Ionic liquids (ILs) are salts with melting points below 100 degree Celsius. A lot of attention has been drawn to the ILs lately because of their relative non-volatility, non-flammability, wide liquid range, and high conductivity. These properties make ILs very good candidates as potential green solvent alternatives to volatile organic solvents. We have successfully prepared a series of halide salts based on 1-methylimidazole and pyridine. The alkyl halides used to produce the corresponding quaternary ammonium halide salts include 1-bromobutane, 1-bromopentane, 1-bromooctane, 1-bromodecane, 1-bromododecane, 1-bromooctadecane. These salts were purified by washing with ethyl acetate and diethyl ether and converted to ILs bearing the phosphate and bis(trifluoromethylsulfonyl)imide anions. These liquids were prepared in different grades of purity by varying the temperature of the halide salt synthesis. Degree of color and reaction temperature was used to designate purity level. The structures of the salts were confirmed using H-1 and C-13 NMR. The grades of purity were detected by using UV- Vis and fluorescence spectroscopy. The liquids were screened for their toxicity to a variety of microorganisms. Preliminary results indicate that bacterial growth inhibition caused by ILs is dependent on concentration, alkyl chain length and bacterial strain. It was also observed that alkyl chain length affects mycelial growth. This is part of a larger collaborative research project where other similar series of ionic liquids will be prepared and tested. This work was supported in part at BNL by the U. S. DOE Office of Basic Energy Sciences under contract # DE-AC02-98CH10886.