ISO 10204:1992 pdf download – lron ores — Determination of magnesium content — Flame atomic absorption spectrometric method.
4.7 Background solution.
Dissolve 10 g 01 pure Iron wire [minimum purity 99,9 % (rn/rn). ci magnesium content los, than
0,0002 % (rn/rn)] In 50 ml of hydrochloric acid (42) and oxidize by adding nitric acid (4.4) drop by drop. Evaporate until a syrupy consistency Is obtained. Add 20 ml ci hydrochloric acid (42) and dilute to 200 ml with water. Dissolve 17 g or sodium carbonate (4.1) in water, add carefully to the iron solution and heat to remove carbon dioxide. Transfer the cooled solution to a 1 000 ml one-mark volumetric flask, dilute to volume with water end
4.8 Lanthanum chloride solution.
Dissolve 50 g of lanthanum chloride (LsCi.xH2O) [of magnesium content less than 0.002 % (rn/rn)] in 50 ml of hydrochiorlc acid (4.2) and 300 ml of hot water. Cool and dilute to 1 litre.
4.9 MagnesIum standard solution 15 *g Mgml
Dissolve 0,300 0 g or oxide-free magnesium rnelal [minimum purity 99.9 % (rn/rn)] by slowly addIng 75 ml of hydrochloric acid (p 1,19 g/mi), diluted
1 +3. When dissolved, cool, transfer to a 1 000 ml one-mark volumetric flask, dilute to volume with water and mix. Transfer 10 ml of this solutIon to a 200 ml one-mark volumetric flask, dilute to volume with water and mix.
4.10 Magnesium calibration solutions,
Using pipettes. transFer 2.0 ml; 5.0 ml; 10,0 ml; 20,0 ml; 40,0 ml; and 50,0 ml portion, of the magnesium standard solutions (4.9) to 2(10 ml volumetric flasks (see note 2). Add 6 ml of hydrochloric acid (4.2), 60 ml of background solution (4.7) and 40 ml or lanthanum chloride solution (4.8) to each flask. Dilute all the solutions to volume with water end mix. Prepare a zero magnesium calibration solution by transferring 60 ml of the background solution to a 200 ml volumetric flask, add 6 ml of hydrochloric acid (4.2) and 40 ml of lanthanum chloride solution. Dilute all the solutions to volume with water and mix.
NOTE 2 The renge of msgne.lum which cen be covered may vary from instrument to instrument. Attention should be paid to the minimum criteria given in 5.3. For instruments having Ni sensitivity, smaller portions of stand wd soiutlon or a more cluied standard solution can be ued,
5 Apparatus
Ordlmry laborutory uppdrdtus. inludlu oiie-.uai k pIpette. and one-mark volumetnc flasks complying with the specification. of ISO 648 and iSO 1042 respectively, and 5.1 PlatInum crucible. of minimum capacity 30 ml.
5.2 Muffle furnace, capable at maintaining a temperature of approxImately 1100 C.
5.3 AtomIc absorption spectromefer, equipped with an air-acetylene burner.
The atomic absorption spectrometer used In this method shall meet the following criteria.
a) Minimum sensItivity — the absorbance of the most concentrated magnesium calibration solution (4.10) shall be at least 0.3.
b) Graph linearity — the slope of the calibration graph covering the top 20 % of the concentration range (expressed as a change in absorbance) shall not be Ices than 0,7 of the value of the slope for the bottom 20 % of the concentratIon range determined in the same way
C) MinImum stability — the standard deviation of the absorbance of the most concentrated calibration solution and that ol the zero calibration solutIon, each being calculated from a sufficient number of repetitive measurements, shall be lees than 1,5 % and 0.5 % respectively of the mean value of the absorbance of the most concentrated calibration solution.
3 The us. of a strip diart recoider and/or digital readout device ii recommended to evaluate criteria a) b) and c) and br all subsequent meaaurome,it..
4 instrument parameters may vary wIth eadi instrument Th. following paranie(ers were succs1ully used in several laboratories and they can be used as gadeiines.
In systems whore the values shown above for gas flow rates do not apply, the ratio of the gas flow rates may still be a useful guideline.
6 SamplIng and samples
6.1 Laboratory sample
For analysis, use a laboratory sample of minus 100 urn particle size which has been taken In accordar ce with ISO 3061 or ISO 3062 and prepared in acwrddllce will, iSO 3082 ur ISO 3083. In (he cNee of ores having significant Contents 01 combined water or oxidizabl. compounds, us. a particle size of minus 160 um.