对高铁盐中的残留酸测定研究

在铁盐中所含三价铁离子量较高的条件下,对残留酸进行了分析实验研究。笔者提出了以10％的盐酸羟胺溶液还原高铁离子为亚铁离子,改变铁离子的水解特性,并以2.5g/L的甲基橙(MO)为指示剂,用氢氧化钠标准溶液进行滴定。实验证明:对硫酸铁、氯化铁等高铁盐试样进行了残留酸的酸碱滴定,测定的终点变色较为明显,结果较为准确,平行样品的精密度也较好,并适合于批量分析。

纤维膜聚结脱除双酚A反应液中残留的游离酸

研究了纤维膜聚结技术用于脱除双酚A反应液中残留游离酸的实验条件和纤维膜床层的再生条件。结果表明,在聚结温度70℃、95%乙醇用量2%、空速20～30 h-1、纤维膜床层体积1.0 cm3的条件下,可使双酚A反应液的酸度从0.014 mmol/L脱除至≤0.001mmol/L,满足双酚A反应液对酸度的要求;当双酚A反应液的处理量达到纤维膜床层体积的60倍时,床层必须采用丙酮进行再生;在丙酮用量6 mL和再生温度50℃的条件下,纤维膜床层可以得到完全再生。

过氧乙酸灭菌效果及酸残留的实验研究

目的研究过氧乙酸灭菌的效果及酸的残留量对pH值的影响。方法用微生物学无菌检测法和pH值测定法。结果满载,少量装载,重复灭菌时达到无菌效果,△pH均在0.3～0.4之间。结论经过氧乙酸灭菌的塑料瓶能达到无菌要求,酸的残留量对pH值的影响不显著,生产上可用过氧乙酸灭菌法对不耐热的内包材进行灭菌。

无降解离子色谱法对食品中甲醛次硫酸氢钠残留的测定

首次报道了用水直接提取，离子色谱分离、测定食品中甲醛次硫酸氢钠的方法。采用IonPac ASl8作为分离柱，比较了NaHCO3-Na2CO3、Na2B4O7和KOH溶液的淋洗效果，发现KOH淋洗液效果最佳。实验研究了甲醛次硫酸氢钠的热稳定性及食品中常见阴离子与甲醛次硫酸氢钠的分离度。在选定的离子色谱测定条件下，甲醛次硫酸氢钠在0．1～200mg／kg的范围内有较好的线性。方法的加标回收率、相对标准偏差、检出限分别为88％～101％、3．3％～5．0％、0．05mg／kg。方法应用于年糕样品中残留甲醛次硫酸氢钠的检测，获得了满意的结果。

肝素中残留核苷酸检测方法国际协作研究

目的:美国药典会肝素原料个论中拟增加核苷酸杂质的检查方法,全球18家实验室参加了该方法的协作研究以确定检测方法和限度可行性。方法:征集国内2家企业共10批肝素钠样品,及USP提供的测试样品。使用Phenomenex Synergi FUSION-RP C18色谱柱(250 mm×4.6 mm,5μm),样品中的核酸杂质经酶解后,用0.02 mol·L-1醋酸铵和乙腈梯度洗脱分离,流速为1 mL·min-1,检测波长为260 nm。结果:系统适用性及测试样品结果均符合USP的要求,本实验室提交的数据全部被采纳,国内10批样品结果均符合USP拟定限度(<0.1%)。结论:该方法基本可行,较现有方法专属性高。

Gel Filtration Chromatography Combined with Bradford Method for Determination of Total Residual Protein in Ferment Antibiotics

Aim A novel method has been developed for evaluation of the levels of total residual protein in antibiotics produced by fermentation using gel filtration chromatography (GFC) combined with Bradford assay based on determination of residual protein in lincomycin hydrochloride. Methods The chromatographic conditions were SuperdexTM peptide column, 0.01 mol*L-1 phosphate buffer solution as mobile phase, and flow rate of 1 mL·min-1. Five hundred microliters of lincomycin hydrochloride solution (3 g of lincomycin hydrochloride dissolved in 10 mL of mobile phase) was injected into the chromatograph and the eluted solution was collected between 6 min and 14.5 min (protein eluted from column within this period), and the residual content of total protein in the eluted solution was assayed using Bradford assay method. Results The average recovery was more than 90% for bovine serum albumin, the calibration equation for the range of 0-12 μg·mL-1 of protein was y=-0.002 4x2+0.064 2x+0.002 9, r2=0.999 9, RSD=0.1%-0.9%, and the LOD and LOQ were 3 and 10 ng·mL-1 of protein, respectively. Conclusion The novel method for determining the residual protein in ferment antibio-tics is simple, rapid, and precise.

