Spectral analysis

Concept

The principles of spectroscopy and experimental methods are used to determine the structure of the substance and the analysis method of the chemical composition.

English is SpecTralandalysis or Spectrumanalysis. The substances of various structures have their own feature spectroscopy, and the spectral analysis is to use the characteristic spectroscopy to study the substance structure or the method of determining chemical components.

Classification

Spectroscopy mainly includes atomic emission spectroscopy, atomic absorption spectroscopy, ultraviolet - visible absorption spectroscopy, infrared spectroscopy, etc. According to the nature of electromagnetic radiation, spectral analysis can be divided into molecular spectroscopy and atomic spectroscopy.

principle

The molecular absorption spectrum generated by electromagnetic radiation energy generated in 200 to 760 nm interval is called ultraviolet-visible absorption spectrum of the substance, and utilizes UV- It can be seen that the qualitative and quantitative analysis of the absorption spectrum is referred to as an ultraviolet-visible spectrophotometry. The spectrum is generated due to the leaping of the medium price electrons of the molecules, so this absorption spectrum is determined in the distribution and binding of the molecular price electrons. Its application in the field of feed processing analysis is quite wide, especially in determining the content of lead, iron, lead, copper and zinc plasma in the feed. Fluorescence analysis is also a rapid trace analysis method in recent years. This method is simple, fast, high sensitivity, high precision and accuracy, and wide linear range and low detection limit.

History

1858 ~ 1859, German chemical life and physicist Kirhof laid a new chemical analysis method - spectrum analysis method. The two of them were recognized as the founder of the spectral analysis.

Application

Spectroscopy has created a new era of chemical and analytical chemistry, and many chemical elements found through spectral analysis. It has been widely used in many aspects of geological, metallurgy, oil, chemical, agriculture, medicine, biochemistry, and environmental protection. Spectral analysis is one of the commonly used sensitive, fast and accurate modern instrument analysis methods.

Features

(1) Analysis speed faster atomic emission spectrum for steelmaking furnace, can be given in L ~ 2 minutes, more than 20 elements Analysis results.

(2) Easy to operate, some samples can be directly used without any chemical treatment, using computer technology, sometimes simply pressing the keyboard to automatically analyze, data processing and printing analysis results . In terms of toxic alarm, atmospheric pollution detection, molecular spectroscopy is used to measure, and samples are not required, and the alarm can be issued or the degree of pollution can be detected in several seconds.

(3) Do not require pure samples to use a known spectrum to be spectrum qualitative analysis. This is a spectral analysis of a very prominent advantage.

(4) can simultaneously measure multiple elements or compounds to complex separation operations.

(5) Selective elements and compounds that can determine chemical properties. As measured, tantalum, zirconium, hafnium, and mixed rare earth oxides, their lines can be separated and uninterrupted, and become a try force for analyzing these compounds.

(6) Sensitivity can be used to use spectroscopy for trace analysis. Relative sensitivity can reach a thousand to 100 billion, absolute sensitivity can reach 10-8 g to 10-9g.

(7) Sample damage is less useful in the fields of antiquities and criminal reconnaissance.

With the adoption of new technologies (such as the application of plasma light sources), the linear range of quantitative analysis is wider, and elements having different high and low content can be measured simultaneously. Micro-zone analysis can also be performed.

Limitations: Spectral quantitative analysis is based on relatively comparative basis, and a standard sample must be used as a reference, and the composition and structural state of the standard sample should be basically consistent with the sample being analyzed, which is often compared. difficulty.