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PVC plastic in phthalate plasticizers migration behavior in the body fluids

In phthalate plasticizers, PVC plastic often used by Gas Chromatography [3,4], but lower sensitivity. Solid phase micro extraction (SPEM) as a new solvent-free sample pretreatment technology, pollution-free since its introduction in the 1990s, has plastisol coated chain gained rapid development. In this study, the sol - gel fullerene as a stationary phase coating, headspace solid phase microextraction - gas chromatography study of phthalate plasticizers in PVC plastics migration behavior in body fluids.
1 Experimental
1.1 Instruments and reagents
GC3800 GC-MS (Varian, USA) with the COMPAL triple Autosampler (with automatic SPEM function); GrantOLS200 kept shaking water bath; sol - gel fullerene (C60) quartz extraction head. The DEHP, DBP the by Fluk company is purity> 97%; BBP, the DCHP DNOP by Chemservice companies,> 95% purity.
Methanol analytical grade, with double-distilled water. The experimental standard stock solutions were prepared in methanol working standard solution, respectively, with the preparation of simulated human sweat and simulation of human saliva.
Simulate human sweat [5]: the accurate the said the take NaHCO34.2g, NCl0.5g, K2CO30.2g, with a small amount of secondary dissolved in distilled water, set the volume to 1000mL, that have a pH value of 8.8 of analog sweat. Simulated human saliva [5]: Weigh accurately take NaCl4.5g KC0.3g Na2SO40.3g NH4Cl0.4g 90% lactic acid urea 0.2g with a small amount of secondary dissolved in distilled water, constant volume to 1000mL, ie a pH 3.04 analog saliva.
1.2 Preparation of experimental samples
Plasticizers used in different PVC plastics own characteristics its production process is also of the same, for the present experiment selected formula: PV powder, 100 parts of 2,2,4 - trimethyl-pentanediol-1 ,3 - diisobutyrate 10 parts of bis (3,5 - di-tert-butyl-4 - hydroxybenzyl phosphoric acid monoethyl ester nickel salt 2 parts, 1 part of an aliphatic carboxylic acid ester, Tributyl Citrate X parts of the parts, phthalate ester plasticizer. open roll temperature 150 ℃, open mill time of 20min, and then injection molding.
1.3 Chromatographic conditions
DB-5 fused silica capillary column: 30m x 0.3mm × 0.25μm; inlet temperature: 280 ° C; FID detector temperature: 280 ° C; carrier gas speed: 1.0mL/min; split ratio: of 1:5; column temperature: 50 ℃ maintain 4min, heated to 200 ° C and a speed of 30 ℃ / min, and then heated to 280 ° C and a speed of 4 ℃ / min to maintain 16min. The five kinds analyte under this condition effective separation.
1.4 Experimental Methods
Take samples of PVC plastic, cut it into pieces, placed in conical flask with stopper added to simulate human sweat or simulated human saliva soaked stoppered 60r/min (simulated human saliva) or 8r/min (in 37 ° C water bath to simulate the human body sweat) speed oscillation 1h. Remove, rapid removal 10mL vial and the internal standard material and NaCl saturated stamped seal. Headspace solid phase micro-extraction, the extraction temperature is 90 ℃, the extraction time of 60 min, extraction oscillation speed 300r/min, the extraction process, the oscillation speed constant. The extraction is completed, under 280 ℃ thermal desorption 3min, the DHP as internal standard chromatographic analysis.
Results and discussion
2.1 Selection of the extraction temperature
A double effect of temperature on the extraction process, the temperature rises, the increase in energy provided to the system to accelerate the mass transfer, conducive aqueous phthalate ester plasticizer escape, and the substance to be measured in the headspace gas concentration is increased, the The extracted fiber increases its extraction amount, absorption and adsorption process are exothermic process. When the temperature is too high, although beneficial to the evaporation of the high-boiling compounds, but also reduces the distribution coefficient of the analyte in the SPEM coating, resulting in the extraction amount of the part of the analyte but decreased. Figure 1 sol - gel fullerene coating the the plasticizer extraction temperature curve of five kinds of phthalate esters. Considering, 90 ℃ extraction temperature.
2.2 Selection of extraction time
Because of the competition between the different components of extraction, select a suitable extraction time is very important. SPEM process is the process of extraction equilibrium, the equilibrium time of extraction and the oscillation speed, the extraction temperature, the thickness of the coating, the DUT and the diffusion coefficient of distribution between the solution and the extraction head, high-boiling compounds is required than the low-boiling compounds longer extraction time.
