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1、理化检验-化学分册PTCA(PARTB:CHEM.ANAL.)2005年第41卷12工作简报恒电流库仑分析法测定青霉素G钠盐含量梁述忠(徐州工业职业技术学院,徐州221002)摘要:将青霉素G钠盐在pH4.6条件下水解成青霉氨基酸;以银电极为阳极,电解产生滴定++剂Ag,以Ag滴定青霉氨基酸,采用电位法确定库仑滴定终点,由电解定律计算青霉素G钠盐含量。此法取代了汞量法,消除了汞污染,相对误差为0.184%,RSD(n=11)为0.030%。关键词:恒电流库仑分析法;银离子;青霉素G钠盐;青霉氨基酸中图分类号
2、:O657.31文献标识码:A文章编号:100124020(2005)1220914203CONSTANTCURRENT2COULOMETRICTITRATIONOFPENICILLINGINDRUGPOWDERLIANGShu2zhong(XuzhouTechno2VocationalCollegeofIndustry,Xuzhou221002,China)Abstract:Constantcurrent2coulometrywasappliedtothedeterminationofpenicillin
3、G(sodiumsalt)indrugpowder.ThesamplewaspreliminarilyhydrolyzedinalkalinesolutionandinacetatebufferedsolutionofpH4.6insuccessiontoconvertpenicillinGintopenicillicaminoacid.Basedonthequantitativereactionof-SHgroupinthemoleculeofpenicillicaminoacidwithsilver(Ⅰ
4、)toformaprecipitatewiththeformula(CH3)22C2(SAg)2CH(NH2)2COOH,thecontentofpenicillinG(sodiumsalt)wasdeterminedcoulometricallybytitrationwithsilverionelectro2generatedatthesilveranode.ThequantityofpenicillinGwascalculatedbytheFaraday′slaw.Smallamountsofpenic
5、illicaminoacidwasusuallyfoundintheunhydrolyzedpenicillinGsampleduetodegradation,aseparate,unhydrolyzedsampleshouldbetakentodeterminedthisblankvalue,whichafterconvertedintoamountsofpenicillinG,wassubstractedfromthetotalvalueofpenicillinG.Thesubstitutionofth
6、iscoulometricmethodforthemercurimetricmethodmakesitpossibletoavoidtheuseofmecurysaltsandisfavorabletoenviromentalprotection.Acheckfortheaccuracyandprecisionofthepresentmethodwasmadebyanalyzingareferencesample(labelledvalueofpenicillinGcontent(w)is98.04%),r
7、elativeerrorof0.184%,andRSD(n=11)of0.030%wereobtained,whichwerebothbetterthanthoseobtainedbythemercurimetricmethod.Keywords:Constantcurrent2coulometrictitration;Electro2generatedsilverion;Benzylpenicillin(penicillinG)sodiumsalt;Penicillicaminoacid青霉素G钠盐是常用
8、的抗生素类药物,目前常间长,误差引入因素多。[1][2]规分析方法是采用硝酸汞电位滴定法(汞量法)。本试验中采用恒电流库仑分析法测定青霉素该方法最大的缺点就是测定中所产生的硝酸汞废液G钠盐含量:将青霉素G钠盐在碱性溶液中先水解以及生成物青霉氨基酸络汞等对环境造成的污染,生成青霉噻唑酸钠,然后在pH4.6条件下继续水此外,测定中需要配制与标定硝酸汞滴定液,分析时解生成青霉氨基酸,青霉氨基酸分子中含有巯基+(-SH)
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