ASTM D7884 Determination of Carboxybenzaldehyde and Toluic Acid

Scope:

ASTM D7884 is useful to create specifications and can be used as an internal quality control tool in places where these items are manufactured or used. The presence of 4-CBA and p-TOL slows down the polymerization process and 4-CBA colorizes the polymer due to thermal instability.

Procedure:

In ASTM D7884, the PTA sample is dissolved in an ammonium hydroxide solution and a fixed volume of the ammonium hydroxide solution is introduced into a high-performance liquid chromatograph equipped with a UV detector. The contaminants – 4-CBA and p-TOL – are separated from PTA using a C18 chemically bonded column. For quantification, an external standard calibration is used.

Video 01: High Performance Liquid Chromatography (HPLC)

Specimen size:

The temperature should be maintained at a constant 61°C within the range of 20 to 70°C.

Data

In ASTM D7884, the concentration of 4-CBA or p-TOL in mg/kg is calculated using the following equation:

                                  X = m_s ·A·C_s ÷ m·A_s

Where;

X = concentration of 4-CBA or p-TOL in the PTA sample, mg/kg,

A = peak area of 4-CBA or p-TOL in the PTA sample,

m = weight of the PTA sample, g,

A_s = peak area of 4-CBA or p-TOL in the PTA standard,

C_s = concentration of 4-CBA or p-TOL in the PTA standard, mg/kg,

 m_s = weight of the PTA standard, g.

Conclusion:

ASTM D7884 is useful to create specifications and can be used as an internal quality control tool in places where these items are manufactured or used.