Ultraviolet-visible (UV-Vis) spectrophotometer is a common laboratory analytical instrument that detects the absorbance and transmittance of liquid samples within ultraviolet and visible spectral ranges. During detection, incident light penetrates liquid samples, wherein solute substances absorb part of the light while the rest transmits through the sample. The instrument calculates sample absorbance by comparing the intensity of incident light and transmitted light, so as to quantify the target compound concentration in samples. Its detection principle complies with the Beer-Lambert Law, which defines the quantitative correlation between sample absorbance, analyte concentration and optical path length. With standardized testing procedures, the instrument enables rapid, accurate and reliable quantitative analysis of samples in routine laboratory experiments.