Understanding the Major Differences between Single Beam and Double Beam Spectrophotometers

 

Biotechnology research laboratories have several instruments to that help them extract information from biological specimens. Among the popularly used lab machines, spectrophotometers are used for measuring the wavelength of light and its intensity. You will get them in several shapes, sizes, and types.

Here are two types of beam spectrophotometers:

• Single bean spectrophotometer
• Double beam spectrophotometer

Single beam spectrophotometer

In single beam spectrophotometers, the light waves emanating from a source of light pervade a sample as a single beam. Through standardization of the instrument in which a reference is marked in the sample holder, the final value is subtracted from the rest of sample measurements to remove the impact from the cell and the sample. Usually, the sensitivity of light detection beam is high when it passes through the sample as it does not split. Hence, you will notice high energy presence throughout the process.

Double beam spectrophotometer

The name says it all. In double beam spectrophotometers, the source of light divides into two different beams. Here one beam passes through the sample and the other through the reference. Furthermore, the monochromatic beam splits into two beams of equal intensities with the help of a half-mirrored device.

The sample beam passes through a similar-looking cuvette comprising the compound that is meant for investigation in the transparent solvent. The other one or the reference beam passes through another similar cuvette containing the solvent only. A comparative study of these light beams is then conducted after carrying out their measurements with electronic detectors.

Understanding the differences between the instruments

You are familiar with the basic functions of a single and double beam spectrophotometer. So, it’s time now to dig deeper and find out what the major differences are between a single and double-beam instrument:

• Light beam

In the double beam device, the beam coming from the source of light divides into two parts whereas in the single beam device, only one light beam emits from the source of light. Furthermore, in the double beam device, the ray of light illuminates the sample and the reference standard that comes together before reaching the monochromator that is an integral part of the sample. In the single beam spectrophotometer, on the other hand, the ray of light comes through a single source of light used for illuminating the samples as well as reference points.

Tips for Optimizing Double Beam UV Spectrophotometer Performance

• Measurements

Measurements conducted using a single beam spectrophotometer is carried out with a single ray of light. Therefore, they do not yield as much as the double beam spectrophotometer does. The measurements taken with double-beam devices are highly result-driven and affect the samples and references within an equal frame. Moreover, the mechanical and electronic impact on the sample and references also occurs within the same space. Naturally, double beam devices are more popularly used than single beam devices.

• Types of light beams

Talking about the nature of light beams used in single and double ray devices, the differences impact the measurements and the result obtained when testing samples in biotechnology laboratories. While the ray of light in the single beam device cannot split into two, the light rays in the double beam device splits into two when passing over the samples.

Differences in applications

What are those differences between a single beam and double beam spectrophotometer that make them appropriate for specific applications? Run through these pointers to discover more:

1. Single beam spectrophotometers are less expensive than their counterparts and also have lesser impact.
2. The sensitivity of detection is higher in single ray devices and is known to have maximum energy throughout as the ray of light does not split into two.
3. Single beam devices may not be the best choice when you are looking for stability in measurements as it fails to substantiate for fluctuations in the electrical circuit, lack of integrity of mechanical components, fluctuation of voltage, or drifts in light sources.
4. Double beam devices are more efficient and compensate well for fluctuations in the power source.
5. The double beam devices operate more speedily and yield more specific results compared to single beam devices as the former undergoes an auto correction for the amount of light lost when it passes through the sample and the reference.
6. The double beam spectrophotometers cost is more expensive.

Which device should you choose?

You are now well-versed with various functions and components of double and single beam spectrophotometers, and it’s time to get rid of the dilemma as to which one you should buy. Here is how it goes:

The single beam devices maintain a high energy level throughout as the ray of light does not split, making the detection more sensitive. Besides, they are more affordable. The double ray devices take the detection to the highest point by reducing the disturbing instances. Furthermore, the lamp life can be conserved as it does not need to warm up and improves the results significantly. For double beam spectrophotometers that are ideal for laboratory use, drop in at https://www.igenels.com/ for instruments used in microbiology applications.

FAQ

1. What is the detector used in a double beam spectrophotometer?

The detector used in the modern-day UV-Vis double beam spectrophotometers is the photomultiplier tube, comprising an anode, cathode, and several dynodes.

2. What is the limitation of a single beam spectrophotometer?

Single beam spectrophotometers are susceptible to fluctuations in the intensity of source light, resulting on erroneous measurements.

3. Why is a double beam spectrophotometer better than a single beam spectrophotometer?

A double beam spectrophotometer runs faster and provides more specific results as it auto corrects the loss of intensity of light when the beam passes through the reference solution and the sample.