| Phthalates or phthalic acid esters(PAEs) have been identified as an kind of environmental hormone. And much research has been focused on endocrine-disturbing substances, which may result in significant human exposure to this chemicals. Phthalates with high boiling points are composed of one benzene ring and two ester groups, and they can be present both in gas-phase and particle-phase and often in trace up to ultra-trace levels in indoor air. Ionic liquids(ILs) possess fascinating properties, including low volatility, tunable viscosity and miscibility, which make ILs unique and useful for many applications in chemical analysis.In this paper, an analytical methodology using Automatic Thermal Desorption and GC/MS was developed for the determination of the phthalate.in indoor air samples, which were collected by using ionic liquid([MIMCH2COOCH3]NTf2) sampling tubes. Then the preparation, preservation and application of the sampling tubes and standard tubes were investigated. This method simplifies the complicated pre-processing, saves a large amount of organic solvent, and avoid secondary pollution to the environment, which is in line with the "green chemistry" concept and has important practical significance. The main contents of this paper are divided into the following aspects:(1) The establishment of a novel methodFrom the five synthetic ester-functionalized ionic liquids, [MIMCH2COOCH3]NTf2 was screened by a comprehensive comparison. Then the sample tubes were invented with this ionic liquid. Last an analytical methodology using Automatic Thermal Desorption and GC/MS was developed for the determination of the phthalate.in indoor air samples, which were collected by using ionic liquids sampling tubes.An automatic thermal-desorption unit was connected by a transfer line maintained at 250 ℃ to gas chromatograph fitted with mass spectrometer. The thermo-desorption conditions were: the sorbent tubes were desorbed at 220°C and 50 mL He/min for 15 min. The vapors from the primary desorption were collected at 0°C in the cold trap without sorbent. The cold trap was flash heated to 280°C at 40°C/s(temperature of 250°C for the valve, no inlet split or outlet split) and the vapors were transferred via the heated transfer line(250°C) to the GC. The GC temperature program was 100°C(held for 1min) then increased at 10°C/min to 200°C and finally increased at 5°C/min to 250°C(held for 4min).(2) The preparation, preservation and application of sample tubesThe background value, the stability, the efficiency of adsorption-desorption and the capacity of adsorption of sampling tubes were investigated. And the results show that the sample tubes can be stable for 20days; The efficiency of adsorption-desorption range from 80% to 90% to meet the requirements of analysis; The data indicates no penetration when the content are up to 300 ng, and it is practical in most samples. To improve the sample tubes, the glass fiber was replaced by the stainless steel mesh. Furthermore, the different products were characterized by infrared spectroscopy, nuclear magnetic resonance and mass spectrometry. The results demonstrate 1-methyl acetate-3-methylimidazolium bis-trifluoromethyl sulfonyl imide([MIMCH2COOCH3]NTf2) would decompose at 250℃ in some time even below its decomposition temperature.(3) The analysis of samples from indoor airThe pollution status and characteristics of PAEs were investigated in indoor air of 10 homes, 10 offices, 10 laboratories, and PAEs were detected in all samples While the data implied phthalates are more common in indoor air. |
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