Digestão de óleo lubrificante encapsulado em forno de microondas com radiação focalizada por adição de amostra ao reagente pré-aquecido

Evaluation of digestion procedures for simultaneous determination of Ca, P, Mg, K and Na in biodiesel by inductively coupled plasma optical emission spectrometry

“…However, the limitation in the use of this acid is its low boiling point at atmospheric pressure, around 120 o C. To facilitate digestion in open flasks that operate at atmospheric pressure, the addition of an aliquot of sulfuric acid is recommended (which has a boiling point of 330 °C), thereby increasing the oxidative efficiency of the medium and making the decomposition of fat globules possible. [14][15][16][17][18][19][20] Ideally, the best digestion should lead to a complete decomposition of organic material using minimal amounts of nitric acid which should be diluted as much as possible to decrease residual carbon and the acid concentration in the resulting digest solution, with the aim of avoiding critical effects on instrument parts, such as the nebulizer, nebulization chamber and torch in ICP OES. 11 Furthermore, solutions of differing viscosity and surface tension lead to changes in the flow rates of aspiration and nebulization, while the density and volatility affect the transport of the aerosol through the nebulization chamber.…”

Evaluation of Lubricating Oil Preparation Procedures for the Determination of Al, Ba, Mo, Si and V by High-Resolution Continuum Source FAAS

“…11 Three of the most common spectroscopic analytical techniques employed for elemental determination in lubricating oils are the line-source flame atomic absorption spectrometry (LS FAAS), 2 graphite furnace atomic absorption spectrometry (GF AAS), 6 and inductively coupled plasma optical emission spectrometry (ICP OES). 12 The LS FAAS is the simplest and most used by world-wide laboratories, but limitations of this technique for elemental determination in lubricating oils have been stressed, mainly those aspects related to sensitivity and single-element characteristics. 3 Besides, the direct determination of inorganic elements in oils using atomic spectrometry techniques with spray-chambers as sampling units is difficult due to the high levels of organic matter and viscosity.…”

“…13 Several sample pretreatment methods have been proposed in the literature for lubricating oil analysis; among them are the dry ashing, 1,4,5,10 direct dilution in organic solvents, 18-21 emulsions [5][6][22][23][24][25] and acid decomposition in microwave-assisted systems. 7,12,26,27 Nevertheless, little attention has been given in the literature to the development of methods for the direct and multi-element analysis of lubricating oil by HR-CS FAAS. 3 Recently, Filho and Neto 28 analyzed lubricating oil samples prepared by different pretreatment procedures (direct dilution in kerosene, acid decomposition in a cavity microwave-oven and oil-in-water emulsification) in the determination of Cu, Cr, Fe, Ni, Pb, Sb and Zn by HR-CS FAAS.…”

Optimization of an open-focused microwave oven digestion procedure for determination of metals in diesel oil by inductively coupled plasma optical emission spectrometry

“…Determination of metals in organic liquids like oils by plasma-based techniques can be performed utilizing three approaches: (1) dilution of sample in a convenient organic solvent and introduction of the solution obtained into the instrument [2][3][4]; (2) preparation of an emulsion with the sample and its introduction into the spectrometer [5][6][7] and (3) digestion of the sample before injection using microwave radiation, hot plate or dry ashing [8][9][10][11][12][13][14][15][16][17][18]. The use of the first two approaches is suitable when a low manipulation of the samples is required, but it is limited by the small number of metallic standard solutions prepared in oil available in the market [19,20].…”

“…A restricted number of papers report the use of closedvessel microwave ovens for this task [9][10][11][12][13][14], while very few papers describe the utilization of open-focused microwave ovens for the same purpose [15][16][17][18]. It is important to remark that only three papers were found in the current literature reporting the microwave-assisted digestion of diesel oil.…”