BS EN ISO 23470:2018 pdf free

BS EN ISO 23470:2018 pdf free.Soil quality – Determination of effective cation exchange capacity
Weigh to within 0,1 % the selected mass of the test portion (see ISO 11464) and transfer to a container for shaking (6.2). Evaluation of plausible CEC and exchangeable cation values may be performed using the diagram type called Carbonate and Sulphate Field Model (CSF model); see Reference [12]. Two different sample masses are used and plausibility is given when both resulting values (any exchangeable cation pair or the CECs) lie on the y = x line as shown in Annex D.
Add 50 ml of the hexamminecobalt(III)chloride solution (5.2) or calcite saturated hexamminecobalt(III) chloride solution (5.11) and shake for (60±5) min by means of the shaker (6.4). Centrifuge by means of 6.5. Collect the clear filtrate or supernatant. Carry out the determinations no later than 24 h after extraction at the latest, otherwise, ascertain that the storage conditions do not influence the test result.
Such storage may be done after diluting the samples in acidified solutions.
Produce an extraction “blank” under the same conditions, but without the test portion.
The measurement of hexamminecobalt concentration in the extract can be performed by determination of total ammonium nitrogen (according to 7.3.2), direct spectrophotometric measurement (according to 7.3.3) or total cobalt concentrations (according to 7.3.4).
Pipette 10 ml of the extract (see 7.2) into the distilling apparatus flask. Make up to the volume, to around 200 ml, with water (5.1). Add the anti-bumping granules (5.3).
Add to the distillate recovery container 40 ml of boric acid solution (5.4) and a few drops of Tashiro indicator (5.5). Immerse the end of the cooling apparatus to a depth of at least 1 cm in the recovery liquid. Add a few drops of phenolphthalein (5.6) into the distilling apparatus flask.
Assemble the apparatus taking care to ensure its tightness.
Add approximately 10 ml of the sodium hydroxide solution (5.7) and progressively heat the flask so as to distil around 150 ml of liquid within 30 min. After this lapse of time, verify the neutrality of the distillate which flows from the end of the cooling apparatus by means of phenolphthalein paper. If the reaction is alkaline, resume the distillation.BS EN ISO 23470 pdf download.