电位滴定法连续测定水中钙和镁

20093742009374200937420093742009374200937420093742009374200937420093741215100702810012、。EDTA[1-2]、[3]、[4]、[5]、[6]、[7]。TrisEDTA。。11.1TIM840RadiometerAnalyticalRadiometerAnalyticalAg/AgClRadiometerAnalytical0.02mol/LEDTA0.035mol/L(TRIS)-0.055mol/L(HAA)8.00mg/mL2.00mg/mL。1.250mL100mL20mLTIM840EDTAE-V。22.1、EDTACa2+、Mg2+、1。HAApKa=8.9Mg2+lgK1=3.54lgK2=2.41[8]pH10lg(H)0.03Mg2+EDTAlgK8.7。Mg2+HAAMg(AA)2EDTACa2+EDTACa2+EP1。EDTAMgEDTAMg(AA)2EDTAMg(AA)2Mg2+Mg(AA)2Mg2+。EP1EP2EP1Ca2+、Mg2+。Mg2++2HAA→Mg(AA)2+2H+Ca2++EDTA→CaEDTAMg(AA)2+EDTA→MgEDTA+2AA-2.2pH。EDTA、pH=10～11。pH＜10Ca2+、Mg2+EDTA。、0.24%~0.96%98.12%~103.34%0.55%~2.71%95.83%~102.14%。ContinuousDeterminationofCa2+andMg2+inWaterbyPotentiometricTitrationLUHai-yan1,LIXuan21RedMatrixChinaLtd.,GuangdongGuangzhou510070;2XiningNo.1Vocational-technicalSchool,QinghaiXining810012,ChinaAbstract:Potentiometrictitrationhadthecharacteristicsofoperationsimple,accurate,precisehigh,automaticandwithoutpretreatmentforsamples.ThismethodappliedtotheanalysisofCa2+andMg2+inwater,andtheresultwassatisfacto-ry.Ca2+relativestandarddeviationwere0.24%~0.96%andMg2+were0.55%~2.71%,andrecoveriesofCa2+98.12%~103.34%,andMg2+95.83%~102.14%)wereobtained.Keywords:potentiometrictitration;calcium;magnesium;drinkingwater147··2009374200937420093742009374200937420093742009374200937420093742009374pH＞12Mg2+Mg(OH)2、[9]pH≈10。pH≈10EDTA[1-3]。。-TrisFe3+、Al3+、Cu2+[9]TrisMg2、1Ca2+、Mg2+。pH≈10-Tris。2.341.261RSD0.24%~0.96%RSD0.55%~2.71%。2.41.2298.12%~103.34%100.83%95.83%~102.14%98.98%。1EP280.040.00.0-40.0120.0EP10.02.55.0V2V1mLmV1/(mg/L)/(mg/L)/(mg/L)RSD/%1Ca2+28.0828.2428.4827.9228.6428.4028.290.270.96Mg2+6.686.486.896.436.796.606.640.182.712Ca2+44.8844.5244.4044.6045.0044.8044.700.230.51Mg2+12.2912.0512.0012.2412.4812.1912.210.171.393Ca2+86.2186.3486.1385.7586.4085.9086.120.260.30Mg2+17.8017.5817.6518.0418.1617.9017.850.221.234Ca2+114.60114.32114.88114.24114.68114.80114.590.260.24Mg2+25.6625.4425.8025.5125.5625.7525.620.140.552/(mg/L)/(mg/L)/(mg/L)/%/(mg/L)/(mg/L)/(mg/L)/%144.7024.0068.2598.1212.217.0019.36102.14244.7040.0085.24101.3512.2110.0022.0398.20344.7056.00100.3099.2912.2114.0026.45101.71444.7064.00110.00102.0312.2118.0029.4695.83544.7088.00135.64103.3412.2124.0035.5097.04---------100.83---------98.983TrisMg2+EDTA、。、、、、。[1].—EDTA[S]..1987.[2],,,.EDTA[J].2002,14(4):254-255.[3],.[J].,2005,15(5):538-539.[4].-[J].,1999,25(3):155-157.[5].[J]..2008,20(01):86-87.[6];;,.[J].,2003,29(1):56-57.[7],.[J].2007,31(5):356-357.[8],,,.[J].,1999,27(10):1238.[9].()[M].:2000.123.148··