Gas chromatographic method for the determination of hexaconazole residues in black tea

A highly reliable, quantitative and sensitive analytical method for determining the residues of the fungicide, hexaconazole in black tea is described. The proposed method is based on liquid-liquid extraction followed by gas chromatographic determination, using nitrogen phosphorus detector (GC-NPD) for the identification and quantitation of hexaconazole. The most appropriate solvent mixture for extracting hexaconazole residues from black tea was n-hexane:acetone at 1:1 (v/v). The extract was cleaned up by adsorption column chromatography using activated florisil. Performance of the method was assessed by evaluating quality parameters such as recovery value, repeatability, reproducibility, linearity and limits of detection and quantitation. When the method was assessed for repeatability, the percentage of recovery ranged between 86% and 96% while the relative standard deviation was between 0.30% and 2.35%. In studies on reproducibility the recovery ranged from 81% to 85% and relative standard deviation from 1.68% to 5.13%, implying that the method was reliable. A field trial was conducted to verify the application of this method with real samples. Results prove that the validated method was suitable for extracting hexaconazole residues.

Application of Molecular Distillation Process to Extend the True Boiling Point Curve of Petroleum Residues 400 ℃ ＋

True Boiling Point （TBP） distillation is one of the most common experimental techniques for determination of petroleum properties. The methods for performing TBP distillation experiments are described by ASTM D2892 and by ASTM D5236. However, these methods are established for petroleum fractions that reach temperatures up to 565 ~C. In this work, two petroleum residues were distilled in a falling film molecular distillation prototype and the data were used to obtain the extension of the TBP curve above a temperature of 565 ~C. It was possible to extend the TBP curve of both petroleum up to temperatures close to 700 ~C with consistency and continuity in comparison to the standard curve. In addition, an amount of raw material that was been treated as residue could be reused.

Degradation of ethyl xanthate in flotation residues by hydrogen peroxide

The degradation behavior of ethyl xanthate(EX) salt was the most widely used collector in sulfide mineral flotation and emission of flotation tailings with residual EX was harmful to environment. In this work, hydrogen peroxide(H2O2) was investigated by UV-visible spectroscopy(UV/Vis) at different p H values from 3 to 12. For p H value from 5 to 12, EX was oxidized into ethyl per xanthate(EPX) by H2O2. Then EPX was further oxidized into thiosulfate(TS) salt rather than ethyl thiocarbonate(ETC) and this step was the reaction-limited step. Then depending on p H values, TS was degraded into sulphate and carbonate salts(p H>7) or elemental sulfur(p H<7). The kinetics data show that the degradation rate of EX increases with increasing the H2O2 concentration and is independent on the p H values. Without H2O2, EX is hydrolyzed to carbon disulfide fast at p H value <3.0, but the reaction of hydrolysis is undetectable at p H value >3.0 during test time.

Real-time PCR法检测注射用门冬酰胺酶制剂中大肠杆菌核苷酸残留

目的:建立可定量检测注射用门冬酰胺酶制剂中大肠杆菌核苷酸残留量的实时荧光定量PCR(Real-time PCR)方法,用于注射用门冬酰胺酶制剂中大肠杆菌核苷酸残留的质量控制。方法:选择大肠杆菌23S核糖体RNA基因为靶基因设计扩增引物,以ABI 7500 FAST平台为基础,建立基于SYBR Green荧光染料的Real-time PCR检测方法。结果:该法检测大肠杆菌核苷酸质量浓度在0.009 35~93 500 ng·m L^(-1)范围内线性良好,标准曲线的相关系数为0.999,定量限为0.009 35 ng·m L^(-1)。应用该法对2批注射用门冬酰胺酶制剂进行测定,均未检出大肠杆菌核苷酸残留。结论:该方法可用于注射用门冬酰胺酶制剂中大肠杆菌核苷酸残留的定量测定。

