METHOD FOR IDENTIFICATION AND SEMI-QUANTITATIVE DETERMINATION OF DIOCTYLPHTHALATE IN MIXTURE OF COMPOUNDS, RELEASED FROM PVC PLASTISOL

摘要

FIELD: chemistry.;SUBSTANCE: invention relates to analytical chemistry and can be used to determine dioctylphthalate in equilibrium gas phase over items made from PVC plastisol. To this end, invention uses a method of identifying and semi-quantitative determination of dioctylphthalate in a mixture of compounds, released from PVC plastisol. To determine dioctylphthalate, method uses a frequency meter with an array of 2 piezoelectric crystal resonators with natural oscillation frequency of 10 MHz, electrodes of which are modified by applying individual solutions of multilayer carbon nanotubes (MCNT) with weight of film of 3-5 mcg and polyphenyl ether (PPE) weighing 15-20 mcg. Modified piezoelectric crystal resonators are placed in a closed detection cell and held for 5 minutes to establish a stable zero signal. Then sample of a soft article made from PVC plastisol weighing 1.00 g is placed in a sampler, which is tightly closed with a plug and maintained at a temperature of 20±1 °C for 15 minutes for saturation gas phase with dioctylphthalate vapour. 5 cm³ of equilibrium gas phase is extracted using a syringe and injected into closed detection cell and for 120 s change in oscillation frequency of piezo sensors is recorded. Every second feedback of sensors is detected, followed by regenerating system for 2 minutes with dried air. Sample in sampler is then heated in a drying chamber to 30±1 °C for 10 minutes, followed by collecting with a syringe 5 cm³ of equilibrium gas phase and repeatedly injected into closed detection cell, measuring for 120 s change in oscillation frequency of piezo sensors at 20 and 30 °C. Signals of sensors are used to automatically calculate area under curve for each sensor: S_(MCNT), S_(PPE), Hz·s, and ratio of areas is calculated at 20 °C and 30 °C respectively - parameter Specified parameters are used to make conclusion on presence of dioctylphthalate in samples: if A^30/2020, then dioctyl phthalate is present in samples of PVC-plastisol with concentration higher than allowable amount of migration (DCM, mg/dm³), If A^30/20≤1, content of dioctylphthalate at level of allowable amount of migration and its content is less than content of other volatile compounds present in sample.;EFFECT: invention provides identification and semi-quantitative determination of dioctylphthalate, released from PVC plastisol.;1 cl, 1 ex