In modern scientific research and industrial production, the UV-VIS-NIR spectrophotometer has become a necessary analytical tool. As a highly sensitive and accurate instrument, it can accurately measure the absorption characteristics of substances in the ultraviolet, visible, and near-infrared spectral regions, providing key data support for qualitative and quantitative analysis of substances. From chemical analysis to biological research, from materials science to environmental monitoring, UV visible spectrophotometers have a wide range of applications.

The core working principle of UV visible spectrophotometer is based on Lambert Beer's law. When a parallel monochromatic light is vertically irradiated through a uniform, non scattering absorbing substance solution, the absorbance (A) of the solution is proportional to the concentration of the absorbing substance (c) and the thickness of the liquid layer (b), and its mathematical expression is:

A=ε⋅b⋅c

Among them, ε is the molar absorptivity, which is the characteristic constant of the substance. By measuring the absorption of light by samples at different wavelengths, the instrument can determine the content and structural information of substances.

The structure of the instrument mainly includes a light source, a monochromator, a sample cell, and a detector. The light source provides a continuous spectrum of ultraviolet and visible light regions, the monochromator decomposes the composite light into monochromatic light, the sample cell holds the sample solution, and the detector converts the optical signal into an electrical signal for amplification and measurement.

The accuracy of test results is influenced by both sample and instrument factors. The concentration, purity, and solution state (such as pH value, ionic strength, temperature) of the sample directly affect the spectral characteristics. For example, excessive concentration may cause absorption values to exceed the linear range, impurities may produce additional absorption peaks, and changes in the pH value of the solution may alter the form of the substance.

In terms of instruments, wavelength accuracy, absorbance accuracy, and stray light are key factors. Inaccurate wavelength can lead to measurement deviation, noise in absorbance, and baseline drift can affect the reliability of the results, while stray light can cause the measured absorbance to be lower. Regular calibration and maintenance of instruments are necessary measures to ensure the accuracy of test results.

The concentration of the solution sample should be controlled within an appropriate range (absorbance 0.2-0.8) to ensure clarity, transparency, and chemical stability. If there is turbidity, it needs to be filtered or centrifuged. Solid samples need to ensure uniformity and transparency, while powder samples need to be thoroughly ground or processed using the pressing method.

Instrument preheatingTurn on the power and preheat for 15-30 minutes to ensure the stability of the light source and detector.

Wavelength calibrationUse standard light sources such as mercury lamps to calibrate wavelengths and ensure accuracy.

Sample preparationSolution samples need to be accurately prepared and filtered, while solid samples need to be processed into a uniform state.

Baseline correctionCorrect background absorption with blank samples.

Sample testingPut it into the sample pool and measure it according to the set wavelength range and scanning speed.

data processingDraw standard curves or analyze spectral characteristics to obtain concentration or structural information.

As a manufacturer of analytical instruments, Shanghai Spectral Analysis Instrument Co., Ltd. relies on its UV visible spectrophotometer productsWidely applied in various fields, it has won a good reputation in the market.