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,t= i`� .r".r .��„«� =t� ... ,.,.� y, _ �� . � -�s: � -"�� r `mac �; `...��•"��'i�l �'P a P>`ooedure for Burets Method CHLORIDE (cant'd) APPgeN2 o Lb ` 1. Take a water sample by filling a clean WMI-graduated cylinder to the I00-ml-mark.Pour thee sample Into a clean 250•mL Erlenmeyer flask. 2. Add the consents of one Chloride 2Indicator Powder Allow and swirl to mist. 3. Titrate the sample with Silver Nitrate Standard Solution white swirling the flask until the color changes from yellow to md•brown.See Notes A and D. 4. Multiply the number of mL of Silver Nitrate Standard Solution used by 5 ko obtain the mg4.chloride (CI)?'See Notes Cand D. (Procedure for Dlgltal Titrator Method I. Take a water sample by filling a clean 50•rnl.graduated cylinder to die 50-reel.mark.Pour the sample into a clean 125-mL Erlenmeyer flask. 2. Add the contents of ase CWorfde 2yndieatorPowder Pi11ow and swirl to mix. 3. Ifperforming a hand-held titration,attach a clean,srraighs•stem delivery tube to a 1.128N Silver NiCarr Tirratiurr Muvidge. Twist cartridge onto titmtor body.If Digital Tivasor is to be attached so a laboratory stand,use a clean 90°delivery tube. a. Flush the delivery tube by turning dee delivery knob to eject'i fewdrops of titrant.Reset the co nicrt,a zero and wipe the tits. 5. Titrate the sample while swirling the flask until the color changes from yellow to red-brown. 6. Read the concentration of chloride(in mg.9.)direc[ly(rain the digital counter window.(For chloride con- centrations below 50mg/L as Cl-,uses 0.2256N Silver Nitrate Titration Cartridge and divide the mad- ing by 5 to determine the mg/L chloride.The results may be expressed as mg/L sodium chloride by multi- plying the mg/L chloride by 1.65.) Notes A. S?Iver Nitrate solutions decompose when exposed to light.For this reason,an occasional test should be made to determine the strength and ustsbilhy of the Silver Nitrate Standard Solution.Pipet 10.00 snL of �—� Sodium Chloride Standard Solution,1000 mg/L as Cl,intoa 100-mL graduated tyiindtrand dilute to the ]0OnL mark with detniryera5ved water.Pour intoa 250-mL Erlenmeyer flask and analyze according to the procedure for water ramples.If the amount of Silver Nitrate Standard Solution required exceeds 21 mL,the solution should be discarded and replaced with a fresh supply. R. When the total amount of Silver Nitrate Standard Solution required exceeds 25 mLper titration,a sample dilution is recommended to minimize errors from multiple buret readings.The final results ar.then multi- r plied by the dilution factor. More concentrated titrating solutions are available for samples which consistently require more than 25 mL of Silver NinateStandard Solution,0.0141N per test.When using Silver Nitrate Smndwd Solution, ; 0.I41N, multiply the number of mL used by 50 io ubtain the mg/L chloride. C. '!be amount cf reagent blank caused by the indicator can be determined by running the test on de• i' mineralized waster.This value is subtracted from the final reading before multiplying by 5 toobtain the ne- suits as mgrs.chloride.The reagent blank also shows dee true end point much more clewly in the absence : of the silver eltloride precipitate. D. Tbe results rraq be expressed as mA sodium chloride by multiplying the mg4-chloride_by 1.65. E. iron in excess of 10 mg/L masks the end point.Onhophosphate in escess of 25 mgiL vri11 pttxiplule the silver,tuerfattneq front 10 mall.a more sulfite can bt tlitrninated a ith 3RSF Hydrogen Peroxide. Using r a glass utolog;ical pipet and piper filler,add these drops of 30%Hydroyea Peroxide per 100 mL of Lam- . c ple before running the test.SWfrde interference can be removed by adding the contents of one Sulfdelu- h btiter Reagem Powder Pillow to about 125 mL of the ample,mixing for one minute and Gltuing e *mtrgh a`,_'ted filter paper.Cyanlde,bromide and iodide interfere dirtcdy and are titrartil as Woride. F. The standard,additions method check can be performed as follows: 1. Snap die,neck off a fresh Volutttes Ampule Sit-ri6rd for C1;roride(Cat.No. 14230.10). 2. Using dee TenSette"Pipet.add 0.10 mL.0.20 teed,and 0.30 end,seapectively,to three IDMmL Water trtmples.Mix ash well. rz 3. Analyse each sample as descsibtd in the procedure and etsmpue the results with the original teat s, ti ! umple.Foch 0.1•mL addition of standard should cause tar Iraase of 2.5 mL in dic amount of ti- -4. n:puisrd to reach the geed point for the Durst Method and 23 digits for the.Digital Turnor Mrehod. •A/q.W 6—mod-$wr+M,h.Mr L.nrrr.w r run wr r - i a 4� d NOR logo,It lacIffil 11 1