Standard test method for determination of additive elements in both lubricating oils and additives by inductively coupled plasma atomic emission spectrometry
1 Scope
1.1 This standard is applicable to determination of the content of common additional elements such as calcium, zinc, magnesium, sulfur, phosphorus, barium, boron, lithium and cobalt in lubricating oil and additives. The content range listed in the precision table is the exploratory element content scope of statistical tests; for the rest content range, this standard has not carried out investigation to the precision.
1.2 This standard has not put forward a proposal to all the safety problems involved; users of this standard shall establish appropriate safety and health practices, and determine proper rules and regulations before use.
2 Normative References
The following documents contain provisions which, through reference in this standard, become provisions of this standard. For dated reference, subsequent amendments (excluding correction) to, or revisions of, any of these publications do not apply. However, parties that enter into an agreement according to this standard are encouraged to study whether the latest edition of these documents can be used. For undated references, the latest edition of the referenced document is applicable to these specifications.
GB/T 4756 Petroleum Liquids-Manual Sampling (GB/T 4756-1998, ISO 3170: 1988, MOD)
GB/T 6682 Water for Laboratory Use-Specifications (GB/T 6682-1992, ISO 3696: 1987, NEQ)
GB/T 6683 Petroleum Products-Determination of Precision Data in Relation to Methods of Test (GB/T 6683-1997, ISO 4259: 1992, NEQ)
3 Summary of Method
Preprocess the sample in pressure vessel with hydrogen peroxide and nitric acid and convert it into acidic water solution; determine the element content in the sample solution with inductively coupled plasma emission spectrometer (ICP-AES).
4 Significance and Use
Elements such as calcium, zinc, magnesium, sulfur, phosphorus, barium, boron, lithium and cobalt are common elements in lubricating oil and polymeric lubricant additives; their content is a major parameter which shows lubricating oil property. This standard has provided a kind of standard method which determines the additional element content in lubricating oil and additives. This method adopts pressure vessel method for sample handling, solves the problem of volatile element losses during dry method cineration; the process of sample handling is simple and convenient, and reliable determinations may be carried out to various elements simultaneously.
5 Apparatus
5.1 Inductively coupled plasma emission spectrometer: Inductively coupled plasma emission spectrometer of sequential scanning or full spectrum direct reading may be used. When sulfur and phosphorus are determined, spectral lines below 190nm shall be used; instruments are required to be possessed of function of optical path vacuum pumping or air elimination.
5.2 Pressure vessel: 50mL capacity, the outer cylinder is 1Cr18NiTi stainless steel material, the inner cup is PTFE material, the recommended operating temperature is less than 180℃. The maximum bearing pressure is 5MPa. See Figure 1 for the structural diagram of pressure vessel.
