AAS – Atomic Absorbing Spektrometry：原子吸收光谱法原子吸收spektrometry–.pptVIP

AAS ?Atomic Absorption Spektrometry Kl韒ov?Eva Maarov?Darja Brno University of Technology 2005 Fundamentals Analytic method that measures the concentrations of elements Most of the free atoms of most of elements are in the basicenergy condition at temperatures2000-3150 K and because of absorption of the photons theyare getting to some of the higher energy levels. In ASS they have the most probability to get tothe junctions between basic and nearest energyexcited state. These junctions match to basicresonance curve, which are the most sensitive for atoms. Comparative methode, absorbance value is measured For AAS applies Bouger-Lambert-Beers Law: Data evaluation Calibration curve method Instrumentation Atomic absorption spectrometer,that contains 4 basic parts: The light source Atomic cell Monochromator Detector Device Different types of Atomic absorption spectrometers The light source Provides radiation Hollow cathode lamp Is made of the element to be determined Filled with an inert gas (Ar,He) The atomic cell Is instrumental to the atomisation Sample is changed to form free atoms in gas state (generation of free atoms of elements) Types of atomisation Flame atomisation (slotted burners) Temperature of flame is directed according to Oxidant-fuel ratio (ethyne-air,ethyne-dinitrogenoxide are often used) Types of atomisation Electrothermal atomisation (grafit cuvettes) Higher temperature is reached here (3150K) Monochromator Optical grid Is used to select the specific wavelenght of light ?spectral line Detector Works on principle of the photoefect A photomultiplier tube Produces an elecrical signal proportional to the light intensity Applications Clinical analysis ?analysing metals in biological fluids such as blood and urine Environmental analysis ?monitoring our environment (levels of various elements in water,air, petrol etc.) Pharmaceuticals Industry Mining ?determining gold in rocks Wordlist Mining ?d鵯n?pr鵰ysl, t鞛ba Comparativ