ASTM D7740 Standard Practice for Optimization, Calibration, and Validation of Atomic Absorption Spectrometry for Metal Analysis of Petroleum Products and Lubricants
1. Scope
1.1 This practice covers information on the calibration and operational guidance for elemental measurements using atomic absorption spectrometry (AAS).
1.1.1 AAS Related Standards - Test Methods D1318, D3237, D3340, D3605, D3831, D4628, D5056, D5184, D5863, D6732; Practices D7260 and D7455; and Test Methods D7622 and D7623.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
D1318 Test Method for Sodium in Residual Fuel Oil (Flame Photometric Method)
D3237 Test Method for Lead in Gasoline by Atomic Absorption Spectroscopy
D3340 Test Method for Lithium and Sodium in Lubricating Greases by Flame Photometer
D3605 Test Method for Trace Metals in Gas Turbine Fuels by Atomic Absorption and Flame Emission Spectroscopy
D3831 Test Method for Manganese in Gasoline By Atomic Absorption Spectroscopy
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products
D4307 Practice for Preparation of Liquid Blends for Use as Analytical Standards
D4628 Test Method for Analysis of Barium, Calcium, Magnesium, and Zinc in Unused Lubricating Oils by Atomic Absorption Spectrometry
D5056 Test Method for Trace Metals in Petroleum Coke by Atomic Absorption
D5184 Test Methods for Determination of Aluminum and Silicon in Fuel Oils by Ashing, Fusion, Inductively Coupled Plasma Atomic Emission Spectrometry, and Atomic Absorption Spectrometry
D5863 Test Methods for Determination of Nickel, Vanadium, Iron, and Sodium in Crude Oils and Residual Fuels by Flame Atomic Absorption Spectrometry
D6299 Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
D6732 Test Method for Determination of Copper in Jet Fuels by Graphite Furnace Atomic Absorption Spectrometry
D6792 Practice for Quality System in Petroleum Products and Lubricants Testing Laboratories
D7260 Practice for Optimization, Calibration, and Validation of Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) for Elemental Analysis of Petroleum Products and Lubricants
D7455 Practice for Sample Preparation of Petroleum and Lubricant Products for Elemental Analysis
D7622 Test Method for Total Mercury in Crude Oil Using Combustion and Direct Cold Vapor Atomic Absorption Method with Zeeman Background Correction
D7623 Test Method for Total Mercury in Crude Oil Using Combustion-Gold Amalgamation and Cold Vapor Atomic Absorption Method
3. Terminology
3.1 Definitions:
3.1.1 absorbance, n - logarithm to the base 10 of the ratio of the reciprocal of the transmittance.
3.1.2 atomic absorption spectrometry, n - analytical technique for measuring metal content of solutions, based on a combination of flame source, hollow cathode lamp, photomultiplier, and a readout device.
3.1.3 atomizer, n - usually a flame source used to decompose the chemical constituents in a solution to its elemental components.
3.1.4 blank, n - solution which is similar in composition and contents to the sample solution but does not contain the analyte being measured.
3.1.5 burner, n - flame device used to atomize the analyte by burning in a high temperature flame mixed of a fuel and an oxidant.
3.1.6 calibration, n - process by which the relationship between signal intensity and elemental concentration is determined for a specific element analysis.
3.1.7 calibration curve, n - plot of signal intensity versus elemental concentration using data obtained by making measurements with standards.
3.1.8 calibration standard, n - material with a certified value for a relevant property, issued by or traceable to a national organization such as NIST, and whose properties are known with sufficient accuracy to permit its use to evaluate the same property of another sample.
3.1.9 certified reference material, n - reference material one or more of whose property values are certified by a technically valid procedure, accompanied by a traceable certificate or other documentation which is issued by a certifying body.
3.1.10 check standard, n - material having an assigned (known) value (reference value) used to determine the accuracy of the measurement system or instrument.
3.1.10.1 Discussion - This practice is not used to calibrate the measurement instrument or system.
3.1.11 detection limit, n - concentration of an analyte that results in a signal intensity that is some multiple (typically two) times the standard deviation of the background intensity at the measurement wavelength.
3.1.12 dilution factor, n - ratio of sample weight of the aliquot taken to the final diluted volume of its solution.
3.1.12.1 Discussion - The dilution factor is used to multiply the observed reading and obtain the actual concentration of the analyte in the original sample.
3.1.13 graphite furnace, n - electrothermal device for atomizing the metal constituents.
3.1.14 hollow cathode lamp, n - device consisting of a quartz envelope containing a cathode of the metal to be determined and a suitable anode.
3.1.15 hydride generation, n - device to atomize some metals which form gaseous hydrides.
3.1.16 monochromator, n - device that isolates a single atomic resonance line from the line spectrum emitted by the hollow cathode lamp, excluding all other wavelengths.
3.1.17 nebulizer, n - device that generates an aerosol by flowing a liquid over a surface that contains an orifice from which gas flows at a high velocity.
3.1.18 NIST, n - National Institute of Standards and Technology, Gaithersburg, MD. Formerly known as National Bureau of Standards.
3.1.19 precision, n - closeness of agreement between test results obtained under prescribed conditions.
3.1.20 quality assurance, n - system of activities, the purpose of which is to provide to the producer and user of a product, measurement, or service the assurance that it meets the defined standards of quality with a stated level of confidence.
3.1.21 quality control, n - planned system of activities whose purpose is to provide a level of quality that meets the needs of users; also the uses of such a system.
3.1.22 quality control sample, n - for use in quality assurance program to determine and monitor the precision and stability of a measurement system; a stable and homogenous material having physical or chemical properties, or both, similar to those of typical samples tested by the analytical measurement system.
3.1.22.1 Discussion - This material should be properly stored to ensure sample integrity, and is available in sufficient quantity for repeated long term testing.
3.1.23 reference material, n - material with accepted reference value(s), accompanied by an uncertainty at a stated level of confidence for desired properties, which may be used for calibration or quality control purposes in the laboratory.
3.1.24 refractory elements, n - elements forming difficultto-dissociate oxides during combustion.
3.1.25 repeatability, n - difference between two test results, obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long term and correct operation of the test method, exceed the values given only in one case in twenty.
3.1.26 reproducibility, n - difference between two single and independent results, obtained by different operators working in different laboratories on identical test materials, would in the long run, in the normal and correct operation of the test method, exceed the values given only one case in twenty.
3.1.27 spectrometer, n - instrument used to measure the emission or absorption spectrum emitted by a species in the vaporized sample.
3.1.28 spectrum, n - array of the components of an emission or absorption arranged in the order of some varying characteristics such as wavelength, mass, or energy.
3.1.29 standard reference material, n - trademark for reference materials certified by NIST.
