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石灰性土壤中有效钼含量低,变幅大,用硫氰酸钾比色法或原子吸收光谱法测定,灵敏度较低,很不适用。选用极谱催化波法灵敏度很高,可检出千亿分之六(0.06ppb)的钼。而且波高稳定,简便易行,样品不需萃取浓集,适于石灰性土壤中有效钼的测定。 (一)试前准备选用jp—IA型示波极谱仪。滴汞为阴极,饱和甘汞电极作参比电极,钼电极为辅助电极。试剂制备。选用药剂均为分析纯。pH3.3草酸铵—草酸溶液。称取24.90克草酸铵与12.60克草酸溶于水,定容至1升。定前校正pH为3.3。 12.5N硫酸——浓硫酸1份徐徐注入2份
In calcareous soils, the available molybdenum content is low, the amplitude is large, and the sensitivity is low when it is determined by potassium thiocyanate colorimetric method or atomic absorption spectrometry, which is not suitable. The polarographic catalytic wave method is highly sensitive and can detect six parts per billion (0.06 ppb) of molybdenum. And the wave height is stable, simple and easy, the sample without extraction concentration, suitable for the determination of available molybdenum in calcareous soil. (A) Preparation of pre-test selection jp-IA oscilloscope polarography. Drop mercury as cathode, saturated calomel electrode as reference electrode, molybdenum electrode as auxiliary electrode. Reagent preparation. Selected pharmaceuticals are analytical grade. pH3.3 ammonium oxalate-oxalate solution. Weigh 24.90 grams of ammonium oxalate and 12.60 grams of oxalic acid dissolved in water, set the volume to 1 liter. Pre-calibration pH was 3.3. 12.5N sulfuric acid - 1 part concentrated sulfuric acid slowly into 2 parts