Simultaneous determination of germanium,arsenic, tin and antimony by molecular emission cavity analysis after hydride generation and gas chromatographic separation

Arsenic (0.1–5 μg), antimony (1–40 μg), tin (0.5–10 μg) and germanium (0.2–10 μg) are determined simultaneously by reduction to their hydrides with sodium tetrahydroborate(III), followed by gas chromatographic separation on a column of 10% E-301 silicone gum rubber on Porapak Q, and measurement of the emissions at 490 nm in an oxygen/hydrogen flame within a cavity. Detection limits for 1-ml samples are 35 ng As, 400 ng Sb, 85 ng Sn and 100 ng Ge. A more sensitive determination of arsenic (0.05–3 μg) and antimony (0.1–5 μg) in binary mixtures is also described; the detection limits are 15 ng As and 40 ng Sb.     

Determination of trace elements in manganese metal and compounds by ion-exchange chromatography and atomic absorption spectrometry : part 2. Determination of Bi,Cd, In,Zn, Pb,Fe(III), Ga,Cu(II), Co and U(VI)

Traces of the specified elements are separated from 1 g of manganese (II), using a 30- g column of AG50W-X8 cation-exchange resin and mixtures of hydrochloric acid and acetone as eluents. The trace elements are separated into three groups and are determined by atomic absorption spectrometry, except uranium for which spectrophotometry is used. Recoveries for 10 μg amounts (20 μg for gallium) vary between 94% (for gallium) and 103% (for uranium). A combined elution curve, results for the analysis of synthetic mixtures and for the determination of ten trace elements in samples of manganese metal, chloride and dioxide are presented.     

石墨炉原子吸收光谱法测定矿石中铂、钯、铑、铱

矿石样品铂、钯、铑和铱经铅试金富集,所得金属合粒用硝酸-盐酸溶解,用石墨炉原子吸收光谱法测定矿石样品中铂、钯、铑和铱的含量。在优化的石墨炉工作条件下测得:铂的质量浓度在20～150μg.L-1、钯在15～120μg.L-1、铑和铱在6～100μg.L-1范围内与其吸光度呈线性关系,检出限(3s/k)依次为4.6,4.0,1.5,1.5μg.L-1。方法用于分析了2种矿石国家标准物质(GBW 07341、GBW 07342),测定结果与认定值相符。方法的回收率在87.6%～105.5%之间。测定值的日内和日间相对标准偏差(n=7)分别在2.8%～3.6%和3.5%～4.7%之间。     

Levels, trends and risk assessment of arsenic pollution in Yangzonghai Lake, Yunnan Province, China

The arsenic contamination accident in Yangzonghai Lake, Yunnan has been of wide concern. In order to investigate the arsenic distribution and concentration trends after the accident, samples including lake water, sediments, soil, aquatic organisms and crops were collected in November 2008, as well as in February, May and September 2009. The average arsenic concentrations (arithmetic average) in lake water in the four sampling events were 176.9, 147.3, 159.3, and 161.1 μg/L, while those in the sediments were 32.87, 62.41, 62.99, and 46.96 μg/g, respectively. The highest content of total arsenic in soil in the vicinity of Yangzonghai was 23.33 μg/g, which was below the limits of the relevant national standard. The total arsenic levels in most aquatic plants were in the range of 100–200 μg/g, with Vallisneria natans (Lour.) Hara having the highest concentration of ～300 μg/g. The arsenic levels of fish and shrimps were in the range of 1.52–11.4 μg/g (dry weight).     

Polarographic determination of isoniazide, N-acetylisoniazide and isonicotinic acid by superimposed sinusoidal tension]

The a.c. polarographic determination of isoniazid (INH), N-acetylisoniazid (AcINH) and isonicotinic acid (INA) is described. Under the optimal conditions of pH, ionic strength and electrical parameters, the limits of detection are 0.5 μg ml^-1 for AcINH, 0.2 μg ml^-1 for INH, and 0.03 μg ml^-1 for INA.     

