a handheld device provides for measuring the concentration of dialdehyde in a dialdehyde solution . the device comprises an optically transparent first container being under vacuum whereby to draw in a first predetermined quantity of the dialdehyde solution ; a first light source positioned to transmit light in the range of 420 nm to 620 nm through the optically transparent first container ; a first sensor positioned to receive the transmitted light , wherein the first sensor is configured to measure an optical absorbance of the transmitted light and configured to transmit an electronic signal proportional to the optical absorbance ; and a microprocessor in electronic communication with the first sensor , wherein the microprocessor is configured to indicate the concentration of the dialdehyde in the dialdehyde solution based on the electronic signal received from the first sensor .