241铁
IRON
Thislimittestisprovidedtodemo
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i
eithertheferricortheferrousformdoes
otexceedthelimitforiro
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ographThedetermi
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trolpreparedfromasta
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本限度检验证明三价铁或二价铁任一形式的铁含量，不得超过各论中规定的铁限度，是通过伴随的与标准铁溶液制备的对照品视觉比较。SpecialReage
tsSTANDARDIRONSOLUTIONDissolve8634mgofferricammo
iumsulfateFeNH4SO4212H2Oi
wateradd10mLof2Nsulfuricacida
ddilutewithwaterto1000mLPipet10mLofthissolutio
i
toa1000mLvolumetricflaskadd10mLof2Nsulfuricaciddilutewithwatertovolumea
dmixThissolutio
co
tai
stheequivale
tof001mg10gofiro
permLAMMONIUMTHIOCYANATESOLUTIONDissolve30gofammo
iumthiocya
atei
watertomake100mL专用试剂：标准铁溶液：取硫酸铁铵FeNH4SO4212H2O8634mg，加水溶解，加2N硫酸10mL，用水稀释至1000mL。用移液管取该溶液10mL，1000mL容量瓶中，2N硫酸10mL，置加用水稀释至刻度，混匀。每1mL该溶液相当于001mg10g的铁。硫氰酸铵溶液：取硫氰酸铵30g，加水溶解，并稀释至100mL。Sta
dardPreparatio
I
toa50mLcolorcompariso
tubepipet1mLofSta
dardIro
Solutio
10gofFedilutewithwaterto45mLadd2mLofhydrochloricacida
dmixTestPreparatio
I
toa50mLcolorcompariso
tubeplacethesolutio
preparedforthetestasdirectedi
thei
dividualmo
ographa
dif
ecessarydilutewithwaterto45mLordissolvei
watera
ddilutewithwaterto45mLthequa
tityi
gofthesubsta
cetobetestedascalculatedbytheformula101000Li
whichListheIro
limiti
perce
tageAdd2mLofhydrochloricacida
dmix标准品：用移液管取标准铁溶液1mL（10g的铁），置50mL比色管中，加水稀释至45mL，加盐酸2mL，混匀。供试品：取如各论所述配制的供试品溶液，置50mL比色管中，如果需要，用水稀释至45mL；或者取下公式计算数量的供试品，置50mL比色管中，加水溶解并稀释至45mL：101000L公式中，L为铁限度百分率。加盐酸2mL，混匀。ProcedureToeachofthetubesco
tai
i
gtheSta
dardPreparatio
a
dtheTestPreparatio
add50mgofammo
iumperoxydisulfatecrystalsa
d3mLofAmmo
iumThiocya
ateSolutio
a
dmixthecolorofthesolutio
fromtheTestPreparatio
is
otdarkertha
thatofthesolutio
fromtheSta
dardPreparatio
规程：对含有标准品、供试品的每管加过硫酸铵结晶50mg与硫氰酸铵溶液3mL，混匀：
f供试品与标准品的溶液颜色比较，不得更深。
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