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ISO 17992-2013 pdf free download
ISO 17992-2013 pdf free download.Iron ores Determination of arsenic content Hydride generation atomic absorption spectrometric method
Minerals defer — Dosage de l’arsenic — Méthode par spectrométrie d’absorption atom ique a génération d’hydrure.
Using pipettes, transfer 0 ml, 0,1 ml, 0,5 ml, 1 ml, 3 ml, 4 ml, 6 ml, 10 ml, 20 ml, 30 ml, and 40 ml of arsenic standard solution C (4J.9), respectively, to 100 ml one—mark volumetric flasks. Add 15 ml of the background solution (4J) and 10 ml of ascorbic acid solution (4JS) and 10 ml of potassium iodide solution (4d4) to each, then add hydrochloric acid (4.11) to the flasks until the mark and mix. Stand for at least 3 h, then use for determination.
NOTE I The detection limit of the method can vary because of differences between instruments (atomic absorption spectrometers and hydride generators). For Instruments with high sensitivity, a calibration solution with low arsenic conent can be used.
NOTE 2 Where the arsenic content in a sample is known to be within a certain range, the set of calibration solutions can be varied to provide good results within that range.
7.4.5 Adjustment of the atomic absorption spectrometer
Optimize the response of the instrument as specified in £1. Set the wavelength for arsenic (193,7 nm) and align the position of the quartz tube to obtain minimum absorbance. Fit the instrument, adapter, and connectors of the hydride generator and adjust in accordance with the manufacturer’s instructions. Light the appropriate flame or heat electric furnace to the appropriate temperature. After several minutes of preheating, adjust the flow of carrier gas to the appropriate flow rate. Adjust correlative parameters to obtain maximum absorbance while injecting the calibration solution (Z43) of highest arsenic content (not less than 0,25).
7.4.6 Atomic absorption measurements
Aspirate the calibration and test solutions or diluted test solutions in order of increasing absorption, starting with the blank test solution, or diluted blank test solution, and the zero calibration solution. When a stable response is obtained for each solution, record the readings. Aspirate the test solutions or diluted test solutions at the proper points in the calibration series and record their readings. Aspirate water between each calibration and test solution. Repeat the measurement at least twice.
Obtain the net absorbance oleach calibration solution by subtracting the average absorbance of the zero calibration. In a similar manner, obtain the net absorbance of the test solution or diluted test solution by subtracting the absorbance of the corresponding blank test solution.
Prepare calibration graphs by the net absorbance values of the calibration solutions against the concentration, in micrograms of arsenic per millilitre (the test solution or, if diluted test solution is the final test solution).
Convert the net absorbance readings of the final test solution to micrograms of arsenic per millilitre by means of the calibration graph.
With concentration readings, the calculation should be made from absorbencies to permit checking of the graph’s linearity and the blank test value.ISO 17992-2013 pdf free download.
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