ISO 9647 pdf download – Steel – Determination of vanadium content— Flame atomic absorption spectrometric method (FAAS)

ISO 9647 pdf download – Steel – Determination of vanadium content— Flame atomic absorption spectrometric method (FAAS).
6.2 Ancillary equipment
Scale expansion can be used until the noise observed is greater than the readout error and is always recommended for absorbances below 0.1. If scale expansion has to be used and the instrument does not have the means to read the value of the scale expansion factor, the value can be calculated by measuring a suitable solution with and without scale expansion and then dividing the signals obtained.
7 Sampling
Carry out sampling in accordance with ISO 14284 or appropriate national standards for steels.
B Procedure
8.1 Test portion
Weigh to the nearest 0,001 g a test portion according to the presumed vanadium content as follows:
a) for vanadium contents from 0,01 % to less than 0,20%: a test portion of approximately 1,00 g;
b) for vanadium contents from 0,2 % to 1,0 %: a test portion of approximately 0,20 g.
8.2 Blank test
In parallel with the determination and following the same procedure, carry out a blank test using the same quantities of all reagents as used for the determination, including pure iron (5.1) Instead of the test portion.
8.3 Determination
8.3.1 Preparation of the test solution
Place the test portion (&1) into a 250 ml beaker. Add 10 ml of hydrochloric acid (5.2) and 4 ml of nitric acid (5.3), and cover the beaker with a watch-glass. After effervescence ceases, add 10 ml of perchloric acid (5.4) and evaporate the solution until fumes of perchloric acid are visible, then remove the watch- glass and evaporate until no more fumes come out of the beaker.
Allow to cool, add 10 ml of hydrochloric acid (5.2) and 20 ml of water, and heat gently to dissolve the salts. Filter through a medium texture filter paper Into a 100 ml one-mark volumetric flask. Wash with warm hydrochloric acid (5.5) and add the washing fractions to the flask.
Allow to cool, add 10,0 ml of aluminium solution (5.6), dilute to the mark with water and mix.
8.3.2 Preparation of the calibration solutions
8.3.2.1 Vanadium contents <0.2 % Transfer into a series of 250 ml beakers (1,00 ± 0,01) g of the pure iron (51). add 10 ml of hydrochloric acid (5.2) and 4 ml of nitric acid (5.3) to each beaker and cover them with watch-glasses. After effervescence ceases, allow to cool and then respectively add the volumes of vanadium standard solution (5.8) given in Table 1. 10 Precision A planned test of this method was carried out by 23 laboratories, at seven levels of vanadium, each laboratory making three determinations (see Notes 1 and 2) of the vanadium content at each level. The test samples used are listed in Table Ad. and the experimental precision data obtained are shown in Table A2. The results obtained were treated statistically in accordance with ISO 5725-2:1994 and ISO 5725-3:1994. A graphical representation of the experimental precision data is given in Annex B. The smoothed precision data, expressed as a percentage (mass fraction), shown in Tab1 were calculated from the relationships between the vanadium content mean values and repeatability and reproducibility experimental data (see Annex A and Annex 8). NOTE 1 Two of the three determinations were carried out under repeatability conditions as defined in ISO S72S1, i.e. one operator, same apparatus, identical operating conditions, same calibration, and a minimum period. NOTE 2 The third determination was carried out at a different time (on a different day) by the same operator as in note I using the same apparatus with a new calibration. NOTE 3 When revising the present document, the precision data were re-evaluated: this new statistical treatment has led to the removal of a sample (lowest vanadium content level), since the reproducibility parameters (Rn, and R) found were not in line with those corresponding to the other samples (see Table A2).