BS ISO 19747:2020 Fertilizers and soil conditioners — Determination of monosilicic acid concentrations in nonliquid fertilizer materials

BS ISO 19747:2020 Fertilizers and soil conditioners — Determination of monosilicic acid concentrations in nonliquid fertilizer materials.
7 Calibration standards
7.1 Blank: 0 mg/I Si — add 10 ml sodium carhonate—ammoniurn nitrate extractant solution (GA) to a II volumetric flask. Dilute to 11 with water. Stopper the flask and mix by inverting 10 times.
7.2 Standard 1: 0,25 mg/I Si — add 10 ml sodium carhonate—ammonium nitrate extractant solution (M) to a 1 L volumetric flask. Add 5 ml intermediate silicon standard solution (JO). Dilute to 1 1 with water. Stopper the flask and mix by inverting 10 times.
7.3 Standard 2: 0,50 mg/I Si — add 10 ml sodium carbonate—ammonium nitrate extractant solution (M) to a 1 1 volumetric flask. Add 10 ml intermediate silicon standard solution (J..Q). Dilute to 1 1 with water. Stopper the flask and mix well by inverting 10 times.
7.4 Standard 3: 1,0 mg/I Si — add 10 ml sodium carbonate-ammonium nitrate extractant solution (f.4) to a 1 1 volumetric flask. Add 20 ml intermediate silicon standard solution (610). Dilute to 11 with water. Stopper the flask and mix by inverting 10 times.
7.5 Standard 4: 2.0 mg/i Si — add 10 ml sodium carbonate-ammonium nitrate extractant solution (6A) to a 1 1 volumetric flask. Add 40 ml intermediate silicon standard solution (610). Dilute to 11 with water. Stopper the flask and mix by inverting 10 times.
7.6 Spike sample: Prepare a spiked talc sample by drying (9..L1) grinding (912) and weighing out (9Ja) a 0,2 g talc [Mg3Si4Olo(OH)21 test portion sample. Add 100 ml each of sodium carbonate (62) and ammonium nitrate () solutions using a plastic graduated cylinder. Before shaking (92) add 3 ml silicon spike solution (66) to the talc test sample. This talc-spiked test sample is processed and used for the matrix spike recovery test verifying that soluble (spike) rather than insoluble silicon (talc) is extracted and reported using this method.
8 Apparatus
As silica (Si02) is a constituent of commonly used laboratory glassware, and detection limits are at 0,6 g/kg Si. it is important to adhere to strict glassware cleaning instructions.
8.1 Glassware, to be thoroughly acid cleaned prior to use in reagent and calibration standard preparation by soaking in a 40m1/l HNO3 solution (Ml) for 30 mm and rinsing three times with deionized water. Allow glassware to air dry prior to use. Glassware items needed include 100 ml to 1 I volumetric flasks, 1 I beakers, and assorted 5 to 50 ml calibrated pipets. All glassware (including flasks and pipets) shall conform to Class A tolerances as recommended for routine laboratory applications.
8.2 Plastic ware, should be cleaned well with warm clean tap water, followed by triple rinsing with deionized water. Specific plastic ware items needed include: SO to I I graduated cylinders, 200 ml nalgene volumetric flasks with screw closure; 250 ml nalgene erlenmeyer flasks with screw closure; 50 ml centrifuge or test tubes with screw closure; 250 ml to 1 1 nalgene or fluorinated ethylene propylene (FEP) narrow-mouth storage bottles with screw closure; and 20 I wide-mouth dispensing bottles with screw closure (also nalgene or FEP).BS ISO 19747 pdf download.