This document describes the method of determining wear metals in lubricating oil using the Liberty Series II ICP-OES instrument with axially-viewed plasma. The instrument overcomes the challenges of molecular band emissions and carbon build-up in organic solvent analysis by adding oxygen to the auxiliary gas.
The document details a study using the Agilent Liberty Series II Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES) equipped with an axially-viewed plasma to analyze 13 elements in NIST Standard Reference Material 1084a (Wear Metals in Lubricating Oil). The study highlights the use of the Auxiliary Gas Module 1 (AGM-1) Oxygen Accessory to reduce molecular band emissions and prevent carbon build-up when analyzing organic solvents like kerosene.
Results show that the axially-viewed plasma configuration, combined with the oxygen accessory, provides excellent precision and long-term stability. Detection limits for various elements in kerosene were measured and compared against radially-viewed ICP systems, demonstrating significant improvements for several elements.
| RF Generator Frequency | 40 MHz |
|---|---|
| Monochromator Type | 0.75 m Czerny-Turner |
| Power | 1.5 kW |
| Plasma gas flow | 19.5 L/min |
| Auxiliary gas flow | 1.5 L/min |
| Spray chamber type | Inert Sturman-Masters type with double-pass cyclonic action |
| Injector tube id | 1.8 mm |
| Nebulizer type | High flow glass concentric type |
| Sample uptake rate | 0.6 mL/min |
| Integration time | 3 seconds |
The Auxiliary Gas Module 1 (AGM 1) Oxygen Accessory adds a small volume of oxygen to the argon auxiliary gas.
The elements analyzed were Al, Ag, Cr, Cu, Fe, Mg, Mo, Ni, Pb, Si, Sn, Ti, and V.
Detection limits with the axially-viewed ICP are generally better by a factor of up to 10 compared to the radially-viewed ICP.