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CYANIDE, TOTAL Method 335.2 (Titrimetric; Spectrophotometric) STORET NO. 00720 1 Scope and ApphcatlOn 11 ThlS method IS apphcable to the determmatlOn of cyamde III dnnklllg, surface and salllle waters, domestlc and llldustnal wastes 12 The titratlOn procedure uSlllg stlver mtrate wlth p-dlmethylamlllo-benzal-rhodamne llldlcator IS used for measunng concentiatlOns of cyamde exceedlllg 1 mg/1 (025 mg/250 ml of absorblllg hqUld) 13 The colonmetnc procedure IS used for concentratlOns below 1 mg/1 of cyamde and IS sensltlve to about 0 02 mg/1 2 Summary of Method 2 1 22 23 The cyamde as hydrocyamc aCld (HCN) IS released from cyamde complexes by means of a reflux-dlstillatlOn operatlOn and absorbed III a scrubber contallllllg sodmm hydroxlde Solutl0n The cyamde 10n III the absorblllg solutlOn IS then determllled by volumetnc tltratl0n or colonmetncally In the colonmetnc measurement the cyamde IS converted to cyanogen chlonde, CNCI, by reaction wlth chioramllle-T at a pH less than 8 wlthout hydrolyzlllg to the cyanate After the reactlOn IS complete, color IS formed on the addltlOn ofpyndllle-pyrazoione or pyndllle-barbltunc aCld reagent The absorbance IS read at 620 nm when USlllg pyndllle- pyrazolone or 578 nm for pyndllle-barbltunc aCld To obtalll colors of comparable llltenslty, It IS essentlal to have the same salt content m both the sample and the standards ' The tltnmetnc measurement uses a standard solutlOn ofstlver mtrate to tltrate cyamde m the presence ofa stlver sensltive llldlcator 3 DefimtlOns 3 1 Cyamde IS defined as cyamde lOn and complex cyamdes converted to hydrocyamc aCld (HCN) by reactlOn m a reflux system ofa mllleral aCld III the presence ofmagnesmm lOn 4 Sample Handl111g and PreservatlOn 41 The sample should be collected m plastlc or glass bottles of 1 hter or larger Slze All bottles must be thoroughly cleansed and thoroughly rlllsed to remove soluble matenal from contalllers 42 OXldlz111g agents such as chlonne decompose most of the cyanldes Test a drop of the sample wlth potassmm lOdlde-starch test paper (KI-starch paper), a blue color mdlcates the need for treatment Add ascorblc aCld, a few crystals at a time, unttl a drop ofsample produces no color on the mdicator paper Then add an addltlonal 0 06 g of ascorbIc aCId for each lIter of sample volume Approved for NPDES Issued 1974 Editonal reVISIon 1974 and 1978 Techmcal ReVISIOn 1980 3352-1PDF Image | Methods for Chemical Analysis of Water and Wastes
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