In order to attract the attention of primary and secondary school students or cover up the unpleasant smell, manufacturers often add fragrant substances to stationery. However, these fragrant substances are usually composed of dozens to hundreds of aromatic volatile organic compounds, some of which may have an impact on the health of primary and secondary school students.
At present, the developed countries have not put forward the requirements for the volatile organic compounds of stationery, but only issued the relevant requirements for toy products. The EU issued the EU Toy Safety Directive 2009/48/EC, which points out that it should not contain 55 allergenic aromatic compounds, including aldehydes, alcohols, ketones and esters, etc. If trace amounts of these fragrances are technically unavoidable under good production practices, they are allowed to contain no more than 100 mg/kg, and are required to be labeled. However, the upcoming EN71.13 only explains the toxicity of some allergenic aromatic agents, and the corresponding detection methods have not been proposed yet. China has issued mandatory standards GB 21027 - 2007 "General requirements for safety of student products" and environmental protection standard HJ572-2010 "Technical requirements for environmental labelling products: stationery". The main control substances are free formaldehyde, benzene, toluene, ethylbenzene, xylene, chlorinated hydrocarbons and total volatile organic compounds. In view of the EU's requirements for allergenic aromatic compounds for toys, various countries have carried out a number of studies on the detection methods of volatile organic compounds in toys, but few studies on scented stationery. This application note introduces the determination methods of volatile organic compounds in scented stationary and toy, including solvent extraction, headspace, purge and trap, micro - chamber and direct thermal analysis, and analysis their advantages and disadvantages.
- Solvent extraction
Solvent extraction is one of the most widely used methods in organic matter extraction, which mainly includes solvent extraction and supercritical fluid extraction. At present, ultrasonic extraction is widely used in solvent extraction, which can increase the penetration of solvent, improve the dissolution rate of extract, shorten the extraction time and accelerate the extraction process.
- Headspace
In the headspace method, the volatile sample is placed in a closed system to maintain a constant temperature, so that the upper gas is in balance with the components in the sample, and the upper gas is taken for chromatographic analysis. Compared with liquid-liquid extraction and solid phase extraction, headspace can not only avoid the loss of volatiles caused by solvent removal, but also reduce the noise caused by co-extraction, has higher sensitivity and analysis speed, less harm to analysts and environment, and easy to operate.
- Purge and trap
Purge and trap is also called dynamic headspace. The volatile organic compounds in the sample are purged into the trap tube by nitrogen, and the trap tube is generally filled with Tenax TA and other fillers to selectively adsorb the organic compounds. When this process is over, the trap tube is quickly heated to release the adsorbed organics into the gas chromatograph for analysis. As a solvent-free pretreatment method of samples, dynamic headspace method does not cause secondary pollution to the environment, and has the advantages of less sampling, high enrichment efficiency, less interference by matrix and easy to realize on-line detection. It is widely used in the testing of water and soil in environmental monitoring.
- Micro - chamber
The micro - chamber is a new volatile organic compound enrichment device in recent years, which is equivalent to a miniature environmental chamber. The general volume is 50-114 mL. The materials in the micro chamber release VOCs under controllable temperature and airflow. The adsorption tube is installed on the micro chamber for sampling, and the adsorption tube is pyrolyzed for analysis.
- Direct thermal analysis
The direct thermal analysis method uses a sample to be placed in a thermal analysis tube, and the volatile organic compounds are released from the sampling tube after heating to avoid a long solvent elution time, and there is no solvent peak interference in the chromatogram.
Summary
The rapid development of the stationery industry has provided more choices for the majority of students, but at the same time, the quality of stationery products has attracted increasing attention. Whether the flavors and fragrances added to scented stationery and the organic solvents used will affect the health of young people has become a concern of researchers, and some detection work of aromatic compounds in stationery and toy products has been carried out. The widely used detection methods include solvent extraction, headspace, purge and trap, micro - chamber and direct thermal analysis. Among them, solvent extraction and direct thermal analysis are committed to testing the total amount of volatile organic compounds residual in the product, while headspace, purge and trap, and micro - chamber methods focus more on testing the volatile organic compounds released under specific conditions, which is closer to the real use of stationery and toys, and is suitable for follow-up work such as human exposure assessment, and does not use organic solvents, reduces solvent interference, is easy to operate, and is more environmentally friendly and safe.
Comments