Spectroscopy-Potassium Bromide Pellet Method/ATR
Bruker (ALPHA), Bruker (Tensor27), Bruker (VERTEX 70), IRTracer-100, Nicolet iS5
The Fourier transform infrared spectrometer is different from the principle of dispersive infrared spectroscopy. It is an infrared spectrometer developed based on the principle of Fourier transform of infrared light after interference. It mainly consists of infrared light source, diaphragm, interferometer, sample room, It consists of a detector and various infrared reflectors.
It has the advantages of high signal-to-noise ratio, good reproducibility, and fast scanning speed. It can qualitatively and quantitatively analyze the molecular structure of inorganic, organic, and polymer samples. ATR and diffuse reflection accessories can be added without special sample preparation.
The following tests are performed on bulk solids and liquids that are not easy to grind, and are widely used in the fields of medicine and chemical industry, geology and mining, petroleum, environmental protection, gem identification, and criminal investigation identification.
There are many types of instruments available for testing, if necessary, please contact is for further information.
The items that can be selected for infrared testing are: potassium bromide tablet method, ATR mode, diffuse reflection. (Please determine the appropriate test method based on the relevant literature and the state of the sample)
In general, powder samples are suitable for potassium bromide tableting method and diffuse reflection mode, and irregular solid samples and liquid samples are suitable for ATR mode.
The sample preparation process of the potassium bromide tableting method is carried out in a dry box. The data after the test deducts the potassium bromide background peak to eliminate the effect of potassium bromide water absorption.
Test range can be selected: conventional test range (4000-400 cm-1), unconventional test range (6500-200cm-1)
The test fee varies slightly according to each specific scope.
Support infrared spectrum database comparison and retrieval, analyze unknown samples, and infer possible components.
For samples with high water content, please refer to the literature as the Raman test might be better.
- Spectral range: 6000-200 cm-1
- Signal to noise ratio: better than 60000:1
- Resolution: better than 0.25 cm-1
- Accuracy: 0.01 cm-1 (wave number accuracy) 0.07%T (absorption accuracy)
Requirement on Sample
Infrared testing is performed on samples that do not contain water, dark colors, or easily absorb water. In general, the results are not good, and the jitter of the curve will be obvious, not caused by the testing instrument.
Tableting method (powder): does not react with potassium bromide, solid (grindable) or lyophilized powder sample; sample size >10mg (the amount that can actually be taken from the sample bag or centrifuge tube)
ATR (solid liquid and powder): the solid should have a flat surface as much as possible, the area is greater than 1cm2 and the thickness is 10mm (reference value, slightly lower than this value does not affect the test effect), liquid 2mL.
The effect of the potassium bromide tableting method on dark samples may not be ideal. It is recommended to use the ATR mode.
Diffuse reflection (powder): It must be a powder sample with a mass above 0.1g.
In order to ensure the test effect, please provide a sufficient amount of samples to prepare samples to achieve the best signal strength.
Please communicate and confirm before placing an order for liquid samples (water peaks may interfere with the test).
Corrosive, toxic and radioactive samples cannot be tested.
How to determine which test method is suitable for my sample?
- Potassium Bromide Pellet Method method is suitable for powder samples. This method involves the influence of impurity peaks brought by potassium bromide. Generally, the method of deducting potassium bromide background and air background is selected (the specific method can be specified by the customer), and the potassium bromide background can be deducted as much as possible Avoid the impurity peaks introduced by potassium bromide (mainly because potassium bromide is very easy to absorb water, and the influence of the hydroxyl peak is very obvious) ATR method is suitable for various solids, bulk films, liquids, etc. that cannot be ground into powder samples. The advantage of this method is that there are no other impurities Peak interference, but the disadvantage is that some samples have weaker peaks.
Some peaks in the infrared spectrum are not detected or the signal is not strong?
- The provided data is simply processed by smoothing and baseline flattening, and some small impurity peaks will be removed. The original data of the test are saved, and you can contact the staff to obtain it if necessary. For samples with darker colors, especially black samples, adding more during sample preparation will result in poor transmittance, and less signal will be weaker. The testing will try to ensure the signal strength.
Can the ordinate of my data be converted from absorbance to transmittance?
- It can be converted through omnic or origin software, or note the desired ordinate name when placing an order.
What are the requirements for infrared testing to ensure data quality?
1. The sample must be purified in advance to ensure sufficient purity;
2. The sample must be dewatered and dried in advance to avoid damage to the instrument and avoid interference of water peaks on the sample spectrum;
3. Samples that are prone to deliquescent should be placed in a desiccator.
4. For samples that are volatile, sublimate, and unstable to heat, please use a container with a sealed lid or stopper to hold and close tightly. At the same time, it must be labelled properly.
5. For toxic and corrosive samples, the user must seal the container. The samples must be clearly marked on the label of the sample bottle when sending samples.