复合食品包装膜袋中2,4-二氨基甲苯的气-质联用测量

目的研究气-质联用法测定复合食品包装膜袋中的2,4-二氨基甲苯,并调查潮州市部分食品包装企业生产的复合食品包装膜袋中2,4-二氨基甲苯的含量。方法样品在100℃下用水浸泡,浸泡液经甲苯提取、三氟乙酸酐衍生化后将衍生物进行气-质联用分析。结果 2,4-二(三氟乙酰氨基)甲苯定量离子的峰面积和二氨基甲苯的质量浓度有线性关系,范围为1~100μg/L,相关系数达0.9994,检出限为0.2μg/L,回收率为89.0%~95.2%,RSD值为1.80%~4.70%。调查结果显示,30个样品中有5个样品检出2,4-二氨基甲苯,质量浓度在1.1~6.4μg/L,其中1个样品中的2,4-二氨基甲苯质量浓度达到6.4μg/L,超出标准限量要求(小于4μg/L)。30个样品的合格率达到96.7%,表明辖区内该类产品中2,4-二氨基甲苯的含量状况基本良好。结论气-质联用方法检出限低,回收率高,结果准确可靠。     

气相色谱-质谱法测定复合包装袋中的二氨基甲苯

用二氯甲烷作为萃取溶剂,样品中加入氯化钠降低2,4-二氨基甲苯在水中的溶解度,减压蒸馏除去样品中未反应的衍生化试剂及副产物,采用气相色谱-提取离子扫描质谱检测复合食品包装袋中二氨基甲苯的含量。方法回收率（75~95）%之间,相对标准偏差小于4.6%,检出限0.0002mg/L,满足定量分析的要求。     

复合食品包装袋中二氨基甲苯测量不确定度评定

按照GB/T 5009.119-2003《复合食品包装袋中二氨基甲苯的测定》的方法处理分析样品,通过建立二氨基甲苯不确定度的数学模型来研究包装用复合膜袋二氨基甲苯不确定度评定的方法,同时分析测定过程中不确定度的各种来源并计算各种不确定度的分量。该检测方法不确定度评定结果为:当2,4-二氨基甲苯含量为0.5mg/L,其扩展不确定度为0.041mg/L(k=2)。     

复合药品包装膜、袋中二氨基甲苯测定方法

1、摘要 本文研究了复合药品包装袋中二氨基甲苯的气相色谱测定方法。方法灵敏检出限为0．001mg／L。     

四月份部分有机氟产品市场参考价格

产品名称规格型号产地价格 (元 /吨 )2 -氟 -4 -溴苄基溴≥ 99%国产 1 0 0 0 0 0 02 -氟 -4 -溴甲苯≥ 99%国产 90 0 0 0 03 ,4 -二氯三氟甲基苯 无色透明液体 99% 国产面议3 ,5-二硝基 -4 -　氯三氟甲苯 淡黄色晶体国产面议3 ,5-二硝基三氟甲苯≥ 99%国产 4 50 0 0 03 ,5-双三氟甲基　苯胺淡黄色液体 99% 国产面议3 -氨基 -4 -　氟三氟甲苯 ≥ 99%国产 650 0 05-氯 -2 -氨基　三氟甲基苯淡黄色透明液体 98 5% 国产面议氨基三氟甲苯≥ 98%国产 63 0 0 0八氟环丁烷国产面议对氟苯胺 无色透明液体 99% 国产面议对氟苯酚白色结晶 99%国产面议对…     

氢化物-原子荧光光谱法依次测定锌精矿中砷、锑、铋、锡

用氢化物～原子荧光光谱法，一次性分解样品，在L2半胱氨酸存在下，实现了锌精矿中As、sb、Bi、Sn的连续测定。其回收率分别为93．8％～104．0％、95．0％～108．3％、93．0％～110．6％和95．7％～104．7％；检出限分别为0．35、0．31、0．19和0．35μg／L。用该方法分析锌精矿样品，结果满意。     

气相色谱-质谱法测定复合食品包装袋中2,4-二氨基甲苯

本文采用GC-MS气相色谱-质谱联用法测定复合食品包装袋中2,4-二氨基甲苯含量。沸水浸取2,4-二氨基甲苯后,用二氯甲烷作溶剂进行液-液萃取,加入氯化钠提高萃取效率,将浓缩的样品直接进行GC-MS定量定性分析。实验结果表明线性范围在0.002～0.01mg/L,线性方程为:Y=5136+69.526X(r=0.9994),检出限小于0.002mg/L,加标回收率在71%～95%之间。     

