Effect of different pre-treatment conditions on VOC determination results in water-based coatings

For several typical VOCs in water-based coatings, different pre-treatment conditions are selected for determination, and the effect of different pre-treatment conditions on experimental results is discussed. The study shows that after the sample, oscillation 50 times, at 60 degrees C, ultrasonic extraction of 10 min, water-based coatings in ethylene glycol, 2-amino-2-methyl-1-propylene alcohol, 1,2-propylene glycol can achieve a relatively high level of volatile organic compounds in water-based coatings (Volatile Organic Compounds, VOC) content has become the focus of consumers.
of volatile organic compounds in the existing standards is that any organic compound with an initial boiling point below or equal to 250 degrees C
C at the 101.3 kPa standard
. Because of the wide variety of VOCs in coatings and the low boiling point, rapid and effective extraction is the key to analysis. In this study, different pre-treatment conditions were used to determine several typical VOCs in water-based coatings, revealing their influence on VOC measurement results, and thus providing data support and theoretical basis for the formulation of relevant standards. Through qualitative analysis of VOC in water-based coatings, it is found that the typical VOCs involved in water-based coatings on the market include ethylene glycol, 2-amino-2-methyl-1-propylene alcohol, and 1,2-propylene glycol.1 Experimental Part
1.1 Instrument and Reagent
Gas Chromatography-Mass Spectrometry Unit (450GC-220MS, VARIAN, USA); ×0.32mm ×1.8m); centrifuges (80-2B, Shanghai Anting Scientific Instrument Factory); Electronic analysis balance (AB 104-N, METLER-Tolido Instruments Shanghai Co., Ltd.).
1.2 Experimental conditions
chromatography conditions: sample port temperature, 260 degrees C; column flow rate, 1.0mL/min; severity ratio, 30:1; program heating conditions, initial temperature 80 degrees C, maintain 1 min, 10 degrees C/min to 230 degrees C, maintain 15 min; Mass spectrometrical conditions: ionism, EI Ionized energy, 70eV; ion trap temperature, 150 degrees C; transmission line temperature, 250 degrees C; electron multiplifier voltage 1,600 v; mass spectrometry segmented scan, 0 to 5.6 min; full-scan operation, scanning range 40 to 650 m/z; solvent delay time, 5.6 to 7.3 min.
1.3 pre-treatment conditions
in order to confirm the impact of different pre-treatment conditions on the measurement results, the sample recovery rate experiment was designed. Mix the water-based paint samples well with a glass rod. About 0.2 to 0.5 g samples were taken, with 0.0040 to 0.0050 g g g g g g g g glycol, 2-amino-2-methyl-1-propylene alcohol and 1,2-propylene glycol added, and 0.2-propylene glycol added. 0040 to 0.0050 g isodol, add the appropriate amount of diluted solvent (acetylene) in the sample bottle dilution, seal the sample bottle and fully shake, respectively, after the following A, B, C, D, E, F experimental steps, sit still, to be analyzed.
different pre-treatment steps are designed as follows:
Experimental Step A is solvent extraction, and Experimental Step B adds glass beads to the sample as it dissolves to increase molecular diffusion.
taking into account that the boiling point of glycol in water-based coatings currently covered by national standards GB 18582-2008 and GB24408-2009 is 196 to 198 degrees C, 2-amino-2-Methane The boiling point of base-1-propylene alcohol is 165 degrees C, the boiling point of 1,2-propylene glycol is 187 degrees C, and the boiling point of methanol is 65.4 degrees C, so the designed ultrasonic extraction temperature is up to 65 degrees C. The following are three ultrasonic extraction steps at different water temperatures: C, D, E, and F. The experimental step C is 10 min for ultrasonic extraction at a water temperature of 20 degrees C, D for ultrasonic extraction at 40 degrees C, and the experimental step E is 10 min for ultrasonic extraction at a water temperature of 60 degrees C; The experimental step F is to extract 10 min of ultrasonic waves at a water temperature of 65 degrees C.
1.4 Results and Discussion
The recovery rates of ethylene glycol, 2-amino-2-methyl-1-propylene alcohol and 1.2-propylene glycol were shown in Figure 1, Figure 2, and Figure 3, respectively, under six different pretreatment conditions.
results show that under step E, the recovery rate of glycol can reach 92.4 to 98.2, with an average of 95.6, and the recovery rate of 2-amino-2-methyl-1-propylene alcohol can reach 93.1 to 9 8.4, the average is 96.2; 1,2-propylene glycol recovery rate can reach 93.4 to 98.6, the average is 95.3; compared to other pre-treatment conditions, the recovery rate of the three parts can reach the best effect, as shown in Figure 4.
2 Conclusion
This study, aiming at three typical VOCs in water-based coatings, used different pre-treatment conditions for determination, and explored the effect of different pre-treatment conditions on the experimental results. Ultrasonic extraction of 10 min, take the upper liquid, transfer to the automatic sample bottle, ethylene glycol, 2-amino-2-methyl-1-propylene alcohol, 1,2-propylene glycol can achieve a relatively high recovery rate.