The holographic blazed grating monochromator has the advantages of high wavelength accuracy, good monochromaticity and low stray light. Linear regression method and coefficient method are added to the concentration test method. USB interface is added, and large capacity memory can store 30. 721G/722G visible spectrophotometer enables quantitative and qualitative analysis of samples within the visible spectrum. It can be widely used in pharmaceutical manufacturing, health, clinical tests, biochemistry, petrochemical industry, environmental protection and quality control fields. ● 7-inch multi color touch-screen, good human-computer interface. Built in SCM technology,auto 0%,auto 100%,error-free T/A transformation. It operates on the principle of Beer–Lambert law-based absorbance measurement, utilizing a.