How to identify thermal paper containing BPA
At present, in order to ensure the safe use of thermal paper, many people will choose thermal paper that does not contain BPA, but they have no way to identify whether it is really free of BPA, and many thermal paper manufacturers will To save costs, use ordinary thermal paper containing BPA to make up the number, resulting in many people not buying the thermal paper they want. The following small crown will bring you the identification of thermal paper containing BPA.
1 Materials and methods
1.1 Materials and Instruments
1.1.1 Instruments and equipment
Shimadzu LC-20A High Performance Liquid Chromatograph (Shimadzu Corporation of Japan): Equipped with two high-pressure pumps, fluorescence detector, SIL-20A autosampler, column thermostat, and chromatographic data workstation.
Water bath, shaker.
Acetonitrile and methanol: chromatographically pure, Bailingwei Technology Co., Ltd.; ultrapure water (Millipore, resistivity 18.2MΩ/cm).
BPA (BiaphenolA): 100mg/L, Shanghai Anpu Scientific Instrument Co., Ltd.
1.2 Experimental method
1.2.1 Preparation of standard products
Take 1mL of BPA standard solution into a 100mL brown volumetric flask, and dilute to the mark with acetonitrile to prepare a standard stock solution with a concentration of 1mg/L.
1.2.2 Sample pretreatment
Cut out a 2.5cm×2.5cm square piece of heat-sensitive paper, cut it into pieces with scissors, and place it in a 50mL test tube. Add about 25mL of methanol and place in a 60°C water bath for 1h. After taking it out, shake it on a rotary shaker for 30 minutes, let it stand, cool to room temperature, and dilute to 25mL with methanol. Pass through a 0.2 μm syringe filter (nylon), and the filtrate is used for HPLC analysis.
2 Results and Discussion
2.1 Sample pretreatment conditions
When methanol was used as the extraction solvent, the recovery rate was between 96% and 101%.
2.2 Selection of mobile phase
The methanol-water system has a better separation effect between the target and impurities, and the best effect is when the ratio is 70:30.
2.3 Linear relationship and detection limit
The minimum detection limit of this method is 0.02μg/cm2.
2.3 Recovery and precision of the method
The recovery rate of this method is between 96.0%-101.2%; the relative standard deviation is within 2.01%, which can fully meet the requirements of the test for accuracy and precision.
The pre-measurement treatment of the method is simple, and the process loss is less. The peak shape is good, the result is accurate and reliable, the recovery rate of BPA is between 96.0% and 101.2%, the relative standard deviation is within 2.01%, and the detection limit is 0.02μg/cm2, which can meet the requirements of BPA in thermal paper. Phenol A testing requirements.