What is meant by chemical interferences?
Chemical interferences. Chemical interference occurs when an analyte is not totally decomposed in flame. There is less atoms present, and therefore a reduced absorbance of the analyte.
What is the function of monochromator in AAS?
Monochromator is a vital optical component of the Atomic Absorption Spectrometer. It plays the function of isolating the wavelengths of interest from the broad spectrum of wavelengths emanating from the hollow cathode lamp.
Why is atomization necessary in AAS?
Sample atomization limits the accuracy, precision, and limit of detection of the analytical instrument. The purpose of the atomization step is to convert the analyte to a reproducible amount of gaseous atoms that appropriately represents the sample.
What are the components of AAS?
The standard AAS instrument consists of four components: the sample introduction area, the light (radiation) source, the monochromator or polychromator, and the detector (figure 1).
What are spectral interferences?
Spectral Interferences Spectral interference is caused by radiation overlap of absorption line due to emissions from another element or compound. Spectral interference is also effected by the radiation of an emission line of another element or compound, or background radiation from flame, solvent or sample.
What are interferences in flame photometry?
Spectral interferences are realized when some flame species other than the analyte emits or absorbs radiation sufficiently close to the characteristic wavelength of the analyte. Generally, spectral interferences are more common in emission spectroscopy than in absorption spectroscopy.
What is the function of slit?
The slit function is the monochromatic image of the entrance slit of the spectrometer on the detector. Accurate knowledge of this slit function for all wavelengths and field angles is very important both for the spectral calibration and for the DOAS retrieval algorithm.
Does AAS use a monochromator?
The Monochromator and PMT Since the basis for the AAS process is atomic ABSORPTION, the monochromator seeks to only allow the light not absorbed by the analyte atoms in the flame to reach the PMT.
What is atomizer in spectroscopy?
AAS systems are either flame atomic absorption spectrometers (F-AAS) or graphite atomic absorption spectrometers (G-FAAS). In F-AAS, the atomizer is a flame furnace, and in G-FAAS, the atomizer is a graphite furnace. The sample is introduced into the atomizer. In F-AAS, the heat of the flame produces the free atoms.
What is flame atomizer?
In a flame atomizer, a solution of the sample is nebulized by a flow of gaseous oxidant, mixed with a gaseous fuel, and carried into a flame where atomization occurs. As shown in Figure, a complex set of interconnected processes then occur in the flame.
What is the correct order of AAS?
What are the two steps in the processing of AAS?
The process of atomic absorption spectroscopy (AAS) involves two steps:
- Atomization of the sample.
- The absorption of radiation from a light source by the free atoms.
What kind of interference does extra al or Ti cause?
Addition of extra Al or Ti will not affect the signal – decreased absorbance. Ionization interference affects Gp 1 and 2 only. These include Ba, Ca, Sr, Na, K This occurs only in hot flames.
When does chemical interference occur in atomic absorption?
Chemical interference occurs when an analyte is not totally decomposed in flame. There is less atoms present, and therefore a reduced absorbance of the analyte. Compound Formation. Compounds cannot be broken down in flame.
How does ICP-MS correct for polyatomic interferences?
Current ICP-MS instrumental software corrects for all known atomic “isobaric” inter- ferences, or those caused by over- lapping isotopes of different elements, but does not correct for most polyatomic interferences.
How is absorbance of an element measured in AAS?
If an absorbing wavelength of an element , not being determined but present in the sample falls within the measuring line of the element of interest, the absorbance of the element will be measured together with the analyte of interest and give a higher absorbance value. Note: Interference due to overlapping lines is rare in AAS.