Determination of metals in lubricating oils by flame atomic absorption spectrometry using a single-bore high-pressure pneumatic nebulizer

Abstract

The behaviour of a single-bore high-pressure pneumatic nebulizer (SBHPPN) as a tool for the analysis of lubricating oils by flame atomic absorption spectrometry (FAAS) was investigated. The effects of the sample oil content [from 10% to 100% (w/w) oil in 4-methylpentan-2-one, IBMK] and the carrier nature (IBMK and methanol) on the characteristics of the aerosols generated, on the analyte transport efficiency and on the analytical figures of merit in FAAS were studied. A pneumatic concentric nebulizer (PCN) was used for comparison. Increasing the oil content increases the viscosity of the sample. With the PCN this gives rise to coarser aerosols, making it impossible to nebulize samples with an oil content higher than 70% (w/w). Using the SBHPPN, the viscosity of the sample scarcely affects the characteristics of the primary aerosols. Hence, the SBHPPN is able, by using the appropriate carrier, to nebulize pure lubricating oils. Among the carriers tested, IBMK is the most advisable because it is fully miscible with all the oil samples. The SBHPPN provides higher sensitivities and lower limits of detection than the PCN. Compared with a method based on organic dilution, the use of the SBHPPN for the direct analysis of lubricating oils by FAAS makes it possible, in addition to increasing the analysis throughput, to detect elements at lower concentrations. Moreover, the SBHPPN provides similar results to those obtained using a previous acid digestion step.

Liquid-sample introduction in plasma spectrometry

“…In line with these considerations, a new pneumatic nebulizer, which works at high gas and liquid pressures, the so-called single-bore highpressure pneumatic nebulizer (SBHPPN) (Fig. 2d), has been developed [9].…”

Determination of Wear Metals in Lubrication Oils: A Comparison Study of ICP-OES and FAAS

“…MIBK, DIBK, alcohols, xylene and naphtholite, among others, have been used with FAAS. 1,2,5,9 Xylene and kerosene are often used with ICP-OES. 14,15 When organic solvents are used, calibration standards must be made from organo-metallic substances.…”

“…The method's drawbacks are high sample consumption, narrow linear determination range and difficulties in determining refractory elements. [1][2][3][4][5][6][7][8][9] However, these are seldom of interest to maintenance personnel (except phosphorus, which is an important additive element in lubrication oils).…”

The determination of trace metals in lubricating oils by atomic spectrometry

“…More robust and less susceptible to noise atomic absorption techniques have been successfully and extensively applied. Most of the FAAS methods rely on particle independent sample preparation procedures, where the w/o emulsion, prepared in toluene and in MIBK, was directly aspirated into the flame using different nebulizers, such as pneumatic concentric and single-bore high pressure pneumatic ones [6,34,[40][41][42]. Method calibration generally required the use of metallo-organic standards.…”