Speciation analysis of antimony in extracts of size-classified volcanic ash by HPLC–ICP-MS

Although there is concern about the presence of toxic elements and their species in environmental matrices, for example water, sediment, and soil, speciation analysis of volcanic ash has received little attention. Antimony, in particular, an emerging element of environmental concern, has been less studied than other potentially toxic trace elements. In this context, a study was undertaken to assess the presence of inorganic Sb species in ash emitted from the Copahue volcano (Argentina). Antimony species were extracted from size-classified volcanic ash (<36 microm, 35-45 microm, 45-150 microm, and 150-300 microm) by use of 1 mol L(-1) citrate buffer at pH 5. Antimony(III) and (V) in the extracts were separated and quantified by high-performance liquid chromatography combined on-line with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). Antimony species concentrations (microg g(-1)) in the four fractions varied from 0.14 to 0.67 for Sb(III) and from 0.02 to 0.03 for Sb(V). The results reveal, for the first time, the occurrence of both inorganic Sb species in the extractable portion of volcanic ash. Sb(III) was always the predominant species.     

The toxicity outcome of silica nanoparticles (Ludox?) is influenced by testing techniques and treatment modalities

We analyzed the influence of the kind of cytotoxicity test and its application modality in defining the level of hazard of the in vitro exposures to nanostructures. We assessed the cytotoxicity induced by two different Ludox? silica nanoparticles (NPs), AS30 and SM30, on three human cell lines, CCD-34Lu, A549, and HT-1080. Dynamic light scattering measurements showed particle agglomeration when NPs are diluted in culture medium supplemented with fetal calf serum. We examined the impact of such particle aggregation on the cytotoxicity by exposing the cells to NPs under different treatment modalities: short incubation (2?h) in serum-free medium or long incubation (24–72?h) in serum-containing medium. Under this last modality, NP suspensions tended to form aggregates and were toxic at concentrations five- to tenfold higher than in serum-free medium. The results of cell survival varied considerably when the long-term clonogenic assay was performed to validate the data of the short-term MTS assay. Indeed, the half maximum effective concentrations (EC₅₀) in all the three cell lines were four- to fivefold lower when calculated from the data of clonogenic assay than of MTS. Moreover, the mechanisms of NP toxicity were cell-type-specific, showing that CCD-34Lu are prone to the induction of plasma membrane damages and HT-1080 are prone to DNA double-strand break and apoptosis induction. Taken together, our results demonstrate that the choice of testing strategy and treatment conditions plays an important role in assessing the in vitro toxicity of NPs.

Speciation of very low amounts of arsenic and antimony in waters using dispersive liquid–liquid microextraction and electrothermal atomic absorption spectrometry

A new procedure for the determination of inorganic arsenic (III,V) and antimony (III,V) in water samples by dispersive liquid–liquid micro extraction separation and electrothermal atomic absorption spectrometry (ETAAS) is presented. At pH 1, As(III) and Sb(III) are complexed with ammonium pyrrolidine dithiocarbamate and extracted into the fine droplets formed when mixing carbon tetrachloride (extraction solvent), methanol (disperser solvent) and the sample solution. After extraction, the phases are separated by centrifugation, and As(III) and Sb(III) are determined in the organic phase. As(V) and Sb(V) remain in the aqueous layer. Total inorganic As and Sb are determined after the reduction of the pentavalent forms with sodium thiosulphate. As(V) and Sb(V) are calculated by difference. The detection limits are 0.01 and 0.05 µg L^− 1 for As(III) and Sb(III), respectively, with an enrichment factor of 115. The relative standard deviation is in the 2.9–4.5% range. The procedure has been applied to the speciation of inorganic As and Sb in bottled, tap and sea water samples with satisfactory results.     

