AOAC OMA# 2011.14 (Final Action Review)-OMB

2011.14 (SEPTEMBER 2017) MTE-01/03 REPORT

ISO/NP 15151 | IDF 229 FOR ERP USE ONLY DO NOT DISTRIBUTE

9.3

Determination

9.3.1

Preparation of the test solution

9.3.1.1 Wet digestion with internal standard Cool the digested solution (9.2.1.1) to room temperature while reducing to atmospheric pressure. Add 0,5 ml of H 2 O 2 (5.7) to all tubes except the blanks, to neutralise the nitric vapour. Transfer the content of the tube quantitatively in a sampler tube. Dilute to 25 ml with water. Mix thoroughly. If necessary continue with the dilution procedure in 9.3.1.2. 9.3.1.2 Dilution According to the type of test sample and element measured, dilute (dilution factor f 1 ) the test solution (9.3.1.1) by using the micropipette (6.5) in the required one-mark volumetric flasks (6.3). NOTE Concentration of nitric acid in test solution after dilution is generally that of nitric acid solution (5.3). ICP-AES measurement Analytical lines, selectivity, limits of determination and quantification, precision, linear working area, and interferences have to be established before operating the ICP-AES system. Set the spectrometer at the required wavelength depending on the element (analyte) of the determination (see Annex B). Each value is the average from at least three individual measurements of the test sample and standard solutions. Average the values if falling within an accepted range. NOTE An ionization buffer can be used if applicable 9.3.2.1 Calibration The volumes and corresponding concentrations are only given for guidance. Select both within the linear range of the particular instrument used (at least 5 concentrations including zero member). Transfer the volumes of the solutions mentioned in Table 2, by using the (micro) pipette (6.4 or 6.5), in six 100 ml one-mark volumetric flasks (6.3) respectively. Dilute with water to the 100 ml mark and mix. The obtained calibration solutions are tabled in Table 2. 9.3.2

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