Perchlorate is a persistent toxic substance. Because the thyroid gland of the human body absorbs and is affected by perchlorate, it reduces the absorption of iodine, thereby disturbing metabolism and endangering human health. The European Food Safety Authority (EFSA) assesses the risk of exposure to perchlorate in the long-term and short-term. The results show that perchlorate in a single intake of food and water has little effect on health, but long-term intake of perchloric acid Salt, the harm to the human body should cause concern, especially pregnant women, embryos, and babies are the most vulnerable.
The main sources of perchlorate pollution are aerospace, pyrotechnics, the arms industry, rubber products, fuel coatings, etc. However, how perchlorate enters tea through the above sources, and there is no scientific conclusion yet. Industry experts speculate that the use of chemical fertilizers, irrigation water, industrial wastewater or tap water in the tea planting process, the use of chlorine-containing disinfectants in food processing, and the migration of packaging materials may all become sources of contamination of tea perchlorate. Therefore, high-chlorate high-sensitivity detection schemes for tea and various possible sources of pollution are particularly important.
Since the United States observed high levels of perchlorate in drinking water in California in 1997, perchlorate has become a hot spot in US environmental pollution research. The EU has considered limiting the perchloric acid limit in food to 0.75 mg/kg. At the same time, a mandatory standard for tea from China is being developed, which states that the perchlorate content in tea should be below reasonable limits. .
A more serious problem is that the proposed standard may be further tightened. The head of the Food Pollution Project of the Department of Biohazard and Contamination Research of the European Food Safety Authority (EFSA) has stated that EFSA recommends that the perchlorate content in tea is 0.55-0.58 mg/Kg and the proposed 0.75 mg/Kg standard in the assessment report. More relaxed. The EU will comprehensively consider the scientific opinions of all parties and announce the testing standards that are officially suitable for the entire EU. It is expected that the mandatory standards will be officially promulgated in 2016. Once the standard is enacted, China's tea exports to the EU will be severely hampered.
In response to the above situation, Luchuang Instrument released a detection scheme for perchlorate in tea, and established an analytical method for perchlorate in tea using IC-8618+ multi-function ion chromatograph. The tea powder sample was leached and purified by RP column and analyzed by ion chromatography. Compared with the more traditional liquid chromatograph method, the mobile phase of ion chromatography is basically water after being suppressed by the electrolytic suppressor, and the stable polymer exchange chromatography column can greatly reduce the baseline noise of the mass spectrum, thereby obtaining Higher analytical sensitivity.
The method is applied to the determination of perchlorate in tea leaves. The method has the advantages of simple pretreatment and high accuracy, and the recovery rate of the standard addition is over 95%. With high sensitivity and detection limit of 0.02 mg/kg or less, it fully meets the EU's proposed limit of 0.75 mg/Kg, and even more stringent 0.55-0.58 mg/Kg.
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