Simultaneous determination of wear metals in lubricating oils by inductively-coupled plasma atomic emission spectrometry

Abstract

The simultaneous determination of 15 different wear metals in lubricating oil by inductively-coupled plasma-atomic emission spectrometry is described. An aerosol formed from a solution of the lubricating oil in 4-methyl-2-pentanone is injected into the axial channel of an inductiveiy-coupied plasma where the atomic spectra are excited. Detection limits range 0.0004 to 0.3 ppm for the elements studied. Low and high viscosity oils (nominally 1.9 X to 2.45 X m2/s, respectively) can be accommodated without biasing the analytical results. Approximately 1.5 min are required for completing the analyticai cycle for one sample. Relevant data on precision and accuracy are included.

The determination of trace metals in lubricating oils by atomic spectrometry

“…These procedures may produce higher background signals and require the use of metallo-organic standards for the determination of several elements, including refractory, medium volatility and volatile elements. In this way, the introduction of lubricating oil samples diluted in 4-methyl-2-pentanone [16], xylene [17,18], or kerosene [19,40] has been employed. An automated on-line sample dilution with organic solvent was also proposed, leading to a lower dilution factor and minimized matrix interferences by the use of internal standardization.…”

“…However, organic standards are relatively expensive and may lead to inaccurate results due to concentration changes of the final organic analytical solutions resulting from the evaporation and deposition of these species on the walls of the storage container [14]. Thus, many different procedures have been used aimed at matrix simplification, including, extraction methods to separate the analyte from the sample matrix, ashing of the sample, sometimes after the sample oil has been adsorbed onto a porous inert material such as silica gel [15], followed by one of the following procedures: (i) acid dissolution [4] (ii) sample dilution with appropriate organic solvents [16][17][18][19][20][21], (iii) acid digestion of the sample [22][23][24][25] and (iv) conversion of the sample into oil-inwater emulsions and micro-emulsions [26][27][28][29][30][31][32][33]. The first two procedures are extremely time consuming and have a considerable risk of sample contamination and analyte loss as volatile species.…”

Inductively coupled plasma--atomic emission spectrometry: trace elements in oil matrices

“…Under these conditions, Smith provided any data on the accuracy and precision of their results. In this laboratory, Abercrombie had found that an inductively coupled argon plasma could be sustained when oil diluted 1:10 w/v with 4-methyl-2-pentanone was nebulized and the resulting aerosol carried into the plasma (33). He employed the plasma to obtain calibration curves for a number of elements in an oil matrix.…”

Determination of Refractory Elements in Used Lubricating Oil by ICPOES Employing Emulsified Sample Introduction and Calibration with Inorganic Standards

“…The traditional way to introduce oil samples into the ICP is diluting it directly in an organic solvent (kerosene, MIBK, xylene, etc.). [15][16][17][18][19] This procedure does not minimize the problems associated with the high organic load, and necessarily requires the use of expensive and unstable analyte metallorganic standards for calibration. Alternatively, the acid decomposition of oil samples in microwave systems minimizes the organic load of samples, and allows the use of aqueous inorganic standards for calibration.…”