Speciation of butyltin compounds in environmental and biological samples using headspace single drop microextraction coupled with gas chromatography-inductively coupled plasma mass spectrometry

A method based on headspace single drop microextraction (HS-SDME) in combination with gas chromatography-inductively coupled plasma mass spectrometry (GC-ICP-MS) was proposed for the speciation analysis of butyltin compounds in environmental and biological samples. The sodium tetraethylborate (NaBEt4) and sodium tetrahydroborate (NaBH4) were used as the derivatizing reagent for in situ derivatization of the butyltins. For the two derivatizations, the HS-SDME parameters such as organic solvent, drop volume, sample pH, stirring rate, temperature, extraction time and the ionic strength were examined systematically. The analytical performance including the linearity ranges, limits of detection (LODs) and reproducibilities of the two derivatizations were compared under the respective optimized conditions. Derivatization with NaBEt(4) proved to be more sensitive and robust than that with NaBH4, leading to the LODs of 1.4 ng/L for MBT, 1.8 ng/L for DBT and 0.8 ng/L for TBT. The reproducibilities, expressed as relative standard deviations (RSDs), were in the range of 1.1-5.3% (c=1 microg/L, n=3). With tripropyltin (TPrT) as internal standard, HS-SDME-GC-ICP-MS with NaBEt(4) derivatization was applied for the speciation analysis of butyltins in real seawater and shellfish samples. The butyltins found in the real-world samples are 31ng/L MBT, 79 ng/L DBT and 32 ng/L TBT for seawater, and 11.6-30.4 ng/g MBT, 11.8-8.9 ng/g DBT and 12.8-52.6 ng/g TBT for different shellfish samples. For validation, the developed method was also employed for the speciation analysis of butyltins in certified reference material (CRM) of PACS-2 sediment, and the determined values are in a good agreement with the certified values. The developed method is simple, rapid, sensitive, and cost-effective and provides an attractive alternative for butyltins speciation in biological and environmental samples with complex matrix.     

治肺癌复方中铬,镍的形态分析

本实验对含１３味中药的治肺癌复方原药，头煎及二煎残渣和浸汁，经０．４５μ膜分离的颗粒物，可溶态，以及可溶态分别通过阳离子交换树脂，用三氯甲烷萃取后所得各自柱截留物，穿过物，有机相，水相等共１５个样品中铬，镍，按照中药微量元素初级和次形态分析的要求，进行分析测定，以此计算出一套形态分析参数和相关数据，为探讨中草约中微量元素的化学形态提供了新的信息。     

Carrier element-free coprecipitation (CEFC) method for the separation, preconcentration and speciation of chromium using an isatin derivative

A new, simple, rapid and sensitive separation, preconcentration and speciation procedure for chromium in environmental liquid and solid samples has been established. The present speciation procedure for Cr(III) and Cr(VI) is based on combination of carrier element-free coprecipitation (CEFC) and flame atomic absorption spectrometric (FAAS) determinations. In this method a newly synthesized organic coprecipitant, 5-chloro-3-[4-(trifluoromethoxy) phenylimino]indolin-2-one (CFMEPI), was used without adding any carrier element for coprecipitation of chromium(III). After reduction of chromium(VI) by concentrated H₂SO₄ and ethanol, the procedure was applied for the determination of total chromium. Chromium(VI) was calculated as the difference between the amount of total chromium and chromium(III). The optimum conditions for coprecipitation and speciation processes were investigated on several commonly tested experimental parameters, such as pH of the solution, amount of coprecipitant, sample volume, etc. No considerable interference was observed from the other investigated anions and cations, which may be found in natural water samples. The preconcentration factor was found to be 40. The detection limit for chromium(III) corresponding to three times the standard deviation of the blank (N = 10) was found 0.7 μg L⁻¹. The present procedure was successfully applied for speciation of chromium in several liquid and solid environmental samples. In order to support the accuracy of the method, the certified reference materials (CRM-TMDW-500 Drinking Water and CRM-SA-C Sandy Soil C) were analyzed, and standard APDC-MIBK liquid-liquid extraction method was performed. The results obtained were in good agreement with the certified values.     