Speciation studies by capillary electrophoresis – simultaneous determination of iodide and iodate in seawater

A capillary electrophoresis (CE) method was developed for the simple and highly-sensitive determination of iodine species in seawater. The proposed method is based on the on-capillary preconcentration of iodide and iodate using the principle of transient isotachophoresis (tITP) stacking, and direct UV detection of the separated species at 226 and 210 nm, respectively. The preconcentration procedure takes advantage of the electrokinetic introduction of the terminating ion [2-(N-morpholino)ethanesulfonate (MES)] into the capillary, that enables a longer tITP state. The appropriate conditions for the tITP step were optimized by varying the MES and sample injection time and the concentration of cetyltrimethylammonium chloride (CTAC). The latter component of the separation electrolyte (SE) was shown to strongly affect the migration and therefore the enrichment of iodide due to specific ion-association. The optimized separations were performed in 12.5 mM CTAC, 0.5 M NaCl (pH 2.4). Valid calibration is demonstrated in the range 3–60 g L^–1 iodide (R=0.9992) and 40–800 g L^–1 iodate (R=0.9994). The detection limits achieved were 0.23 g L^–1 (2 nM) for iodide and 10 g L^–1 (57 nM) for iodate. Such sensitivity and linearity thresholds allowed the reported tITP-CE system to be applied to direct speciation analysis of surface and seabed seawater. The comparison of CE results with those of an ion-chromatography (IC) technique proved that the method has acceptable accuracy.     

Comparison of Modifiers for Mercury Speciation in Water by Solid Phase Extraction and High Performance Liquid Chromatography–Atomic Fluorescence Spectrometry

Diethyldithiocarbamate and 2-mercaptoethanol modifiers were compared for the preconcentration of mercury species in water by C₁₈ solid phase extraction (SPE). The recovery values of mercury species were determined by high performance liquid chromatography–atomic fluorescence spectrometry. The eluent type, pH, chloride ion concentration, humic acid concentration, and storage time were evaluated to compare the preconcentration efficiency. L-cysteine was employed to elute the mercury compounds. Less eluent was needed for 2-mercaptoethanol modified SPE than for diethyldithiocarbamate modified SPE at an L-cysteine concentration of 0.12%. Diethyldithiocarbamate modified SPE could be used over a wider pH range and higher humic acid concentrations, whereas 2-mercaptoethanol modified SPE was less affected by the chloride concentration. Both modified SPE systems stored mercury species for 5 days, but diethyldithiocarbamate modified SPE could be stored longer. Diethyldithiocarbamate SPE provided limits of detections of 3.5, 2.5, and 4 ng · L^?1 and average recoveries of 90.78 ± 3.37%, 96.79 ± 5.12%, and 84.88 ± 5.37% for mercury(II), methylmercury, and ethylmercury, respectively. The relative standard deviation was less 6.5%. For 2-mercaptoethanol modified SPE, the limits of detection were 1.4, 1, and 1.6 ng · L^?1 and the recoveries were of 87.66 ± 8.45%, 86.70 ± 2.61%, and 91.31 ± 6.98% for mercury(II), methylmercury, and ethylmercury, respectively, with a relative standard deviation below 9.7%. Water should be characterized for its physical and chemical characteristics before mercury preconcentration to choose the most suitable method.     

Study on Speciation of Pr(III) in Human Blood Plasma by Computer Simulation

Biological effects of metal are controlled by its in vivo speciation l'2. It is not possible todetermine in vivo speciation of metals with analytical methods so far. The lowmolecular-weight complex distribution of biometal ions in blood plasma was studied bycomputer simulation'. Soluble species of rare earth were also reported 2'3. However,insoluble species of rare earth in blood plasma have not been studied, it is the aim of thispaper to study insoluble species by computer simulation.We impr…     

GC–FID as a primary method for establishing the purity of organic CRMs used for drugs in sport analysis

The National Analytical Reference Laboratory has synthesized and characterized 67 anabolic steroid marker metabolites, both unlabelled and deuterated, and 37 key glucuronide and sulfate steroid conjugate pure substance reference materials. Work is also in process to establish their full traceability so that they can be issued as certified and primary reference materials. Both identity and purity have been rigorously characterized using a number of techniques and a primary method for purity assessment developed, based gas chromatography combined with flame ionization detection for the parent steroids and HPLC with evaporative light scattering detection for non-volatile steroid conjugates. Strategies for establishing traceability and for estimating measurement uncertainty are reported. The strategies described are considered applicable to a wide range of organic pure substance reference materials.     

