Abstract: An apparatus and method are disclosed for determining the cleanliness of an electronic circuit assembly (ECA) such as printed circuit boards (PCB) following normal cleaning and flux removal processes. The apparatus and method are used to quantitatively measure the organic contaminants such as the amount of rosin flux remaining on an ECA. The apparatus utilizes small volumes of isopropanol and a spectrophotometric analytical instrument. The apparatus generally provideds for washing the "cleaned" or defluxed ECA with a measured volume of isopropanol and thereafter measuring the organic contaminants in the wash solution by spectrometric analysis. The results can then be compared to a standard.