{HEAD ~ The present invention} includes a method of detecting contamination in a fluid sample includes bringing a fluid sample into contact with a pair of spaced apart electrodes and applying a plurality of voltages across the electrodes, wherein the plurality of voltages vary in magnitude between {TAIL ~ a first and second voltage level} 
{ HEAD ~ The present invention } includes a method of detecting contamination in a fluid sample includes bringing a fluid sample into contact with a pair of spaced apart electrodes and applying a plurality of voltages across the electrodes , wherein the plurality of voltages vary in magnitude between { TAIL ~ a first and second voltage level }
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