Pressurized-liquid extraction for determination of illicit drugs in hair by LC–MS–MS

An LC–MS–MS-based procedure for determination in hair of 14 different drugs of abuse belonging to the classes cocaine, amphetamine-like compounds, opiates, and hallucinogens has been developed. A pressurized-liquid extraction procedure was used and proved useful for quantitative recovery of all the analytes tested. This procedure, in conjunction with a simple decontamination step, performed to avoid false-positive samples, enabled the detection of all the analytes with LOQ ranging from 1.8 to 16 pg mg^?1 and accuracy varying from 85 to 111 %. The procedure was validated in accordance with the SOFT/AAFS guidelines and seems to be suitable for routine determination of the drugs tested in hair.     

Speciation of Antimony in Soils and Sediments by Liquid Chromatography–Hydride Generation–Atomic Fluorescence Spectrometry

The methodology for antimony speciation was optimized for liquid chromatography coupled to hydride generation – atomic fluorescence spectrometry. An anion exchange column was employed with isocratic elution. Ammonium tartrate was shown to be the optimum mobile phase and extracting solution for this analysis. The highest efficiency and resolution for the antimony species was achieved using 5 percent methanol in 300 millimoles per liter ammonium tartrate acidified with hydrochloric acid to pH 4.5. The retention times of antimony(V), trimethylantimony, and antimony(III) were 2.6, 3.9, and 5.2 minutes, respectively. The calibration curves were linear with limits of detection of 0.1, 0.2, and 0.43 microgram per liter for antimony(III), antimony(V), and trimethylantimony, respectively. The precision, evaluated by the relative standard deviation, ranged from 1.2 to 5.3 percent. The average recovery from these environmental samples by a single-step procedure was approximately 26 percent. The results also revealed that the correlation between the sum of each species by the single-step procedure and total digestion was significant for the investigated soils and sediments.     

Integrated procedure for multiresidue analysis of dissolved and particulate drugs in municipal wastewater by liquid chromatography–tandem mass spectrometry

For the first time, an integrated procedure for a quantitative multiresidue analysis of dissolved and particulate illicit drug target residues was developed and validated in three different wastewater matrices. The procedure consists of a comprehensive sample enrichment, fractionation and cleanup followed by the determination of target analytes by triple quadrupole liquid chromatography–tandem mass spectrometry in both positive and negative ionisation polarities. The enrichment of illicit drugs from suspended solids and aqueous samples was performed using pressurised liquid extraction and solid phase extraction (SPE), respectively. The performance of different SPE cartridges was investigated in order to optimise the overall recovery and to reduce the matrix effects. The optimal results were obtained by combining mixed cation exchange (Oasis MCX) cartridges for fractionated enrichment, weak anion exchange for an additional extract cleanup and optimised chromatographic separation to minimise the impact from co-extracted interferences. The method was applied for the analysis of raw wastewater (RW), activated sludge (AS) and secondary effluent (SE) samples collected at four different wastewater treatment plants. The average contributions of the particulate drugs in the RW and AS were 1–28 and 23–65 %, respectively. This suggested that the total mass loads of some drugs might be underestimated by neglecting the particulate fraction. Moreover, relatively high distribution coefficients, determined for 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (RW?=?1211 L/kg) and 11-hydroxy-Δ⁹-tetrahydrocannabinol (RW?=?1,786 L/kg) implied that adsorption might play a significant role in their overall removal during wastewater treatment.

Changes in the intra- and inter-fibrillar structure of lyocell (TENCEL®) fibers caused by NaOH treatment

