ISO 8655-7:2005 pdf download.Piston-operated volumetric apparatus 一Part 7: Non-gravimetric methods for the assessment of equipment performance.
4.1 Photometric method
The photometric method of testing piston-operated volumetric apparatus relies upon the relationship between the concentration of a chromophore in solution and its absorbance of light at a specified wavelength, as desaed by the Beei—Lambert law. The method can use one of two procedures, depending on the needs of the calibalion. In both methods, the test volume of liquid to be measured is delivered by the piston-operated volumetnc apparatus under test into a known volume of liquid, and the degree 01 dilution Is calculated from pliotornetnc measurements
The first method Is suitable for test volumes > 20 % of the total volume. The total volume depends on the size of the photometric measunng cell and shall be large enough to adequately fill the cell in the UVN1S photometer. In this method a known volume of solution is prepared having an abscbance near the upper end of the working range of the photometer and Its absorbance Is measured. The piston-operated volumetric apparatus being tested is used to add an unknown volume of diluent, e.g. water or buffer. The resulting solution is mixed well and its absorbance is measured. The unknown volume delivered can be calculated from the decrease in absorbance.
The second method is suitable for test volumes <20 % of the total volume. In this method a known volume of diluent is prepared The piston-operated volumetric apparatus being tested Is used to add an unknown volume of a sample solution of chrornophore having known absorbance. The resulting solution is mixed well and its absorbance is measured. The unknown volume delivered is then calculated from the increase in absorbance. Annex A and Annex B give examples for test procedure and calculation.
The photometric method of testing piston-operated volumetric apparatus relies upon the relationship between the concentration of a chromophore in solution and its absorbance of light at a specified wavelength, as desaed by the Beei—Lambert law. The method can use one of two procedures, depending on the needs of the calibalion. In both methods, the test volume of liquid to be measured is delivered by the piston-operated volumetnc apparatus under test into a known volume of liquid, and the degree 01 dilution Is calculated from pliotornetnc measurements
The first method Is suitable for test volumes > 20 % of the total volume. The total volume depends on the size of the photometric measunng cell and shall be large enough to adequately fill the cell in the UVN1S photometer. In this method a known volume of solution is prepared having an abscbance near the upper end of the working range of the photometer and Its absorbance Is measured. The piston-operated volumetric apparatus being tested is used to add an unknown volume of diluent, e.g. water or buffer. The resulting solution is mixed well and its absorbance is measured. The unknown volume delivered can be calculated from the decrease in absorbance.
The second method is suitable for test volumes <20 % of the total volume. In this method a known volume of diluent is prepared The piston-operated volumetric apparatus being tested Is used to add an unknown volume of a sample solution of chrornophore having known absorbance. The resulting solution is mixed well and its absorbance is measured. The unknown volume delivered is then calculated from the increase in absorbance. Annex A and Annex B give examples for test procedure and calculation.
