ISO 9647:2020 pdf free
ISO 9647:2020 pdf free.Steel一Determination of vanadium content一Flame atomic absorption spectrometric method (FAAS)
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.
Place the test portion (8.1) 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.
Fit the vanadium hollow-cathode lamp (see 6.1) to the atomic absorption spectrometer (6.1), switch on the current and allow it to stabilize. Adjust the wavelength in the region of 318,4 nm to minimum absorbance, if possible. Following manufacturer’s instructions, fit the correct burner, light the flame,adjust it to a red feather and the observation height in the flame to about 20 mm and then allow the burner temperature to stabilize. Taking careful note of the manufacturer’s instructions regarding the minimum flow rate of acetylene, nebulize alternately the calibration solution of highest concentration and the zero member, adjust the gas flow and burner position (horizontally, vertically and rotationally) until the difference in absorbance between the calibration solutions is at a maximum.ISO 9647 pdf free download.
