Mine water geochemistry and metal flux in a major historic Pb-Zn-F orefield, the Yorkshire Pennines, UK.

Recent studies have shown up to 6 % of rivers in England and Wales to be impacted by discharges from abandoned metal mines. Despite the large extent of impacts, there are still many areas where mine water impact assessments are limited by data availability. This study provides an overview of water quality, trace element composition and flux arising from one such area; the Yorkshire Pennine Orefield in the UK. Mine drainage waters across the orefield are characterised by Ca-HCO3-SO4-type waters, with moderate mineralization (specific electrical conductance: 160-525 µS cm(-1)) and enrichment of dissolved Zn (≤2003 µg L(-1)), Ba (≤971 µg L(-1)), Pb (≤183 µg L(-1)) and Cd (≤12 µg L(-1)). The major ion composition of the waters reflects the Carboniferous gritstone and limestone-dominated country rock, the latter of which is heavily karstified in parts of the orefield, while sulphate and trace element enrichment is a product of the oxidation of galena, sphalerite and barite mineralization. Contaminant flux measurements at discharge sites highlight the disproportionate importance of large drainage levels across the region, which generally discharge into first-order headwater streams. Synoptic metal loading surveys undertaken in the Hebden Beck sub-catchment of the river Wharfe highlight the importance of major drainage levels to instream baseflow contamination, with diffuse sources from identifiable expanses of waste rock becoming increasingly prominent as river flows increase.

Biological responses to contaminants in the Humber Estuary: disentangling complex relationships.

Due to the ecological importance of estuaries, it is necessary to understand the biological effects that potentially toxic contaminants induce in bioindicator species. A key aspect is whether effects at lower levels of biological organisation transfer through the system to higher levels. In understanding such processes, characterising multivariate relationships between contaminants, sediment toxicities and detoxification processes are important. Worms (Hediste diversicolor) and sediments were collected along the Humber Estuary, England, and inorganic and organic contaminants were quantified. Sediment toxicities and glutathione-S-transferases (GSTs) activity in the ragworm were analysed. Concentrations of metals were highest near urban and industrial areas, whereas organic contaminants appeared at upstream locations. GST activity correlated with heavy metals. The genotoxicity, oestrogenicity, dioxin and dioxin-like activity were higher at upstream locations. Oestrogenicity correlated with alkylphenols and some organochlorines, whilst genotoxicity correlated with organochlorines and heavy metals. Despite this, higher level biological responses could not be predicted, indicating that homeostasis is operating.

The development and evaluation of a conducting matrix for the electrochemical regeneration of the immobilised co-factor NAD(H) under continuous flow.

Through the preparation of a novel controlled pore glass-poly(pyrrole) material we have developed a conducting support that is not only suitable for the co-immobilisation of enzymes and co-factors, but also enables the facile electrochemical regeneration of the co-factor during a reaction. Employing the selective reduction of (rac)-2-phenylpropionaldehyde to (S)-phenyl-1-propanol as a model, we have demonstrated the successful co-immobilisation of the HLADH enzyme and co-factor NAD(H); with incorporation of the material into a continuous flow reactor facilitating the in situ electrochemical regeneration of NAD(H) for in excess of 100 h. Using this approach we have developed a reagent-less, atom efficient system applicable to the cost-effective, continuous biosynthesis of chiral compounds.

Comparative PBT screening using (Q)SAR tools within REACH legislation.

Small to medium sized enterprises (SMEs) in the EU are facing challenges due to the introduction of new legislation designed to protect consumers and the environment, REACH (Registration, Evaluation, Authorisation and Restriction of CHemicals). There can be high costs associated with implementing REACH because data on mammalian toxicity, environmental toxicity and environmental fate properties is required and if this data is obtained experimentally the cost is significant. These costs can be reduced if reliable quantitative structure-activity relationships ((Q)SAR) models are instead used to obtain the required information. In this paper we investigate how easily freely available (Q)SAR models can be applied for persistent, bioaccumulative and toxic (PBT) screening of 17 chemicals of interest to SMEs. In this study the PBT predictions obtained from the more user-friendly PBT Profiler and the Danish(Q)SAR database for the chemicals were compared with the results taken directly from the EPI Suite software. It was found that these widely used (Q)SAR databases might have some errors and examples are provided. It was concluded that extra care must be taken when considering the use of these databases for PBT screening. In addition, to increase the likelihood of a correct prediction, data estimates from various (Q)SAR models relevant to the PBT endpoints must be compared.

Immobilization of thermophilic enzymes in miniaturized flow reactors.