Some effects of NaOH treatment at concentrations of up to 8 M on (1) the porous structure, (2) the degree of swelling, (3) carboxyl content using methylene blue sorption and 9H-fluoren-2-yl-diazomethane (FDAM) methods, (4) dyeing, (5) the molecular weight distribution measured by gel permeation chromatography (GPC), (6) crystallinity determined by wide angle X-ray diffraction (WAXD) and (7) the tensile properties of lyocell fibers were investigated. The porous structure of fibers was visualised using fluorescence microscopy and transmission electron microscopy (TEM) on fiber cross-sections and was also studied by inversion size exclusion chromatography (ISEC). Mean pore diameter and pore area of fibers were not changed by NaOH treatments. The pore volume increased above 2.5 M NaOH. NaOH-treated samples showed higher dye uptake, higher swelling, but lower carboxyl and moisture content and increased crystallinity. As the NaOH concentration increased, the depth of colour following dyeing with C.I. Direct Red 81 also increased due to deep penetration of alkali into the fiber. In general, fiber properties were distinctly different in the ranges 0 to approximately 3 and 3–8 M NaOH. A part of this paper was presented at the 5th Central European Conference 2007, Fiber Grade Polymers, Chemical Fibers and Special Textiles, Krakow-Bielsko-Biala, Poland, 5–8 September 2007. Hale Bahar ?ztürk, Antje Potthast, Thomas Rosenau, Bill MacNaughtan, John R. Mitchell, Thomas Bechtold—Members of European Polysaccharide Network of Excellence (EPNOE), .     

Speciation of aluminium in tea infusions by use of SEC and FPLC with ICP–OES and ES–MS–MS detection

Speciation of Al in tea infusions was studied by size exclusion chromatography (SEC) and anion-exchange fast protein liquid chromatography (FPLC). Fractions were collected throughout the chromatographic separations and Al was determined “off line” by inductively coupled plasma optical emission spectroscopy (ICP–OES). Black, green, and red tea samples were investigated. The total concentration of Al in tea infusions was determined by ICP–OES and ranged between 0.5 and 4 mg dm⁻³. The pH of tea infusions ranged between 5.3 and 5.5. Data from SEC–ICP–OES analysis indicated that 10–35% of total Al in tea infusions was eluted at a retention volume corresponding to a molecular mass of approximately 3800 Da. The remaining Al was adsorbed on the column resin. The same tea infusions were also analysed by anion-exchange FPLC–ICP–OES. It was found experimentally that the same percentage of total Al as from the SEC column was eluted at a retention volume that corresponded to negatively charged Al-citrate. The remaining Al was adsorbed on the column resin. Identification of Al-binding ligands eluting under the chromatographic peak was performed by electrospray ionisation tandem mass spectrometry (ES–MS–MS) analysis. It was proven that ionic Al species in tea infusions (10–35% of the total Al) corresponded to negatively charged Al-citrate. The remaining species that was adsorbed on the SEC or FPLC columns was most probably bound to phenolic compounds. Speciation of Al in tea with milk or lemon was also studied. Results for tea with milk indicated that Al-citrate was not transformed and that approximately 60% of total Al was transformed into high-molecular-mass Al species. This fraction was subjected to sodium dodecyl sulfonate polyacryl gel electrophoresis (SDS–PAGE). The results indicated that Al was occluded by milk proteins (mostly caseins). When citric acid was added to tea infusions the percentage of negatively charged Al-citrate remained either the same or increased to 40% of total Al.     

Determination of basic drugs of abuse in human serum by online extraction and LC–MS/MS

A new quantitation method for the determination of drugs of abuse (opiates, amphetamine and derivatives, cocaine, methadone and metabolites) in serum by using online extraction coupled to liquid chromatography (LC)–mass spectrometry (MS)/MS has been developed. The online extraction is carried out using two extraction columns simultaneously and one analytical column. One extraction column is loaded, while the other one is eluted by a gradient. The elution gradient also separates the analytes in the analytical column. For the sample preparation, serum is spiked with a mixture of deuterated analogues of the drugs. After protein precipitation with methanol/zinc sulphate, centrifugation, evaporation and reconstitution, the sample is injected into the LC system. The quantitation is based on the analysis of two multiple reaction monitoring transitions per drug. The recovery of the protein precipitation step is over 80% for all analytes. Intra- and interday precision, as relative standard deviation, is lower than 6%, and in the case of accuracy, RE is lower than 15%. Only the most polar analytes showed matrix effects. The limits of quantitation for the analysed compounds vary between 0.5 and 2.8 ng/mL. The developed method was used to quantify basic drugs in samples “from driving under the influence of drugs” cases. The results were compared with those obtained by using solid-phase extraction–GC–MS.     

