Rare earth element determination in heavy crude oil by USN-ICP-MS after digestion using a microwave-assisted single reaction chamber

Abstract

In this work a method for rare earth element (REE) determination by inductively coupled plasma mass spectrometry (ICP-MS) was proposed after heavy crude oil digestion by microwave-assisted wet digestion (MAWD) using a single reaction chamber (SRC) system.

Feasibility of Rare Earth Element Determination in Low Concentration in Crude Oil: Direct Sampling Electrothermal Vaporization-Inductively Coupled Plasma Mass Spectrometry

“…An infrared drying system (T/IR, Spectral Systems) was used for drying the aqueous reference solution on the graphite platform before introduction into the ETV system. The same ICP-MS equipment coupled to ETV system was used with an USN (U6000AT+, CETAC Technologies, USA) for the determination of REE after MAWD, according to previous works. , The operating parameters for ETV-ICP-MS and USN-ICP-MS are listed in Table S-1. The digestion of samples was performed using a microwave oven (Multiwave 3000 Sample Preparation System, Anton Paar, Austria) operating at maximum pressure and temperature of 80 bar and 280 °C, respectively. , The water content in crude oil samples was determined by potentiometric Karl Fischer titration according to ASTM D 4377-00 method, using an automatic titrator (836, Metrohm, Switzerland) .…”

“…The same ICP-MS equipment coupled to ETV system was used with an USN (U6000AT+, CETAC Technologies, USA) for the determination of REE after MAWD, according to previous works. , The operating parameters for ETV-ICP-MS and USN-ICP-MS are listed in Table S-1. The digestion of samples was performed using a microwave oven (Multiwave 3000 Sample Preparation System, Anton Paar, Austria) operating at maximum pressure and temperature of 80 bar and 280 °C, respectively. , The water content in crude oil samples was determined by potentiometric Karl Fischer titration according to ASTM D 4377-00 method, using an automatic titrator (836, Metrohm, Switzerland) . Chloride determination in crude oil samples (expressed as NaCl) was performed by ion chromatography (850 Professional IC system, Metrohm) after microwave-assisted extraction, according to the procedure described in previous work …”

“…Among the techniques commonly used for the determination of REE are neutron activation analysis (NAA), inductively coupled plasma optical emission spectrometry (ICP OES), and inductively coupled plasma mass spectrometry (ICP-MS) . The determination of REE has been more commonly performed by ICP-MS than the ICP OES in view of the better sensitivity and possibility of reaching lower limits of quantification (LOQs). − Conventional nebulization is a common approach for the introduction of samples for ICP OES and ICP-MS. However, this system requires suitable pretreatment protocols that are not simple to be carried out due to the well-known difficulties in digesting crude oil. − In this case, the pretreatment step should preferably involve a high digestion efficiency (solutions with low residual carbon content and residual acidity) to ensure accurate results and suitable analytical throughput, among other factors. − , In the particular case of crude oil, these requirements are not easily achieved because of stable carbon-based compounds and the presence of aromatic compounds (such as resins and asphaltenes), which can increase the stability of matrix components and, consequently, hamper the digestion efficiency. − , Therefore, it is commonly necessary to use pressurized systems and devices allowing high temperatures (up to 270 °C) and pressures (higher than 80 bar) with high amount of acids and long digestion times. − An alternative to methodologies requiring a prior digestion step is the use of NAA.…”

Multivariate optimization of a procedure employing microwave-assisted digestion for the determination of nickel and vanadium in crude oil by ICP OES

“…In recent times, several analytical strategies of sample preparation have been proposed for determining metals in petroleum and its derivatives [11][12][13][14][15][16][17][18][19][20][21]. Flores et al have proposed various sample digestion procedures employing microwave-induced combustion for the determination of metals in crude oil and its derivatives utilizing spectroanalytical techniques [13][14][15][16][17]. The first work was established for the determination of rare earth elements in crude oil using inductively coupled plasma mass spectrometry (ICP-MS) equipped with an ultrasonic nebulizer (USN) [13].…”

“…The first work was established for the determination of rare earth elements in crude oil using inductively coupled plasma mass spectrometry (ICP-MS) equipped with an ultrasonic nebulizer (USN) [13]. Subsequently, they developed a method for quantification of rare earth element in heavy crude oil by USN-ICP-MS [14]. For that, the sample digestion was performed using a microwaveassisted single reaction chamber.…”