ISO TS 13899-3:2005

ISO TS 13899-3:2005 pdf free.Steel一Determination of Mo, Nb and W contents in alloyed steel一Inductively coupled plasma atomic emission spectrometric method一Part 3:Determination of W content.
The sample is dissolved in a hydrochloric, nitric and hydrofluoric acid mixture and fumed with a phosphoric and perchloric acid mixture. Hydrofluoric acid and an internal standard element (if used) are added and the solution is diluted to known volume. The solution is filtered and nebulized into an inductively coupled plasma (ICP) spectrometer and the intensity of the emitted light from the element is measured simultaneously with the light emitted from the internal standard element.
The method uses a calibration based on close matrix matching of the calibration solutions to the sample and close bracketing of the tungsten content around the approximate concentration of tungsten in the sample to be analysed.’ This compensates for matrix interferences and provides high accuracy, even in highly alloyed steels where spectral interferences can be severe. Nonetheless, all interferences shall be kept to a minimum and it is therefore essential that the spectrometer used meets the performance criteria specified in the method for the selected analytical lines.
In order to accurately matrix match, it is necessary to know the content of all elements in the sample (to the nearest %). To this end, it may be necessary to carry out a preliminary analysis of the sample by a semi-quantitative method.
Choose a suitable element to be added as internal standard and prepare a 1 000 mg/l solution. The internal standard chosen shall be pure, shall not be present in the sample, and shall not interfere with analytical wavelengths, nor should the internal standard element wavelength be interfered with by elements in the test solution.
The internal standard shall be soluble in the acids used and it shall not cause precipitation. Moreover, the excitation conditions of the analytical line and the internal standard element line should match.
Weigh, to the nearest 0,001 g, 0,5 g of high purity tungsten [minimum 99,95 % (mass fraction)] and dissolve in a mixture of 10 ml hydrofluoric acid (4.1) and 20 ml nitric acid (4.3). Cool and transfer the solution quantitatively to a calibrated 500 mI one-mark plastic volumetric flask. Dilute to the mark with water and mix. 1 ml of this solution contains 1 mg of W.
It is not permitted to use pre-prepared tungsten standard solutions supplied by second parties.
Prepare standard solutions for each element of which more than 1 % (mass fraction) is contained in the test sample. Use pure elements or oxides with tungsten contents less than 10 μg/g. Commercial certified standard solutions can also be used if the tungsten content is less than the value specified above.
NOTE If a large amount of an element is to be added (e.g. iron), it might be more advantageous to use the pure metal and weigh the correct amount (see 7.3 and 7.4). In this case, use the dissolution procedure described in 7.1.2.
The spectrometer can be either the simultaneous or the sequential type. A sequential type can be used either with or without an internal standard. However, if a sequential spectrometer is to be used with an internal standard, it shall be ftted with an arrangement which allows for the simultaneous measurement of the internal standard line.ISO TS 13899-3 pdf download.

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