A method for assessing a corrosion inhibitor in a coolant, comprises providing a test kit comprising a first chamber containing an acid buffer and a solvent immiscible therein and a second chamber containing an indicator, the second chamber being in fluid communication with the first chamber and being configured such that retraction of the second chamber draws fluid into the first chamber and advancement forces fluid into the second chamber; drawing a coolant sample into the first chamber; contacting the coolant sample with the acid buffer and solvent in the first chamber and extracting the corrosion inhibitor into the solvent; allowing the solvent and buffer to separate in the first chamber; forcing a portion of the separated solvent into the second chamber; contacting the separated solvent with the indicator in the second chamber, and obtaining a visual indication of the presence of corrosion inhibitor in the coolant sample.