Student Research Projects

Comparison of Different Colorimetric Techniques in Determining Cyanide in Wine

Student Joana Clark '16 (Chemistry)
Faculty Mentor(s)
Department Chemistry
Course Chemistry 210: Analytical Chemistry

Abstract

The goal of this experiment was to identify the presence of cyanide in table wine using different methods, comparing the data to see which technique was more accurate and precise. The methods tested in this experiment were the LaMotte test kit, the chloramine-t method and the ninhydrin method. All three of these methods experienced a color change in the presence of CN- and the concentration was determined on the absorbance read at different wavelengths. Based on the results from known standards, the ninhydrin technique turned out to be the best method for accuracy and precision. The matrix in the wine samples clearly had an effect on the absorbance readings for all of the methods. For the water samples, the test kit and ninhydrin test was able to handle the matrix of the water; however, the chloramine-t method was not able to handle its matrix. To removed the matrix effect, the ninhydrin method used a micro distillation process that separated the CN- from the sample. This gave a more accurate reading of the CN- in the sample and it had a higher percent recovery for the spiked sample. Overall, it was determined that there was about 0.02-0.05 ppm of CN- in different white wine samples.