Uncertainty evaluation in the analysis of biological samples by sector field inductively coupled plasma mass spectrometry. Part B: measurements of As, Co, Cr, Mn, Mo, Ni, Sn and V in human serum

This protocol was developed to estimate the uncertainty of measurements in the sector field inductively coupled plasma mass spectrometry analysis of As, Co, Cr, Mn, Mo, Ni, Sn and V in human serum by utilizing in-house validation data. The approach is outlined in the Eurachem/Citac Guide and other relevant publications. The results generated were the followings: (i) coefficients of regression >0.9995 over two orders of magnitude of metal concentration; (ii) method quantification limits between 0.05 μg/L (Cr, Mn) and 0.49 μg/L (As); (iii) mean trueness checked against a certified reference material between 95.4% (As) and 107.7% (Ni); (iv) repeatability better than 10.2% over the range 0.1-2.0 μg/L; (v) reproducibility better than 12.0% over the range 0.1-2.0 μg/L; and (vi) expanded uncertainty budget comprised between 14.7% (Mn) and 27.9% (Cr) over the range 0.1-2.0 μg/L.     

Determination of Ca, Mg, Fe, Cu, and Zn in blood fractions and whole blood of humans by ICP-OES

Inductively coupled plasma – optical emission spectrometry (ICP-OES) was applied to the determination of the elements Ca, Mg, Fe, Cu, and Zn in blood plasma, erythrocytes, lymphocytes, and whole blood to obtain reliable data on their distribution in blood fractions. The samples were carefully collected to avoid contamination. Two different nebulizers (Babington and Meinhard) were tested and optimized for this analytical problem. Line selections for all elements of interest were performed (LODs were 0.8 μg/L for Ca, 1.7 μg/L for Cu, 3.0 μg/L for Fe, 1.1 μg/L for Mg, and 4.2 μg/L for Zn). Recoveries were determined as approx. 100%, and standard reference material was analyzed to obtain reliable data on element distribution. The optimized method was applied to the determination of Ca, Mg, Fe, Cu, and Zn in the course of a clinical study on blood and blood fractions of two groups of humans of differing health. The concentrations measured in blood fractions were verified by balancing with the values found in whole blood.     

The simultaneous determination of As,Cd, Co,Hg, Mo,and Zn in fresh water by neutron activation analysis

A radiochemical neutron activation method for the simultaneous determination of arsenic, cadmium, cobalt, mercury, molybdenum, and zinc in fresh water is described. The method is based on anion-exchange separation in hydrochloric acid media followed by simple precipitations. The determination limits, based on analysis of a 5-ml sample without preconcentration, and with a well-type NaI(Tl) detector, are as follows: As, 10^-3 μg l^-1 ; Cd, 6 × 10^-2 μg l^-1 ; Co, 4 × 10^-3 μg l^-1 ; Hg, 7 × 10^-3 μg l^-1 ; Mo, 10^-1 μg l^-1 ; Zn, 2 × 10^-1 μg l^-1. The method is adequate for the analysis of natural fresh waters.     

硫代砷化物的合成、鉴定和定量分析方法研究

制备了4种硫代砷酸盐,采用电喷雾-高分辨质谱( ESI-HR-MS )进行鉴定,确证为一硫代砷酸盐( Hn AsSOn-33)、二硫代砷酸盐( Hn AsS2 On-32)、三硫代砷酸盐( Hn AsS3 On-3)和四硫代砷酸盐( Hn AsS4 n-3)。以合成的硫代砷酸盐为标准品,建立了基于离子色谱-电感耦合等离子质谱( IC-ICP-MS)同时测定4种硫代砷酸盐、亚砷酸盐和砷酸盐的方法。本方法线性范围为3.3~833μg/L,线性相关系数R2>0.99,方法检出限为0.4~25μg/L。本研究合成的硫代砷酸盐标准物质及建立的定量分析方法,对后续富含硫化物的天然水体中不同形态砷的迁移和转化研究具有重要意义。     

Spectrophotometric Determination of Trimethoprim in Pure Form and in Pharmaceutical Preparations using Bromothymol Blue,Bromocresol Green and Alizarin Red S

ABSTRACT

Simple, sensitive and selective methods for the determination of trimethoprim (TMP) in pure form and in pharmaceutical formulations are described. The methods are based on the reaction of TMP as a π-electron donor with bromothymol blue (BTB), bromocresol green (BCG) and alizarin red S (ARS) as electron acceptors. The coloured products are quantified spectrophotometrically at their corresponding λ_max.

