Mosquito repellent clasp is made of silica gel or Microfibre textile cloth combined with plant essential oil. The natural plant mosquito repellent ingredients, such as lemon citronella, lavender, clove and other substances are slowly volatilized to achieve the mosquito repellent effect. Mosquito repellent buckles are widely used in children's mosquito control in summer. Although these products belong to the ranks of pesticides, most of them have not been registered with pesticides, that is, no toxicity safety test and mosquito repellent effect test have been carried out, and there is no corresponding national standard at present. Although most of the mosquito repellent products claim to be blended with Citronella and other natural plant essential oils, without any chemical components, and safe to use, some studies show that some mosquito repellent products contain insect repellent, benzene series, synthetic musk, pyrethroid and other pesticide components, which seriously affect children's health.
At present, the commonly used detection methods of pyrethroids are mainly gas chromatography, gas chromatography-mass spectrometry, liquid chromatography, etc. In view of the lack of relevant standards for the determination of pyrethroid pesticide residues in children's mosquito repellent buckles in China, Tan Lijun, et al. Of Hunan Institute of commodity quality supervision and inspection, established a gas chromatography method for the rapid determination of pyrethroid pesticide residues in children's mosquito repellent buckles with methanol as extraction solvent, ethyl acetate as eluent solvent and electron capture detector. This method has high sensitivity and accurate results, which can meet the requirements of the detection of pyrethroids in children's mosquito repellent buckles and provide technical support for strengthening the supervision of children's mosquito repellent products.
Main instruments and reagents
Gas chromatograph: 7890b, equipped with ECD detector, Agilent Technology Co., Ltd;
Solid phase extraction column: alumina column (6ml, 1000mg), Shanghai Dima Technology Co., Ltd;
Pulverizer: pulverisette 14, Feichi instruments, Germany;
Electronic balance: ms105du type, sensitivity 0.01 mg, METTLER TOLEDO international trade (Shanghai) Co., Ltd;
Bifenthrin, fenpropathrin, highly effective Cypermethrin, permethrin, Cypermethrin, flufenpropathrin, Fenvalerate and deltamethrin: the mass concentration is 100 mg / L, the number is s – 25891, Beijing bailingwei Technology Co., Ltd;
Hexane, acetone, dichloromethane, methanol, ethyl acetate: chromatographic purity, Merck reagent company, USA;
Nitrogen: 99.999% purity, Changsha Saizhong Special Gas Co., Ltd;
Sample of mosquito repellent clasp: siliceous and liquid, commercially available.
Instrument operating conditions
Chromatographic column: HP-5 column (30 m × 0.32 mm, 0.25 μ m, Agilent Technology Co., Ltd.); column temperature box temperature rising procedure: initial column temperature of 100 ℃, hold for 1 min, raise to 180 ℃ at 15 ℃ / min, hold for 5 min, raise to 280 ℃ at 8 ℃ / min, hold for 5 min; inlet temperature: 260 ℃; detector temperature: 280 ℃; carrier gas: nitrogen, flow rate of 2.0 ml / min (constant flow) ; injection mode: non split injection; detector: electron capture detector.
Positive sample preparation
The sample of silica gel mosquito repellent clasp was smashed into 1 mm particles with a grinder, and a certain amount of 8 kinds of pyrethroids mixed standard solution was added. The sample was diluted with methanol, soaked completely, and the solvent was volatilized completely, then a positive sample containing a certain amount of pyrethroids was prepared.
Sample treatment
Weigh 1g of liquid mosquito repellent buckle sample directly, purify it with neutral alumina solid-phase extraction column, elute it with ethyl acetate, concentrate and volume it to 1.0ml with rotary evaporation instrument, and then inject the sample for determination. The sample of the gelatinous mosquito repellent buckle was first crushed into about 1 mm particles by a grinder, then weighed 1 g, added methanol for ultrasonic extraction, the extraction liquid was purified by a small column of neutral alumina solid-phase extraction, eluted with ethyl acetate, concentrated and constant volume to 1.0 ml by a rotary evaporator, and then injected for determination.
Determination result
Under the optimized experimental conditions, the mass concentration of 8 pyrethroids in the range of 0.05-1.00 mg / L has a good linear relationship with the peak area, the correlation coefficient is greater than 0.998, and the detection limit is 0.48-2.90 μ g / L. The average recoveries of the three samples were 93.8% - 119.7%, and the RSD of the results was 0.88% - 6.43% (n = 5).
Excerpted from Volume 29, issue 2, chemical analysis and metrology, 2020
Reference materials | analysis and test | sample processing | measurement technology | summary
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