Specific reasons for bronopol biocides containing free formaldehyde

Abstract:Bronopol (CAS 52-51-7) itself does not contain free formaldehyde, however, it may release trace amounts of formaldehyde under certain conditions due to its chemical properties and environmental factors. The following is a detailed analysis of the specific reasons:

1. Chemical Hydrolysis Reaction

The molecular structure of bronopol contains nitro and bromine substituents, which are susceptible to hydrolysis under alkaline or high-temperature conditions. During this process, some chemical bonds within the molecule break, potentially releasing trace amounts of formaldehyde. Specifically:

1.1 Alkaline Environment: In aqueous solutions with higher pH levels, bronopol undergoes gradual decomposition, leading to the formation of formaldehyde.

1.2 High Temperature and Long-Term Storage: Elevated temperatures or prolonged storage periods accelerate the hydrolysis reaction, thereby increasing the likelihood of formaldehyde release.

2. Interference from Detection Methods

Certain detection methods, such as acetylacetone spectrophotometry, may overestimate the formaldehyde content in bronopol solutions. This occurs because:

2.1 Side Reactions between Reagents and bronopol: Acetylacetone not only reacts with formaldehyde but also directly interacts with bronopol molecules to form colored compounds, resulting in elevated test results.

2.2 More Accurate Detection Methods: Interference can be minimized by using post-column derivatization in high-performance liquid chromatography (HPLC), which shows that the actual amount of formaldehyde released is typically less than 1 ppm.

3. Influence of Synthesis and Storage Conditions

3.1 Synthetic Raw Materials: Formaldehyde is used as one of the raw materials in the production of bronopol, but residual amounts are minimal.

3.2 Storage Stability: Exposure to light or contact with metals (such as aluminum) may accelerate decomposition. Therefore, it is recommended to store bronopol sealed and away from light to prevent side reactions.

The R&D team at Puyuan Pharm has developed 12 specialized types of bronopol (BNP) based on industrial-grade brominol for various applications. Through advanced crystallization, refining, purification, washing, drying, standing, and free formaldehyde control, these products achieve higher purity levels. They exhibit superior bactericidal, antiseptic, mildew, and algae-killing effects, remain fluffy and resistant to caking, and maintain stable bactericidal efficacy. Additionally, strict control over free formaldehyde ensures environmental and product safety.