UPLC-MS/MS法快速测定水产品中孔雀石绿和结晶紫残留量

建立了水产品中孔雀石绿、结晶紫、隐色孔雀石绿和隐色结晶紫残留量的超高液相色谱-串联质谱分析方法,该方法可快速、准确地定性和定量。采用C18色谱柱进行分离,以乙腈-10 mmol/L乙酸铵缓冲溶液(p H=4.5)作为流动相,在ESI正离子模式下检测。结果表明:MG、CV、LMG和LCV含量在0.1~5.0 ng/m L的范围内线性关系良好(r0.999),方法检出限均为0.05μg/kg。在添加水平为0.1、0.5、2.0μg/kg时,4种待测组分的平均回收率为87.8%~116.7%,测定结果的相对标准偏差均小于10%(n=6)。该方法简便、准确、高效,适用于水产品中孔雀石绿和结晶紫残留量的快速检测。     

柱前电化学衍生-高效液相色谱法测定水产品中孔雀石绿及隐性孔雀石绿

建立柱前电化学氧化-高效液相色谱测定水产品中孔雀石绿(MG)及隐性孔雀石绿(LMG)残留量的方法。试样经乙酸铵缓冲液/乙腈提取,酸性氧化铝吸附剂净化,乙腈和乙酸铵缓冲液(78∶22,ν∶ν)等度洗脱,柱前600 m V电压下LMG被氧化衍生成MG,618 nm波长检测,测定结果为总量;当电压为0 m V时,结果仅为样品中MG含量。并在各自相应浓度范围内线性良好,相关系数不低于0.996,三水平加标平均回收率为76.0%~95.0%,相对标准偏差(RSD)为1.7%~8.6%。方法的检出限为2.0μg/kg,定量限为5.0μg/kg。方法精密度、准确度和检出限等性能指标均达到兽残分析的要求,可用于水产品中的孔雀石绿及隐性孔雀石绿的检测。     

对国家标准中高效液相色谱法测定孔雀石绿及隐色孔雀石绿的方法改进研究

本研究采用高效液相色谱法对水产品中孔雀石绿和隐色孔雀石绿残留量进行检测,在GB/T 19857-2005的基础上,对该方法进行了改进.此方法简便、定量准确、精密度高,适用于水产品中孔雀石绿及其代谢物隐色孔雀石绿残留量的检测.     

对国家标准中高效液相色谱法测定孔雀石绿及隐色孔雀石绿的方法改进研究

本研究采用高效液相色谱法对水产品中孔雀石绿和隐色孔雀石绿残留量进行检测,在GB/T 19857-2005的基础上,对该方法进行了改进。此方法简便、定量准确、精密度高,适用于水产品中孔雀石绿及其代谢物隐色孔雀石绿残留量的检测。     

结晶紫褪色分光光度法测定亚硝酸根

基于稀盐酸介质中,亚硝酸根与结晶紫的褪色反虚,建立了测定痕量亚硝酸根的新方法。在结晶紫的最大吸收波长595nm处,方法的线性范围为0．08—2μg／mL。该方法选择性好、灵敏度高,用于火腿肠和自来水中亚硝酸根的测定,结果令人满意。     

罗非鱼鱼鳞对水中结晶紫的吸附特性和机理研究

通过吸附实验,考察鱼鳞投入量、结晶紫初始浓度和溶液pH等因素对罗非鱼鳞吸附水中结晶紫性能的影响,并通过红外光谱、BET比表面积、扫描电镜、吸附动力学和吸附等温线来分析吸附机理。结果表明:当溶液pH为7、温度30℃,吸附剂投加量为3g/L、吸附时间为20min,结晶紫浓度为40mg/L时,吸附效果最好,结晶紫的吸附率和吸附容量可分别达到66.69%和8.27mg/g;鱼鳞对结晶紫的吸附过程符合Lagergren准二级动力学模型,吸附过程属于物理吸附;吸附等温线符合Freundlich吸附等温式,当温度30℃时鱼鳞对结晶紫的最大吸附量为18.9mg/g;且罗非鱼鱼鳞中的胶原蛋白和羟基鳞灰石均参与了结晶紫染料的吸附。     

改性麦壳对结晶紫的吸附作用研究

主要研究了改性麦壳对结晶紫的吸附作用,结果表明麦壳能有效地结合结晶紫,吸附反应迅速,30min基本达到平衡;增加结晶紫的初始浓度,吸附量随之增大;增加吸附剂的用量,吸附量随之减小;溶液pH值在4～8范围内,吸附效果较好;盐度离子对吸附稍有影响,溶液中钠和钾离子的存在使结晶紫的吸附量降低,钙和镁离子的存在使吸附量升高;升高温度,对吸附有利。     

