Synthesis of Amphiphilic Silica Nanoparticles for Latent Fingerprint Detection

4-(Chloromethyl) phenyltrichlorosilane was used to modify silica spheres to obtain a sensitive and selective nanoparticle powder for detecting latent fingerprints. Various analytical techniques were used to characterize the nanoparticles and to show that the structure and properties are well-suited for forensic science. The synthesis of the particles was optimized based on the performance in terms of detection and the development of a test set of latent prints. The new material offers simple synthesis, convenient use for routine casework, and low price. These advantages suggest potential application for crime scene investigations.     

Total synthesis of masked Alternaria mycotoxins—sulfates and glucosides of alternariol (AOH) and alternariol-9-methyl ether (AME)

The synthesis of different protected alternariol derivatives using intramolecular cyclization of iodoresorcylic acid phenyl esters by palladium-catalyzed C–H activation as key step is presented. Furthermore, chemical sulfation and glucosylation were applied for the preparation of conjugated Alternaria mycotoxins. These compounds are suspected to be formed during metabolism in contaminated plants. Therefore, all synthetic conjugates prepared within this work serve as reference materials for further studies in the fields of bioanalytics and toxicology of mycotoxins.     

Multi-detection method for five common microalgal toxins based on the use of microspheres coupled to a flow-cytometry system

Freshwater and brackish microalgal toxins, such as microcystins, cylindrospermopsins, paralytic toxins, anatoxins or other neurotoxins are produced during the overgrowth of certain phytoplankton and benthic cyanobacteria, which includes either prokaryotic or eukaryotic microalgae. Although, further studies are necessary to define the biological role of these toxins, at least some of them are known to be poisonous to humans and wildlife due to their occurrence in these aquatic systems. The World Health Organization (WHO) has established as provisional recommended limit 1 μg of microcystin-LR per liter of drinking water. In this work we present a microsphere-based multi-detection method for five classes of freshwater and brackish toxins: microcystin-LR (MC-LR), cylindrospermopsin (CYN), anatoxin-a (ANA-a), saxitoxin (STX) and domoic acid (DA). Five inhibition assays were developed using different binding proteins and microsphere classes coupled to a flow-cytometry Luminex system. Then, assays were combined in one method for the simultaneous detection of the toxins. The IC₅₀'s using this method were 1.9 ± 0.1 μg L⁻¹ MC-LR, 1.3 ± 0.1 μg L⁻¹ CYN, 61 ± 4 μg L⁻¹ ANA-a, 5.4 ± 0.4 μg L⁻¹ STX and 4.9 ± 0.9 μg L⁻¹ DA. Lyophilized cyanobacterial culture samples were extracted using a simple procedure and analyzed by the Luminex method and by UPLC–IT-TOF-MS. Similar quantification was obtained by both methods for all toxins except for ANA-a, whereby the estimated content was lower when using UPLC–IT-TOF-MS. Therefore, this newly developed multiplexed detection method provides a rapid, simple, semi-quantitative screening tool for the simultaneous detection of five environmentally important freshwater and brackish toxins, in buffer and cyanobacterial extracts.     

加速溶剂萃取-气相色谱-串联质谱法同时测定贝类中64种农药残留

建立了加速溶剂同步萃取净化-气相色谱-串联质谱(GC-MS/MS)同时测定贝类中64种农药残留的方法。加速溶剂萃取的萃取溶剂为90%(v/v)乙腈水溶液,萃取温度为85℃、冲洗体积60%萃取池体积、循环次数1次,同时使用0.8 g N-丙基乙二胺(PSA)和0.8 g石墨化炭黑(GCB)在线净化,提取液浓缩定容后,在多反应监测(MRM)模式下测定,外标法定量。结果表明,64种农药在10.0～1 000μg/L范围内呈现良好的线性关系,决定系数(r²)均大于0.989,方法的定量限为2.0～10.0μg/kg;对文蛤空白基质进行加标回收试验,添加水平为5.0、10.0和100μg/kg以及定量限水平,得到的平均回收率为69.4%～129.7%,精密度为0.7%～16.0%(n=6)。该方法提取和净化同步完成,操作简单,重复性好,灵敏度高,能够满足于贝类水产品中多种农药残留的同时筛查。     

New lipophilic rhodamines and their application to optical potassium sensing

New lipophilic fluorescent rhodamines were synthesized directly from 3,6-dichlorofluoresceins and the respective long-chain amines with excellent solubility in lipids and lipophilic membranes. Spectrophotometric and luminescent properties of the dyes are reported and discussed with respect to their application in new optical ion sensors. One rhodamine (2a) was applied in a poly(vinyl chloride)-based sensor membrane for continuous and sensitive optical determination of potassium ion, using valinomycin as the neutral ion carrier.     

