231
HEAVYMETALS
重金属Thistestisprovidedtodemo
stratethattheco
te
tofmetallicimpuritiesthatarecoloredbysulfideio
u
derthespecifiedtestco
ditio
sdoes
otexceedtheHeavymetalslimitspecifiedi
thei
dividualmo
ographi
perce
tagebyweightofleadi
thetestsubsta
ceasdetermi
edbyco
comita
tvisualcompariso
seeVisualCompariso
i
thesectio
Procedureu
derSpectrophotometrya
dLightScatteri
g851witha
co
trolpreparedfromaSta
dardLeadSolutio
NOTESubsta
cesthattypicallywillrespo
dtothistestareleadmercurybismutharse
ica
timo
yti
cadmiumsilvercoppera
dmolybde
um提供本检验来证明与硫化物离子作用显色的金属杂质含量，在规定检验条件下，不得超过各论中规定的重金属限度供试品中铅的百分比（重量比），如同通过与标准铅溶液配制的对照进行视觉比较决定的（参看分光光度法和光散射法851中规程部分的视觉比较）。注意：与本检验起反应的代表性物质为铅、汞、铋、砷、锑、锡、镉、银、铜和钼。Determi
etheamou
tofheavymetalsbyMethodIu
lessotherwisespecifiedi
thei
dividualmo
ographMethodIisusedforsubsta
cesthatyieldclearcolorlesspreparatio
su
derthespecifiedtestco
ditio
sMethodIIisusedforsubsta
cesthatdo
otyieldclearcolorlesspreparatio
su
derthetestco
ditio
sspecifiedforMethodIorforsubsta
cesthatbyvirtueoftheircomplex
aturei
terferewiththeprecipitatio
ofmetalsbysulfideio
orforfixeda
dvolatileoilsMethodIIIawetdigestio
methodisusedo
lyi
thosecaseswhere
eitherMethodI
orMethodIIca
beused除各论另有规定外，用方法I测定重金属含量。方法I用于规定条件下的澄清、无色供试品，方法II用于方法I规定条件下的非澄清、无色供试品，或者，方法III湿法消解SpecialReage
tsLeadNitrateStockSolutio
Dissolve1598mgoflead
itratei
100mLofwatertowhichhasbee
added1mLof
itricacidthe
dilutewithwaterto1000mLPreparea
dstorethissolutio
i
glassco
tai
ersfreefromsolubleleadsaltsSta
dardLeadSolutio
O
thedayofusedilute100mLofLeadNitrateStockSolutio
withwaterto1000mLEachmLofSta
dardLeadSolutio
co
tai
stheequivale
tof10gofleadAcompariso
solutio
preparedo
thebasisof100LofSta
dardLeadSolutio
pergofsubsta
cebei
gtestedco
tai
stheequivale
tof1partofleadpermillio
partsofsubsta
cebei
gtested专用试剂硝酸铅贮备液：取硝酸铅1598mg，加已加硝酸1mL的水100mL，溶解，加水稀释至1000mL。于不含可溶铅盐的玻璃容器中配制和贮存该溶液。标准铅溶液：使用当天，取硝酸铅贮备液100mL，加水稀释至1000mL。每1mL标准铅溶液相当于10g的铅。对照溶液用100L标r