Analytical applications of furnace atomic non-thermal excitation spectrometry (FANES) and molecular non-thermal excitation spectrometry (MONES). Part. 5. Study of the MONES of PO and HPO for the determination of trace amounts of phosphorus

Abstract

A method for the determination of phosphorus by the molecular non-thermal excitation spectrometry (MONES) of PO and HPO has been developed. The phosphorus was introduced into the furnace atomic non-thermal excitation spectrometry (FANES) source as a solution of sodium dihydrogen phosphate. The measurements were carried out at the bands that gave the maximum signals, for PO at 246.4 nm and for HPO at 507 nm. The electrical, thermal and chemical conditions were optimised and are discussed. In addition, the influence of La³⁺ as a chemical modifier on the MONES of PO and HPO was investigated. The best values for the detection limit were 700 pg of P (MONES of PO) and 3400 pg of P (MONES of HPO). By comparison with the best values obtained with commercial electrothermal atomisation atomic absorption spectrometry instruments, these values are better by factors of 8 and 1.6, respectively. However, the determination of P by FANES at 213.5/213.6 nm is the best method for investigations of phosphorus using the FANES source, in the presence of La³⁺ as a chemical modifier.