Application of synergistic β-lactamase inhibitors and antibiotics in the treatment of wounds infected by superbugs

Amoxicillin appears to be clinically drug-resistant due to the presence of β-lactamase in bacteria. Here, we designed and prepared a hollow Prussian Blue (HPB)-based therapeutic nanoplatform that was constructed by encapsulating amoxicillin into polyethyleneimine with β-lactamase inhibitor 4-carboxyphenylboronic acid (4-Cpba) decorated HPB nanoparticles (CPA NPs). The antibacterial effect of the CPA NPs on drug-resistant bacteria was observed by in vitro colony-forming unit, minimum inhibitory concentration, scanning electron microscopy, and fluorescence tests. The results show that amoxicillin effectively inhibited Escherichia coli and Staphylococcus aureus-resistant bacteria in the presence of 4-Cpba. The in vivo experimental results show that the CPA NPs exhibited a synergistic anti-infective effect in vivo, which inhibited the inflammatory response and apoptosis induced by the drug-resistant bacterial infection, and promoted wound healing in mice. The hematoxylin and eosin staining and blood biochemical experiments revealed that the acute toxicity of the material was negligible and it had good biocompatibility. Our results verify our design that CPA NPs can restore the antibacterial activity of amoxicillin.     

Stereoselective determination of drugs and metabolites in body fluids,tissues and microsomal preparations by capillary electrophoresis (2000–2010)

During the past two decades, chiral capillary electrophoresis (CE) emerged as a promising, effective and economic approach for the enantioselective determination of drugs and their metabolites in body fluids, tissues and in vitro preparations. This review discusses the principles and important aspects of CE-based chiral bioassays, provides a survey of the assays developed during the past 10 years and presents an overview of the key achievements encountered in that time period. Applications discussed encompass the pharmacokinetics of drug enantiomers in vivo and in vitro, the elucidation of the stereoselectivity of drug metabolism in vivo and in vitro, and bioanalysis of drug enantiomers of toxicological, forensic and doping interest. Chiral CE was extensively employed for research purposes to investigate the stereoselectivity associated with hydroxylation, dealkylation, carboxylation, sulfoxidation, N-oxidation and ketoreduction of drugs and metabolites. Enantioselective CE played a pivotal role in many biomedical studies, thereby providing new insights into the stereoselective metabolism of drugs in different species which might eventually lead to new strategies for optimization of pharmacotherapy in clinical practice.     

Quantitative LC–MS/MS method in urine for the detection of drugs used to reverse the effects of chemical castration

The chemical castration law, which targets child molesters with recidivism, was introduced in Korea in 2011. For this, leuprolide, a gonadotropin-releasing hormone agonist, is used to decrease testosterone production and suppress libido. In order to achieve efficient law enforcement, it is necessary to monitor intentional ingestion of drugs that antagonize the effect of leuprolide. Therefore, an analytical method for the simultaneous detection of mirodenafil, sildenafil, tadalafil, udenafil, vardenafil, icariin, alprostadil, and yohimbine, which are the major impotence treatment drugs, legitimately or otherwise, in Korea, as well as their selected metabolites, in human urine was established and validated using liquid chromatography–tandem mass spectrometry (LC–MS/MS). First, different sample preparation methods, two solid-phase extractions with different cartridges and protein precipitation, were compared and protein precipitation was chosen for the entire study because it showed better matrix effects and recoveries. Thus, the drugs and metabolites in urine were extracted by protein precipitation and then filtered and analyzed by LC–MS/MS with polarity switching electrospray ionization. The validation results of selectivity, matrix effect, recovery, linearity, intra- and inter-assay precision and accuracy were satisfactory. The limits of detection ranged from 0.25 to 10 ng/mL, and the limits of quantification were 2.5 to 50 ng/mL. The drugs and metabolites in urine did not show any degradation under storage for 7 and 15 days at 4 and ?20 °C as well as after three freeze–thaw cycles. The developed method will be very useful for monitoring the illegal use of impotence treatment drugs.     

