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Summary Gas chromatography of polychlorinated biphenyls and chlorinated pesticides in water samples is carried out after adsorption
from a 25–500 mL sample, on a cartridge containing 100 mg aminopropyl-bonded porous silica. The clean-up step in which the
PCBs and chlorinated pesticides are separated in different eluates is achieved by passing 25 mL of 40% aqueous methanol through
the NH2 Sep-Pak cartridge. The PCBs are desorbed with 500 μL ethylacetate, which is concentrated and analysis by GC-ECD. The average
recovery, at 1 ppb is >97% with a standard deviation <2. The limits of detection are 0.1 ng μL−1 and 5 pg μL−1 respectively for Cl3-PCB and Cl8-PCB congeners. In the separation of PCBs from the chlorinated pesticides tested in this work, only the Aldrin is adsorbed
for 60% with the PCBs by the NH2 Sep-Pak cartridge. The method described is rapid, simple and reproducible. 相似文献
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Summary Gas chromatography of polychlorinated biphenyls and chlorinated pesticides in water samples has been performed after adsorption
from a 50–250 mL sample on to a cartridge containing 100 mg cyanopropyl-bonded porous silica. The PCBs are desorbed with 500
μL ethyl acetate, which is concentrated and analysed by gas chromatography with electron-capture detection (GC-ECD).
The average recovery of 1 ppb PCB congeners at from distilled water and from Marta river water is ≥95% (standard deviation
≤2.5). The average recovery of 20 ppb Aroclor 1260 from Marta river water was ≥91% (standard deviation ≤3.5).
In the separation of the PCBs from the chlorinated pesticides only aldrin, heptachlor and 4,4′-DDD are adsorbed with the PCBs
by the CN Sep-Pak cartridge. The method proposed is rapid, simple and reproducible. 相似文献
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The global market of food supplements is growing rapidly with a large turnover. Fish oil supplements represent a significant part of this turnover as they are believed to have important health benefits. Conversely, there are few papers in the literature about the quality control of fish oil capsules. As prior studies illustrate, a perfect agreement with the label is rarely found, and in some isolated cases, large amounts of soybean oil are also detected, indicating a true adulteration rather than a non-compliance with the label. None of the available studies refer to the Italian market, which ranks first in Europe in the consumption of food supplements. In this present communication, a quality control of fish-oil-based supplements from the Italian market was carried out for the first time. With minor deviations, all results showed substantial agreement with the label. However, the most important conclusion from this research is that compliance with the label is not enough to judge a product of good quality. The analysis of the overall fatty acid composition showed that some supplements have a high level of saturated fatty acids, and therefore they did not undergo a proper purification process. This may represent a safety issue since the purification process also allows the removal of toxic contaminants. 相似文献
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