Liquid phase microextraction applications in food analysis

Over the last years, liquid-phase microextraction (LPME) in its different application modes (single drop microextraction, dispersive liquid-liquid microextraction and hollow fiber-LPME) has been increasingly applied for the extraction of both inorganic and organic analytes from different matrices. Its advantages over conventional extraction procedures (simplicity, effectiveness, rapidity and low consumption of organic solvents) has also attracted its application in the complex food analysis field, in which it has clearly provided good and challenging results. A comprehensive review dealing with those articles published since its introduction till the end of March 2011 is presented, offering also a critical vision of the analytical potential of LPME for the analysis of foods.     

Removal of Zn(II) Ions from Aqueous Solution Using BPHA‐Impregnated Polyurethane Foam

Zn(II) ions sorption onto N‐Benzoyl‐N‐Phenylhydroxylamine (BPHA) impregnated polyurethane foam (PUF) has been studied extensively using radiotracer and batch techniques. Maximum sorption (～98%) of Zn(II) ions (8.9 × 10^?6 M) onto sorbent surface is achieved from a buffer of pH 8 solution in 30 minutes using 7.5 mg/mL of BPHA‐impregnated polyurethane foam at 283 K. The sorption data follow Langmuir, Freundlich and Dubinin‐Radushkevich (D‐R) isotherms. The Langmuir constants Q = 18.01 ± 0.38 μ mole g^?1 and b = (5.39 ± 0.98) × 10³ L mole^?1 have been computed. Freundlich constants 1/n = 0.29 ± 0.01 and C_m = 111.22 ± 12.3 μ mole g^?1 have been estimated. Sorption capacity 31.42 ± 1.62 μ mole g^?1, β = ?0.00269 ± 0.00012 kJ² mole^?2 and energy 13.34 ± 0.03 kJ mole^?1 have been evaluated using D‐R isotherm. The variation of sorption with temperature yields ΔH = ?77.7 ± 2.8 k J mole^?1, ΔS = ?237.7 ± 9.3 J mole^?1 K^?1 and ΔG = ?661.8 ± 117.5 k J mol^?1 at 298 K reflecting the exothermic and spontaneous nature of sorption. Cations like Fe(III), Ce(III), Al(III), Pb(II) and Hg(II) and anions, i.e., oxalate, EDTA and tartrate, reduce the sorption significantly, while iodide and thiocyanate enhanced the sorption of Zn(II) ions onto BPHA‐impregnated polyurethane foam.     

稀土-N-苯甲酰苯胲络合物吸附极谱波的研究及测定钆

本工作研究了在NH_4Cl溶液(pH=4.50～7.00)中N-苯甲酰苯胲(BPHA)-稀土络合物的极谱行为以及电极反应机理;提出了测定钆的一种新方法,用此方法可检测1.0×10~(-6)～1.2×10~(-5)mol·L~(-1)的钆。     

分散液液微萃取-数码比色法测定水样中痕量钒

研究了分散液液微萃取-数码比色法测定水样中的痕量钒. 在酸性介质中, 痕量钒(V)和N-苯甲酰-N-苯基羟胺(BPHA)作用, 生成紫红色螯合物, 用乙醇做分散剂, 以三氯甲烷为萃取剂进行分散液液微萃取, 萃取液点样在薄层硅胶板上用数码相机进行数码成像. 成像斑点的灰度值和钒(V)的浓度成正比, 据此建立了测定水样中痕量钒的新方法. 对影响萃取富集效率和数码成像效果的因素进行了优化. 钒(V)浓度在5.0～400 μg•L－1范围内有良好的线性关系(r＝0.9993), 检出限为0.87 μg•L－1. 方法已应用于实际水样分析, 加标回收率在97.4%～102.7%之间, 相对标准偏差在1.7%～3.3%之间. 方法具有仪器成本低、方便快速、灵敏度高、环境友好等特点, 可满足野外现场的检测要求.     

Bestimmung von Rhenium in Molybd?n-, Wolfram- und Vanadiumlegierungen nach vorheriger Extraktionstrennung mit N-Benzoyl-N-phenylhydroxylamin (BPHA)

Ohne Zusammenfassung

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Determination of rhenium in molybdenum, tungsten and vanadium alloys after preceding extractive separation with N-benzoyl-N-phenylhydroxylamine (BPHA)

     

Sensitive spectrophotometric determination of vanadium with 2-(5-bromo-2-pyridylazo)-5-diethyl-aminophenol (5-Br-PADAP)

A new sensitive and highly selective method is described for the spectrophotometric determination of microgram amounts of vanadium(V). First, vanadium is isolated by extraction withN-benzoyl-N-phenylhydroxylamine (BPHA) in chloroform from about 4M hydrochloric acid medium. Then, chloroform is evaporated and the residue mineralized with mixture of cone. perchloric and nitric acid. Finally, a colour reaction of vanadium(V) separated with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) in an acetate buffer (pH 4.5) gives a molar absorptivity of 5.48×10⁴l·mol^–1·cm^–1 at 585 nm. The proposed method was applied for the determination of traces of vanadium in aluminium samples. The results obtained show a good precision and accuracy of the method.     

Using NAA to the Determination of Antimony in Trichlorosilane with Substoichiometric Extraction

Neutron activation analysis has been applied to the determination of trace of antimony based on the substoichiometric extraction of Sb(III) with BPHA (N-benzoyl-N-phenyl hydroxylamine). The antimony contens in trichlorosilane or high purity silicon can be determined by the proposed method down to ppb range. The effect of acid concentration, shaking time, the amount of carrier and the decontamination factors were studied.     

Non-chromatographic atomic spectrometric methods in speciation analysis: A review

In recent years, knowledge of the different chemical forms of the elements has gained increasing importance. There has been significant progress in methods that hyphenate chromatographic separations with atomic spectrometry. These hyphenated methods can provide the most complete information on the species distribution and even structure. However, they can be lengthy, relatively costly and difficult to bring to the routine. On the other hand, it is important to remember that chromatographic techniques represent only a minor part of the separation procedures available and, in certain cases, the application of basic chemistry to sample treatments can give quantitative information about specific chemical forms. In this sense, non-chromatographic procedures can provide methods that offer sufficient information on the elemental speciation for a series of situations. Moreover, these non-chromatographic strategies can be less time consuming, more cost effective and available, and present competitive limits of detection. Thus, non-chromatographic speciation analysis continues to be a promising research area and has been applied to the development of several methodologies that facilitate this type of analytical approach. In view of their importance, the present work overviews and discusses different non-chromatographic methods as alternatives for the speciation analysis of clinical, environmental and food samples using atomic spectrometry for detection.