Methods for controlling depolymerization of polymer compositions

A method of controlling the rate of depolymerization of a polymer during a biocide treatment in preparing an oil field application fluid, comprising:

• contacting a pH buffer with water to form a first aqueous mixture, wherein the pH buffer is present in an amount effective to maintain the first aqueous mixture within a pH range of from about 4 to about 8;
• contacting the first aqueous mixture with an amount of a THP salt to form a second aqueous mixture wherein the THP salt is present in an amount of 250 ppm or more and is effective to reduce bacteria count in the second aqueous mixture, wherein pH of the second aqueous mixture is maintained within a pH range of from about 4 to about 8, and contacting the second aqueous mixture with the polymer, wherein the polymer is selected from the group consisting of guar, carboxymethyl guar, hydroxyethyl guar, hydroxypropyl guar, carboxymethylhydroxypropyl guar, cationic guar, hydrophobically modified guar, hydrophobically modified carboxymethyl guar, hydrophobically modified hydroxyethyl guar, hydrophobically modified hydroxypropyl guar, cationic hydrophobically modified hydroxypropyl guar, hydrophobically modified carboxymethylhydroxypropyl guar, and hydrophobically modified cationic guar.