Colorimetric Test for Analytes Determination

As a classical wet chemical method, colorimetry is a technique that determines the concentration of an analyte by measuring its absorbance at specific wavelengths in the ultraviolet and visible spectra. It has both qualitative and quantitative properties, and its qualitative analysis involves recording the change in color to show qualitative chemical measurements and identification of the element. This can be a change in shading of the color or a change into a completely different color. The quantitative aspect involves sensory equipment that can measure the wavelength of the color. Changes in wavelength can be measured precisely and help indicate changes. Nowadays, colorimetric methods are very popular in many fields such as food chemistry, environmental analysis, and biochemistry. At BOC Sciences, our colorimetric method allows for consistent color determination and comparison that is more sensitive, accurate and repeatable than visual observation.

Principle of Colorimetric Test

There are two basic absorption laws of absorption that are important in colorimetric evaluation:

• Lambert's law: Lambert's law states that when monochromatic light passes through a solution of constant concentration, the absorption by the solution is proportional to the length of the solution
• Beer's law: Beer's law states that when monochromatic light passes through a solution of constant length, the absorption by the solution is proportional to the concentration of the solution

Figure 1. Colorimetric Detection of Bacteria. (Tram, K; et al. 2016)

What We Offer

At BOC Sciences, the most commonly used measurement in colorimetric methods is to determine the amount of analyte present in a solution by measuring the absorbance or transmittance of UV/Visible light at a specific wavelength versus the absorbance or transmittance of a solution of known concentration of the analyte. If a solute absorbs light of a specific wavelength, the absorbance is proportional to the concentration of the substance in solution. When a standard substance with the same absorbance and known concentration is identified, measuring the absorption of light by the sample gives accurate information about the concentration. We can reasonably ensure that the substances with the same absorbance also have the same concentration.

Application of Our Services

BOC Sciences' colorimetric test can be used for many analytes that are critical to different industrial operations:

• In petroleum refining processes, ammonia, phenols, iron and sulfides can be quickly measured using colorimetric methods
• In the wastewater treatment industry, colorimetric methods are applied to monitor ammonia, chlorine and phosphate
• In the medical and food & beverage industries, colorimetric methods can effectively test for residual disinfectants (chlorine, hydrogen peroxide, ozone, peracetic acid) to ensure the proper disinfection

Advantages of Colorimetric Test

Our well-designed colorimetric method is one of the simplest, fastest, and most adaptable means for analyzing samples under a wide range of environments and conditions.

• Excellent sensitivity and selectivity
• Stability testing to monitor changes over time
• Easy manufacturing control
• The test usually requires little to no sample preparation and can be completed in minutes
• Most of the colorimetric tests can measure below one part per million (ppm) and can be analyzed even at low concentration
• Our colorimetric methods can be adapted for both field or laboratory work

Figure 2. Sensitivity and specificity of the OvGST1a colorimetric NINA-LAMP assay. (Poole, C. B; et al. 2017)

Instruments of Colorimetry

• Colorimeter
• Spectrophotometer