BS ISO 18068:2014 pdf free

BS ISO 18068:2014 pdf free.Cotton fibres一Test method for sugar content一Spectrophotometry
Add 2,0 ml of 3,5-dihydroxytoluene/sulfuric acid solution (6.6.1) immediately to the colorimetric tube preheated to 70 °C in a water bath (5.3), and mix them by shaking to form a mixed solution, and again keep the mixed solution at a constant temperature of 70 °C for 40 min. Remove the tube from the bath.Subsequently, add further 20 ml of the fatty acid alkanolamide solution (6.6.2) to the mixed solution, mix them by shaking the tube, immediately cool down the resultant solution to room temperature and make it up to the mark with the 0,4 g/l fatty acid alkanolamide solution (6.6.2) and allow it to stand for 5 min to form a final solution. Transfer an appropriate amount of the final solution intoa 1 cm cuvette to form a blank reagent. Measure and record the absorbance of the blank reagent at a wavelength of 425 nm using a Spectrophotometer (5.1).
Pipette 1,0 ml of each of the standard solutions into a different 25 ml colorimetric tube, and treat each aliquot in the different tube in the same way as that described in 8.1.2.
Prepare a calibration curve with the concentration of the sugar standard solution as the abscissa and the corresponding absorbance (obtained by subtracting the absorbance of the blank reagent from the absorbance of the sugar standard solution) as the vertical coordinate.
Since the sensitivity of fatty acid alkanolamide solution may change slightly over a long period of time,it is good practice to run a calibration curve weekly for correcting slight changes in the standard curve.
Place the three test specimens (see 7.4) in three separate 250 ml flasks. Add 200 ml of the 0,05 g/l fatty acid alkanolamide solution (6.6.3) to each flask. Shake for 10 min in the mechanical shaker (5.12).
Turn over the cotton fibre with a glass rod. Shake the flasks for another 10 min and then filter the three test specimen solutions respectively through the filter (5.11) using vacuum air pump (5.10).
Pipette 1,0 ml of each of the three test specimen solutions (see 8.3.1) into a separate 25 ml colorimetric tube. Treat in the same way as 8.1.2.BS ISO 18068 pdf free download.