食品中铝测定方法的研究与改进

对食品中铝含量测定方法进行改进,用微波消解法代替湿法消解。采用样品在微波消解后获得的待测试液,以纯水为介质,控制溶液酸度,在最佳条件下,铝在0．0—5．2μg范围内线性良好（r=0．9996）,相对标准偏差为0．5％-1．0％,样品加标回收率为91．0％～105．0％。该方法简单,快速,重现性好,灵敏度高,结果令人满意。     

光度比浊法测定烟草中硫酸根的含量

在丙二醇介质中,基于硫酸根离子与钡离子形成稳定的胶体沉淀,建立了光度比浊法测定烟草中硫酸根含量的分析方法。硫酸根浓度在0．O～60．0μg／mL范围内符合比耳定律,相关系数0．9992。用于测定烟草样品中的硫酸根含量,回收率范围95．8％～104．9％;变异系数1．7％(n=10)。样品测定结果与重量法基本一致,相对误差小于4．0％。方法操作简便、准确、快捷,具有实用价值。     

食品中甜蜜素的高效液相色谱法

本文建立了甜蜜素的高效液相色谱法,结果表明样品中甜蜜素含量为0～1．0mg／g范围内,峰面积与甜蜜素含量呈良好的线性关系,相关系数为0．9977,对0．1mg／mL标准溶液连续测定7次,相对标准偏差为3.65％,加标回收率为95．4％～102．2％之间,食品中共存的苯甲酸、山梨酸、安赛蜜等不影响测定,方法简捷、准确。用于实际样品测定,结果令人满意。     

Effects of iron type in Fenton reaction on mineralization and biodegradability enhancement of hazardous organic compounds

The mineralization and biodegradability increase and their combination of two traditional and two relatively new organic contaminants by Fenton reagents with three different types of iron, Fe(2+), Fe(3+), and Fe(0) were investigated. The traditional contaminants examined were trichloroethene (TCE) and 2,4-dichlorophenol (2,4-DCP) while 1,4-dioxane (1,4-D) and 1,2,3-trichloropropane (TCP) were studied for the relatively new contaminants. The mineralization and biodegradability were represented by dissolved organic carbon (DOC) reduction and the ratio of biodegradable dissolved organic carbon and DOC, respectively. For all four contaminants, Fenton reagent using Fe(2+) was more effective in the DOC reduction than Fenton reagents using Fe(3+) and Fe(0) in most cases. The types of Fe that provided maximum biodegradability increase were not the same for all four compounds, Fe(3+) for TCE, Fe(0) for 2,4-DCP, Fe(2+) for 1,4-D, and Fe(3+) for TCP. When the combination of DOC elimination and biodegradability increase (least refractory fraction) was considered, Fe(2+) was the best choice except for 2,4-DCP which was susceptible to Fe(0) catalyzed Fenton reagent the most. The least refractory fractions remaining after 120 min of reaction were 20-25% for TCE, 2,4-DCP, and TCP and 30-40% for 1,4-D. The iron type in Fenton reaction also affected the type of mineralization kinetics of TCE, 2,4-DCP, and TCP as well as the types of degradation by-products of these contaminants. Some of the by-products found, such as isopropanol and propionic aldehyde, which were produced from Fe(0) catalyzed Fenton degradation of TCP, have not been previously reported.     

Application of Box-Wilson experimental design method for 2,4-dinitrotoluene treatment in a sequential anaerobic migrating blanket reactor (AMBR)/aerobic completely stirred tank reactor (CSTR) system