柠檬酸交联环糊精金属有机框架材料的制备及对结晶紫的吸附

环糊精金属有机框架材料(CD-MOFs)是一种绿色环保的新型金属有机框架材料，但由于其水稳定性差，在实际应用中受到了限制。通过交联CD-MOFs和柠檬酸(CA)来提高环糊精基MOFs的水溶液稳定性。研究制备了CA改性的CA-γ-CD-MOF复合材料，并作为吸附剂从水溶液中去除阳离子染料结晶紫。在15mg CA-γ-CD-MOF用量、20℃、pH 6和60mg/L初始结晶紫浓度下，CA-γ-CD-MOF对结晶紫的平衡吸附能力为79.86mg/g,相应的清除率达到99.83%。此外，CA-γ-CD-MOF在经过3次吸附解吸循环，吸附率仍达第一次的98%以上，表现出良好的再生能力。动力学和吸附等温线研究表明，吸附遵循拟二阶动力学，CA-γ-CD-MOF吸附结晶紫是一种自发的单层吸热过程。因此，CA-γ-CD-MOF是一种高效、绿色、可循环利用的吸附剂。     

改性榴莲壳对结晶紫的吸附性能研究

以改性榴莲壳作为吸附剂,采用静态吸附法处理结晶紫模拟废水溶液。结果表明,提高改性榴莲壳投加量、振荡速率、pH以及延长吸附时间有利于对结晶紫的吸附,而温度的变化对结晶紫的吸附影响不明显。当改性榴莲壳投加量为0.5g,结晶紫初始质量浓度为20mg/L,吸附时间为60min,振荡速率为140r/min时,改性榴莲壳对结晶紫的去除率可达99.78%。吸附动力学过程可用准二级动力学模型描述,等温吸附过程可由Freundlich吸附等温模型描述。改性榴莲壳与结晶紫之间发生多层吸附,最大吸附量为298.51mg/g,吸附过程是以物理吸附占主导的自发、放热过程。改性榴莲壳在印染废水中有较好的应用前景。     

食品中合成色素快速检测法研究及其应用

研究了食品中可能添加的非食用色素苏丹红,孔雀石绿,碱性橙Ⅱ号等的快速检测方法,并建立了同时测定饮料中人工合成色素柠檬黄,日落黄,胭脂红,苋菜红,亮蓝,靛蓝等多组分的方法,该方法与国标方法比较,检测结果相对误差小于5%,同时具有样品处理简单、快速、易操作的优点,适用于现场快速检测.     

Equilibrium, kinetics and mechanism modeling and simulation of basic and acid dyes sorption onto jute fiber carbon: Eosin yellow, malachite green and crystal violet single component systems

Batch experiments were carried out for the sorption of eosin yellow, malachite green and crystal violet onto jute fiber carbon (JFC). The operating variables studied are the initial dye concentration, initial solution pH, adsorbent dosage and contact time. Experimental equilibrium data were fitted to Freundlich, Langmuir and Redlich-Peterson isotherm by non-linear regression method. Langmuir isotherm was found to be the optimum isotherm for eosin yellow/JFC system and Freundlich isotherm was found to be the optimum isotherm for malachite green/JFC and crystal violet/JFC system at equilibrium conditions. The sorption capacities of eosin yellow, malachite green and crystal violet onto JFC according to Langmuir isotherm were found to 31.49 mg/g, 136.58 mg/g, 27.99 mg/g, respectively. A single stage batch adsorber was designed for the adsorption of eosin yellow, malachite green and crystal violet onto JFC based on the optimum isotherm. A pseudo second order kinetic model well represented the kinetic uptake of dyes studied onto JFC. The pseudo second order kinetic model successfully simulated the kinetics of dye uptake process. The dye sorption process involves both surface and pore diffusion with predominance of surface diffusion at earlier stages. A Boyd plot confirms the external mass transfer as the rate limiting step in the dye sorption process. The influence of initial dye concentration on the dye sorption process was represented in the form of dimensionless mass transfer numbers (Sh/Sc(0.33)) and was found to be agreeing with the expression:     

Manufacturing of patterned ZnO films with application for photoinitiated decolorization of malachite green in aqueous solutions

Patterned thin films, ZnO, are successfully prepared on glass substrates by the sol-gel method using dip-coating technique. The films, formed of ZnO nanocrystallites with hexagonal crystal structure, are characterized by means of scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction. The as obtained ZnO films are studied with respect to photo-initiated bleaching of malachite green in aqueous solutions. The bleaching process is investigated at various initial concentrations of malachite green in the aqueous solutions by using ZnO films of different thicknesses. The obtained results are promising for the development of ZnO photocatalysts by the sol-gel method.     

