In the chemical industry, we usually come into contact with many solutions that need to measure the chromaticity. These solutions are often transparent or translucent, which requires a desktop spectrophotometer to measure the color. Translucent solution, because of its projectivity, needs a desktop spectrophotometer to measure its chromaticity. Here is a brief introduction to the application of desktop spectrophotometer under the index of platinum cobalt chromaticity.

Textile, printing and dyeing, petroleum, battery and other chemical industries often produce a lot of industrial wastewater in the production process. The national standard for detecting the chromaticity of wastewater mainly adopts platinum cobalt colorimetry and dilution multiple method.

Platinum cobalt chroma is expressed in Hazen. Each liter of solution contains 1 mg of platinum. The color of chloroplatinic acid and 2 mg of cobalt chloride hexahydrate solution is 1 unit of platinum cobalt chroma. The general value range is 1-500. It is suitable for determining the color of transparent or liquid chemical products with platinum cobalt color number slightly close to the reference. This color feature is usually brown yellow.

Figure 1: platinum cobalt colorimetric standard solution

The traditional platinum cobalt colorimetry has three disadvantages: 1. The manufacturing process of standard colorimetric solution is complex; First, prepare the standard colorimetric mother liquor, dissolve 1.00G of cobalt chloride hexahydrate (CoCl2 · 6H2O) and 1.05g of chloroplatinic acid or 1.25g of potassium chloroplatinate into water in a 1000ml volumetric flask, add 100ml of hydrochloric acid solution, dilute to the score line, and mix evenly. Add the body technique number of the standard colorimetric mother liquor shown below into 10 500ml and 14 250ml volumetric flasks respectively, dilute to the scribed line with distilled water and mix.

Figure 2: preparation of platinum cobalt standard colorimetric solution

2. It is difficult to store the solution; The prepared solution should be put into a brown glass bottle with a stopper and placed in the dark. The mother liquor can be kept for 1 year and the diluted solution can be kept for 1 month. The solution often needs to be reconfigured, which is very troublesome.
3 is the limitation of human eye colorimetry; Platinum cobalt colorimetry is based on human eye judgment. The color is affected by environmental light source, observation angle and other factors. There are some differences in the actual visual colorimetry.

In view of the shortcomings of platinum cobalt colorimetry in the actual color comparison, a spectrophotometer can also be used to compare the color of the solution. There are three advantages of using spectrophotometer for measurement: 1. There is no need to configure solution and do not consider the problem of material storage; 2. The instrument is easy to operate and can be measured directly; 3. Platinum and cobalt data are clear at a glance.

Next, the desktop spectrophotometer cs-821n is used to introduce the measurement process. First, adjust the instrument measurement mode to [liquid chromaticity] measurement. Under this measurement mode, the chromaticity indexes of platinum cobalt, Gardner, Saybolt and ASTM can be measured.

Figure 3: select [liquid chroma] for measurement

After calibration according to the prompt, place the solution to be measured at the transmission measuring port, as shown in Figure 4 below.

Figure 4: transmission measuring port

When measuring the solution, the instrument can directly feed back the platinum cobalt value of the solution. As can be seen in Figure 5, the platinum cobalt chromaticity value of the solution is 121.85. Through the value, the platinum cobalt chromaticity of the solution can be intuitively known for the convenience of subsequent work.

Figure 5: measuring solution

In addition to its application in water quality analysis, platinum cobalt chroma can also be used to measure the chroma of solutions of chemicals and petrochemical products, such as glycerol, solvent, plasticizer, carbon tetrachloride, petroleum alcohol, etc. The desktop spectrophotometer can meet the measurement of the above solutions. Welcome to contact us for more information about spectrophotometer.