectly

Call the specialized service technician.

Align according to manufacturer instructions

Thank you.