Photodegradation of crystal violet in TiO(2) suspensions using UV-vis irradiation from two microwave-powered electrodeless discharge lamps (EDL(-2)): products, mechanism and feasibility

Aqueous crystal violet (CV) solutions containing P25-TiO(2) photocatalyst were irradiated with ultraviolet-visible (UV-vis) light from two microwave-powered electrodeless discharge lamps (EDL(-2)). The results demonstrated that approximately 94.4% of CV was effectively removed after 3 min of irradiation, with a pseudo-first order kinetic constant of 0.838 min(-1). According to 32 kinds of products, a five-step degradation pathway of CV was proposed. Further investigations showed that (1) three kinds of N-demethylated products and 4-dimethylaminobenzophenone (DLBP) were the main intermediates; (2) malachite green (MG) and leuco-crystal violet could not be generated by N-demethylation and phototransformation reactions, respectively; (3) bis(4-(dimethylamino)phenyl)methanone preferentially generated via decomposition of the conjugated structure of CV could be further N-demethylated into DLBP. Moreover, the unique degradation pathways of CV and MG were ascribed to the different substituents on the conjugated structures. Additionally, the cost and kinetic constant of different processes was also evaluated, and the results indicated the feasibility of this method for treatment of CV in field situations.     

Removal of malachite green by adsorption and precipitation using aminopropyl functionalized magnesium phyllosilicate

We report a method for the removal of malachite green (MG) by adsorption and precipitation using nano-sized aminopropyl functionalized magnesium phyllosilicate (AMP) clay. MG, which is used in aquaculture and fisheries, is a carcinogenic and mutagenic compound. In response to these health risks, many efforts have been focused on adsorption of MG onto various adsorbents, which is a versatile and widely used technique for removing MG from water. Herein, we describe the adsorption and precipitation of MG using AMP clay, as well as the alkaline fading phenomenon of MG. In this study, prepared AMP clay and the precipitate product after the reaction of MG-AMP clay mixture were characterized. In addition, adsorption isotherms and kinetics, as well as thermodynamic studies are presented. Based on the results, we suggest a macro- and microscopic removal mechanism for the adsorption and precipitation of MG using AMP clay. An AMP clay dosage of 0.1 mg mL⁻¹ exhibited a maximum removal capacity of 334.80 mg g⁻¹ and 81.72% MG removal efficiency. With further increases of the AMP clay dosage, removal capacity by AMP clay gradually decreased; at dosage above 0.2 mg mL⁻¹ of AMP clay, the removal efficiency reached 100%.     

Ocular hazards of the colors used during the festival-of-colors (Holi) in India--malachite green toxicity

The objective of this study was to evaluate the nature of the colors used and their toxicity to the eye upon exposure to them during celebration of Holi (our festival-of-colors). Color powders and formulations were procured at random in and around Delhi during the festival. The green/bluish-green colors reported with the higher incidence of ocular toxicity were subjected for further evaluation. Eyewash fluid collected from the patients exposed to the colors was also subjected for analysis. This study was further extended to evaluate the corneal penetration of malachite green using goat cornea in perfusion chamber. In 16/18 color samples collected, malachite green or 4-[(4-dimethylaminophenyl)-phenyl-methyl]-N,N-dimethyl-aniline was detected at different concentrations. In the eyewash fluid of four patients, HPLC estimation confirmed the presence of malachite green at concentrations of 1.3, 0.18, 3.5 and 5.4 microg in 250 ml which was responsible for its reported toxicity. The in vitrotrans-corneal penetration studies did not show any detectable amount of malachite green in effluent fluid-in vitro tissue retention studies revealed that increasing the contact time increases tissue concentration. After 2 min of exposure, the tissue concentration was significantly higher. To conclude, malachite green was extensively used in our festival of Holi and has caused severe ocular irritation with epithelial defect upon exposure, though it did not penetrate through the cornea-further in vitro and in vivo studies are required on colors used in Holi.     

Enhanced malachite green removal from aqueous solution by citric acid modified rice straw

In this paper, rice straw was thermochemically modified with citric acid (CA) as esterifying agent. Two introduced free carboxyl groups of esterified rice straw were further loaded with sodium ion to yield potentially biodegradable cationic sorbent. In order to investigate the effect of chemical modification on the cationic dye sorption of rice straw, the removal capacities of native and modified rice straw sorbing a cationic dye (malachite green) from aqueous solution were compared. The effects of various experimental parameters (e.g. initial pH, sorbent dose, dye concentration, contact time) were investigated. For modified rice straw (MRS), the malachite green (MG) removal percentage came up to the maximum value beyond pH 4. For the 250 mg/l of MG solution, the 1.5 g/l or up of MRS could almost completely remove the dye from aqueous solution. Under the condition of 2.0 g/l sorbent used, the percentage of MG sorbed on MRS kept above 93% over a range from 100 to 500 mg/l of MG concentration. The sorption isotherms fitted the Langmuir or Freundlich models. The sorption equilibriums were reached at about 10 h. The sorption processes followed the pseudo-first-order rate kinetics. After chemical modification, the intraparticle diffusion rate constant (k(id)) was obviously increased. The results in this study indicated that MRS was an excellent sorbent for removal of MG from aqueous solution.     

