How to choose Kyushu Space Card
UV-visible spectrophotometer
How do we evaluate the pros and cons of an UV-Vis spectrophotometer? First, let's examine its appearance. Then, we explore several important indicators that have a major impact on the use of the instrument:
1. Stray light It means that there should be light in places where there should be no light. It is the main source of error in spectral measurements. Of course, the smaller the value, the better.
2. Photometric accuracy Photometric accuracy refers to the difference between the actual measured photometric reading and the true value. It is the direct requirement of the user for the instrument, and every user must pay attention to it.
3. Noise noise is also one of the important indicators of the instrument. It characterizes the instrument's ability to make dilute solutions. This indicator is also as small as possible.
4. The spectral bandwidth refers to the band width at a height of 1/2 of the intensity curve of the monochromatic spectral line emitted from the monochromator. Characterize the spectral resolution of the instrument. According to Beer's law, the spectral bandwidth should be as small as possible, but if the source energy of the instrument is weak, the sensitivity of the optical sensor is low, the spectral bandwidth is small, and the ideal measurement result is not obtained. Therefore, be careful when selecting and using the instrument.
5. Stability stability is one of the most important indicators for users. The purpose of the instrument is to be stable and reliable, and unstable is not reliable.
6. Noise noise is also one of the important indicators of the instrument. It characterizes the instrument's ability to make dilute solutions. This indicator is also as small as possible.
7. Wavelength Accuracy and Repeatability Each value of the instrument is measured at a certain wavelength. If the wavelength shown and the actual wavelength deviate by a million miles, then what is the agreement between the measured value and the true value? What? The importance of this indicator can be seen.
In short, these indicators are independent and interrelated, and each indicator has a great impact on the use of the instrument. I hope that everyone can buy UV, visible spectrophotometer, compare and do more judgments, and find a stable and reliable helper.
When we choose, we need to consider the optical structure and light source, detection method, sample type and data processing according to the needs of our laboratory.
Optical construction
In general, ultraviolet spectrophotometers are classified into single beam and double beam. 1 Single beam type mainly relies on single beam light for measurement. A beam of light of a given wavelength passes through the control and then through the actual sample solution to obtain a light absorbing result.
In the double beam type, a beam of light is split into two beams by a mirrored chopper wheel, and the control sample and the actual sample are separately measured. It is possible to minimize lamp drift and reduce measurement time. Some dual-photometers do not use a calender wheel, but instead use a beam splitter instead of splitting one beam into two parallel beams and simultaneously measuring the control and destination samples. Because of the increased measurement speed, dual beam spectrophotometers are useful in the study of measuring the dynamics of some solutions over time.
2. Sample type
In most sample types, the spectrophotometer accepts sample wells, small glass tube cuvettes, suction tubes, and microplates.
Samples are typically used in small syringes from 1 μl to 5 ml, and some instruments are equipped with various sample fixtures to meet a variety of changing needs.
3. Light source and detection method
The spectrum of the spectrophotometer is also an important factor to consider.
Ultraviolet spectrophotometers typically cover wavelengths of 190 nm and 380 nm and are typically illuminated with xenon lamps. Some special instruments provide spectral ranges that meet the needs of photonics and semiconductor research.
Some instruments can choose from a variety of sources: ultraviolet, visible, and even infrared (780 nm to 3,000 nm). Tungsten and halogen lamps typically cover only the visible portion (approximately 380 nm to 800 nm). The xenon lamp can cover the ultraviolet and visible regions.
The bandwidth of the spectrophotometer is highly dependent on the width of the slit of the monochromator. It is possible to project a spectrum that is precisely required for the experiment. A rigorous bandwidth allows the instrument to perform high-resolution absorbance measurements on complex mixtures. The slit width of the variable monochromator enables a spectrophotometer to meet a variety of experimental needs.
Spectrophotometers typically measure the absorbance using a photomultiplier tube and a photodiode.
4. Sample type
In most sample types, the spectrophotometer accepts sample wells, small glass tube cuvettes, suction tubes, and microplates.
Samples are typically used in small syringes from 1 μl to 5 ml, and some instruments are equipped with various sample fixtures to meet a variety of changing needs.
5. Data Management
Most stand-alone spectrophotometers include software that drives instrument operation and management data. High-performance instruments, often used in conjunction with PCs, require additional software from the manufacturer.
It can be seen that the ultraviolet, visible spectrophotometer is a conventional laboratory analytical instrument. It can be widely used in the qualitative and quantitative analysis of inorganic and organic substances, and plays an important role in the fields of scientific research, pharmaceutical, chemical, environmental protection, health, and epidemic prevention.
Egg Waffle Maker,Egg Puff Maker,Egg Waffle Machine,Round Commercial Waffle Maker
Guangdong Puda Electrical Appliance Co., Ltd. , https://www.elecapoka.com