Papers by Keyword: GC

Abstract: Bad breath is mainly caused by malodorous materials, volatile sulfur compounds (VSC), hydrogen sulfide (H₂S). Pharmaceutical drugs should be effective but limited, because bacteria at deep periodontal pocket may be sterilized but cannot be washed out and the malodorous compounds remain. The absorbents for the malodorous compounds are expected to prevent the teeth from decaying and peiodontics disease. The layered double hydroxides, of which composition is A_1-xB_x(OH)₂C_x/n·mH₂O, where A and B are zinc and Fe ions are effective as the absorbents for VSC. The VSC adsorption capabilities of zinc or iron oxide in comparison with that of layered double hydroxides containing zinc or iron ion. The high capacity of sulfide adsorption of layered double hydroxide may be due to the large number of adsorption sites of layered double hydroxide materials. The layered double hydroxides (LDH) have a structure favorable for ion or free molecules exchange, and high affinity with sulfide may be involved in iron or zinc containing LDH materials.

Abstract: Etiology of halitosis is often concerned with gram-negative anaerobic bacteria, which produce the malodorous compounds such as volatile sulfur compounds (VSC), hydrogen sulfide and methyl mercaptan. The absorbents for the malodorous compounds are expected to prevent the teeth from decaying and peiodontics disease. The VSC adsorption capabilities of layered double hydroxides, of which composition is A_1-xB_x(OH)₂C_x/n·mH₂O, where A and B are Mg and Fe ions, and C are carbonate (CO₃^2- : MgFe LDH CO₃) and fluorine (F ^- : MgFe LDH F) ions in aqueous medium was studied by GC/FPD. The concentration of H₂S rapidly decreased for first 1 hours of soaking in H₂S water and fell to 0% in 4-5 h when MgFe LDH CO₃ was applied. MgFe LDH F was used, then the H₂S concentration was quickly decreased the same as MgFe LDH CO₃, and 8 mg/l of fluorine was released at a time. The iron ion was not detected in the H₂S water after soaking for 18 hours. The MgFe LDHF are expected to be likely adsorbent for the fast removal of VSC from the mouth and fluorine releasing agent.

Abstract: The degradation of polycarbonate (PC) food contact materials was studied based on analysis with GC-MS, FTIR, UV-Vis and TG techniques. It was evident that the processing temperature of the materials significantly enhanced the release of bisphenol A, an endocrine disruptor. Investigation of the redshift of UV band also revealed that high temperatures accelerated the aging degradation of PC.

Abstract: Most etiology of bad breath is often concerned with gram-negative anaerobic bacteri, and pharmacotherpy using pharmaceutical drugs should be effective but limited, because bacteria at deep periodontal pocket may be sterilized but cannot be washed out and the malodorous compounds remain. The absorbents for the malodorous compound such as volatile sulfur compounds (VSC), hydrogen sulfide (H₂S), are expected to prevent the teeth from decaying and peiodontics disease. The VSC adsorption capabilities of layered double hydroxides, of which composition is A_1-xB_x(OH)₂C_x/n·mH₂O, where A and B are Mg and Fe ions, and C are carbonate (CO₃^2- : MgFe HTCO₃) and chlorine (Cl ^- : MgFe HTCl) ions in aqueous medium was studied by GC/FPD. The concentration of H₂S rapidly decrease to less than 15% for first 1 hours of soaking in H2S water and fell to 0% in 4-5 h when the MgFe HTCO₃ and MgFe HTCl were used. The iron ion was not detected in the H₂S water after soaking for 18 hours.The MgFe HTCO₃ and MgFe HTCl are expected to be likely adsorbent for the fast removal of VSC from the mouth.

Abstract: Many people worldwide assess themselves as having halitosis, often caused by bio-film and microbial putrefaction of the debris in the mouth, leading to the production of mal-odorous compounds, volatile sulfur compounds (VSC) such as hydrogen sulfide (H₂S), methyl mercaptan and dimethyl sulfide. Some desulfurizing agents such as CaO and Na₂CO₃ in the industry are widely used, but there are few dental desulfurizing agents or adsorbents for removal of VSC. Ag ion exchanged zeolite material showed a high adsorptive property of H₂S in aqueous solution (H₂S water), however Ag sulfides were formed in aqueous solution. The VSC adsorption capabilities of layered double hydroxides, of which composition is A_1-xAl_x(OH)₂B_x/n·mH₂O, where A is Mg and/or Zn and B is CO₃^2-, in aqueous medium was studied by FPD/GC. The concentration of H₂S fell to 0% in 2 h when the Zn hydrotalcite was used, while that decreased to 20% in 18 h when the Mg hydrotalcite heated at 500 °C was used. The zinc ion was not detected in the H₂S water after soaking for 18 hours.The Zn hydtotalcite is expected to be likely adsorbent for the fast removal of VSC from the mouth.