Beer's law is obeyed in case of BTB in the range 2.9-23.2 μg/ml (CHCl₃), 2.9-20.0 μg/ml (CH₂Cl₂) and 5.0-29.0 μg/ml (ClC₆H₅), in the case of BCG 2.9-27.5 μg/ml (H₂O/alc.), 2.9-18.3 μg/ml (CHCl₃) and 2.9-20.3 μg/ml (CH₂Cl₂) and for ARS in the range 3.0-12.0 μg/ml in H₂O/alc medium.

The specific absorptivities, molar absorptivities, Sandell sensitivities, standard deviations and percent recoveries are evaluated. Application of the suggested methods to dosage forms is presented and compared with the pharmacopoeial method. The interference from additives and sulfa compounds, especially sulfamethoxazole, has been overcome by extraction into chloroform or methylene chloride.     

GC-ECD determination of cypermethrin and its major metabolites in soil, elm bark, and litter

An analytical method has been developed for the simultaneous determination of residues of four pairs of isomers of the pyrethroid insecticide cypermethrin, and their main metabolites, cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethyl-cyclopropanecarboxylic acid (CCA) and 3-phenoxybenzoic acid (PBA), in elm bark, litter, and soil in the control of elm bark beetles, the vector of the Dutch elm disease. The residues of cypermethrin isomers and their metabolites were extracted with methanol under acidic conditions from elm bark, litter, and soil, cleaned up with liquid-liquid partitioning, and chromatographed by GC-ECD together after the CCA and PBA in the sample had been derivatized with α-bromo-2,3,4,5,6-pentafluorotoluene. The average recoveries of cypermethrin isomer pairs were 82 to 112% with relative standard deviations (RSDs) of 2.3 to 10% at the fortification levels of 2, 10, 100 μg/g in elm bark, 2, 15, 150 μg/g in litter, and 0.2, 2, 20 μg/g in soil. The recoveries of cypermethrin metabolites were 83 to 107% with RSDs from 2 to 12% at the fortification levels of 0.5, 5, and 10 μg/g in elm bark, and litter, and 0.1, 1, and 10 μg/g in soil.     

Determination of bismuth,lead and tellurium in copper by atomic absorption spectrometry with introduction of solid samples into an induction furnace

Atomic absorption spectrometry with an induction furnace is used for the determination of bismuth (0.015–10 μg g^-1), lead (0.2–15 μg g^-1) and tellurium (0.04–5 μg g^-1) in 2–30-mg samples of copper and low-alloy copper dropped into the furnace. Calibration graphs of peak area versus mass of element were constructed by use of standardised alloys. The accuracy, precision and limits of detection of the method are described for numerous copper samples. With alloys containing more than 0.1 μg Bi g^-1, 0.2 μg Pb g^-1 and 0.8 μg Te g^-1, average relative standard deviations are 7%, 6% and 8%, respectively. The limits of detection for bismuth, lead and tellurium are 0.01, 0.1 and 0.02 μg g^-1, respectively.     

Chemical-garden formation, morphology, and composition. II. Chemical gardens in microgravity

We studied the growth of metal-ion silicate chemical gardens under Earth gravity (1 g) and microgravity (μg) conditions. Identical sets of reaction chambers from an automated system (the Silicate Garden Habitat or SGHab) were used in both cases. The μg experiment was performed on board the International Space Station (ISS) within a temperature-controlled setup that provided still and video images of the experiment downlinked to the ground. Calcium chloride, manganese chloride, cobalt chloride, and nickel sulfate were used as seed salts in sodium silicate solutions of several concentrations. The formation and growth of osmotic envelopes and microtubes was much slower under μg conditions. In 1 g, buoyancy forces caused tubes to grow upward, whereas a random orientation for tube growth was found under μg conditions.     

