Determination of dissociation constants of uniprotic acids with known spectrum of

acidic or basic component

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

HA A- + H+

[HA] =

Ct [H+][H+] + Ka

[A-] =

Ct Ka

[H+] + Ka

D XHA XA= +

cHA

sHA

= cA

sA

+

R = D - XHA = D - cHAsHAT

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

R = D - XHA = D - cHAsHAT

cHA =f (Ka)

sHAD

rafa_Ka.m

Determination of Pka value for an uniprotic acid with known spectrum of HA

species

Calling function rafa_Ka

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

Di-protic Acids

[H]2 + Ka1 [H] + Ka1 Ka2

Ct [H]2

[H2A] =

[H]2 + Ka1 [H] + Ka1 Ka2

Ct Ka1 [H]2

[HA] =

[H]2 + Ka1 [H] + Ka1 Ka2

Ct Ka1 Ka2[A] =

R = D - XH2A = D - cH2AsH2AT

cH2A =f (Ka1, Ka2)

pKa1= 3.0 pKa2=4.0

pKa1= 3.0 pKa2=4.5

pKa1= 3.0 pKa2=5.0

pKa1= 3.0 pKa2=5.5

pKa1= 3.0 pKa2=6.0

pKa1= 3.0 pKa2=6.5

pKa1= 3.0 pKa2=7.0

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

its components

HA A- + H+

[HA] =

Ct [H+][H+] + Ka

[A-] =

Ct Ka

[H+] + Ka

XHA XAD = +

cHA

sHAcA

sA

= +

R = D - XHA - XA = D - cHAsHAT- cA sA

T

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

Interferences+

+ Interferences

pH-metric titration of a mixture containing an acid with known spectrum of components

D sHA sA

R = D - XHA -XA= D - cHAsHAT - cA sA

T

cHA =f (C0,Ka) cA =f (C0,Ka)

rafa_CKa.m

Determination of concentration and Pka

values for an uniprotic acid with known spectrum of

HA and A component

Calling function rafa_CKa

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

Rank Annihilation Factor Analysis for Spectrophotometric Study of Complex Formation Equilibria

Anal. Chim. Acta486, 109-123, 2003

M + nL MLnM + nL MLn

[M] [L][MLn]

Kf= n[M] [L][MLn]

Kf= n

CL = [L] + [ [MLn]

CM = [M] + [ [MLn]

Kf[L]n+1 + (nKfCM – KfCL) [L]n + [L] –CL = 0

[MLn] = Kf CM[L]n / (1+Kf[L]n)

[M] = CM / (1 + Kf[L]n)

One-step complex formation equilibria

XMLnD = XL +

cL

sLcMLn

sMLn

= +

R = D - XL = D - cLsLT

+ Interferences

cL= f(Kf,n)

Rank Annihilation Factor Analysis for Spectrophotometric Study of Complex Formation Equilibria

One step complex formation (n=2)

M + 2L MLM + ML2

[L] [M]

[ML2]

CL=0.001KL=106.

5

rafa_MLn.m

Determination of stoichiometry and

formation constant values for an MLn complex with known spectrum of ligand

n=1

n=2

n=3

n=4n=

5

?Create the data for ML3 system and use RAFA for determination of Kf and its stoichiometry.

MLn.m

Simulation of MLn complex formation system

Calling function MLn

[M] [L][ML]

K1=

[ML] [L][ML2]K2=

CL = [L] + [ML] + 2 [ML2]CM = [M] + [ML] + [ML2]

K1K2[L]3 + (K1(1+K2(2CM –CL)))[L]2 + (1+K1(CM –CL))[L]–CL = 0

ML + L ML2

M + L ML

Two successive step complex formation

A = AL + AML + AML2 + R

= L [L]T + ML [ML]T + ML2 [ML2]T + R

= E CT + R

Two successive step complex formation

R = D - XL = D - cLsLT

cL= f(K1 , K2)

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

12

543

54

123

11

111

52

0.20.51

0.1 0.2 0.3 0.40.1 0.3 0.4 0.2

0.1 0.2 0.3 0.40.1 0.3 0.4 0.2

0.60.30.20.150.12

1.70.80.50.350.26

2.31.10.70.50.38

1.40.80.60.50.44

=

0.60.60.60.60.6

1.71.61.51.41.3

2.32.22.12.01.9

1.41.61.82.02.2

=

12

543./

12

543./

A simple mathematical rule

12

543

54

123

12

543./

11

111

52

0.20.51

00

000

3.260.26

-1.54-1.24-0.74

12

543

54

123

32

451./

0.331

1.250.83

1.662

0.250.43

-0.746 0.1980.538

-1.212-1.0621.538

-0.076 1.924-0.276 0.174

Mean centering

Mean centering

Rank = 2 Rank = 2 Rank = 1

Rank = 2 Rank = 2 Rank = 2

HA A- + H+

[HA] =

Ct [H+][H+] + Ka

[A-] =

Ct Ka

[H+] + Ka

D XHA XA= +

cHA

sHAcA

sA

= +

D’ = D ./ cHA

Determination of dissociation constants of uni-protic acids

Mean centering (D’)

cHA = f(Ka)

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

Rafa_mcKa.m

Determination of dissociation constants of

uni-protic acids

Calling function rafa_mcKa

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

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

cHA =f (Ka1, Ka2)

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

D’ = D ./ cHA Mean centering (D’)

Rafa_mcH2A.m

Determination of dissociation constants of

di-protic acids

Calling function rafa_mcH2A

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