Electrospray ionization source with a rear extractor

A new electrospray source design is introduced by having an extractor electrode placed at 1 to 2 mm behind the emitter tip. The extractor was integrated into the sprayer body as a single device. An insulating tube was used to isolate the emitter from the extractor and to deliver the sheath gas for the electrospray. The electric field strength at the emitter was primarily determined by the relative position and the potential between the needle and the extractor; therefore, the spraying condition was insusceptible to the change of sprayer position or orientation with respect to the ion sampling inlet. Such design allowed the use of much lower operating voltage and facilitated the optimization of sprayer position by keeping the electric field parameter constant. Using an emitter capillary of 150 and 310 μm in inner and outer diameters, strong ion signal could still be acquired with 2‐kV emitter potential even if the distance between the emitter and ion inlet was extended to >70 mm. Charge reduction of protein ions using 2 extractor‐based electrosprays of opposite emitter polarities was also demonstrated.     

索氏提取法提取豆腐柴根茎叶中的总黄酮

用索氏提取法提取豆腐柴根、茎、叶中总黄酮并进行含量测定.以芦丁为标准品,用分光光度法在502nm处测定提取物中总黄酮的含量.考察乙醇浓度、料液比和时间对于提取效率的影响.结果表明,60％的乙醇浓度、1∶40g/mL的料液比和提取时间为2.0h是提取豆腐柴中黄酮化合物的最优条件.在此条件下,根总黄酮含量为5.034mg/g、茎为5.785mg/g、叶为23.148mg/g.     

Specific boundary conditions for the simulation of extraction for ECRIS,LIS, and H−-sources

The necessity of a three-dimensional simulation of the extraction has been accepted for electron cyclotron resonance ion sources (ECRIS) as well as for negative ion sources. For an ECRIS, the magnetic hexapole together with the solenoidal mirror field defines a minimum B structure which confines the plasma. Depending on the magnetic flux density distribution, the plasma density in front of the extraction electrode might be non-homogeneous. In H^?-sources, magnetic filter fields are used to separate electrons with different energies or to separate electrons from negative ions. These magnetic filters influence the ions as well. Besides these asymmetry effects other quantities have to be considered, namely the correct formulation of initial conditions of all present charged particles. For ECRIS the initial conditions for ions are assumed to be in the electronvolt range, whereas it can be in the kilo electronvolt range for laser ion sources. Another quantity of interest is the electron energy and the distribution of electrons in real space and their movability if magnetic fields are present.     

Determination of Phthalate Esters in Textiles by Solid Phase Extraction and Gas Chromatography–Mass Spectrometry

A sensitive and rapid method was developed for the determination of seven phthalate esters in baby waterproof fabrics, decorated waterproof tarpaulins, and printed textiles by solid phase extraction followed by gas chromatography–mass spectrometry. The method showed good linearity with correlation coefficients between 0.9958 and 0.9999 and limits of quantification and detection from 23 to 274 micrograms per liter and 7 to 82 micrograms per liter, respectively. The maximum recoveries were between 96.2 and 100.9 percent with relative standard deviations from 1.06 to 6.87 percent. The protocol was applied to the determination of phthalate esters in textiles: the samples contained more than 0.1 percent phthalate esters, which exceed relevant standards.     

Conductivity,impurity profile,and cytotoxicity of solvent‐extracted polyaniline

Understanding the correlation between the preparation, purification, impurity leaching, and cytotoxicity of polyaniline is crucial for the application of this conducting polymer in biomedicine. Polyaniline hydrochloride was purified in a Soxhlet extractor by using six different solvents: methanol, 1,2‐dichloroethane, acetone, ethyl acetate, hexane, or 0.2 M aqueous hydrochloric acid. The chromatographic analyses of impurities leached out of the polymer into the solvents confirmed differences in impurity profiles, which depended on the polarity of the extraction solvent. Compared with the original polymer, the conductivity of purified polyanilines increased in dependence on the amount and type of extracted impurities. The cytotoxicity of purified samples determined on the mouse embryonic fibroblast cell line NIH/3T3 using MTT assay improved as well. Methanol and 0.2 M hydrochloric acid were the most efficient solvents capable of extracting low‐molecular‐weight impurities, and thus reducing polyaniline cytotoxicity. The absence of cytotoxicity was observed at an extract concentration of 10%. Extraction with suitable solvents can, therefore, be a possible way of obtaining cyto‐compatible polyaniline with sufficient conductivity. Copyright © 2015 John Wiley & Sons, Ltd.     

