What are the interferences in AAS?
HCL is the most commonly used lamp in AAS as a line source. Interference is a phenomena that leads to changes (either positive or negative) in intensity of the analyte signal in spectroscopy. Interferences in atomic absorption spectroscopy fall into two basic categories, namely, non-spectral and spectral.
What are the factors that cause interference in AAS?
SPECTRAL INTERFERENCES Spectral interferences are caused by presence of another atomic absorption line or a molecular absorbance band close to the spectral line of element of interest. Most of these interferences are due to molecular emission from oxides of other element is a sample.
What are the chemical interferences encountered in the analysis of calcium by atomic absorption spectroscopy?
Ionization enhancements and refractory-compound formations are the most important interferences found in the analysis for calcium. Pro- tecting agents and the method of additions can both be used to overcome these interferences.
What is atomic absorption spectroscopy PDF?
Atomic absorption spectrometry (AAS) is an analytical technique that measures the concentrations of elements. Atomic absorption is so sensitive that it can measure down to parts per billion of a gram (µg dm–3) in a sample. The technique makes use of the wavelengths of light specifically absorbed by an element.
What are the applications of AAS?
Atomic absorption spectroscopy is utilized across many industries and is instrumental in the detection of metals within a sample. As such, this process is commonly utilized in pharmacology, archaeology, manufacturing, mining, and forensics.
How can spectral interference be prevented?
Avoidance: ICP-OES
Several modern ICP instruments have the capability of avoiding the spectral interference by going to another line. Many instruments can make measurements simultaneously on several lines for 70+ elements in the same time it used to take to make a measurement on a single line/element combination.
How do you overcome spectral interference?
Spectral interferences can be overcome by the application of higher mass resolution (HR) in sector field ICP-MS instruments [22] or by using kinetic energy discrimination (KED) and/or chemical resolution in the collision/reaction cell of quadrupole-based ICP-MS units [23,24].
What is ionization interference and how it can be overcome?
Ionization interference is a phenomenon which shows a change in emission intensity, causing the ioniza- tion equilibrium to shift, when coexisting elements include easily ionizable elements such as Na, K, Rb, and Cs. Generally, this results in greater intensity of neutral lines and reduced intensity of ionic lines.
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).
Which light is used in AAS?
hollow cathode lamp
The normal light source used in AAS is a hollow cathode lamp. This type of lamp contains a hollow cathode made of the element being analysed, and an anode electrode. Both these sealed in a hollow tube filled with a noble gas.
How do you overcome any inter element interferences?
Chemical interferences occur when there is a difference in the way the sample and the calibration standard react in the plasma, resulting in ionization. These can be easily overcome by the addition of an ionization buffer.
What is isobaric interference?
Isobaric interference is a result of equal mass isotopes of different elements present in the sample solution. Low-resolution instruments cannot distinguish between the isotopes. There are many examples in the intermediate mass regions where the second and third row transitions and the rare earths appear.
How can spectral interference be minimized?
Spectral interferences in flame emission spectrometry can be significantly reduced through the use of selective spectral-line modulation (s.l.m.).
What is interference spectrophotometer?
An interference is a phenomenon that affects the measurement or the population of ground state atoms of an analyte element.
Which detector is used in AAS?
A photomultipier tube (PMT) is used for the measurement of low radiant power. The schematic of a PMT is similar to that of a traditional phototube. In a traditional phototube there are two electrodes, an anode and a cathode. When voltage is applied to the electrodes, the photons hit the cathode and generate electrons.
Why HCL is used in AAS?
ATOMIC FLUORESCENCE SPECTROMETRY
A HCL is composed of a silica envelope that contains 1–5 Torr of argon or neon and two metal electrodes. HCLs are almost ideal line sources for AAS because of their high stability and narrow linewidth (0.002 nm), but their relatively low intensity is a disadvantage for AFS.
What is the main application of AAS?
Atomic absorption spectrometry (AAS) is an easy, high-throughput, and inexpensive technology used primarily to analyze elements in solution. As such, AAS is used in food and beverage, water, clinical research, and pharmaceutical analysis.
What is inter element correction?
Inter-element correction factors are used to compensate for any inter-element interferences that may occur in a sample. Any effect of potentially interfering elements on analyte wavelengths can be calculated using the software, and a table of factors generated automatically.
What is doubly charged interference?
A spectral interference occurs when an interfering ion has the same mass to charge ratio (m/z) as an analyte ion, leading to a false positive result. An interfering ion can be a polyatomic ion, a singly charged isobaric ion or a doubly charged ion, which has twice the mass number of the analyte.
What is drift in ICP-MS?
Drift can be defined as a continuous or incremental change in response of a measuring instrument due to changes in the metrological properties of that measuring instrument [33]. Drift in sensitivity is known to affect the accuracy of ICP-MS analysis generally and can in some cases be quite severe.
How does the background correction in spectral interference work?
In this method of background correction, the signal from a continuum source, such a deuterium lamp, is subtracted from the signal from a line source, such as the analyte’s hallow cathode lamp. A chopper alternates the radiation passing through the instrument between the deuterium continuum and the analyte source.
What are main components of a AAS?
Why hollow cathode lamps are used in AAS?
A hollow cathode lamp is used as a spectral line source for Atomic Absorption (AA) instruments. AAS lamps utilize the hollow cathode effect to generate light at wavelengths for the element of interest. The emission line selected must avoid wavelength overlaps, and have good intensity with low noise.
What is the detection limit of AAS?
Typical detection limits of flame atomic absorption spectrometry (FAAS) are of the order of 1–100 µg L−1, making it a perfect tool for the determination of minor and trace elements, at least for contaminated samples.
What is inter element?
interelement (not comparable) Between elements.