Immunoassays for two quaternary ammonium compounds, benzyldimethyldodecylammonium chloride (BDD12AC) and didecyldimethylammonium chloride (DDAC)

• Main Author: Bull, Jennifer Patricia
• Language: English
• Published: 2009
• Online Access: http://hdl.handle.net/2429/7604

A competitive enzyme-linked immunosorbent assay (CELISA), based on polyclonal antibodies, was developed to measure benzyldimethyldodecylammonium chloride (BDD₁₂AC), a component of benzalkonium chloride (BAK). The polyclonal antibodies recognized free benzyldimethyldodecylammonium bromide (BDD₁₂AB), with a 50% inhibition (IC₅₀) of 0.66 µg/mL and a detection limit of 0.043 µg/mL. The two other components of BAK, benzyldimethyltetradecylammonium chloride (BDT₁₄AC) and benzyldimethylhexadecyl-ammonium chloride (BDH₁₆AC), as well as other alkyldimethylbenzylammonium compounds (ADBACs), were recognized to varying degrees by the antibodies. The antibodies also recognized a commercial BAK compound (77% C₁₂: 23% C₁₄). The antibodies cross-reacted minimally with other compounds such as fatty acids and alcohols, amino acids, amines, and short-chain quaternary ammonium compounds. CELISA and HPLC were used to quantify BDD₁₂AB and BAK (Aldrich) spikes in milk solutions. BDD₁₂AC was also measured in five commercial products containing BAK, using both analyses. HPLC analysis correlated well with CELISA analysis for these commercial products. CELISAs were also developed for didecyldimethylammonium chloride (DDAC) using three novel haptens. The three resulting antisera recognized DDAC to different degrees, with IC₅₀'s ranging from 0.05 µg/mL to 17.2 µg/mL. Cross-reactivity with compounds representing DDAC's different epitopes were observed for the three sera at varying degrees. The antisera also showed varying degrees of susceptibility to detergent effects, where one serum cross-reacted more with sodium dodecyl sulfate (SDS) than DDAC. Performance of one of the sera raised against DDAC was a marked improvement over a previously described anti-DDAC serum, produced by Chen et al. (1995). This new antiserum could be used to detect DDAC in environmental samples since the IC₅₀ is 50 ppb, well under the discharge limit of 700 ppb.