Fast, Safe and Accurate Analysis of Peroxide Traces in Petrochemicals

Peroxides are reactive compounds that may impact product quality and promote auto polymerisation. Traditional methods for quantifying Peroxides are iodometric titration methods. An alternative to the titration methods is the Fast Peroxide Analyser (FPA) developed by Da Vinci Laboratory Solutions (DVLS). This analyser is based on a flow injection technique which eliminates safety hazards and provides fast & accurate results. Several application notes describe the FPA analysis of Peroxide traces in petrochemicals.

Flow Injection System

The Fast Peroxide Analyser is based on Agilent HPLC hardware configured with a Reaction Module, AutoSampler or Sampling Valve and a Variable Wavelength Detector. Depending on the matrix a Pressure Station with Sampling Valve is used for a safe handling of a pressurised liquefied gas sample contained in a cylinder.

The petrochemical sample is injected into the reagent stream of acidified Iodide and transferred to the Reaction Module. The Peroxides present in the sample react with Iodide to Iodine and form a yellow-brownish color. The Reaction Module is designed by Da Vinci to optimise the conversion to Iodine. This is the same reaction that takes place in an iodometric titration (Equation One). After the reaction the yellow-brownish color of Iodine is measured by an UV-VIS detector.

ROOR + 2 I^- + 2 H⁺ → I₂ + 2 ROH
Equation One: Redox reaction of Iodide with Peroxide

Determine Peroxides in Chemical Products

The Fast Peroxide Analyser was initially developed to monitor Peroxides in alpha-olefinic streams, however the application range has been extended to determine Peroxides in various chemical products such as:

• Alcohols & Ethers;
• Aromatics;
• Dicyclopentadiene;
• Styrene & Vinyl Pyridines.

An application note describes the analysis results of various chemical samples. The results show that the DVLS FPA can be used for a fast and accurate determination of Peroxides in a wide range of chemical products. Depending on the product, detection level is quantified in sub ppb active Oxygen.

Analyse Peroxide Traces in 1,3 Butadiene

In the second application note the FPA analysis is compared with ASTM D5799 method for the analysis of Peroxide Traces in 1,3-Butadiene. Two Butadiene samples are analysed in tenfold to measure the repeatability. Figure Two shows the chromatogram and comparison table, which exhibits that the current iodometric titration D5799 method suffers from poor repeatability & reproducibility for the intended range.

The DVLS FPA analysis results demonstrate that the FPA greatly improves the repeatability and estimated reproducibility. It also significantly reduces the analysis time.

Quantify Peroxides in Styrene

The third application note describes the analysis of Peroxides in Styrene monomer using the FPA system compared with the iodometric titration method ASTM D2340. Two production batches of polymerization grade Styrene were analysed during transshipment using both ASTM D2340 and the DVLS FPA. The analysis results show that the traces of Peroxides in Styrene monomer can be analysed fast and accurately with the FPA. The comparison with ASTM D2340 demonstrates that the FPA greatly improves the repeatability, reproducibility and LOD (Figure Three).