Due to the large difference more than five kinds of the carbon chain lengths of the phthalate ester plasticizer, the boiling point difference is also larger. 120min, the longer the carbon chain of DEHP and DNOP extraction amount yet constant, headspace extraction of the non-equilibrium system Ai proposed theory [6], the content of the analyte in the fiber under certain conditions, is proportional to its solution, The initial concentration, can be quantitatively analyzed. Comprehensive analysis of the factors of time and sensitivity, selected extraction time of 60 min.
2.3 salt effect
To increase the ionic strength of the sample can be increased to the sample on the coating of the distribution coefficient K, the analyte more easily to the head of the coating was extracted retained to enhance the amount of the extraction and analysis of sensitivity of the coating. The effect of the salt effect depends on the polarity of the analytes, the salt concentration, and the sample matrix. Reported in the literature, adding NaCl, KCl, and Na2SO4 salt effect can be generated. Phthalate esters having a certain polarity, NaCl was added in this experiment so that a saturated NaCl solution, and can increase the ionic strength of the solution, reducing the shackles of the matrix on the volatile matter, improve its activity, increasing the headspace in the concentration of the analyte, change of the distribution coefficient between the coating and the headspace gas, so that the analyte more easily be extracted head coating retention, and improve the extraction amount of the coating, and the analytical sensitivity.
2.4 Thermal desorption time selection
Partition coefficient of thermal desorption time and the GC inlet temperature, extract, carrier gas flow rate. Desorption temperature of 280 ° C, thermal desorption GC injector. At such high temperatures, the distribution coefficient of the extract is decreased, the coating treat EUT reservations soon disappear. Meanwhile GC vaporization chamber, carrier gas flow is also desorbed accelerated. At the same temperature, analyte desorption completely or not directly related to the desorption time. Desorption incomplete will not only affect the determination of the sensitivity of the method, but also contaminate subsequent samples, but prolonged high-temperature desorption will shorten the life of the extraction head. Figure 3 sol - gel fullerene coating of the five kinds of phthalate plasticizers desorption time curve.
Can be seen from Figure 3, in the inlet temperature of 280 ° C, 5 plasticizer desorption 2.5min after each chromatographic peak area reaches a maximum, so this time of the thermal desorption experiments 3min.
2.5 soaking conditions are selected
2.5.1 Selection of soak temperature
Analog the children toy touch behavior, human normal body temperature of 37 ° C for the soak temperature.
2.5.2 The selection of soaking time
Children in the use of PVC plastic toys, phthalate plasticizers transferred through sweat and saliva to a child's body there is a process of accumulation, PVC plastic products also directly affect the soaking time in simulated human sweat and simulation of human saliva analysis The speed and sensitivity of detection. In order to determine phthalate plasticizers time to reach equilibrium in the soaking solution, select the five kinds of phthalate plasticizers PVC plastic samples 3g soaking temperature at 37 ° C, the oscillation speed 80r/min, were immersed in simulated human sweat and simulation of human saliva at different times, sol - gel fullerene extraction head extraction, analysis SPEM conditions above and chromatographic conditions measured soak time plasticizer elution of the chromatographic peak area.
Different plasticizer eluted at different speeds, but the overall trend is the same. When the the soaking time over 60min, five kinds of phthalate plasticizers in simulated human sweat and simulation of human saliva dissolution volume to reach equilibrium. Therefore, the selected soak time for 60min.
Choice of 2.5.3 oscillation speed
The oscillation speed is an important factor affecting the speed of analysis, the measured object is eventually SPME extraction contains three migration process: migration of the solution from the solid sample to reach the peak air from the solution-phase migration of air from the top-phase to the extraction head coated layer migration. Phase from the solution and the ceiling air migration velocity oscillations increase, accelerating the diffusion of the analyte from the solution to the top of air phase, the headspace analysis, the concentration of the analyte increases, there is conducive to reduce the time to reach equilibrium, and to shorten the analysis time , improve the sensitivity of the analysis.
This experiment focuses on the migration behavior of phthalate plasticizers in the body fluids of children in the use of PVC plastic toys and therefore select soak oscillation speed should simulate the behavior of the reach of children toys, select the oscillation speed should be slower. To take more than five kinds of the phthalate plasticizers quality scores are 3% PVC plastic samples 3g, choose a different oscillation speed simulated human sweat and simulation of human saliva soaked 60min in 20mL soaking temperature of 37 ℃ extraction, the extraction head of the sol - gel fullerene SPEM conditions described above and chromatographic conditions for analysis, the determination of the plasticizer in different oscillation speed elution chromatogram peak area.