Statistical Analysis of Regularity of Pesticide Residues in Vegetables Produced in Inner Mongoli

[Objective]The paper was to study regularity of pesticide residues in vegetables produced in Inner Mongolia.[Method]Mathematical statistic analysis was carried out on 6 800 samples of veggies,fruits,leguminous vegetables,nuts and seeds produced in Inner Mongolia.[Result]The dominated vegetables in Inner Mongolia were green leafy vegetables,solanaceous vegetables and melon vegetables,and their yields accounted for 70%of the total vegetables production.Since 2003,with the rapid increase of detected vegetable numbers,the status of vegetable quality safety had entered into a new stage of sustainable steady after a rapid decline or periodic fluctuation,and the differences in safety levels were obvious,of which the range of exceeding standard rate of pesticide residues in solanaceous vegetables,melon vegetables and leguminous vegetables(about 55%of the total vegetables)was under 2%,with average values of 1.1%,1.6%and 3.1%,respectively.They belonged to stable type.The exceeding standard rate of pesticide residues in green leafy vegetables and Chinese cabbage group(about 30%of total vegetables)presented a decreasing trend year by year,wondering in the range of 7%-10%.They belonged to main risk type.The time period of exceeding standard of pesticide residues in root vegetables and cole vegetables was under predictable,and its exceeding standard rate in some years was over 5%(amplitude variation is over 15percentage points).They belonged to random risk type.The kinds of pesticides,which exceeding standard rate in vegetables were relatively intensive,presented variance in different vegetable species.70%of the pesticides belonged to intermittent over-limits and the probability was below 5%.About 20%tradition pesticides often exceeded standard and their probabilities were over 30%.The exceeding standard of organophosphorus and carbamates pesticides in vegetables presented a decreasing tend,while the risk of some new pesticides containing nitrogen element and high effective pyrethroids showed an increasing tendency.[Conclusion]The paper provided decision making services for agricultural management departments.

A Test for Stabilization of an Oligomeric Protein by Introduction of Aromatic Residues into the Interface

The design of variants to enhance conformational stability of proteins is an important aspect of protein engineering. Oligomeric proteins are often stabilized by aromatic clusters located within the subunit interfaces. In the present study, the authors constructed five variants of Ps3aHSD （Pseudomonas sp. B-0831 3a-hydroxysteroid dehydrogenase） in which one or two residues at the dimer interface were replaced with aromatic residues, and examined the effects of introducing aromatic residues in this region on protein thermostability. Under their experimental conditions, all variants formed dimers, similar to wild-type Ps3aHSD. Thermal denaturation experiments indicated that Tm of all variants was 0.2-16.2 °C lower than that of wild-type protein, indicating less stable thanwild-type protein. The results collectively suggest that aromatic residues of natural oligomeric proteins are strictly posted in the interface to facilitate optimal interactions and avoid conformational strain.

Solid superacid-catalyzed hydroconversion of an extraction residue from Lingwu bituminous coal

A solid superacid was prepared as a catalyst. The catalyst was characterized by ammonia temperature- programmed desorption, surface property measurement, and analyses with scanning electron micros- copy and Fourier transform infrared spectrometry. A extraction residue from Lingwu subbituminous coal was subject to non-catalytic and catalytic hydroconversion using cyclohexane as the solvent under pres- surized hydrogen at 300 ℃ for 3 h. The results show that the total yield of petroleum ether-extractable arenes from catalytic hydroconversion is much higher than that from non-catalytic hydroconversion. The cleavage of Car-Cask bonds in the residue could significantly proceed during catalytic hvdrncnnvarsion

Analysis of Residues Formed during the Liquefaction Process of Wheat Straw

Wheat straw(WS) was liquefied to analyze the reaction process of WS under the acid-catalyzed conditions. WS was liquefied almost completely in the presence of ethylene carbonate/ethylene glycol(EC/EG) blend solvents within 40min at 150 ℃. The residues with different liquefaction time were investigated by SEM, FTIR, and XRD. The residues exhibited loose structure and rough surface due to the presence of stacked irregular platelets. The FTIR results demonstrated that lignin was more easily liquefied in the presence of EC/EG blend solvents than cellulose because the bands of cellulose were stronger and the bands of lignin were much weaker during the liquefaction process of WS. Moreover, the XRD result of all residues declared that WS was gradually liquefied, dissolved and decomposed to small fragments of lower molecular weight, and condensed in part in the later stage of liquefaction.

