ISO 6101-4:1997 pdf free download.Rubber — Determination of metal content by atomic absorption spectrometry — Part 4: Determination of manganese content.
This part of ISO 6101 specIfies an atomic absorption spectrometiic method for the determination of the manganese content of rubbers.
The method is applicablc to raw rubber and rubber products having manganese contents above 0,5 ppm. Manganoso contents below this limit may be determined, provided that suitable adjustments are made to the mass of the test portion and/or to the concentrations of the solutions used. The use of the standard additions method may lower the bottom limit of detection.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this part of ISO 6101 At the time of publication, the editions Indicated were valid. All standards are subject to revision, and parties to agreements based on this part of ISO 6101 are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards.
ISO 123:1985, Rubber latex — Sampling.
ISO 2471 990, Rubber — Determination of ash.
ISO 648:1977, Laboratory glassware — One-mark pspettes.
ISO 1042:1983. Laboratory glassware — One-mark volumetric flasks.
ISO 1772:1975. Laboratory crucibles in porcelain and silica
ISO 1795:1992. Rubber, raw. natural and synthetic — Sampling and further prepara live procedures.
ISO 4793:1980, Laboratory sinterod (fitted) filters — Porosity grading, classification and designation.
3 Principle
A test portion is ashed at 550 °C ± 25 °C in accordance with ISO 247:1990, method A. The ash is dissolved in hydrochloric acid. The solution is aspirated into an atomic absorption spectrometer and the absorption is measured at a wavelength of 279,5 nm, using a manganese hollow-cathode lamp as the manganeso omission source. Any silicates are volatilized by sulfuric and hydrotluoric acid
NOTE — ISO 6955:1982. Analytical spectroscopic methods Flamo omission, atomic absorption, and atomic fluorescence
— Vocabulary. dotinn 11w swIrnmcdric terms iisd in this part at ISO 6101.
4 Reagents
During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and only distilled water or water of equivalent purity.
4.1 Hydrochloric acid, p — 1,18 Mg)m.
4.2 Hydrochloric acid, diluted 1 + 2.
Dilute 1 volume of concentrated hydrochionc acid (4 1) with 2 volumes of water.
4.3 Sulfuric acid, p — 1,84 Mg/rn3.
4.4 Sulfuric acid, diluted 1+3.
Add carefully 1 volume of concentrated sulfuric acid (4.3) to 3 volumes of water.
4.5 Hydrofluoric acid, p 1,13 Mg/rn3, 38 % (rn/rn) to 40 % (rn/rn).
4.6 Standard manganese stock solution, containing 1 g of Mn per cubic decimetre.
Either use a commercially available standard manganese solution, or prepare as follows:
7.2.1 DestructIon of organic matter
Ash the test portion in accordance with method A of ISO 247:1990, in the muffle furnace (5.3), maintained at 550 °C ± 25 °C. If the ash is black, caused by small amounts of carbon black, stir carefully with the platinum or borosdicate-glass rod (59) and continue heating.
7.2.2 Dissolution of inorganic residue
After ashing. allow the crucihle and its contents to cool to ambient temperature. Add 20 cm3 of concentrated hydrochloric acid (4.1). Heat the mixture on the steam bath (5.8) for at least 10 mm Do not let the reaction mixture boil. Allow to cool to ambient teiriperalure and transfer the solution quantitatively, with the aid of water, to a SI) cm3 one-mark volumetric flask (see 5.5). If the ash is not totally dissolved, proceed as follows:
Transfer the solution and the mindissolved ash quantitatively, with the aid of water, to a platinum crucible (5.10). Add a few drops of concentrated sulfuric acid (4.3) and 5 cm3 of hydrofluonc acid (45). Heat on the electric hotplate or sand bath (5.7) in a fume cupboard and evaporate to dryness, while stirring with a platinum rod (5.9). Repeat this digestion with the same quantities of sulfuric and hydrofluoric acids two more times.
Allow to cool to ambient temperature, add 20cm3 of concentrated hydrochloric acid (4.1), heat for 10 mm and transfer quantitatively, with the aid of water, to a 50 cm3 one-mark volumetric flask (see 55)
Dilute to the mark with water and mix thoroughly. Insoluble matter may settle and, if so, shall be filtered off using a filter crucible (5.4) just before making speetrometric measurements in accordance with 7.3.
Test solutions should contain approximately 12 % hydrochloric acid. II evaporation, etc.. has reduced or Increased this concentration, adjust accordingly with concentrated hydrochloric acid (4.1) or water.
7.3 Preparation of the calibration graph
7.3.1 Preparation of calibration solutions
7.3.1.1 Into a series of five 100 cm3 one-mark volumetric flasks (see 5.5) introduce, using pipettes (see 5.6), the volumes of standard manganese soluton (4.7) indicated in table 1. Dilute to the mark with 1 + 2 hydrochloric acid (4.2) and mix thoroughly.
Switch on the spectrometer (5.1) sufficiently in advance to ensure stabilization. With the manganese hollow-cathode tube suitably positioned, adjust the wavelength to 279,5 nm and the sensitivity and slit aperture according to the characteristics of the instrument.
AdJUSt the pressures and flow rates of the air and of the acetylene in accordance with the manufacturers instructions so as to obtain a clear blue, non-luminous, uxidiiing Ilame, suited to the characteristics of the particular spectrometer being used.
Aspirate the set of cahbration solutions in succession into the tiame and measure the absorbance of each solution twuce, averaging the readings. Take care that the aspiration rate is constant throughout this process. Ensure also that at least one calibration solution is at or below the analyte level found in the rubber being tested.
Aspirate water through the burner after each measurement.
7.3.3 Plotting the calibration graph
Plot a graph having, for example, the masses, in micrograms, of marugartese contained in 1 cm3 of the calibration solutions as abscissae and the corresponding values of absorbance, corrected for the absorbance of the calibration blank, as ordinates. Represent the points on the graph by the best straight line as judged visually or as calculated by the least-squares fit method.
7.4 Determination
7.4.1 Spectrometric measurements
Carry out duplicate spectrometnc measurements at a wavelength of 279,5 nm on the test solution prepared in 7.2.2. following the procedure specified in 7.3.2.
7.4.2 Dilution
If thc instrument response for the test solution is greater than that found for the calibration solution having the highest manganese content, dilute, as appropriate, with 1 + 2 hydrochloric acid (4.2) in accordance with the following procedure.
Pipette carefully a suitable volume (V cm3) of the test solution into a 100 cm3 oneinark volumetric flask (see 5.5) so that the manganese concentration lies within the range covered by the calibration solutions. Dilute to the mark with
8.3 The test result is the average of two determinations, rounded to two decimal places when the manganese concentration is expressed as a percentage and to the nearest whole number when the concentration is expressed in milligrams per kilogram.
8.4 Report the manganese content as a percentage if greater than or equal to 0.1 %, or in milligrams per kilogram if less than 0.1 %.
9 Test report
The test report shall include the following information:
a) a reference to this part of ISO 6101,
b) all details necessary for the complete identification of the product tested;
c) the method of sampling;
d) the type of instrument used (flame or graphite furnace spectrometer);
e) the results obtained and the units in which they have been expressed;
f) any unusual features noted during the determination:
g) any operation not included in this part of ISO 6101, or in the International Standards to which reference is made, as well as any incident which might have affected the results.