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COMPARATIVE STUDY OF DIFFERENT PREPARATION PROCEDURES FOR CRUDE OIL SAMPLES FOR THE DETERMINATION OF SALINITY BY ICP OES

Luiza Vieira 1 ; Maiara Krause 1 ; Tiago Cunha 1 ; Estáquio Castro 1 ; Geisamanda Brandão 1 ; Maria Tereza Carneiro 1
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The presence of chloride salts in crude oil is the main cause of corrosion in crude oil refineries. Chlorides when subjected to high temperatures tend to react with water vapor producing hydrochloric acid, promoting rapid corrosion in the distillation towers. Consequently, determination of the trace elements associated with the chloride in crude oil is of great importance for studies related to chloride hydrolysis. The crude oil samples are complex and the determination of trace elements in these samples by atomic spectrometry requires that the samples undergo preparation. This work aims to evaluate three different procedures for the preparation of samples for the determination of Ca, Mg, Sr, Na and Ba, principal counter ions of chlorides, in crude oil by ICP OES. The first evaluated procedure was based on the introduction of crude oil in the form of nanoemulsion.1 The second method evaluated was emulsion breakdown induced extraction (EIBE)2. Finally, the third procedure was the sample preparation by combustion.3 It was possible to conclude in the experiments that the sample preparations by means of nanoemulsion and EIBE constitute simpler and faster procedures. They allow minimum manipulation of the samples favoring a reduction in the risk of contamination and a lower risk of loss of analyte by volatilization since the samples were not submitted to conventional heating in the preparation stage. Furthermore, they used small volumes of acids and presenting low operating costs. A negative point is the high dilution factor of these methods making it difficult to detect the analytes in samples of low salinity. The preparation of the sample by means of combustion, which have presented a low dilution factor, had a positive point in the determination of the analytes in samples of low salinity. However, sample preparation time, high cost, higher risk of contamination (due to the great manipulation and to be carried out in open container) and the use of large volumes of acids were the main negative points of this preparation.