Mass spectrometic study of speciation in aluminium-fluoroquinolone solutions

Fluoroquinolones (FQLs) are synthetic antibacterial agents containing a 4-oxo-1,4-dihydroquinoline skeleton. When concomintantly administered with other drugs which may contain metal ions, particularly Al(3+) (antacids, phosphate binders, vaccines etc) they may form metal-drug complexes. Pharmacokinetic studies showed that aluminium-quinolone interactions lead to reduced bio- availability and altered activity of the drug with possible development of the toxic effects of aluminum ion. Reliable speciation in Al(3+) - quinolone systems at micromolar concentration level is needed to better understand pharmaco- and toxicokinetics of the FQLs in the presence of Al. In this work, the speciation in solutions containing Al(3+) and FQL family members (fleroxacin, moxifloxacin and ciprofloxacin) was studied by electrospray mass spectrometry (ESI-MS), ESI-MS/MS, and laser desorption ionization (LDI) MS. The dominating species identified in all the three Al(3+)-FQL solutions, at ca 30-50 μmol L(-1) total Al concentration and 2:1 to 1:3 metal-to-ligand ratio in the pH range 3.0- 6.0, were the ions related to the complexes AlL(2+), AlL(2)(+) and AlL(3)(0) (L = ligand in the monodeprotonated form). Mixed protonated and hydroxo complexes were also formed at lower and higher pH values respectively and, as expected, dimeric and polymeric species were not observed in ESI spectra. LDI measurements confirmed the existence of the mononuclear complexes found by ESI, and indicated the formation of polymeric species. The ion [2Al(3+) +5(-)](+) was identified with all three FQLs. This ionic species most probably arises from Al(2)L(2) by clustering with free ligand anions. Comparison of literature potentiometric data with mass spectral data indicated good agreement between speciation schemes. The obtained results suggest the presence of strong interaction between FQLs and Al(3+) which may be important in affecting absorption of these drugs in the gastrointestinal tract.     

Speciation of molybdenum in river water by size fractionation and catalytic determination.

A speciation scheme of trace molybdenum was proposed for river water based on size fractionation by filtration and ultrafiltration and the catalytic spectrophotometric determination of the reactive molybdenum concentration (CR). The total concentration (CT) of molybdenum was determined by the same method after acid decomposition to obtain the concentration (CT - CR) of unreactive molybdenum. Most molybdenum in natural river-water samples was found to be reactive species. A large part of the molybdenum was found in the fraction of molecular weight (MW) < 10(3), and was estimated to be MoO4(2-) from the chemical equilibria of molybdate ions. The residual part of molybdenum was found in the colloidal and particle fractions (MW > or = 10(4)), and was characterized as reactive molybdenum adsorbed or complexed on humic iron aggregates. The coexistence of silicate contributed to a decrease of the particle size of humic iron aggregates associated with molybdenum. The above-mentioned speciation results were confirmed by an analysis of artificial samples. The changes in the fractionation results by acidification (0.1 M HCl) were also used to characterize molybdenum in natural water.     

陈化温度及掺杂对分子筛负载SO42-/ZrO2-Co2O3固体超强酸性能影响的研究

采用共沉淀和低温陈化的方法,制备了分子筛负载SO42-/ZrO2-Co2O3固体超强酸(XSZC).用IR、XRD、XPS对XSZC样品的结构进行了表征,用流动指示剂法测定了XSZC样品的酸强度,并将其用于催化乙酸与甘油的酯化反应,考察了其催化活性.结果表明,低温陈化的XSZC样品的IR图谱在900~1 200 cm-1内出现了更强的SO42-的伸缩振动吸收峰;XRD谱图显示,低温陈化和掺杂对样品生成ZrO2四方相有利.XPS图谱中Zr3d的结合能发生化学位移是XSZC样品酸性增加的微观原因.     

