Simulation experiment on OH-PCB being ingested through daily diet: Accumulation, transformation and distribution of hydroxylated-2, 2', 4, 5, 5'-pentachlorobiphenyl (OH-PCB101) in mice.

Animals exposure to polychlorinated biphenyls (PCBs) may result in retention of hydroxylated PCBs (OH-PCBs). OH-PCBs can be accumulated in animals, including humans, through the transmission of food chain. However, there are few studies on the accumulation and metabolism of OH-PCBs exposed to the body through daily diet. Therefore, this study was conducted to investigate the fate of OH-PCBs after being ingested through dietary intake. By adding 3-OH-PCB101 and 4-OH-PCB101 to the edible tissue of crucian carp, which were used as raw materials to prepare mouse feed, with an exposure concentration of 2.5 µg/kg ww. The exposure experiment lasted for a total of 80 days. The blood, feces and 11 tissues of mice at different times were analyzed qualitatively and quantitatively. It was found that major OH-PCB101 were accumulated in intestine or excreted with feces. A small part was accumulated in heart, lung and spleen. For the first time that the conversion from OH-PCB101 to PCB101 in mice was discovered, which shows from another perspective that persistent organic pollutants are difficult to be completely degraded in the environment. 4-MeO-PCB101, 3-MeSO2-PCB101, and 4-MeSO2-PCB101 were also found in various tissues. The results of this study show that after OH-PCBs accumulated in animals re-enter the organism through the food chain, they can be metabolized again and may be reversely transformed into the parent compounds. The present research shed new light on simulating the metabolic transformation process of OH-PCBs exposed to mammals through ingestion of fish. Available data show that second-generation persistent organic pollutants in the environment still need to be continuously concerned.

Identification of 2,2',4,5,5'-Pentachlorobiphenyl (PCB101) metabolites and their transmission characteristics in silver crucian carp (Carassius auratus gibelio).

Polychlorinated biphenyls (PCBs) have been attracting global concern due to their persistence and toxicity. However, the study on the metabolites of PCBs in freshwater fish is limited. In this study, the metabolites of 2,2',4,5,5'-Pentachlorobiphenyl (PCB101) in silver crucian carp (Carassius auratus gibelio) were identified for the first time. After intraperitoneal injection of PCB101 (2 mg/kg), the results showed that it could be metabolized to at least three types of metabolites, including hydroxylated (OH-), methoxylated (MeO-) and methyl sulfonated (MeSO2-) PCB101. The OH- metabolites identified in most tissues were 3-OH-PCB101and 4-OH-PCB101, such as liver, gallbladder, blood and muscle. MeSO2- metabolites identified in gallbladder, blood and brain were 3-MeSO2-PCB101 and 4-MeSO2-PCB101. Meanwhile, the MeO- metabolite identified in liver, gallbladder, blood and spleen of silver crucian carp was 4-MeO-PCB101. The investigation of the types and structures of PCB101 and its metabolites, as well as the tissue distribution and accumulation characteristics in silver crucian carp are beneficial to understand the transformation and metabolic mechanisms of PCBs in aquatic organisms. It is of great significance to identify potential pollution hazards of precursor compounds and their metabolites on aquatic products and ensure the quality and safety of aquatic products.

Dehydrogenation of methylcyclohexane over Pt-based catalysts supported on functional granular activated carbon.

Herein, we developed the dehydrogenation of methylcyclohexane over Pt-based catalysts supported on functional granular activated carbon. Sulphuric acid, hydrogen peroxide, nitric acid and aminopropyl triethoxy silane were adopted to modify the granular activated carbon. The structural characterizations suggested that the carbon materials had a large surface area, abundant pore structure, and a high number of oxygen-containing functional groups, which influenced the Pt-based catalysts on the particle size, dispersion and dehydrogenation activity. The hydrogen temperature-programmed reduction technique was utilized to investigate the interaction between the active component Pt and the various functionalized granular activated carbon materials. The CO pulse technique revealed the particle sizes and dispersion of the as-prepared Pt-based catalysts. Finally, the Pt-based catalysts were successfully applied to study their catalytic activity in the dehydrogenation reaction of methylcyclohexane. The results showed that the Pt-based catalyst over granular activated carbon functionalized with sulphuric acid groups had a higher conversion of methylcyclohexane (63%) and a larger hydrogen evolution rate (741.1 mmol gPt -1 min-1) than the other resulting Pt-based catalysts at 300 °C.

An Effective and Efficient Sample Preparation Method for 2-Methyl-Isoborneol and Geosmin in Fish and Their Analysis by Gas Chromatography-Mass Spectrometry.

The intensive aquaculture strategy and recirculating aquaculture system often lead to the production of off-flavor compounds such as 2-methyl-isoborneol (2-MIB) and Geosmin (GSM). The regular purge and trap extraction followed by analysis with gas chromatography-mass spectrometry (GC-MS) usually involve a complicated assembly of facilities, more working space, long sample preparation time, and headspace solid-phase microextraction (SPME). In this work, a method with easier sample preparation, fewer and simplified facilities, and without SPME on GC-MS analysis is developed for the determination of 2-MIB and GSM in fish samples. Unlike previous methods, solvent extract from samples, QuEChERS-based cleanup, and solid-phase extraction for concentration are applied. The LOD (S/N > 3) and LOQ (S/N > 10) of this method were validated at 0.6 µg/kg and 1.0 µg/kg for both 2-MIB and GSM, which are under the sensory limit (1 µg/kg). Application of this method for incurred fish samples demonstrated acceptable analytical performance. This method is suitable for large-scale determination of 2-MIB and GSM in fish samples, owing to the use of simple facility and easy-to-operate procedure, rapid sample preparation, and shorter time for GC-MS analysis without SPME.