The colorimeter is one of the most interesting pieces of scientific equipment, and it can be found in almost any lab from the college level upwards. In the standard configuration, there is a beam of light shot through a prism. After which, the light coming from the prism hits a water-based sample while a detector on the far end records how much light has passed through. What can be discovered by completing assays of the sample is how the transmittance & absorbance of light correlate to concentration. Turbidity is also measured, which is essentially a measurement of the degree of “murkiness” in water. For most people who work in a lab, the colorimetry machine was the first “real” piece of lab equipment they laid their hands on. Because of that, many people hold a level of fondness for this kind of equipment.
Why does every lab have a colorimeter somewhere?
Colorimetric assays are the foundation of modern science & lab education because they can very effectively produce precise numbers correlating to the amount of solute in a solvent as well as simple data collection even when using amounts of water in the realm of just a few nanoliters.
The first sample is placed into an aqueous solution inside a rectangular tube called a cuvette. Very small amounts of sample can be used with the proper dilution factors in play. Then, it is simply a matter of inserting the cuvette into the machine and turning it on.
When the beam shot through the sample has ended, the machine forwards a reading from the end of the passageway that gives insight into how much light managed to pass through. This information is typically displayed in absorbance which measures how much light radiated away from the sample. Solutions of certain chemicals have their absorbance fluxuate linearly with concentration, so when the right wavelengths are set with regards to the prism on the colorimeter the concentration of many known chemicals can be analyzed.
Running colorimetry equipment is extremely inexpensive while the insights they provide are insanely valuable. Relatively untrained technicians can discover & extrapolate a vast variety of information with the absorbance value produced by the machine.
What is this used for?
People have long wanted to be able to take a sample and accurately know how much of what they’re looking for is suspended in the solution. While it was discovered that color changes depending on the concentration, at very similar concentrations the difference in color is far too slight for the human eye to detect. The science of colorimetry allows for extremely precise & replicable results when dealing with samples of certain substances in a laboratory setting. It can help troubleshoot issues in the human body when certain fluids are running & other data are factored in and new substances can be tested, made, and perfected thanks to colorimetry.
As far as lab equipment is concerned with the grand scheme, it is a basic piece of equipment that doesn’t really do much special. Still, useful applications include monitoring the growth of bacterial cultures, checking for toxic levels of certain substances, as well as checking the viability of soil samples. Much of our science is based on colorimetric data, it isn’t uncommon to find tables full of the normal absorbance and transmittance data for commonly measured items for use in calculations. It is also worth mentioning that the colorimeter is an excellent tool for helping students understand the basic concepts like analysis and the nature of preparing samples.
Reinventing the wheel
Old school colorimeters were more like something you’d see in a Microsoft catalog from the 90s. Besides the massive automated analyzer machines used by hospitals, the handheld colorimeter was a device operated primarily by hand with regards to making solutions via pipette and then manually inserting them into the machine. Results had to be recorded manually and maintenance was required frequently to keep the machines working accurately.
A more modern take on this wonderful device takes advantage of the digital network available surrounding laboratory equipment and modern data collection technology. A wireless colorimeter turns a tablet or computer into the display screen of the device and allows for a much more compact piece of equipment. Modern sensors are much smaller & well made and the wireless connectivity makes for a rapid-fire recording of samples back to back. Having to frequently fumble around with sample cuvettes and meticulously deal with temperamental machines, wastes valuable lab time as well as increases the chances of human error. These machines are small, convenient, much more accurate & applicable than their predecessors, and more often than not are not extremely pricey.
Time is of the essence in the classroom, which incidentally enough is one of the institutions who make more frequent use of these modern colorimeters. The correlation between absorption and concentration can be taught much faster, allowing students to see in practically real time the effects of adding more solute to any given solvent.
Labs that are strapped for space also benefit greatly from these small platform driven devices that upload all of their data to a central location. Routine assays and quality control work can be done at the drop of a hat. Even those with ample space can benefit from having the machine hooked up directly to a mobile device.
Since the very beginning of modern science, there’s been a push to make lab conditions as efficient, safe, and accurate as possible. Much of the equipment we use tends to exploit the phenomena in a complex but measurable way to allow us greater insight into its composition. Since colorimeters are used in such a widespread fashion, it makes sense that it would eventually get a modern revamp. Much of our compiled information on many different aspects of biology and chemistry can be traced all the way back to an original colorimetric analysis many decades ago. Expect colorimeters to continue to get more and more sophisticated as time goes on, right now they’ve managed to eliminate just about all of the drawbacks associated with the older machines.