FORDLABORATORYTESTMETHODAQ150-01
TESTFORPHOSPHATECONTAMINATIONOFHIGHSTRENGTHSCREWS
Application
ThismethodisusedtoinspectthesurfacesofhighstrengthscrewsforP0contamination,whichresultsin
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brittleness.
Note:Thismethodisbasedonthereductionofmolybdate-phosphatewithascorbicacidproducingablue
complex(molybdenumblue)whichisstableat23+/-2Cforaboutfourhours.
ApparatusandReagentsRequired
1.TestSolution-Ammonium-molybdate/Sulphuricacid
Preparation:Dissolve10g(NH)MoO.4HOA.R.(ammonium-molybdate)indistilledwaterand
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makeupto100mL.Addthesolutionto300mLofHSO(50%byweight)andcoolto23+/-2C.
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2.TestSalt-AscorbicAcidA.R.
3.1NHSO
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4.1NNaOH
5.StandardSolution
Preparation:Dissolve0.1917gKHPOA.R.(potassium-dihydrogenphosphate)in1000mLofdeionized
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water.Thisstandardsolutioncontains100mg/LPO.
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6.GraduatedCylinders(10mL,50mL,5x100mL);beakers(250mLtallform,400mLshortform);
graduatedpipettes;200mLvolumetricflask;liftingtongsorforceps.