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Determination of dissociation constants of uniprotic acids with known spectrum of acidic or basic component.

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Presentation on theme: "Determination of dissociation constants of uniprotic acids with known spectrum of acidic or basic component."— Presentation transcript:

1 Determination of dissociation constants of uniprotic acids with known spectrum of acidic or basic component

2 HA A - + H + [HA] = C t [H + ] [H + ] + K a [A - ] = C t K a [H + ] + K a DX HA XAXA =+ c HA s HA = cAcA sAsA + R = D - X HA = D - c HA s HA T

3 Determination of dissociation constants of uniprotic acids with known spectrum of acidic or basic component R = D - X HA = D - c HA s HA T c HA =f (K a ) s HA D

4 rafa_Ka.m Determination of Pka value for an uniprotic acid with known spectrum of HA species

5 Calling function rafa_Ka

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9 ? Investigate the effects of extent of spectral overlapping on the determined pKa value by RAFA

10 Di-protic Acids [H] 2 + K a1 [H] + K a1 K a2 C t [H] 2 [H 2 A] = [H] 2 + K a1 [H] + K a1 K a2 C t K a1 [H] 2 [HA] = [H] 2 + K a1 [H] + K a1 K a2 C t K a1 K a2 [A] = R = D - X H2A = D - c H2A s H2A T c H2A =f (K a1, K a2 )

11 pK a1 = 3.0 pK a2 =4.0

12 pK a1 = 3.0 pK a2 =4.5

13 pK a1 = 3.0 pK a2 =5.0

14 pK a1 = 3.0 pK a2 =5.5

15 pK a1 = 3.0 pK a2 =6.0

16 pK a1 = 3.0 pK a2 =6.5

17 pK a1 = 3.0 pK a2 =7.0

18 Determination of amount and pKa values of an acid in a mixture with known spectrum of its components

19 HA A - + H + [HA] = C t [H + ] [H + ] + K a [A - ] = C t K a [H + ] + K a X HA XAXA D = + c HA s HA cAcA sAsA =+ R = D - X HA - X A = D - c HA s HA T - c A s A T Determination of amount and pKa values of an acid in a mixture with known spectrum of its components Interferences + +

20 pH-metric titration of a mixture containing an acid with known spectrum of components D s HA sAsA R = D - X HA -X A = D - c HA s HA T - c A s A T c HA =f (C 0,K a )c A =f (C 0,K a )

21 rafa_CKa.m Determination of concentration and Pka values for an uniprotic acid with known spectrum of HA and A component

22 Calling function rafa_CKa

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28 ? Use RAFA_CKa and determine the amount and pKa values of a known acid in an unknown mixture

29 Rank Annihilation Factor Analysis for Spectrophotometric Study of Complex Formation Equilibria Anal. Chim. Acta 486, , 2003

30 M +nLML n M +nLML n [M] [L] [ML n ] K f = n [M] [L] [ML n ] K f = n C L = [L] + [ [ML n ] C M = [M] + [ [ML n ] K f [L] n+1 + (nK f C M –K f C L ) [L] n + [L]–C L =0 [ML n ] =K f C M [L] n / (1+K f [L] n )[M] = C M / (1+K f [L] n ) One-step complex formation equilibria

31 X MLn D = XLXL + cLcL sLsL c MLn s MLn =+ R = D - X L = D - c L s L T + Interferences c L = f(K f,n) Rank Annihilation Factor Analysis for Spectrophotometric Study of Complex Formation Equilibria

32 One step complex formation (n=2) M +2LMLM +ML 2 [L] [M] [ML 2 ] C L =0.001K L =10 6.5

33 rafa_MLn.m Determination of stoichiometry and formation constant values for an MLn complex with known spectrum of ligand

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39 n=1 n=2 n=3 n=4 n=5

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41 ? Create the data for ML 3 system and use RAFA for determination of Kf and its stoichiometry.

42 MLn.m Simulation of MLn complex formation system

43 Calling function MLn

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52 [M] [L] [ML] K1=K1= [ML] [L] [ML 2 ] K2=K2= C L = [L] + [ML] + 2 [ML 2 ] C M = [M] + [ML] + [ML 2 ] K 1 K 2 [L] 3 + (K 1 (1+K 2 (2CM –CL)))[L] 2 + (1+K 1 (C M –C L ))[L]–C L = 0 ML + L ML 2 M + L ML Two successive step complex formation

53 A = A L + A ML + A ML2 + R =  L [L] T +  ML [ML] T +  ML2 [ML 2 ] T + R = E C T + R Two successive step complex formation R = D - X L = D - c L s L T c L = f(K 1, K 2 )

54 Determination of dissociation constants of uni-protic acids without known spectrum

55 = = / A simple mathematical rule

56 / / Mean centering Rank = 2 Rank = 1 Rank = 2

57 HA A - + H + [HA] = C t [H + ] [H + ] + K a [A - ] = C t K a [H + ] + K a DX HA XAXA =+ c HA s HA cAcA sAsA =+ D’ = D./ c HA Determination of dissociation constants of uni-protic acids Mean centering (D’) c HA = f(K a )

58 Titration of an uni-protic acid or a mixture containing an uni-protic acid

59 Rafa_mcKa.m Determination of dissociation constants of uni-protic acids

60 Calling function rafa_mcKa

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66 ? Use mean centering based method for determination of acidity constant of an uniprotic acid in a mixture

67 Determination of dissociation constants of di-protic acids without known spectrum

68 c HA =f (K a1, K a2 ) Determination of dissociation constants of di-protic acids without known spectrum D’ = D./ c HA Mean centering (D’)

69 Rafa_mcH2A.m Determination of dissociation constants of di-protic acids

70 Calling function rafa_mcH2A

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76 ? Use mean centering based method for determination of acidity constant of an di-protic acid in a mixture


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