Bioanalysis of drugs and their metabolites by chiral electromigration techniques (2010–2020)

The further development and application of capillary electromigration techniques for the enantioselective determination of drugs and their metabolites in body fluids, tissues, and in vitro preparations during the 2010 to 2020 time period continued to proof their usefulness and attractiveness in bioanalysis. This review discusses the principles and important aspects of capillary electrophoresis- based chiral drug bioassays, provides a survey of the assays reported during the past 10 years and presents an overview of the key achievements encountered in that time period. For systems with charged chiral selectors, special attention is paid on assays that feature field-amplified sample injection to enable the determination of ppb levels of analytes and optimized online incubation procedures for the rapid assessment of a metabolic pathway. Applications discussed encompass the pharmacokinetics of drug enantiomers in vivo and in vitro, the impact of inhibitors on metabolic steps, the elucidation of the stereoselectivity of drug metabolism in vivo and in vitro, and drug enantiomers in toxicological, forensic, and doping analysis.     

Speciation,separation and enrichment of Cr(III) and Cr(VI) in environmental samples by ion-pair solvent extraction using a β-diketone ligand

A simple speciation, separation and enrichment method has been developed for the determination of Cr(III) and Cr(VI) ions in different samples by ion-pair solvent extraction with a β-diketone ligand, 2-(4-methoxybenzoyl)-N′-benzylidene-3-(4-methoxyphenyl)-3-oxo-N-phenyl-propono hydrazide (MBMP). Cr(III) was separated from Cr(VI) as Cr(III)-(MBMP)-perchlorate ternary ion-pair complex. The influences of various analytical parameters including pH, amount of reagent, shaking time, sample volume and ionic strength on the recovery of Cr(III) and/or Cr(VI) were investigated. Total chromium was obtained after reducing Cr(VI) to Cr(III) with NH₂OH?·?HCl. Recoveries were found to be higher than 95% and the relative standard deviation (RSD) was less than 2%. The method detection limit based on 3σ criterion for Cr(III) was found to be 0.32?µg?L^?1. The formed ternary ion-pair complex, Cr(III)?:?MBMP?:?2ClO₄, has a molar ratio of 1?:?1?:?2. The developed method has been applied successfully to the speciation of chromium in various natural water, soil, sediment and hair samples with satisfactory results.     

Enantiomeric analysis of drugs in water samples by using liquid–liquid microextraction and nano-liquid chromatography

The nano-LC technique is increasingly used for both fast studies on enantiomeric analysis and test beds of novel stationary phases due to the small volumes involved and the short conditioning and analysis times. In this study, the enantioseparation of 10 drugs from different families was carried out by nano-LC, utilizing silica with immobilized amylose tris(3-chloro-5-methylphenylcarbamate) column. The effect on chiral separation caused by the addition of different salts to the mobile phase was evaluated. To simultaneously separate as many enantiomers as possible, the effect of buffer concentration in the mobile phase was studied, and, to increase the sensitivity, a liquid–liquid microextraction based on the use of isoamyl acetate as sustainable extraction solvent was applied to pre-concentrate four chiral drugs from tap and environmental waters, achieving satisfactory recoveries (>70%).     

Sweeping-micellar electrokinetic chromatography for the simultaneous analysis of tricyclic antidepressant and β-blocker drugs in wastewater

The simultaneous analysis of tricyclic antidepressant (amitriptyline, clomipramine, doxepin and nortriptyline) and β-blocker (alprenolol, labetalol and propranolol) drugs in wastewater was developed via sweeping-micellar electrokinetic chromatography (MEKC) together with a simple liquid-liquid extraction step. For sweeping-MEKC, the amount of organic modifier in the separation electrolyte, the concentration of phosphoric acid in the sample matrix and the injection time of the sample were optimized. Sensitivity enhancements of up to 305-fold were achieved via sweeping. This allowed limits of detection (LOD) from 7 to 27 ng/mL. The relative standard deviations of migration time, corrected peak area and peak height were less than 3.2%, 7.8% and 4.5%, respectively. Liquid-liquid extraction using dichloromethane as solvent afforded up to 21-fold enrichment of the drugs from spiked wastewater. No interference of the sample matrix was observed and recoveries were obtained in the range of 77-113% for all analytes except labetalol at three spiking levels of 16, 80 and 160 ng/mL. Detection at the ng/mL level makes this simple, environmentally friendly and cost effective method competitive against recently reported methods using advanced liquid-phase separation techniques for monitoring similar drugs in wastewater.