Evaluation of a potential non‐leaching biocide using the marine fouling diatomAmphora coffeaeformis

The toxicity and degree of leaching of the antimicrobial agent 3‐(trimethoxysily)‐propyloctadecyldimethyl ammonium chloride (Dow Corning® 5700) on coated surfaces has been studied using the test alga Amphora coffeaeformis. Cell viability studies indicated a toxic effect of DC5700‐coated surfaces compared to the controls. Leaching coated surfaces in seawater reduced their toxicity to adhered cells. After 7 d, DC5700 leachates caused significant effects on cell growth although consecutive leaching for further 7 d periods produced leachates with no significant effects on the cells compared to the controls. The extraction and gas Chromatographic separation of leachate samples showed the presence of volatile components of DC5700. The results show the toxicity of the biocide to the test alga but since leaching removed the DC5700 from the surfaces, an alternative bonding system would be necessary in order for it to be used as a non‐leaching biocide.