Residue curve maps of ethyl acetate synthesis reaction

The residue curve maps are considered as a powerful tool for the preliminary design of reactive distillation. The residue curve maps of ethyl acetate synthesis reaction were calculated based on the pseudo-homogeneous rate-based kinetic model and the NRTL activity coefficient model. The results show that the unstable node branch emerges from the ethyl acetate/water edge, moving toward the chemical equilibrium surface with the increase of Damkoeler value （D）, and the node reaches the ternary reactive azeotrope when D-∞ eventually. Conceptual design for the ethyl acetate synthesis of reactive distillation based on the residue curve maps is presented at last.

Development on the Technique of Total Recovery of Benzoic Acid Residue

Benzoic acid residue is solid waste produced from the production of benzoic acid by oxidizing toluene.Because it contained important chemical raw materials such as benzoic acid,benzyl benzoate and fluorenone,it is necessary to recover them from the residue.In this work the technique featured with high efficiency evaporation and vacuum distillation was developed to obtain total recovery and utilization of the benzoic acid residue.By controlling the operation temperature at 260℃ and the pressure of 16kPa in the rising and falling film evaporators,heavy components separated efficiently from the residue can be polymerized and the light components consisting of 63% of the residue entered into a benzoic acid vacuum distillation column.Keeping the temperature of polymerization at(280±10)℃,coumarone resin was produced after adjusting the softening point according to the market requirements.Vacuum distillation was operated under the following conditions:top temperature at 186℃,top pressure of 16kPa,bottom temperature at 240-250℃,reflux ratio being 3︰1.Benzoic acid of 98% purity was distilled out from the column as a side stream and the bottom product was crude benzyl benzoate.By the developed technique,the benzoic acid residue was splitted into three products,benzoic acid,crude benzyl benzoate and coumarone resin without any surplus waste.

Mechanistic insights for efficient inactivation of antibiotic resistance genes: a synergistic interfacial adsorption and photocatalytic-oxidation process

Advanced oxidation processes(AOPs) have been applied to address multiple environmental concerns including antibiotic resistance genes(ARGs). ARGs have shown an increasing threat to human health,and they are either harbored by antibiotic-resistant bacteria(ARB) or free in the environment.However, the control of ARGs has been substantially limited by their low concentration and the limited knowledge about their interfacial behavior. Herein, a novel AOP catalyst, Ag/TiO_(2)/graphene oxide(GO),combined with a polyvinylidene fluoride(PVDF) ultrafiltration membrane was designed with a synergistic interfacial adsorption and oxidation function to inactivate ARGs with high efficiency in both model solutions and in secondary wastewater effluent, especially when the residue concentration was low.Further analysis showed that the mineralization of bases and phosphodiesters mainly caused the inactivation of ARGs. Moreover, the interfacial adsorption and oxidation processes of ARGs were studied at the molecular level. The results showed that GO was rich in sp^(2) backbones and functional oxygen groups,which efficiently captured and enriched the ARGs via p-p interactions and hydrogen bonds. Therefore,the photogenerated active oxygen species attack the ARGs by partially overcoming the kinetic problems in this process. The Ag/Ti O2/GO catalyst was further combined with a PVDF membrane to test its potential in wastewater treatment applications. This work offers an efficient method and a corresponding material for the inactivation and mineralization of intra/extracellular ARGs. Moreover, the molecularlevel understanding of ARG behaviors on a solid–liquid interface will inspire further control strategies of ARGs in the future.

Amendment of Acid Soils with Crop Residues and Biochars

The liming potential of some crop residues and their biochars on an acid Ultisol was investigated using incubation experiments. Rice hulls showed greater liming potential than rice hull biochar, while soybean and pea straws had less liming potential than their biochars. Due to their higher alkalinity, biochars from legume materials increased soil pH much compared to biochars from non-legume materials. The alkalinity of biochars was a key factor affecting their liming potential, and the greater alkalinity of biochars led to greater reductions in soil acidity. The incorporation of biochars decreased soil exchangeable acidity and increased soil exchangeable base cations and base saturation, thus improving soil fertility.