Various instruments currently used for elemental analysis mainly include:
1. Ultraviolet\visible light spectrophotometer (UV);
2. Atomic Absorption Spectrophotometer (AAS);
3. Atomic fluorescence spectrophotometer (AFS);
4. Atomic emission spectrophotometer (AES); ICP-AES or ICP-OES or inductively coupled plasma emission spectrometer
5. Mass spectrometry (MS);
6. X-ray spectrophotometer (XRF);
ICP-OES: is a type of atomic emission spectroscopy, formerly known as ICP-AES, was renamed ICP-OES;
ICP-MS: Inorganic mass spectrometry (MS), used to analyze the valence and content of elements, and also used for isotope analysis;
FAAS and GAAS: Flame atomic absorption and graphite furnace atomic absorption.
Hydride atomic absorption: HGAAS (HAAS)
Features and applications of AAS:
1. High sensitivity FAAS can test metals at ppm-ppb level;
2. Simple atomic absorption line, good selectivity and little interference.
3. The operation is simple and fast, and the automatic sampling can measure hundreds of samples per hour;
4. The measurement precision is good, the flame absorption precision can reach 1-2%, and the non-flame can reach 5-10%
5. There are many elements to be measured, more than 70 kinds of elements can be tested, and some non-metals can be tested indirectly by chemical reaction.
Disadvantages: The detection linear range is relatively narrow, which is not suitable for the detection of medium and high content elements. When measuring different elements, you need to change different element lights. It is not possible to measure multiple elements at the same time.
Features of Atomic Fluorescence:
1. It has a low detection limit and high sensitivity.
2. Less interference and simpler spectral lines.
3. The instrument has simple structure and low price.
4. The analysis calibration curve has a wide linear range, up to 3 to 5 orders of magnitude.
5. Because the atomic fluorescence is emitted in all directions in space, it is relatively easy to make multiple instruments, which can realize simultaneous measurement of multiple elements.
Features and applications of ICP-AES:
1. High temperature, 104K
2. Ring channel, with high stability
3. Inert atmosphere, stable electrode discharge
4. With good detection limits, some elements can reach 10-3~10-5ppm.
5. ICP has good stability, high precision, and the relative standard deviation is about 1%.
6. The matrix effect is small.
7. Small spectral background.
8. High accuracy, relative error of 1%.
9. Small self-priming effect
10. Wide linear range, measuring concentration range from ppm to tens of percent
Qualitative and quantitative analysis of more than 70 inorganic elements
Environmental Chemistry, Biochemistry, Marine Chemistry, Material Chemistry
Generally, only liquids can be measured.
Main features of mass spectrometer:
(1) Mass measurement range: the relative atomic (molecular) mass range of the sample can be analyzed, the gas range: 2-100, organic mass spectrometry tens to thousands.
(Two) distinguishing ability:
When two adjacent peaks of equal intensity, the peak valley is not greater than 10% of the peak height, the two peaks have been separated.
R = m1/(m2-m1) = m1/⊿ m
(3) Absolute sensitivity: the smallest sample amount that can be detected
Relative sensitivity: the ratio of large and small components that can be detected simultaneously
Analysis sensitivity: the ratio of input sample to instrument output signal
1. Organic compound test;
2. Cooperate with gas chromatography GC-MS;
3. Cooperate with liquid chromatography LC-MS;
4. With ICP, ICP-MS, test elements and their valence states, and test element isotope.
X Fluorescence Photometer (XRF):
Features:
1. Fast, it only takes 2min-3min to test a sample;
2. Non-destructive: test directly without damaging the sample during the test;
3. Wide content range: ppm-100%;
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