[jmarjorie]

Dear Collegues,

A compound contains the following substances with the corresponding functions :

1) Malic acid ( Function : organic acid catalyst)
2) Sodium Hexametaphosphate (Function : Inorganic  
   buffering agent)

      MALIC ACID                    CITRIC ACID

           COOH                          CH2-COOH
      HO-C-H                       HO-C-COOH
           CH2                            CH2-COOH
           COOH

- Can Malic acid be substituted by Citric acid for
this purpose as an organic acid catalyst ?
Citric acid is very similar in structure to Malic acid
Both are metabolites in Krebs/Citric acid cycle

- Can Sod.Hexametaphosphate be substituted by sodium
citrate as the buffering agent ?
Citric acid/Sodium Citrate buffer

Aim is to achieve dual purpose of citric acid : As an
organic acid catalyst and buffering agent.
Is this possible?

Thanks in advance,
jmarjorie
chemicals555@yahoo.com

[AWK]

Catalyst shows specific properties in some reactions depending on its mechanism of action.
So you should specify problem more precisely.
Buffer solution usually contain two reagents which are conjugated acid-base pairs according to Bronsted-Lowry theory. So, simple substitution cannot always work.