Design,synthesis, and antifungal evaluation of novel coumarin-pyrrole hybrids

A series of coumarin derivatives bearing a pyrrole scaffold were designed, prepared, and assessed for their in vitro antifungal activities against six phytopathogenic fungi. The antifungal activity screening results suggest that some synthesized hybrids exhibited potential fungicidal activities against the tested fungi. In particular, compounds 6j , 6k , 6o , 6p , and 6r displayed significant antifungal effects against Rhizoctorzia solani, and possessed EC₅₀ values of 3.94, 7.75, 6.38, 6.25, and 7.67 μg/ mL, respectively. The above activities are more potent than the commercialized fungicide Boscalid (11.52 μg/mL) and Osthole (9.79 μg/mL). These results provide a significant reference for further rational design of coumarin-based fungicides.     

The spectrophotometric determination of antimony in water,effluents, marine plants and silicates

A spectrophotometric procedure is described for the determination of antimony in natural waters (including sea water and effluents), algae and silicates. After a preliminary oxidative digestion for waters, or acid attack for algae and silicates, the element is quantitatively coprecipitated at pH 5.0 with hydrous zirconium oxide. The precipitate is dissolved in acid, and, after reduction with titanium(III) chloride, antimony is oxidized to antimony(V) with sodium nitrite. The ion pair of the SbCl₆^- ion with crystal violet is extracted with benzene and its absorbance is measured at 610 nm (molar absorptivity 74,000 l mol^-1 cm^-1). Extraction with toluene causes some loss of sensitivity. The detection limit is 0.005 μg l^-1; relative standard deviations are 0.5% and 1.1% for spiked distilled water (0.5 μg l^-1) and sea water (0.26 μg l^-1), respectively. A wide range of anions and cations cause no interference at levels many times those in natural waters. The technique can be adapted for application to marine algae and silicates; relative standard deviations are 1.8% and 2% for samples of Pelvetia canaliculata (0.19 μg Sb g^-1) and a Pacific Ocean red clay (1.08 μg Sb g^-1), respectively. Results for the U.S. Geological Survey Standard rocks GSP1 (2.7 ppm) and DTS1 (0.53 ppm) are in good agreement with those of earlier workers.     

Synthesis, characterization, and antimicrobial evaluation of oxadiazole congeners

A series of 1,3-oxazole, 1,3-thiazole, isomeric 1,2,4-oxadiazole, 1,3,4-oxadiazole, and 1,2,3,4-tetrazole heterocycles was synthesized. All the compounds shared as a common feature the presence of a 4-hydroxyphenyl substituent. The structures of the synthesized compounds were confirmed by MS, 1H-NMR, and elemental analysis. In vitro antimicrobial activity for all the newly synthesized compounds at concentrations of 200-25 μg/mL was evaluated against Gram+ve organisms such as methicillin-resistant Staphylococcus aureus (MRSA), Gram-ve organisms such as Escherichia coli (E. coli), and the fungal strain Aspergillus niger (A. niger) by the cup plate method. Ofloxacin and ketoconazole (10 μg/mL) were used as reference standards for antibacterial and antifungal activity, respectively. Compounds 15, 16, and 20 showed notable antibacterial and antifungal activities at higher concentrations (200 μg/mL), whereas 17-19 were found to display significant antibacterial or antifungal activity (25-50 μg/mL) against the Gram+ve, Gram-ve bacteria, or fungal cells used in the present study.     

