Document M449jbpYmp2RRyrvV3ZXXXy7L

?&*--***.^ - - '* ^ *"'*is it. v^ r?5 . ( 'll lO LE D EVKT.OPMEXT CO.,Xxc. 5 0 0 PlFTII A V E 2*TJE , _ ; .. . New Yo r k . ,,. . . PLEASE A D D R E S S ALL COM M UNICATIONS TO TH E COMPANY .- ' Messrs. P.L, Becker W.C* Arkell J.8. Ellithorp C.^. Buxm S.C. Preaecfct . G.R. Cowgill / P. Thaanxsapj Gentlenon- Mr. H.W. Conner of the Wm. sYfigley Jr. Company has -written ms & letter dated January 21st to shich he attached oop&es of Hubbard`s Modification of the Method of Wilkins Willoughby, Kraemer end Smith in connection with Blthieone Methods. Mr. Conner collected the above information while at Dr. Hubbard* laboratory in Cincinnati and while permission has been granted to dis tribute this information among the interested parties, by Dr. Hubbard, he wishes this matter to be regarded as confidential by all who use it, as he may later wish to publish it. Very truly yours. CHICLE DEVELOPMENT COIOMHT SSY-W Enel, oc: MLB S3. Yates,/ President Copy of Hubbard* Modification of the Method of Wilkins , Willoughby, Kraemer and Smith (Difhlsoae Method) g g 00C6444 Mr. S. a. Yates, Pres., Chicle Development Co., 500 Fifth Ave., Kew York, K. Y. Jan. 2 1, 1936 Dear Mr. Yates; With the active Interest now evinced in compar ing alternative Dithizone methods, it might be well to distribute copies of the procedure which has been devel oped by Hubbard at Cincinnati. Dr. Hubbard looked over the notes which I took when visiting his laboratory and has given us permission to distribute them among the interested parties. He wishes, however, that the matter be regarded as confiden tial by all who use it, inasmuch as he may later wish to publish it. Yours truly, V&l. ttRIGLSY JH. COMPANY HWC:m -Enc.- per ii. A. Conner K. 000.6445 N 7598.01 HUBBARD'S MODIFICATION OF THE METHOD OF WILKINS, WILLOUGHBY, KRAEMEH AND SMITH (Ind. Eng. Chem., Anal. Ed. 7:33-55-1935. ) Cut 5 g. sample to leas than 1 cm. size. Burn in 100-500 ml. capacity silica evaporating dish over a matted gas flame. After charring is well under way, the surface may be flashed with the flame. Place in muffle at 500C. for 1 hour. Cool, and add 5 ml. cone. HNOg (washing down sides). Heat over open flame to evaporate acid. Return to muffle for 1/2 hour. Cool, and add 5 ml. water, 5 ml. N&C1-HG1 solution, 2 ml. Concentrated EC1. Warm to dissolve all ash (except for slight silica residue). Add 15 ml. ammonium citrate solution. (Will Keep iron and calcium in solution.} Transfer to ISC ml. Squibb separatory funnel. Add one drop phenol red. Shake. Make slightly alkaline by adding cono. HE&OH until indicator changes from red, to yellow, to red. (pH 7.5) Add 2 ml. K.CN solution, (to complex other metals). Add 5 ml. aliquots of Dithizone $1, separating "A", as Willoughby does, and transfer to a separatory funnel. After extraction of "X" according to Willoughby, 20 xml. of KKOjjJg solution is obtained, containing lfi EROg. Add a drop of phenol red and neutralize as before, with KE4OE. Add 2 ml. of KCN. Add 1 ml. aliquots of Dithizone #2 until Dithizone layer is a definite purple, not a pure red. The Dithizone layer is diluted to 20 ml. with chloroform. Free Dithizone is removed from the chloroform solution by four 20 ml. aliquots of Winters solution "FH . The red complex is run into 10 ml. of HC1., (concentrated acid diluted with 9 volumes of water) in a clean separatory funnel. K i 0006446 The blue-green Dithizone layer, to which is added 0.15 ml. or ab solute ethyl alcohol (with stirring), is then placed in one oup ~ of a colorimeter set at 31 mm. Into the other oup is placed a standard solution of Dlthizone in chloroform equivalent to .03 mg. of '1". (The setting of 31 is chosen in preference to setting of 30 since the blank contributes .001 mg. of *Znt as an average.! A determination consists of parallel technique on one or more samples, one blank and one standard based on an initial .03 mg. sample of "2." as X(K0g)g. REAGENTS;- Potassium C y a n i d e ..... 10 g. in 100 ml. water. H a d + EC1 ............. 5 ml. cone. EC1 diluted to 100 ml. with water and saturated with EaCl at room temperature. Ammonium Citrate ...... 40 g. citric acid mono-hydrate neutralized with HH4K diluted to a liter. (Add 2 ml. of chloroform as a preservative.) Phenol R e d .......... .. .04# solution made up with EaOIi according to Clark & hubs. Dithizone #1 .............. 04 g. Dlthizone per liter CHClg. Dithizone # 2 ............. 1 g. Dithizone dissolved in 30 ml. CECis and extracted in a large separatory funnel with 900 ml. of 1/2# (by volume) EE4OK. Aqueous phase is separated and neutralized with 10# (by volume) EC1. Precipitated Dlthizone is taken up in chloroform and diluted so as to be equivalent to approx imately .01 mg. MX" per liter. This solu tion is stored under EgSOg (e#). Winters Solution "F" ... 10 ml. EH4OK plus 10 ml. of 10# KCE diluted to a liter. Add 5 ml. Dlthizone #2 plus 10 ml. CHClg ifc a l&fg separatory funnel. This will leave a do-leaded aqueous solu tion which retains some yellow ammonium Dithizone complex. Prepare ahead and allow to stand in sunlight to bleach the oolor. Standard Lead Solution .. 0.1598 g. X(IiOg) plus 10 ml. cone. KKO3 diluted to 1 liter. Dilute with distilled water 1:10 so that 1 ml. is equivalent to 0 .0 1 mg. of lead. (Dithizone from Eastman. EC1, BHOg, HH4OH are Grasselli C.P. Grade. Remaining reagents are Merck blue label reagent grade.) 0005447