Direct phosphorus determination on solid plant samples by electrothermal vaporization-inductively coupled plasma atomic emission spectrometry

Phosphorus (P) is not a typical element that is determined with the electrothermal vaporization (ETV) technique because of its volatility and its lack of sensitivity. However, direct solid sampling is possible when ETV is coupled with inductively coupled plasma atomic emission spectrometry (ICP-AES) for the determination of P in plant samples. Obtaining good results was governed by some special operating conditions. The concentrations studied necessitated the use of the ICP spectrometer in radial view configuration. The behavior of P during vaporization was studied between 270 and 1900 degrees C. External calibration was carried out using solid external (cellulose) spiked with aqueous standard solutions. Several reference plant materials were used to validate the accuracy of the method. Analytical results agreed with certified values when cellulose was used in calibration. Relative standard deviations varied from 2 to 14%. A detection limit of 30 mu g g(-1) was achieved for a typical mass sample of 2 mg.