Simple Spectrophotometric Determination of Iron in Diesel Oil after Sample Preparation Employing Extraction Induced by Emulsion Breaking

This work reports the development of a simple and fast method for the spectrophotometric determination of Fe in diesel oil using the classic reaction with 1,10-phenanthroline after its extraction induced by emulsion breaking (EIEB). The extraction parameters of EIEB were optimized (concentration of HNO3 and Triton X-100 (R) in the emulsifying solution) as well as the adjustment of the pH of the final solution, a necessary step to complete the colorimetric reaction. The developed method presented a limit of detection of 0.004 mg L-1 and a limit of quantification of 0.013 mg L-1 and was applied in the analysis of six samples of diesel oil with different specifications. The results were statistically similar to those obtained by graphite furnace atomic absorption spectrometry (GF AAS). A recovery test was also performed by spiking the samples with 1.0 mg L-1 of Fe in the form of an organometallic compound, yielding recovery percentages between 83 and 108%.

Automated summary

This work presents a simple and fast spectrophotometric method for determining the Fe content in diesel oil. The method involves the extraction of Fe using emulsion breaking and the classic reaction with 1,10-phenanthroline. The optimized extraction parameters and pH adjustment of the final solution were necessary for completing the colorimetric reaction. The method showed a low detection limit and was validated by comparison with graphite furnace atomic absorption spectrometry (GF AAS).