Production of Bacillus sphaericus entomopathogenic biomass using brewery residues

The use of brewery residues—yeast and trub—has been evaluated aiming to minimize the costs of the industrial production of Bacillus sphaericus-based bioinsecticide. Both brewery residues promoted growth and sporulation of the three B. sphaericus strains that were isolated from Brazilian soils (S1, S2, and S20). However, distinct growth and sporulation behaviors were observed in relation to the different nutritional conditions and strain used. The maximum sporulation percentage was obtained through the cultivation of S20 strain in brewery residual yeast. In general, the entomopathogenic biomasses produced showed good results for toxicity to Culex larvae. The minimum values of larvae population (LC50) were observed for the S20 strain grown on yeast brewery residue-containing media. After fermentation, a considerable decrease in the organic material of alternative media was verified, although the residual values were still higher than that considered appropriate for effluent discharge.     

贝类体内麻痹性贝类毒素的提取方法研究

采用浓度系列为0.04、0.07、0.10、0.15、0.20、0.25、0.30、0.40、0.50、0.70、1.0 mol/L的HCl和HAc溶液作为提取液,分别取10 mL提取液与10 g栉孔扇贝性腺混合,在沸水浴中加热5 min提取麻痹性贝类毒素(PSP);同时采用0.3 mol/L HAc和0.2 mol/L HCl,于冰水浴中进行超声波提取麻痹性贝类毒素5~30 min。提取完成后将混合物于4℃冷冻离心机内离心5 min(3500 r/min),取上清液并以0.1 mol/L NaOH或5 mol/L HCl调整至pH为2.0~4.0。经超滤膜过滤后的提取液以高效液相色谱柱后衍生荧光检测法进行毒素分析,研究毒素组分间的转化关系和提取效率,并与超声波提取法进行了比较。结果表明,采用0.04~0.25 mol/L HCl和0.04~1.0 mol/L HAc从贝肉中提取PSP毒素,各毒素组分浓度差异不大,当HCl浓度大于0.25 mol/L时,N-磺酰氨甲酰基类毒素C1浓度急剧降低,HCl浓度大于0.5 mol/L时,N-磺酰氨甲酰基类毒素C2和GTX5浓度急剧降低,三者在酸度过大的情况下分解或转化为膝沟藻毒素-2(GTX2),膝沟藻毒素-3(GTX3)和石房蛤毒素(STX)。在相同浓度酸的情况下,超声波提取液中C1毒素的浓度显著低于沸水浴提取法,但C2的浓度略高于沸水浴提取液。     

Adsorption of small uremic toxin molecules on MFI type zeolites from aqueous solution

Adsorption properties of zeolites were investigated for the removal of p-cresol from aqueous solutions at 37 °C within the context of studying alternative methods to dialysis for removing uremic toxin from blood. MFI-framework type zeolites with different degrees of hydrophobicity and charge compensating cations were prepared: one pure silica MFI and four alumino-silicate MFIs (Si/Al = 30), with H⁺, Na⁺, K⁺ and Mg²⁺ as charge compensating cations. Adsorption isotherms and microcalorimetric measurements show a high affinity of p-cresol for all MFI type zeolites. The best capacity is obtained for the pure silica MFI, whereas the alumino-silicate samples show a higher affinity in the low concentration range. In the case of pure silica sample, the microscopic adsorption mechanism including the role of confined water is elucidated with the help of NMR, X-ray analysis (including Rietveld refinement) and Monte Carlo simulations. For all samples the high affinity is preserved in physiological serum solution, even in the presence of other toxin molecules such as urea. It is also shown that the compensating cation state of the samples is imposed by the physiological medium.     

Lead(II) Potentiometric Sensor Based on 1,4,8,11‐Tetrathiacyclotetradecane Neutral Carrier and Lipophilic Additives

A potentiometric sensor for lead(II) ions based on the use of 1,4,8,11‐tetrathiacyclotetradecane (TTCTD) as a neutral ionophore and potassium tetrakis‐(p‐chlorophenyl)borate as a lipophilic additive in plasticized PVC membranes is developed. The sensor exhibits linear potentiometric response towards lead(II) ions over the concentration range of 1.0×10^?5–1.0×10^?2 mol L^?1 with a Nernstian slope of 29.9 mV decade^?1 and a lower limit of detection of 2.2×10^?6 mol L^?1 Pb(II) ions over the pH range of 3–6.5. Sensor membrane without a lipophilic additive displays poor response. The sensor shows high selectivity for Pb(II) over a wide variety of alkali, alkaline earth and transition metal ions. The sensor shows long life span, high reproducibility, fast response and long term stability. Validation of the method by measuring the lower limit of detection, lower limit of linear range, accuracy, precision and sensitivity reveals good performance characteristics of the proposed sensor. The developed sensor is successfully applied to direct determination of lead(II) in real samples. The sensor is also used as an indicator electrode for the potentiometric titration of Pb(II) with EDTA and potassium chromate. The results obtained agree fairly well with data obtained by AAS.