Rapid quantification of total protein with surface‐enhanced Raman spectroscopy using o‐phthalaldehyde

In this study, surface‐enhanced Raman spectroscopy (SERS) based quantification method for the total protein using o ‐phthalaldehyde is reported for the first time. For this purpose, o ‐phthalaldehyde was chosen to form a complex with protein, and SERS signal was observed in the presence of gold nanoparticles. A calibration curve was obtained by plotting the intensity of the SERS signal at 727 cm −1 versus the concentration of protein standard (bovine serum albumin, BSA). Thus, the correlation was found to be linear within the range of 0.054–0.72 mg/ml of BSA, and the limit of detection was determined to be 0.08 mg/ml. All tests were carried out using a portable Raman instrument with an analysis time of 5 min. In addition, the ability of the developed method to quantify total protein in milk samples was investigated, and the obtained results were compared to the conventional ultraviolet methods.