Use of perchloric acid as a reaction medium for speciation of arsenic by hydride generation-atomic absorption spectrometry

Simple and inexpensive methods for the speciation of arsenite, arsenate, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) in environmental water samples were developed. In these methods a hydride generation-atomic absorption spectrometry (HG-AAS) technique was employed and perchloric acid (as a reaction medium), L-cysteine (as a pre-reducing agent for a certain contact time between its addition and analysis) and sodium tetrahydroborate(III) (NaBH4, as a reducing agent) were used. The use of L-cysteine greatly enhances the absorption signals of all four arsenic species at low acid concentration (0.001-0.04 M). The methods developed for the determination of total arsenic and total inorganic arsenic and speciation of the four arsenic species in environmental water samples are as follows. (i) DMA: 0.005 M acid and 0.04% NaBH4 in the absence of L-cysteine. DMA can also be speciated in the presence of L-cysteine as follows: 2 M acid, 2.5% L-cysteine after a contact time of approximately 5 min and 0.6% NaBH4. (ii) As(III): 5 M acid and 0.08% NaBH4 in the absence of L-cysteine. (iii) Total inorganic arsenic (As(III) + As(V)]: 8 M acid and 0.6% NaBH4 in the absence of L-cysteine. (iv) Total arsenic: 0.01 M acid, 5% L-cysteine after a contact time of 5 min and 2% NaBH4. (v) MMA: 8 M acid, 3% L-cysteine after a contact time of 50 min and 0.6% NaBH4. (vi) As(V): by difference. Detection limits and recoveries of added spikes for all analyses were found to be 0.5-1.7 ppb and 90-112% respectively.     

Capillary electrophoresis on-line coupled with hydride generation-atomic fluorescence spectrometry for speciation analysis of selenium

A new method for speciation analysis of two inorganic selenium species was developed by on-line coupling of capillary electrophoresis (CE) with hydride generation-atomic fluorescence spectrometry (HG-AFS) and on-line conversion of Se(VI) to Se(IV). Baseline separation of Se(VI) and Se(IV) was achieved by CE in a 50 cm x 75 microm inside diameter (ID) fused-silica capillary at -20 kV using a mixture of 15 mmol.L(-1) NaH2PO4 and 0.5 mmol.L(-1) cetyltrimethylammonium bromide (pH 7.5) as electrolyte buffer. Se(VI) was on-line reduced to Se(IV) by mixing the CE effluent with concentrated HCl. The precision (relative standard deviation, RSD, n=7) ranged from 0.7 to 1.3% for migration time, 6.4 to 3.7% for peak height response, and 5.9 to 6.1% for peak area for the two selenium species at the 500 microg.L(-1) (as Se) level. The detection limits were 33 and 25 microg.L(-1) (as Se) for Se(VI) and Se(IV), respectively. The recoveries of the two selenium species in five locally collected water samples ranged from 88 to 114%. The developed method was applied to speciation analysis of inorganic selenium species in spiked natural water samples.     

川芎中微量元素的初级形态分析

中药川芎是伞形科藁木属川芎的干燥根茎,用于活血化瘀,治疗缺血性心、脑血管疾病及慢性心衰、肾衰,疗效良好。目前对于川芎及其提取物的药理作用、临床应用及其化学成分的研究较多,     

Comparison of gas chromatographic hyphenated techniques for mercury speciation analysis

In this study, we evaluate advantages and disadvantages of three hyphenated techniques for mercury speciation analysis in different sample matrices using gas chromatography (GC) with mass spectrometry (GC-MS), inductively coupled plasma mass spectrometry (GC-ICP-MS) and pyrolysis atomic fluorescence (GC-pyro-AFS) detection. Aqueous ethylation with NaBEt(4) was required in all cases. All systems were validated with respect to precision, with repeatability and reproducibility <5% RSD, confirmed by the Snedecor F-test. All methods proved to be robust according to a Plackett-Burnham design for 7 factors and 15 experiments, and calculations were carried out using the procedures described by Youden and Steiner. In order to evaluate accuracy, certified reference materials (DORM-2 and DOLT-3) were analyzed after closed-vessel microwave extraction with tetramethylammonium hydroxide (TMAH). No statistically significant differences were found to the certified values (p=0.05). The suitability for water samples analysis with different organic matter and chloride contents was evaluated by recovery experiments in synthetic spiked waters. Absolute detection and quantification limits were in the range of 2-6 pg for GC-pyro-AFS, 1-4 pg for GC-MS, with 0.05-0.21 pg for GC-ICP-MS showing the best limits of detection for the three systems employed. However, all systems are sufficiently sensitive for mercury speciation in environmental samples, with GC-MS and GC-ICP-MS offering isotope analysis capabilities for the use of species-specific isotope dilution analysis, and GC-pyro-AFS being the most cost effective alternative.