Single beam and dual beam UV-VIS absorption spectrophotometers

What is UV-VIS spectrum and absorption, transmittance

  • UV-VIS spectrum or UV-VIS molecular absorption spectrum is due to the molecules absorbing radiation from the incident beam in the UV-VIS region.
  • UV-VIS spectrometer is a device used to measure the absorption of molecules at the radiation used.
  • And usually the radiation chosen must be selective and have the best absorption for the molecule (if there are no interfering factors)
  • To choose the appropriate wavelength or radiation, people conduct a "spectrum scan" to choose the maximum or appropriate absorption wavelength
  • A compound can have many maximum absorption wavelengths (peaks)
  • Determined by Lambert Beer's law.

Transmittance (T) is the ratio of the amount of light passing through a sample (P) to the amount of light initially incident on the sample (incident light, Pₒ)

Transmittance T = PPo
The absorbance (A) of a sample is defined as the reciprocal of the logarithm of the transmittance.

Absorbance A=−log⁡T=−log⁡PPo

 

Quang Phổ So Màu UV VIS

UV VIS Color Spectrometer

Single beam absorption spectrometer

  • Simple design, only one beam is directed to the sample.
  • Advantages: cheaper than the 2-beam type
  • Disadvantages: cannot eliminate interference factors due to the sample background.
Nguyên tắc hoạt động của máy quang phổ hấp thụ phân tử UV VIS một chùm tia

Operating principle of single beam UV VIS molecular absorption spectrophotometer

Dual beam absorption spectrometer

  • More complex structure
  • Higher cost
  • Removes background factor, covet or monochromaticity of wavelength used.
  • So has higher accuracy
Nguyên tắc hoạt động của máy quang phổ hấp thụ phân tử UV VIS hai chùm tia

Nguyên tắc hoạt động của máy quang phổ hấp thụ phân tử UV VIS hai chùm tia

 

Applications of Single Beam and Dual Beam UV-VIS Absorption Spectrophotometers

  • Based on the absorption spectrum, the molecule can be qualitatively identified. Based on the absorption or transmittance, the analyte content can be quantified according to the Beer Lambert law.

Confounding factors

  • In a mixture there are many substances that can absorb at the wavelength used
  • The thickness of the cuvette wall is different, either reflecting or partially absorbing
  • The ambient temperature is also a factor that affects the measurement of the absorption of the molecule
  • The “purity” of the wavelength used, usually has a certain deviation.

Where to buy UV VIS spectrophotometer?

SMLH is the official representative of PEAK Instruments in the Vietnamese market. Please contact us for direct consultation on Single-beam and Dual-beam UV-VIS Absorption Spectrophotometers

Hotline 0987445016