Preparation of polar group derivative β-cyclodextrin bonded hydride silica chiral stationary phases and their chromatography separation performances

Three new polar group-substituted β-cyclodextrin derivatives were synthetized and they covalent bonded to hydride silica to obtain chiral stationary phases. Their separation results of 35 chiral pyrrolidine compounds were also presented and discussed.     

Stereocontrolled synthesis of (±)-methyl 3,6-epoxy-4,6,8-triethyl-2,4,9-dodecatrienoate, a major metabolite of Caribbean sponge, Plakortis halichondrioides, using reactions of alkylidenecarbenes in one pot

(±)-Methyl (2Z,6R*,8R*,9E)-3,6-epoxy-4,6,8-triethyl-2,4,9-dodecatrienoate, a major metabolite of the Caribbean sponge, was synthesized in a stereocontrolled manner from γ-caprolactone. The key step was one-pot generation of alkylidenecarbenes at two sites followed by 1,2 hydride shift and intramolecular 1,5 C-H insertion.     

Arsenic speciation in water samples containing high levels of copper: removal of copper interference affecting arsine generation by continuous flow solid phase chelation

A simple continuous flow method is proposed to eliminate copper interference in arsenic speciation by hydride generation, based on the selective retention of this interfering ion in an iminodiacetate chelating resin previous to the hydride generation process. The arsines generated were cold trapped and measured by ICP/OES. The proposed method allows about 98% of the copper present in the samples to be removed. Minor co-retention of As(V) was observed as a result of electrostatic interaction between the arsenate anion and the nitrogen of the iminodiacetate group of the chelating resin Muromac A-1, the charge distribution of which is modified when copper is chelated. The species As(III), MMA and DMA were not retained in the microcolumn, probably because these species are mainly in the molecular form at the working pH value (4.5). In synthetic samples containing 50 g l^–1 of each arsenic species together with 100 mg l^–1 copper, the recoveries obtained were: As(V) 97.6%, As(III) 100%, MMA 99.8%, and DMA 99.9%. The method was applied to arsenic speciation in river water samples containing high levels of copper.     

Sequential spectrophotometric determination of inorganic arsenic species by hydride generation from selective medium reactions and colour bleaching of permanganate

A simple spectrophotometric method is presented for the sequential determination of inorganic arsenic (As) species in one sample. It is based on the sequential arsine generation from As(III) and As(V) using selective medium reactions, collection of the arsine generated in an absorbing solution containing permanganate and ethanol at 5 °C and subsequent reduction of permanganate by arsine. The decrease in permanganate absorbance at 524.2 nm is monitored for As determination. The acetic acid/sodium acetate and HCl mediums were used for selective arsine generation from As(III) and remaining As(V) in one solution, respectively. The effect of interferences and their possible mechanisms were discussed. Interferences from transition metal ions were removed by using a Chelex 100 resin. Under optimized conditions, the established method is applicable to the determination of 3-30 μg of each arsenic species. Good recoveries (96-102%) of spiked artificial sea water, tap water and standard mixtures of As(III) and As(V) were also found. The method is simple, accurate, precise and environmental friendly.     

Simultaneous determination of trace arsenic, antimony, bismuth and selenium in biological samples by hydride generation-four-channel atomic fluorescence spectrometry

A new and sample technique for the simultaneous determination of trace arsenic, antimony, bismuth and selenium in biologic samples by hydride generation-four-channel nondispersive atomic fluorescence spectrometry was development. The conditions of instrumentation and hydride generation of arsenic, antimony, bismuth and selenium were optimized. For reducing hexavalent Se to the tetravalent state was to heat the sample with 6 mol l⁻¹ HCl, and then pre-reducing pentavalent As and Sb to the trivalent state was achieved by the addition of 0.05 mol l⁻¹ thiourea. The interferences of coexisting ions were evaluated. Under optimal conditions, the detection limits for As, Sb, Bi and Se were determined to be 0.03, 0.04, 0.04 and 0.03 ng ml⁻¹, respectively. The precision for seven replicate determinations at the 5 ng ml⁻¹ of As, Sb, Bi and Se were 0.9, 1.2, 1.3 and 1.5% (R.S.D.), respectively. The proposed method was successfully applied to the simultaneous determination of As, Sb, Bi and Se in a series of Chinese certified biological reference materials using simple aqueous standard calibration technique, the results obtained are in good agreement with the certified values.     

Atomic spectrometry based on metallic tube atomizers heated by flame: Innovative strategies from fundamentals to analysis

This review describes recent developments in atomic absorption spectrometry using metallic tube atomizers heated by flames. Sample introduction in spray or gaseous form is emphasized, describing some proposed systems for this task and the fundamentals involved in each context. The latest challenges and future possibilities for use of metallic tubes in atomic/mass spectrometry are also considered.     

顺序注射氢化物发生-原子荧光光谱法同时测定硒和砷的研究

建立了一种顺序注射氢化物发生-原子荧光光谱法测定试样中Se和As的方法,同时讨论了共存离子的干扰情况.在最佳实验条件下,Se和As的检出限分别为0.16和0.095 μg/L,加标回收率为92.4%～104.7%.     

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.     

氢化物发生-原子荧光法测定鹿系列保健品中铅

采用 HNO,3-HClO,4 消解样品,氢化物发生-原子荧光法测定鹿系列保健品中铅.该方法在选定的操作条件下,测定保健品中铅的回收率为 91.0%～108.1%,检出限为 0.395 μg·L-1,相对标准偏差为 1.2%.