| In recent years, food safety concern is a very popular topic, Sudan incident and Guan Sheng Yuan events and poison rice events and fake alcohol poisoning events and clenbuterol poisoning events and a series of food safety incidents hit the nerve of the public. The Sanlu milk powder incident in 2008 pushes food safety concerns of the public into the pole, and even about the mere mention of food. Because of objective reasons or man-made reasons, food is likely to be contaminated by pollutants which harm human body from the natural growth to business. The detection of contaminants in the food has matrix complex, multi-interference,hard to pre-treat and other problems. Therefore, pre-treatment of food has become the key issues of samples of food safety testing.In this paper,Solid-phase micro extraction (SPME) is a new kind of sample preparation technique which I use. It is becoming more and more popular by the analysts due to its strongpoint such as fast, simple, efficient, no organic solvents, easy to carry and so on. The core part of SPME is the extraction fiber, but the currently available fibers manufactured by the foreign companies are all coating fibers and less variety. They are limited by the coating temperature resistance, chemical stability and service duration. Our group studied a new type activated carbon fiber. It is along service duration, low production cost; Stable and efficient analysis features and fills the blankness of the domestic solid-phase micro extraction fiber production. This paper mainly makes a special modification of PAHs for the ACF and then uses the modified fiber to detect PAHs in the roast and waste oil.This paper consists of three parts: First, make a special modification of PAHs for the ACF and increase the adsorption capacity of PAHs to improve the detection limit. The modified optimal conditions of activated carbon fibers are: With 0.05mol / L HCL for the buffer solution, using cyclic voltammetry (-0.200v-+1.800 v), scan rate 500mv / s, cycle 120 times. Compared with unmodified carbon fiber, activating carbon fiber which applied to the ACF-SPME technique and measured by GC, the result of peak area of 16 PAHs from the 8.69×102 1.39×105 and increased to between 3.42×103 and 2.73×105 between the detection limit by the 0.5μg / L to 100μg / L down to 0.1μg / L to 0.5μg / L; RSD 11.34 to 54.32 percent from the fall to 6.19 to 19.42%. The ACF on the selectivity and adsorption of PAHs have to improve.Second, Polycyclic Aromatic Hydrocarbons (PAHs) in roast was successfully determined by solid phase micro extraction (SPME) and Gas chromatography mass spectrometry (GC/MS) with the activated carbon fiber (ACF) as extraction fiber. The optimal conditions to pick up Polycyclic Aromatic Hydrocarbons in the samples are ultrasound with 1ml acetone and 0.5ml methanol. The optimal conditions for ACF-SPME is headspace absorption method, ionic strength 5%, absorption time 60min, absorption temperature 55℃, the linearity 1μg/L - 1000μg/L and the limits of the detection between 0.1μg/kg and 50μg/kg of the sixteen types PAHs with the optimized method.16 PAHs in the samples were separated and quantified by the proposed method. The recoveries of the method range from 83.78%to 113.14% and the relative standard deviations are 2.4%-12.7%.The result of concentration of PAHs in the roast fat is 44.7-480μg/kg; the result of concentration of PAHs in the roast from market is 10.2-201μg/kg. ACF-SPME has the higher the recovery rate of the method for adsorption of low-ring PAHs, compared with the national standard.Third,The experiment found the modified optimal conditions is headspace absorption method, absorption time 30min, absorption temperature 70℃.The benzopyrene or other PAHs in the literature is not found in the wasted oil. Compared the crude Luhua pressed peanut oil with heated Luhua pressed peanut oil and the wasted oil, some same kinds of materials such as hexanal and C9~C14 Saturated aliphatic hydrocarbons have been found in the wasted oil and heated Luhua pressed peanut oil. At the same time, PAHs such as Nap and Ace and Acy and Phe have been found in the heated Luhua pressed peanut oil.
|
PDF Full Text Request