A sequential aerobic completely stirred tank reactor (CSTR) following the anaerobic migrating blanket reactor (AMBR) was used to treat a synthetic wastewater containing 2,4-dinitrotoluene (2,4-DNT). A Box-Wilson statistical experiment design was used to determine the effects of 2,4-DNT and the hydraulic retention times (HRTs) on 2,4-DNT and COD removal efficiencies in the AMBR reactor. The 2,4-DNT concentrations in the feed (0-280 mg/L) and the HRT (0.5-10 days) were considered as the independent variables while the 2,4-DNT and chemical oxygen demand (COD) removal efficiencies, total and methane gas productions, methane gas percentage, pH, total volatile fatty acid (TVFA) and total volatile fatty acid/bicarbonate alkalinity (TVFA/Bic.Alk.) ratio were considered as the objective functions in the Box-Wilson statistical experiment design in the AMBR. The predicted data for the parameters given above were determined from the response functions by regression analysis of the experimental data and exhibited excellent agreement with the experimental results. The optimum HRT which gave the maximum COD (97.00%) and 2,4-DNT removal (99.90%) efficiencies was between 5 and 10 days at influent 2,4-DNT concentrations 1-280 mg/L in the AMBR. The aerobic CSTR was used for removals of residual COD remaining from the AMBR, and for metabolites of 2,4-DNT. The maximum COD removal efficiency was 99% at an HRT of 1.89 days at a 2,4-DNT concentration of 239 mg/L in the aerobic CSTR. It was found that 280 mg/L 2,4-DNT transformed to 2,4-diaminotoluene (2,4-DAT) via 2-amino-4-nitrotoluene (2-A-4-NT) and 4-amino-2-nitrotoluene (4-A-2-NT) in the AMBR. The maximum 2,4-DAT removal was 82% at an HRT of 8.61 days in the aerobic CSTR. The maximum total COD and 2,4-DNT removal efficiencies were 99.00% and 99.99%, respectively, at an influent 2,4-DNT concentration of 239 mg/L and at 1.89 days of HRT in the sequential AMBR/CSTR.     

茶叶中2,4-D残留量的检测

为了解决出口茶叶中2,4-D的残留检测的难题,研究了茶叶中2,4-D的残留检测的方法。样品采用酸性乙腈提取,用三氟化硼甲醇溶液将2,4-D衍生成2,4-D甲酯,经过液-液萃取,用弗罗里硅土柱层析净化除去干扰物质,以气相色谱电子捕获检测器测定,依据色谱峰保留时间定性,外标法峰面积定量。该方法在0.01-0.5mg/kg范围内呈线性,平均回收率为80.1%～93.0%,相对标准偏差为1.4%～4.3%.     

Effect of recycling flux on performance and characteristics of activated sludge hydrolytic–aerobic recycling process in degradation of 2,4-dichlorophenol

The degradation of a model molecule, 2,4-dichlorophenol (2,4-DCP), was studied using an activated sludge hydrolytic–aerobic recycling process (HARP). 2,4-DCP and chemical oxygen demand (COD) total removal efficiency in the recycling process was 98% and 96% at the recycling flux of 15 mL/min after 24 h degradation, respectively. With the recycling flux increasing, the peak values of the concentration of volatile fatty acid (VFA) declined. Polysaccharide and protein contents in EPS were dramatically increased as recycling flux increasing from 5 to 15 mL/min in the HARP. There is obviously fit to the linear correlation between the PN/PS ratios and recycling flux. The zeta potentials decreased with recycling flux increasing. As the recycling flux increasing at a certain degree, the increase in polysaccharide and protein contents of EPS could more favor the stability of the HARP.     

Injection port derivatization following ion-pair hollow fiber-protected liquid-phase microextraction for determining acidic herbicides by gas chromatography/mass spectrometry

Injection port derivatization following ion-pair hollow fiber-protected liquid-phase microextraction (LPME) for the trace determination of acidic herbicides (2,4-dichlorobenzoic acid, 2,4-dichlorophenoxyacetic acid, 2-(2,4-dichlorophenoxy)propionic acid, 3,5-dichlorobenzoic acid, 2-(2,4,5-trichlorophenoxy)propionic acid) in aqueous samples by gas chromatography/mass spectrometry (GC/MS) was developed. Prior to GC injection port derivatization, acidic herbicides were converted into their ion-pair complexes with tetrabutylammonium chloride in aqueous samples and then extracted by 1-octanol impregnated in the hollow fiber. Upon injection, ion pairs of acidic herbicides were quantitatively derivatized to their butyl esters in the GC injection port. Thus, several parameters related to the derivatization process (i.e., injection temperature, purge-off time) were evaluated, and main parameters affecting the hollow fiber-protected LPME procedure such as extraction organic solvent, ion-pair reagent type, pH of aqueous medium, concentration of ion-pair reagent, sodium chloride concentration added to the aqueous medium, stirring speed, and extraction time profile, optimized. At the selected extraction and derivatization conditions, no matrix effects were observed. This method proved good repeatability (RSDs <12.3%, n = 6) and good linearity (r2 > or = 0.9939) for spiked deionized water samples for five analytes. The limits of detection were in the range of 0.51-13.7 ng x L(-1) (S/N =3) under GC/MS selected ion monitoring mode. The results demonstrated that injection port derivatization following ion-pair hollow fiber-protected LPME was a simple, rapid, and accurate method for the determination of trace acidic herbicides from aqueous samples. In addition, this method proved to be environmentally friendly since it completely avoided open derivatization with potentially hazardous reagents.     