Flavusides A and B, antibacterial cerebrosides from the marine-derived fungus Aspergillus flavus

Flavusides A (1) and B (2), two new antibacterial cerebroside derivatives, and the previously described phomaligol A (3), kojic acid (4), methyl kojic acid (5), and dimethyl kojic acid (6) have been isolated from the extract of a marine isolate of the fungus Aspergillus flavus. The structure and absolute stereochemistry of two cerebrosides were assigned on the basis of NMR and Tandem FAB-MS/MS experiments. Compounds 1, 2, and 3 exhibited a mild antibacterial activity against Staphylococcus aureus, methicillin-resistant S. aureus, and multidrug-resistant S. aureus. The minimum inhibitory concentration (MIC) values for each strain are as follows: compounds 1 and 2 showed 15.6 μg/ml for S. aureus and 31.2 μg/ml for methicillin-resistant S. aureus and multidrug-resistant S. aureus, and compound 3 exhibited 31.2 μg/ml for S. aureus and methicillin-resistant S. aureus and 62.5 μg/ml for multidrug-resistant S. aureus.     

ETAAS method for the determination of Cd, Cr, Cu, Mn and Se in blood fractions and whole blood

An electrothermal atomic absorption method (ETAAS) for the direct determination of trace elements (Cd, Cr, Cu, Mn, Se) both in blood fractions (erythrocytes, plasma and lymphocytes) and whole blood was developed. Zeeman background correction and graphite tubes with L’vov platforms were used. Samples were ¶diluted with HNO₃/Triton X-100 and pipetted directly ¶into the graphite tube. Ashing, pretreatment and atomization steps were optimized carefully for the different fractions and elements applying different matrix modifiers ¶for each element. For the lymphocyte fraction a multi-fold injection technique was applied. Low detection limits ¶of the ETAAS method (Cd 0.13 μg/L, Cr 0.11 μg/L, ¶Cu 0.52 μg/L, Mn 0.13 μg/L, Se 0.7 μg/L of whole blood) combined with small quantities of sample necessary for analysis allow determination of trace elements in this matrix. Verification of possible differences in the trace element status of humans was performed with statistical significance (P < 0.05). In addition, a contribution to the determination of normal values of essential elements was achieved. The method was applied for determination of trace elements in human blood and blood fractions of two groups (n = 50) different in health status.     

Indeno[1,2-b]pyridin-5-one derivatives containing azo groups and their hydrazonal precursors: Synthesis,antimicrobial profile,DNA gyrase binding affinity,and molecular docking

The prevalence of germs that are resistant to many antibiotics is rising rapidly the world over. There is a large group of researchers actively looking for better medicines. Here, we designed two series of hydrazonal and indeno[1,2-b]pyridin-5-one bearing hydrazone and azo-groups to test their antimicrobial activity. Molecular structures of all derivatives were assured based on their spectral data and elemental analyses. Results of the antimicrobial activity of the tested hydrazone and azo compounds showed promising potential for several derivatives. The minimum inhibitory concentrations (MICs) of hydrazones 4a - h and 6a - g displayed good antibacterial reactivities with a range of 3.91–250 μg/mL and moderate antifungal activity with a range of 15.6–500 μg/mL. The most promising hydrazone 4f and azo- 6a compounds demonstrated MIC values against Streptococcus faecalis and Escherichia coli equal to 3.91 and 7.81 μg/mL, respectively. Moreover, azo compound 6a showed MIC value equal to 3.91 μg/mL against Enterobacter cloacae species. Additionally, derivative 4f exhibited a significant inhibitory profile against the E. coli gyrase A enzyme (IC₅₀ = 5.53 μg/mL). On the other hand, compound 6a (IC₅₀ 14.05 μg/mL) exhibited the lowest DNA gyrase inhibitory activity as compared to compounds 4f and reference standard drug novobiocin, IC₅₀ 5.53 and 1.88 μg/mL, respectively. Pharmacokinetic and pharmacodynamic profiles and molecular docking studies for the two most promising molecules 4f and 6a were computed and revealed that both compounds have good ADME profiles and high binding affinity to DNA gyrase binding site.