DETERMINATION OF THE ACTUAL INTENSITY BY CORRECTION OF THE EMISSION SPECTRUM LINES OF HEAVY METALS CONTAINED IN CRUDE OIL USING LASER INDUCED PLASMA –TECHNIQUE

Abstract

Laser induced plasma spectroscopy (LIPS) is a novel technique for elemental analysis based on laser-generated plasma. In this technique, laser pulses are applied for ablation of the sample, resulting in the vaporization and ionization of sample in hot plasma which is finally analyzed by the spectrometer. The elements are identified by their unique spectral signatures. The plasma was produced using the fundamental harmonic (1064 nm) of the Nd: YAG laser and the emission spectra were recorded at 3.3 µsec. detector gate delay to study the capabilities of LIPS as a rapid tool for material analysis. LIPS method was developed for elemental analysis of the crude oil. Because of the special features of crude oil as a liquid organic material which makes the analysis process difficult and inaccurate. This difficulty is concentrated due to the effect of the self- (absorption and stimulation), so the properties of the spectral analysis lines of the laser induced plasma spectrum (LIPS) are severely affected, and thus affecting the evaluation process accuracy. In this effort, there was an ability to determine the qualitative evaluation of the various heavy metals in a crude oil sample. For the large number of these metals, three minerals (Fe, Ni and V) were identified for the purpose of clarifying the method, After determining the optimal experimental conditions to improve the sensitivity of the developed LIPS system through the optimal selection of the most important parameters. Here, an analysis method based on global reference line selection was proposed for optimal estimation of the analytic lines properties of the plasma spectrum (actual intensity Ic , optimum temperature Te , highest stability score Ss and without self-strain fs), to improve the analysis accuracy of a crude oil sample using LIPS - technical. The optimum stability score (OSS) method was used to estimate the plasma temperature based on the calculation results from the Boltzmann diagram. Furthermore, the internal reference line for each specific mineral was considered while the correction was made for the analytical lines