ISO-11437-1-1994.pdf
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1、INTERNATIONAL STANDARD IS0 11437-I First edition 1994-l 2-01 Nickel alloys - Determination of trace-element content by electrothermal atomic absorption spectrometric method - Part 1: General requirements and sample dissolution Alliages de nickel - Dosage des 616ments-traces - M F is a dilution facto
2、r given in the relevant part of IS0 11437; m is the mass, in grams, of the test portion. 8.2 Precision 8.2.1 Laboratory tests The methods in the subsequent parts of IS0 11437 have been subjected to interlaboratory testing. 8.2.2 Statistical analysis 8.2.2.1 Results from the interlaboratory test pro-
3、 gramme were evaluated according to IS0 5725. The data were tested for statistical outliers by the Cochran and Dixon tests given in IS0 5725. 4 8.2.2.2 The principle of the Cochran test is that a set of results is an outlier if the within-laboratory variance is too large in relation to the others. D
4、ixon s tests is to determine if the mean from a laboratory is too far from the other laboratory means. Both tests were applied at the 95 % confidence level. 8.2.2.3 Repeatability and reproducibility were calcu- lated according to IS0 5725 at the 95 % confidence level. Results of the statistical anal
5、ysis, including the within-laboratory and between-laboratory standard deviations are given for each element in the relevant part of IS0 11437. 9 Test report The test report shall include the following information: a) a reference to the method used; b) the results of the analysis; c) the number of in
6、dependent replications; d) any unusual features noted during the analysis; e) any operation not included in this part of IS0 11437 or regarded as optional. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 N
7、ot for Resale, 04/22/2007 20:56:01 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 11437-1:1994(E) Optimization and checking of spectrometer performance criteria A.1 Introduction Table A.1 - Programme for graphite tube conditioning Annex A (normative) To obtain the best
8、 results when using the graphite furnace technique, the instrument settings, particu- larly the furnace programme, shall be optimized. Once the instrument settings are optimized, it is essential that the instrument meets certain performance re- quirements before it is used in the method specified in
9、 the relevant part of IS0 11437. A.2 Initial instrument checks and adjustments A.2.1 Switch on the power, cooling water, gas supplies and fume extraction system. 8.2.2 Open the furnace and inspect the tube and contacts, Replace the graphite components if wear or contamination is evident. Inspect the
10、 windows and clean if necessary. If a new tube or graphite contacts are fitted, condition these using the heating programme recommended by the manufacturer. NOTE 2 In the absence of the manufacturer s rec- ommendations, the conditioning furnace programme shown in tableA. should be used. A.3 Radiatio
11、n source Both single-element hollow cathode lamps or electrodeless discharge lamps are suitable. These should be installed and operated as recommended by the manufacturer. After the warm-up time specified by the manufac- turer, the signal from each radiation source should not deviate by more than 0,
12、5 % from the maximum value (i.e. by not more than 0,002 absorbance units) over a period of 15 min. Significantly greater fluctuations are usually indicative of a faulty lamp. NOTE 3 The use of multi-element lamps is not generally recommended. A.4 Spectrometer parameters A.4.1 Wavelength Select the w
13、avelength specified in the relevant part of IS0 11437. A.4.2 Slit Select the slit width recommended by the manufac- turer. Where two slit settings are available, ensure that the type provided for use with the graphite fur- nace is selected. A.4.3 Background correction A.4.3.1 Deuterium background co
14、rrection systems. Select the background correction option and allow the lamps to stabilize for 30 min. Check that the energies of the analyte radiation source and the deuterium radiation source are balanced within the tolerances recommended by the manufacturer. A.4.3.2 Zeeman background correction s
15、ystems. Ensure that the poles of the magnet are clean. 5 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/22/2007 20:56:01 MDTNo reproduction or networking permitted without license from
16、IHS -,-,- IS0 11437-1:1994(E) 0 IS0 A.4.3.3 Test of background correction system. Measure the atomic and background absorbances of 20 pl of a 0,2 % (m/V) magnesium nitrate solution at a wavelength between 200 nm and 250 nm (e.g. Bi 223,l nm) using a charring temperature of 950 “C and an atomization
17、temperature of 1 800 “C. A large background signal should be observed, with no over or under correction of the atomic signal. NOTE 4 In general, the deuterium correction system should be able to correct for broad band background absorbances of up to 0.5 to 0.6 absorbance units. Zeeman systems should
18、 cope with levels as high as I,0 to I,5 absorbance units. A.5 Autosampler The operation of the autosampler should be checked. Particular attention should be paid to the condition of the pipette tip and the position of the tip during sample deposition. The manufacturer s instructions regarding the ad
19、justment of the autosampler should be followed. A.6 Optimization of the furnace heating programme Optimization of the furnace heating programme is essential if good results are to be obtained using this technique. Furnace programmes recommended by manufacturers are often concerned with samples compl
20、etely unrelated to nickel alloys. Consequently, the analyst shall optimize the furnace programme for use with the nickel alloy matrix in the manner de- scribed in A.6.1 to A.6.4. The furnace programme for the nickel alloy matrix being considered here consists of four basic steps: drying, charring, a
21、tomization and cleaning. A.6.1 Drying A.6.1.1 For most samples a drying temperature of 120 “C is satisfactory. To avoid spattering, the tem- perature should be increased to 120 “C in 20 s and then held at that temperature for a time depending on the volume of sample introduced. The following hold ti
22、mes are typical. Injected volume, 1 Hold time, s IO 15 40 30 A.6.1.2 When samples are deposited on the L vov platform, a two-stage drying process is beneficial in preventing spattering. The first stage involves heating the sample rapidly to 80 “C in 1 s and then holding the temperature at 80 “C for
23、a short time. The time during which the temperature is maintained at 80 “C depends on the volume of solution injected. The following hold times are typical. Injected volume, 1 Hold time, s 10 15 40 30 The temperature is then increased over a period of 20 s to 30 s, to a value 20 “C to 40 “C above th
24、e boiling point of the solvent. This higher temperature is held for 15 s to 40 s depending on the volume of sample injected. The following hold times are typical. Injected volume, 1 Hold time, s 10 15 40 40 A.6.1.3 In A.6.1.1 and A.6.1.2, once suitable drying conditions have been selected, the dryin
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