Quick Detection of Contaminants Leaching from Polypropylene Centrifuge Tube with Surface Enhanced Raman Spectroscopy and Ultra Violet Absorption Spectroscopy

Anomalous surface enhanced Raman scattering (SERS) peaks are identified for liquid sample stored in polypropylene centrifuge tubes (PP tube) for months. We observed the unexpected Raman peaks during experiments for Thiamine Hydrochloride aqueous solution stored in PP tube for two months. In order to identify the contaminants we have performed SERS experiments for de-ionized water (DI water) stored in polypropylene centrifuge tube for two months and compared them with fresh DI water sample. We have also carried out Ultra Violet (UV) absorption spectra for both fresh and contaminated water. We believe that the water is contaminated because of chemicals leaching from the PP tube. From the GC-MS data the main contaminant was found to be Phthalic acid and its derivatives. Further SERS and UV absorption experiment for Phthalic acid correlates well with the anomalous peaks identified earlier. We qualitatively confirmed the identification and quantitatively estimated the concentration of suspect contaminants as between 1uM and 10uM with both SERS and UV absorption spectroscopy. With UV absorption spectroscopy, we precisely estimate the concentration as 2.1uM. We have shown that sample in PP tube can be contaminated due to leaching chemicals upon long term storage and suggested SERS and UVabsorption spectroscopy as two quick and simple techniques to detect the contamination.