Equipment and reagents:

Haotianhui brandCAAM-2001EFlame graphite furnace integrated atomic absorption spectrometer, lead hollow cathode lamp, analytical balance (sensitivity)0.1mg）Adjustable electric stove, adjustable electric heating plate, microwave digestion system (equipped with PTFE digestion inner tank).

note:All glassware and PTFE digestion inner tanks require nitric acid solution(1+5)Soak overnight,Rinse repeatedly with tap water,Finally, rinse thoroughly with water.

Unless otherwise specified,The reagents used in this method are all of high purity,Water isGB/T6682Designated secondary water.

Reagent: Nitric acid(HNO₃)Hydrochloric acid(HCL)Lead standard reserve solution certified by the state and awarded with a standard substance certificate(1000μg/mL)Standard solution preparation: lead standard intermediate solution(1.00μg/mL)Accurately absorb lead standard reserve solution(1000μg/mL)0.10mLYu100mLVolumetric flask,Add nitric acid solution(5+95)Up to the scale,Mix well. Lead standard series solution:Extract lead standard intermediate solution separately(1.00mg/L)0mLThe0.500mLThe1.00mLThe2.00mLYu100mLVolumetric flask,Add nitric acid solution(5+95)Up to the scale,Mix well. The mass concentrations of this lead standard series solution are0μg/LThe5.00μg/LThe10.0μg/LThe20.0μg/L.

note:The mass concentration of lead in the standard series solution can be determined based on the sensitivity of the instrument and the actual content of lead in the sample.

Microwave digestion pretreatment:

Weigh solid samples0.2g~0.8g(Accurate to0.001g)In the microwave digestion tank,join5mLnitric acid,Dissolve the sample according to the steps of microwave digestion,Reference table for digestion conditions1After cooling, remove the digestion tank,On the electric heating plate140℃~160Drive acid to ℃1mLabout. After cooling the digestion tank,Transfer digestive juices to25mLVolumetric flask,Wash the digestion tank with a small amount of water2time~3time,Combine the washing solution in a volumetric flask and dilute to the mark with water,Mix well and set aside. Simultaneously conduct a reagent blank test.