Prediction of solvents extraction-the organochlorine pesticides in soil using solubility parameter

Prediction of the optimal extraction solvent based on the solubility parameter to extract the typical organochlorine pesticides from Jiangxi red soil was reported in this paper. Hildebrand solubility parameters, including dispersion coefficient (δ_d), polarity (δ_p) and hydrogen bonding (δ_h), of extraction solvents (including hexane, dichloromethane, hexane/methanol (4:1, v/v), hexane/acetone (1:1, v/v), hexane/dichloromethane (1:1, v/v) and organochlorine pesticides were calculated using group contribution method. The solvents, such as hexane/methanol (4:1, v/v) and hexane/acetone (1:1, v/v) were selected as ideal extraction solvents to extract o,p′-DDT o,p′-DDE and o,p′-DDD with high recoveries (>82%), furthermore, these solvents can be used to extract α-endosulfan, Endrin and HCB with the reliable recoveries (>75%). The estimated finding by solubility parameters was supported by the results of soxhlet extraction.     

液质联用法测定纺织品中烷基酚和烷基酚聚氧乙烯醚

采用高效液相色谱-质谱法测定了纺织品中残留的辛基酚、壬基酚、辛基酚聚氧乙烯醚和壬基酚聚氧乙烯醚,对提取方式、提取溶剂等前处理条件进行了优化,对质谱监测离子进行了选择。该方法检出限(S/N=5)为0.010~0.025 mg/kg,回收率为93%~106%,相对标准偏差为1.0%~5.0%,方法简便、准确,灵敏度高。     

A multi-residue method for characterization and determination of atmospheric pesticides measured at two French urban and rural sampling sites

The extensive use of pesticides to protect agricultural crops can result in the transfer of these compounds into the atmosphere and their diffusion towards urban areas. Precise evaluation of the geographic impact of this type of pollution is important environmentally. In this paper, analytical methods for the sampling, characterization, and determination of agricultural pesticides in air were developed; the methods were then applied in the Paris and Champagne regions. Sixteen pesticides belonging to nine chemical families were monitored. Sampling was carried out in urban (Paris) and rural (Aube district) sites, utilizing either a high-volume pump (12.5 m³ h^–1) (urban site) or a low-volume pump (2.3 m³ h^–1) for the rural site. Quartz filters and polyurethane foams (PUF) were used for sampling in all cases. After extracting the samples and concentrating the recovered solutions, high-performance liquid chromatography (HPLC) analysis with UV detection was performed. Identification of the pesticides was confirmed by applying to the HPLC measurements a novel UV-detection procedure based on the normalized absorbance variation with wavelength (Noravawa procedure). The presence of metsulfuron methyl, isoproturon, linuron, deltamethrin (and/or malathion), and chlorophenoxy acids (2,4-D and MCPP) was found at the urban sampling site at levels ranging from about 1 to 1130 ng m^–3 of air, depending on the compound and sampling period. On the rural sampling site residues of isoproturon, deltamethrin (and/or malathion), MCPP, and 2,4-D were generally detected at higher levels (19–5130 ng m^–3) than on the urban site, as expected. The effects of the weather conditions and agricultural activity on the atmospheric concentrations of pesticides are discussed, as are long-range atmospheric transfer processes for these pesticides.     

On the Construction of Affine Extractors

In this paper, we address the problem of explicit construction of so-called ‘affine extractors’ of δ-entropy ratio, when δ ≤ 1/2 (for δ > 1/2, there is a well-known and easy example based on the Hadamard function). We first give examples for δ slightly below 1/2 and produce then a construction for arbitrary given δ > 0. All these examples are again of a simple algebraic nature. The mathematics involved includes recent developments in the sum-product theory in finite fields and certain new bounds on multilinear exponential sums. Supported in part by NSF grant DMS 0322370. Submitted: May 2005 Accepted: February 2006     

On extractors and exposure‐resilient functions for sublogarithmic entropy

We study resilient functions and exposure‐resilient functions in the low‐entropy regime. A resilient function (a.k.a. deterministic extractor for oblivious bit‐fixing sources) maps any distribution on n ‐bit strings in which k bits are uniformly random and the rest are fixed into an output distribution that is close to uniform. With exposure‐resilient functions, all the input bits are random, but we ask that the output be close to uniform conditioned on any subset of n ‐ k input bits. In this paper, we focus on the case that k is sublogarithmic in n. We simplify and improve an explicit construction of resilient functions for k sublogarithmic in n due to Kamp and Zuckerman (SICOMP 2006), achieving error exponentially small in k rather than polynomially small in k. Our main result is that when k is sublogarithmic in n, the short output length of this construction (O(log k) output bits) is optimal for extractors computable by a large class of space‐bounded streaming algorithms. Next, we show that a random function is a resilient function with high probability if and only if k is superlogarithmic in n, suggesting that our main result may apply more generally. In contrast, we show that a random function is a static (resp. adaptive) exposure‐resilient function with high probability even if k is as small as a constant (resp. loglog n). No explicit exposure‐resilient functions achieving these parameters are known. © 2012 Wiley Periodicals, Inc. Random Struct. Alg., 2013