Simulated human sweat soaking solution and simulation of human saliva soaking when the oscillation speed respectively 80r/min and 60r/min, the dissolution of the peak area of ​​constant. Therefore, the experiments were selected 80r/min and 60r/min to soak oscillation speed.
2.6 The linear range and detection limit
The chromatographic conditions and SPEM conditions, the preparation of a series of five kinds of phthalate plasticizers standard solution and headspace extraction experiments in simulated human sweat and simulation of human saliva, respectively, to obtain the five kinds of phthalates class of plasticizers in the linear range of the simulated human sweat and simulation of human saliva method, linear equations, and the limit of detection, the results in Table 3. The experimental results show that this method wide linear range, high sensitivity, low detection limit.
2.7 precision experiments
Weigh 3g under the chromatographic conditions and SPEM conditions, contains 11 PVC plastic parallel samples of the five kinds of phthalate plasticizers, respectively, in each 20mL simulated human sweat soaking liquid and analog human saliva soaking soaked, then headspace solid phase micro-extraction chromatography analysis, respectively 11 samples in simulated human sweat and simulation of human saliva soaked phthalate plasticizers unit quality release from calculated RSD The results are shown in Table 4. The experiments show that the precision of the method is better, RSD were less than 8%.
2.8 recovery test
Weighed the different phthalate plasticizers content of PVC sample 1g, respectively, according to the above-soaked conditions simulated human sweat soaking solution and simulation of human saliva soaking soaking experiments, DHP as internal standard, conduct Join the recovery experiments, determination of the soaking solution phthalate plasticizers dissolution amount and recoveries, and the results are shown in Table 5. The results show that the method is accurate and reliable measurement results, the recoveries were 82% to 107%.
2.9 PVC plastic samples phthalate plasticizers migrate in simulated body fluids
Medium contact PVC plastic toys for children, sweat and saliva, phthalate plasticizers that enter the body through sweat and saliva, PVC plastic products phthalate ester plasticizer content was its harmfulness does not The linear correlation truly directly harmful to the human body part is that part of the sweat and saliva dissolution. Therefore, the study of PVC samples phthalate ester plasticizer migration behavior of dissolution in body fluids is essential. Made by PVC plastic toys process contain DBP, BBP, DCHP, of DEHP DNOP5 kinds of plasticizers each 1%, 2%, 3%, 5%, 10%, 15%, 20%, 25%, 30% PVC plastic samples, depicting 3.0g, were placed in 50 ml Erlenmeyer flask, were added to the simulated human sweat or simulated human saliva 20ml, soaked at 37 ℃ 60min, when soaked oscillation speed 80r/min (simulated human sweat) 60r/min (simulated human saliva), and then in the SPEM conditions and the chromatographic conditions tested, five kinds of PVC plastic, phthalate plasticizers in simulated human sweat and simulation of human saliva per unit mass migration.
The experimental results show that the plasticizer of the carbon chain is shorter than the longer carbon chain of a plasticizer are more likely to be eluted, and more easily through the sweat and saliva to migrate from PVC plastics. DBP, BBP, DCHP simulated human saliva easier migration, DEHP, DNOP simulated human sweat more easily migrate out. With the increase in the content of phthalate plasticizers sample simulated human sweat soaking solution and simulation of human saliva soaking unit mass migration also increased, but not a linear relationship.
The five kinds of PVC, phthalate plasticizers can be simulated human sweat and simulation of human saliva dissolution unit mass Dissolution of up μg / g level. Phthalate plasticizers can be enriched in the human body, children long-term use of PVC plastic products containing phthalate plasticizers, may lead phthalate plasticizers through sweat and saliva and migrate into the children's body and enriched in the body, resulting in adverse consequences, therefore, the EU PVC plastic toys o-phthalic acid ester plasticizer content is strictly limited. At present, China has not yet used in PVC plastic products phthalate plasticizers restrictions necessary for children with the phthalate plasticizers used in PVC plastic products, in order to effectively protect the children's physical health, stringent restrictions.
3 Conclusions
PVC plastic samples containing five kinds of typical phthalate ester plasticizer migration behavior in simulated human sweat soaking solution and simulation of human saliva soaking, it is found that such substances can migrate from PVC plastic products to human sweat and human saliva, and eventually into the body, causing damage to the human body. Therefore, it is necessary to strictly limit the amount of such substances in PVC plastic products.

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