What are the influencing factors of flame photometry analysis?

    Flame photometer is an atomic emission spectroscopy method that uses flame as the excitation light source. Introduce the sample into a flame, and rely on the thermal and chemical effects of the flame to evaporate, ionize, atomize, and excite luminescence of the sample. According to Lambert Beer's law (the emission intensity I of characteristic spectral lines and the concentration c of the element in the sample, I=acb (where a and b are constants), determine the content of a certain element in the sample. Mainly suitable for alkali metals and alkaline earth metals that are easily ignited by flames.

    The factors that affect flame photometric analysis include:

    1. Excitation conditions:

    A Flame temperature: Sensitivity decreases when the temperature is too low, and severe alkali metal ionization occurs when the temperature is too high, affecting the linear relationship of measurement. Factors affecting flame temperature: Gas type: Low temperature flames such as propane air, butane air, or liquefied petroleum gas air (about 1900 ℃) are more suitable and convenient. Gas and auxiliary gas ratio: Maintain appropriate sample solution suction amount: Excessive amount will cause flame temperature to decrease

    B Changes in liquid level height can cause changes in the concentration of elements after excitation, and the test height must be kept consistent during measurement.

    C Spray: The spray is not clean, which is easy to cause test solution atomization. The test solution must be clear when measuring, and the spray must be cleaned with water or ethanol at any time.

    D Liquid level height: Gas pressure: The gas pressure should be kept constant during measurement.

    2. Types and compositions of samples

    A The ionization and self absorption of elements can cause the correction curve to bend and the linear range to narrow. At high concentrations, potassium undergoes severe self absorption, causing the calibration curve to bend towards the horizontal axis; At low concentrations, due to increased ionization and radiation, the calibration curve bends towards the vertical axis.

    B The physical properties of the sample should be consistent with the composition of the standard solution

    C The presence of ions in the sample has an impact on the measurement, such as the enhancement of spectral lines when alkali metals coexist, which leads to higher results.

    3. Instrument quality

    A Selective monochromator: The quality of the filter is good, which can reduce the interference of coexisting substances.

    B Long term use of photovoltaic cells can lead to fatigue.

    C The impact of the surrounding environment on the instrument.