Atomic Absorption Spectrophotometer

Introduction Atomic absorption absorption spectroscopy (AA orAAS) is one of the commonest instrumentalmethods for analyzing for metals and some metalloids.Metalloids like antimony, arsenic, selenium, and tellurium are now routinely analyzed by hydride generation AAS (HGAAS; see www.shsu.edu/~chm_tgc/sounds/sound.html and www.shsu.edu/chemistry/primers for animations and primers on that method). Inductively coupled plasma (ICP) is also a powerful analytical, instrumental method for these elements but at this point its much higher cost limits it widespread use as compared toAAS.As the animation on AAS here shows, the main parts of the AAS system are a hollow cathode lamp, nebulizer, air/acetylene flame, and optical system. Alternate...

Introduction Background of Atomic Absorption Spectroscopy

Atomic absorption spectroscopy (AAS) determines the presence of metals in liquid samples. Metals include Fe, Cu, Al, Pb, Ca, Zn, Cd and many more. It also measures the concentrations of metals in the samples. Typical concentrations range in the low mg/L range. In their elemental form, metals will absorb ultraviolet light when they are excited by heat. Each metal has a characteristic wavelength that will be absorbed. The AAS instrument looks for a particular metal by focusing a beam of uv light at a specific wavelength through a flame and into a detector. The sample of interest is aspirated into the flame. If that metal is present in the sample, it will absorb some of the light, thus reducing its intensity. The instrument measures...

Technology of Atomic Absorption Spectrophotometry (AAS)

When using atomic absorption spectrophotometry (AAS) as an analytical technique the absorption of light of free atoms is measured. Therefore it is one of the branches of atomic spectroscopy, together with flame photometry (see Standardbase techniques: “Flame Photometry” that measures the intensity of light emitted by free atoms when their electrons return to ground state after the excitation by light). However - unlike flame photometry - AAS is based on the “first half” of the excitation process, while atoms absorb light getting their electrons from the ground state to a higher energy level. Figure 1: Photograph of an atomic absorption spectrophotometer Although the atomic absorption spectrophotometer (fig. 1.) is quite expensive,...

Calibration and General Test of AAS (Atomic Absorption Spectrophotometry) Instrument

Atomic Absorption Spectrophotometry is designed to determine the amount (concentration) of an object element in a sample, utilizing the phenomenon that the atoms in the ground state absorb the light of characteristic wavelength passing through an atomic vapor layer of the element. Apparatus Usually the apparatus consists of a light source, a sample-atomizer, a spectroscope, and a photometer, and a recording system. Some are equipped with a background compensation system. For the light source, a hollow cathode lamp and a discharge lamp are mainly used. To the sample-atomizer, the flame type, electrothermal type, and the cold-vapor type are applied. The cold-vapor flameless type is categorized as the two methods: reduction vaporizing...

Instrumental Techniques for Analytical Chemistry

Introduction Infrared (IR) spectroscopy is one of the most common spectroscopic techniques used by organic and inorganic chemists. Simply, it is the absorption measurement of different IR frequencies by a sample positioned in the path of an IR beam. The main goal of IR spectroscopic analysis is to determine the chemical functional groups in the sample. Different functional groups absorb characteristic frequencies of IR radiation. Using various sampling accessories, IR spectrometers can accept a wide range of sample types such as gases, liquids, and solids. Thus, IR spectroscopy is an important and popular tool for structural elucidation and compound identification. IR Frequency Range and Spectrum Presentation Infrared radiation spans a section...