ATOMIC ABSORPTION SPECTROPHOTOMETRY COOKBOOK原子吸收分光光度法食谱.docVIP

ATOMIC ABSORPTION SPECTROPHOTOMETRY COOKBOOK Section 1 Basic Conditions of Analysis of Atomic Absorption Spectrophotometry Atomic Absorption Spectrophotometry Cookbook Section 1 CONTENTS 1. Principal of Atomic Absorption Spectrophotometry 1 1.1 Why atoms absorb light 1 1.2 Relation between light absorption rate and atomic density 2 1.3 Sample atomization method 3 a) Flame atomic absorption 3 b) Electro-thermal atomic absorption 5 2. Basic Condition for Analysis 9 2.1 Conditions of equipment 9 a) Analysis line 9 b) Slit width 13 c) Lamp current value 14 2.2 Analysis conditions of flame atomic absorption 15 a) Flame selection 15 b) Mixing ratio of oxidant and fuel gas 17 c) Beam position in flame 17 2.3 Analysis conditions of electro-thermal atomic absorption 18 a) Drying condition 18 b) Ashing condition 19 c) Atomizing condition 21 d) Sample injection quantity 23 1. Principal of Atomic Absorption Spectrophotometry 1.1 Why atoms absorb light The atomic absorption spectrometry uses absorption of light of intrinsic wavelengths by atoms. All atoms are classified into those having low energies and those having high energies. The state having low energies is called the ground state and the state having high energies is called the excited state. The atom in the ground state absorbs external energies and is put in the excited state. For example, sodium is mainly in two excited states, having higher energies by 2.2eV and 3.6eV respectively than in the ground state, as shown in Fig. 1.1. (eV is a unit to measure energies and is called an electron volt”.) When 2.2eV energy is given to the sodium atom in the ground state, it moves up to the excited state in (I) and when 3.6eV energy is given, it moves up to the excited state in (II). Energy is given as light, and 2.2eV and 3.6eV respectively correspond to energy of light at 589.9nm and 330.3nm wavelength. In the case of sodium in the ground state, only light of t