Effects of pH and temperature on isotherm parameters of chlorophenols biosorption to anaerobic granular sludge

As the most important parameters affecting the biosorption, pH and temperature were studied in this paper in order to more completely understand their effects on chlorophenols' biosorption onto anaerobic granular sludge. Sorption isotherms of 4-chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP) at various temperatures were determined; the data of 4-CP could be simulated by Langmuir model, while the data of 2,4-DCP could only be reproduced by Freudlich equation. The uptake capacity of 4-CP and 2,4-DCP could reach 1.5mgg(-1) and 5.04mgg(-1) when 2,4-DCP concentration was 90mgL(-1) and 4-CP concentration was 107mgL(-1), respectively. 2,4-DCP was more strongly adsorbed onto the anaerobic granular sludge than 4-CP, which might be correlated with the numbers of chlorine substitute. The Experiments studying pH effects showed that the adsorption capacity of 4-CP and 2,4-DCP was quite pH dependent and increased with decrease in pH.     

Oxidation of pesticides by in situ electrogenerated hydrogen peroxide: study for the degradation of 2,4-dichlorophenoxyacetic acid

This paper reports an investigation on the performance of the H2O2 electrogeneration process on a rotating RVC cylinder cathode, and the optimization of the O2 reduction rate relative to cell potential. A study for the simultaneous oxidation of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) by the in situ electrogenerated H2O2 is also reported. Experiments were performed in 0.3 M of K2SO4, pH of 10 and 3.5. Oxygen concentration in solution was kept in 25 mg L(-1). Maximum hydrogen peroxide generation rate was reached at -1.6 V versus SCE for both, acidic and alkaline solutions. Then, 100 mg L(-1) of 2,4-D was added to the solution. First order apparent rate constants for 2,4-D degradation ranged from 0.9 to 6.3x10(-5) m s(-1), depending on the catalyst used (UV or UV+Fe(II)). TOC reduction was favored in acidic medium where a decreasing of 69% of the initial concentration was observed in the process catalyzed by UV+Fe(II). This figure was an indication that some of the intermediates derived from 2,4-D decomposition remained in solution, mainly as lighter aliphatic compounds.     

Scale up of 2,4-dichlorophenol removal from aqueous solutions using Brassica napus hairy roots

Chlorophenols are harmful pollutants, frequently found in the effluents of several industries. For this reason, many environmental friendly technologies are being explored for their removal from industrial wastewaters. The aim of the present work was to study the scale up of 2,4-dichlorophenol (2,4-DCP) removal from synthetic wastewater, using Brassica napus hairy roots and H₂O₂ in a discontinuous stirred tank reactor. We have analyzed some operational conditions, because the scale up of such process was poorly studied. High removal efficiencies were obtained (98%) in a short time (30 min). When roots were re-used for six consecutive cycles, 2,4-DCP removal efficiency decreased from 98 to 86%, in the last cycle. After the removal process, the solutions obtained from the reactor were assessed for their toxicity using an acute test with Lactuca sativa L. seeds. Results suggested that the treated solution was less toxic than the parent solution, because neither inhibition of lettuce germination nor effects in root and hypocotyl lengths were observed. Therefore, we provide evidence that Brassica napus hairy roots could be effectively used to detoxify solutions containing 2,4-DCP and they have considerable potential for a large scale removal of this pollutant. Thus, this study could help to design a method for continuous and safe treatment of effluents containing chlorophenols.