| Summary: | 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.
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