Decolorization of malachite green, decolorization kinetics and stoichiometry of ozone-malachite green and removal of antibacterial activity with ozonation processes

This study aimed to identify degradation intermediates and to investigate the stoichiometry of decolorization and degradation, decolorization kinetics, and removal of antibacterial activity of malachite green (MG) using ozonization processes. The decolorization of MG was optimal at an acidic pH value of 3 based on molecular ozone attack on MG molecules. The stoichiometric ratio of decolorization between ozone and MG was calculated to be 7.0 with a regression coefficient of 0.995, whereas the ratio for degradation was calculated as 13.1 with a regression coefficient of 0.998. With MG concentrations in the range of 0.30-1.82 mM, the concentration of decolorized MG increased with higher initial concentrations of MG, whereas the ozonolytic decolorization rates of MG, decreased with increasing initial concentration. The pseudo-first-order degradation rate constants (k') decreased with the initial concentration and ranged from 0.769 to 0.223 min(-1). Twelve different intermediates were produced during the ozonation of MG with ozonation times between 5 min and 30 min and were identified by GC-MS. Although 86% of MG in the reaction mixture was removed by ozonation after 10 min, the decrease of antibacterial activity was very low (10%) for Bacillus subtilis and Staphylococcus epidermidis because the degradation intermediates, phenol and benzoic acid, also have antibacterial activity. The antibacterial activity of both MG and its intermediates were removed successfully with ozonation times above 26 min.     

Surface-enhanced Raman scattering of crystal violets from periodic array of gold nanocylinders

The periodic arrays of gold nanocylinder with 121?nm in diameter, 6.3?nm in gap, and 34?nm in thickness are fabricated on glass by electron-beam lithography and lift-off techniques. Some crystal violet molecules are coated on the array by using the dipping and drawing method. In addition, the surface-enhanced Raman scattering (SERS) spectra of these samples with and without gold nanocylinder arrays are characterized specifically. The largest enhancement factor is obtained when the excitation wavelength corresponds to the peak wavelength of localized surface plasmon resonance (LSPR). The density functional theory and the finite-difference time-domain method are used for the calculations of the extinction spectrum of the arrays and Raman spectra of the crystal violet, respectively. These results unambiguously demonstrate that the periodic arrays of gold nanocylinder have good and effective surface-enhanced properties for Raman scattering of crystal violets, and they also show that the excitation wavelength corresponding to the peak one of the LSPR is one of the major reasons causing SERS.     

Isotherm,kinetic, and thermodynamic studies on the adsorption behavior of malachite green dye onto montmorillonite clay

ABSTRACT

Systematic batch mode studies of adsorption of malachite green (MG) on montmorillonite clay were carried out as a function of process parameters which include pH, adsorbent dosage, agitation speed, ionic strength, initial MG concentration, and temperature. Montmorillonite was found to have excellent adsorption capacity. Equilibrium adsorption isotherms were measured for the single-component system, and the experimental data were analyzed by using Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherm equations. It was found that the Langmuir equation appears to fit the equilibrium data. The monolayer (maximum) adsorption capacity (q_m) was found to be 262.494 mg g^?1 for montmorillonite. The experimental kinetic data were analyzed using the first-order, second-order, Elovich, and intraparticle kinetic models and the second-order kinetic model described the adsorption kinetics accurately for MG. Thermodynamic activation parameters such as ΔG*, ΔS*, and ΔH* of the adsorption of MG on montmorillonite were also calculated.     

Comparative analysis of linear and non-linear method of estimating the sorption isotherm parameters for malachite green onto activated carbon

The experimental equilibrium data of malachite green onto activated carbon were fitted to the Freundlich, Langmuir and Redlich-Peterson isotherms by linear and non-linear method. A comparison between linear and non-linear of estimating the isotherm parameters was discussed. The four different linearized form of Langmuir isotherm were also discussed. The results confirmed that the non-linear method as a better way to obtain isotherm parameters. The best fitting isotherm was Langmuir and Redlich-Peterson isotherm. Redlich-Peterson is a special case of Langmuir when the Redlich-Peterson isotherm constant g was unity.