For disinfectant testing, where neutralization agent is important for determining its bactericidal activity. Dey-Engley Neutralizing Broth (Veg.) is capable of neutralizing a broad spectrum of antiseptic and disinfectant chemicals. The medium neutralizes antiseptics and disinfectants including quaternary ammonium compounds, phenolics, iodine and chlorine preparations, mercurials, formaldehyde and glutaraldehyde. Dey- Engley Neutralizing Agar is especially suited for environmental sampling where neutralization of the chemical is important to determine its bactericidal activity. Complete neutralization of disinfectants is vital as disinfectant carryover can cause a false no growth test result. D/E neutralizing media effectively neutralizes the inhibitory effects of disinfectant carryover, allowing differentiation between bacteriostasis and the true bactericidal action of disinfectant. In addition to neutralizing agents this media contains ingredients that enhance the growth of wide variety of microorganisms. Veg. hydrolysate provides the carbon and nitrogen sources. Yeast extract provides vitamins and growth factors required for growth. Dextrose is added as a fermentable carbohydrate source. Thioglycollate is added for neutralizing mercuric compounds, sodium thiosulphate to neutralize iodine and chlorine and sodium bisulphite to neutralize formaldehyde and gluteraldehyde. Lecithin is included to neutralize quaternary ammonium compounds and Tween-80 neutralizes phenols, hexachlorophene, formalin, and combined with lecithin, ethanol. Due to the high concentration of lecithin in the broth medium, turbidity cannot be used to detect growth. Bromocresol purple allows detection of growth via colour change from purple to yellow when organisms ferment the glucose contained in the medium. Growth of Pseudomonas species, which do not ferment dextrose, can be detected by the formation of a pellicle on the surface of the broth.