Headspace single‐drop microextraction with in‐drop derivatization coupled with reversed‐phase high‐performance liquid chromatography method has been developed for the determination of trace level acetaldehyde in polyethylene terephthalate pellets. The headspace microextraction step involves simultaneous extraction, concentration and in situ derivatization of acetaldehyde with 2,4‐dinitrophenylhydrazine. Various factors influencing the performance of headspace single‐drop microextraction, such as extraction solvent, drop volume, temperature and time for extraction, were studied and optimized. The calibration curve was found to be linear over the concentration range of 0.14–3.0 ppm with correlation coefficient of >0.999. The limits of detection and quantitation were 0.07 and 0.14 ppm, respectively. The spiking recovery of acetaldehyde was in range of 103.1 to 105.5%. The method shows good repeatability, with a relative standard deviation of 5.6%. The residual acetaldehyde content estimated in the polyethylene terephthalate pellets by headspace single‐drop microextraction was found to be in agreement with the result obtained by standard ASTM F2013 headspace gas chromatography method. The developed headspace single‐drop microextraction is robust, sensitive and easy to implement in any laboratory.

Acetaldehyde is one of the well‐known undesirable by‐product formed during different stages of polyethylene terephthalate manufacturing process. The migration of acetaldehyde from polyethylene terephthalate, even at trace levels of 10–25 ppb is known to adversely impact organoleptic property of water and/or beverages. We are reporting for the first time in‐situ formation of acetaldehyde in polyethylene terephthalate pellets due to the presence of residual levels of 2‐methyl 1, 3‐dioxolane in the final polymer. A new insight on generation of acetaldehyde through hydrolysis of 2‐methyl 1, 3‐dioxolane present in polyethylene terephthalate resin has been established through water spiking studies in a controlled environment. Further, systematic studies were conducted to also understand the mechanism of formation of 2‐methyl 1, 3‐dioxolane during the polyethylene terephthalate manufacturing.