Flame AAS/flame AES for trace determination in fresh and used lubricating oils with sample introduction by hydraulic high-pressure nebulization

Abstract

In hydraulic high-pressure nebulization (HHPN) an aerosol is produced by means of an HPLC-pump and a special nebulization nozzle, applying a pressure of about 200 bar. This spray technique has been employed for sample introduction of mineral oil samples in flame atomic absorption/flame emission spectrometry. The determination of the trace elements Al, Cr, Cu, Fe, K, Na, Ni, Pb, Si and V has been investigated. Viscosity hardly acts upon the sensitivity of the determination, thereby avoiding a time consuming dilution of oil samples. By means of two interconnecting sampling valves a calibration method based on the standard addition technique can be performed which is both simple and easy to carry out. In samples of used oils, results for Cu and Pb equalled those of XRF-analysis. Regarding Fe traces, data obtained from AAS and XRF measurement correlate. In comparison with sample uptake by pneumatic nebulization, which is restricted to diluted oil samples, detection limits decrease by a factor of 2 to 4, indicating the dilution required in pneumatic nebulization.

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

“…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).…”

“…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 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.…”

“…Method calibration generally required the use of metallo-organic standards. The use of other solvents, such as 4-methylpenthan-2-one, has also been reported [41]. A w/o approach has been adapted for FIA-FAAS using a stream of kerosene for the determination of Fe, Cu, Cr and Pb [43,44].…”

Wear Metal Analysis of Oils

“…Kerosene behaved almost as well as MIBK, but heptane disturbed the air-acetylene flame used significantly. Typical solvents in FAAS analyzes have been xylene, MIBK or their mixtures; xylene seems to be a more stable solvent in these analyzes (16)(17)(18)(19)(20). King (17) tested naphtolite in the zinc analysis by FAAS and observed that napholite has better burn properties and less background disturbances than normally found in other solvents.…”