In the process of crop cultivation, after pesticides are applied, most of them are transformed through various mechanisms, but a small amount remains as residue. Prolonged exposure to these residues can pose serious threats to human health. In recent years, with the expansion of tea, grain, vegetable, and fruit production, many farmers have failed to use pesticides in a proper and rational manner, leading to frequent pesticide pollution incidents. The levels of pesticide residues often exceed safety standards, and this issue is becoming increasingly severe year by year. To ensure food safety, it is essential to develop effective pretreatment technologies for the detection of pesticide residues in food.
As science and technology continue to advance, the number of environmental pollutants that need to be analyzed is increasing, and the concentration of target compounds in samples is getting lower and lower. This presents new challenges for sample pretreatment methods. The quality of the sample directly affects the accuracy and reliability of the test results. Therefore, understanding and improving sample preparation techniques is crucial in modern analytical chemistry.
Common sample preparation techniques include solvent extraction (LLE), solid phase extraction (SPE), solid phase microextraction (SPME), headspace analysis, and membrane extraction. Each method has its own advantages and applications. For instance, LLE is widely used for liquid samples due to its simplicity and effectiveness. SPE offers high recovery rates, reduced solvent usage, and compatibility with automation. SPME is particularly useful for volatile and non-volatile substances, while headspace technology allows for efficient analysis of trace volatile compounds. Membrane extraction is known for its efficiency, low solvent consumption, and compatibility with online instrumentation.
In addition to these, other techniques such as microwave-assisted extraction (MAE) and supercritical fluid extraction (SFE) have also gained popularity. MAE uses microwave energy to speed up the extraction process, reducing both time and solvent use. SFE, on the other hand, utilizes supercritical fluids like carbon dioxide to extract compounds efficiently and cleanly. Derivatization is another important technique that helps improve the detectability of certain compounds by converting them into more analyzable forms.
Despite the availability of advanced techniques, traditional methods such as Soxhlet extraction and ultrasonic extraction are still commonly used in China. However, they often require large sample volumes, long processing times, and significant amounts of organic solvents, which lead to environmental concerns. In contrast, modern techniques like SPE, SFE, and SPME offer faster, more accurate, and environmentally friendly alternatives. Their limited adoption in China has become a major obstacle in improving the efficiency and speed of pesticide residue analysis.
Overall, the development and application of advanced pretreatment technologies are essential for ensuring the safety of food products and protecting public health. As the demand for fast and accurate analysis grows, the transition from traditional to modern methods will play a key role in the future of pesticide residue monitoring.
Herbal extracts are classified according to their efficacy:Immune-boosting extract,Antialcoholic Liver Extract,Sleep Improving Extract, Purgative Extract ,Treat Pharyngeal Extract.
According to the characteristics of the final product, it can be divided into oil, liquid, powder, lens and so on.
Herbal Extract
Herbal extract is a concentrated solution made by extracting the herb's chemical constituents out of the inert herb fiber (cellulose) with a solution of alcohol and water or glycerin. This process allows the beneficial components of plants, such as antioxidants, vitamins, and minerals, to be extracted and used for medicinal or therapeutic purposes. Commonly used herbs include echinacea, ginseng, turmeric, and milk thistle. Herbal extracts can be consumed in various forms, such as capsules, tinctures, or teas.
According to different extraction methods: the volatile oil, oil, extract, fluid extract, dry extract, active components and active parts obtained from plants for preparation production are all extracts.
Herbal extracts were classified according to ingredients: glycosides, acids, polyphenols, polysaccharides, terpenoids, flavonoids, alkaloids, etc. Active Ingredient: natural single ingredient extracted from plants and other substances, the content of the single ingredient should account for more than 90% of the total extract.Herbal extracts are classified according to their efficacy:Immune-boosting extract,Antialcoholic Liver Extract,Sleep Improving Extract, Purgative Extract ,Treat Pharyngeal Extract.
According to the characteristics of the final product, it can be divided into oil, liquid, powder, lens and so on.
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