ISO 13313:2017 pdf free
ISO 13313:2017 pdf free.Iron ores – Determination of sodium – Flame atomic absorption spectrometric method
The caps of the plastic bottles should be of a type that does not contain a separate wad insert. Such inserts usually contain a sodium compound that will contaminate the solution.
To obtain reliable values, the equipment should be cleaned and checked as follows.
a) Rinse all volumetric ware, including the pipettes used for preparing the calibration solutions, with dilute hydrochloric acid (5.3) before use. Check calibration regularly or as needed.
b) Clean PTFE vessels and stirring bars by stirring with 50 ml of dilute hydrochloric acid (5.3) and heating for 15 min. Reject the rinsings and conduct a blank test in each vessel in turn, exactly as specified in 8.3. If any absorbance value is above the limit specified in 8.3, the cleaning procedure should be repeated or acid reagents of a higher purity should be used. At no stage should the stirring bars be handled with the fingers.
c) Platinum vessels, exclusively used for sodium analysis according to this document, can be cleaned by the same method as the PTFE vessels [see b]. Otherwise, they should be pre-cleaned by fusion with lithium tetraborate or lithium borate, until the absorbance readings fall to those for the lithium salt alone.
d) Rinse storage bottles with dilute hydrochloric acid (5.3) before use.
The atomic absorption spectrometer shall meet the following criteria.
a) Minimum sensitivity: the absorbance of the most concentrated calibration solution (see 8.4.4) shall be at least 0,25.
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 less 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 of the zero calibration solution, each being calculated from a sufficient number of repetitive measurements, shall be less than 1,5 % and 0,5 %, respectively, of the mean value of the absorbance of the most concentrated calibration solution.ISO 13313 pdf free download.