Abstract: Many people worldwide assess themselves as having halitosis, often caused by bio-film and microbial putrefaction of the debris in the mouth, leading to the production of mal-odorous compounds, volatile sulfur compounds (VSC) such as hydrogen sulfide (H₂S), methyl mercaptan and dimethyl sulfide. Some desulfurizing agents such as CaO and Na₂CO₃ in the industry are widely used, but there are few dental desulfurizing agents or adsorbents for removal of VSC. Ag ion exchanged zeolite material showed a high adsorptive property of H₂S in aqueous solution (H₂S water), however Ag sulfides were formed in aqueous solution. The VSC adsorption capabilities of layered double hydroxides, of which composition is A_1-xAl_x(OH)₂B_x/n·mH₂O, where A is Mg and/or Zn and B is CO₃^2-, in aqueous medium was studied by FPD/GC. The concentration of H₂S fell to 0% in 2 h when the Zn hydrotalcite was used, while that decreased to 20% in 18 h when the Mg hydrotalcite heated at 500 °C was used. The zinc ion was not detected in the H₂S water after soaking for 18 hours.The Zn hydtotalcite is expected to be likely adsorbent for the fast removal of VSC from the mouth.

Abstract: Discharge of failure was the fault type are likely to occur in transformers, bushings, transformers, and the extent of damage to the equipment is a serious and direct impact on the stable operation of the system, first introduced the principle and gas chromatographic analysis its test methods, then gas chromatography equipment discharge failure is how to judge the conduct described. Through the analysis of transformer oil chromatographic method can be found as early as possible transformers and other equipment inside the existence of latent failures, thus chromatography is to oversee and guarantee the safe operation of an important means of transformer.

Abstract: Since rice bran oil (RBO) is well-known by consumer and more expensive than other oils, some RBO is adulterated with other cheap oils, such as cottonseed oil (CO), palm oil (PO), sunflower oil (SFO) and soybean oil (SO). The types and content of FAs in RBO changes great after adulterated, this will seriously affect the quality of the rice and the people health. In this study, GC was used to detect the change of fatty acids (FAs) after adulterated with those inferior oils. The analysis will provide a reference for the RBO adulteration problem.

Abstract: The waste polymer-polyethylene (PE) was treated in a supercritical water (SCW) system under different operation conditions (such as temperature, heat rate and ratio of water and PE material). The obtained liquid oil products and solid-products were analyzed by conjunct methods including high performance gel penetration chromatography (GPC), Fourier transform infrared spectroscopy (FTIR) and gas chromatography (GC). A relationship of the characteristics of the products and the operation conditions in waste treatment was established. The results of FTIR and GC analyses indicated that the liquid oil products contain a large amount of alkanes, which are suitable for using as fuel oil. Through a series of experiments, the optimum operation conditions were defined as follows：The amount of PE sample: 6g, H2O/PE ratio: 6/1, the reaction temperature (Tem): 460° C, heating rate (Vt): 7.66 (°C / second), the yield of products: 86.0%.

Abstract: Volatile sulfur compounds (VSCs) such as hydrogen sulfide (H₂S), methyl mercaptan and dimethyl sulfide produced in mouth. Some oral (Gram-negative) bacteria produce VSCs, which induces permeability of mucous membrane, cause the oral malordor, dental caries, color change of the dental fillings. Thus, material which adsorbs VSCs should be useful to keep health in mouth. Previously, we reported the H₂S adsorptive properties of zeolite and hydrotalcite materials having micro pores. The amount of H₂S adsorbed on the zeolite or hydrotalcite at room temperature was found to be around 300-400 ppm, and and 3 % of H₂S was desorbed when heated at 400 °C. The hydrotalcite, whose compositon is Mg_1-xAl_x(OH)₂A_x/n·mH₂O, where A is CO₃^2-, and x is 0.25, was heat-treated at 500 °C, and put into aqueous solution containing H₂S. In this study, the relation between heat-treatment tempearture and the sulfide adsorption on hydrotalcite in aqueous solution was investigated. The hydrotalcite materials were hydrothermally synthesized and identified by powder X-ray diffraction method. The change in concentrations of H₂S in aqueous solution was measured using FPD gas chromatography (GC). The concentrations of H₂S was decreased with time for the hydrotalcite heated at 500 °C or 600 °C, and fell to 20 % for 12 hours. But, the concentration was decreased by 40% for 12 hours for the hydrotalcite materials heated at higher temperatue. XRD and FT-IR analysis revealed that the sulfides were into or out of the hydrotalcite structure through topochemical reactions.