The exploitation of enzymes for biotransformation reactions for the production of new and safer drug intermediates has been the focus of much research. While a number of enzymes are commercially available, their use in an industrial setting is often limited to reactions that are cost-effective and they are rarely investigated further. However, the development of miniaturized flow reactor technology has meant that the cost of such research, once considered cost- and time-inefficient, would be much less prohibitive. The use of miniaturized flow reactors for enzyme screening offers a number of advantages over batch enzyme assay systems. Since the assay is performed on a miniaturized scale, enzyme, substrate and cofactor quantities are significantly reduced, thus reducing the cost of laboratory-scale investigations. Since flow reactors use microfluidic systems, where the substrate and products flow out of the system, the problems of substrate inhibition and product inhibition encountered by some enzymes are avoided. Quite often, enzymes fulfil a single-use function in biotransformation processes; however, enzyme immobilization allows enzyme reuse and often helps to increase enzyme stability. We have used an aminoacylase enzyme with potential use for industrial biotransformation reactions and have successfully immobilized it in miniaturized flow reactors. This L-aminoacylase is from the thermophilic archaeon Thermococcus litoralis. Two approaches to enzyme immobilization have been examined, both involving enzyme cross-linking. The first reactor type has used monoliths, to which the enzyme was attached, and the second contained previously cross-linked enzyme trapped using frits, in the microfluidic channels. Two different microreactor designs were used in the investigation: microreactor chips for the monoliths and capillary flow reactors for the cross-linked enzyme. These systems allowed passage of the substrate and product through the system while retaining the aminoacylase enzyme performing the catalytic conversion. The enzyme has been successfully immobilized and used to produce stable biocatalytic microreactors that can be used repeatedly over a period of several months.

A chemiluminescence nanosensor to monitor lipid peroxidation.

Coumarin C343 (C(16)H(15)NO(4)), a dye used to enhance the weak chemiluminescence associated with lipid peroxidation, was conjugated to silica nanoparticles and entrapped in a sol-gel matrix to produce a nanosensor capable of enhancing low-level chemiluminescence by approximately 100%.

Solid-supported chemiluminescence and electrogenerated chemiluminescence based on a tris(2,2'-bipyridyl)ruthenium(II) derivative.

We report a simple and efficient technique for the covalent immobilisation of a tris(2,2'-bipyridyl)ruthenium(II) derivative suitable for both chemiluminescence and electrochemiluminescence detection.

A simple method for the analysis of urinary sucralose for use in tests of intestinal permeability.

BACKGROUND: Sucralose is a unique disaccharide probe which is stable in the colon and can be used to assess permeability over the whole gut. Additional information can be gained when sucralose is administered in combination with lactulose and a monosaccharide such as L-rhamnose in the form of a 'triple sugar test.' We describe a simple assay for urinary sucralose by HPLC with refractive index detection (HPLC-RI). METHODS: Phenyl-beta-D-glucopyranoside (internal standard) was added to 10 mL of urine, which was then passed through a 0.45 microm syringe filter. Elution was with 30% methanol (1 mL/min) on a reverse-phase C18 column. Detection was by refractive index, and integration based upon peak areas. Sixty standards of sucralose in human urine were analysed in order to quantify analytical variation. RESULTS: The standard curve for urinary sucralose was linear from 25 to 500 mg/L (r>0.99). The limit of detection was 11 mg/L. Analytical recovery of sucralose at concentrations of 25, 50 and 100 mg/L was 101.5% (CV 7.59%), 102.9% (CV 5.82%) and 105.0% (CV 4.26%), respectively. CONCLUSIONS: The technique described represents a simple assay for urinary sucralose which performed with acceptable accuracy and precision and should facilitate the use of the triple sugar test in clinical research.

A simple simultaneous flow injection method based on phosphomolybdenum chemistry for nitrate and nitrite determinations in water and fish samples.

A direct spectrophotometric flow injection method for the simultaneous determination of nitrite and nitrate has been developed. The method is based on the oxidation of a phosphomolybdenum blue complex by the addition of nitrite and the decrease in absorbance of the blue complex is monitored at 820 nm. The injected sample is split into two segments. One of the streams was directly reacted with the above reagent and detected as nitrite. The other stream was passed through a copperised cadmium reductor column where reduction of nitrate to nitrite occurs, and the sample was then mixed with the reagent and passed through the cell of the spectrophotometer to be detected as nitrite plus nitrate. The conditions for the flow injection manifold parameters were optimised by experimental design and the concentration of nitrite and nitrate was determined in the linear range from 0.05 to 1.15 mug ml(-1) nitrite and 0.06 to 1.6 mug ml(-1) nitrate with a detection limit of 0.01 mug ml(-1) for nitrite and 0.025 mug ml(-1) for nitrate. The method is suitable for the simultaneous determination of nitrite and nitrate in fish and water samples with a sampling rate of 25+/-2 sample per hour.

The generation of concentration gradients using electroosmotic flow in micro reactors allowing stereoselective chemical synthesis.

The stereoselective control of chemical reactions has been achieved by applying electrical fields in a micro reactor generating controlled concentration gradients of the reagent streams. The chemistry based upon well-established Wittig synthesis was carried out in a micro reactor device fabricated in borosilicate glass using photolithographic and wet etching techniques. The selectivity of the cis (Z) to trans (E) isomeric ratio in the product synthesised was controlled by varying the applied voltages to the reagent reservoirs within the micro reactor. This subsequently altered the relative reagent concentrations within the device resulting in Z/E ratios in the range 0.57-5.21. By comparison, a traditional batch method based on the same reaction length, concentration, solvent and stoichiometry (i.e., 1.0:1.5:1.0 reagent ratios) gave a Z/E in the range 2.8-3.0. However, when the stoichiometric ratios were varied up to ten times as much, the Z/E ratios varied in accordance to the micro reactor i.e., when the aldehyde is in excess, the Z isomer predominates whereas when the aldehyde is in low concentrations, the E isomer is the more favourable form. Thus indicating that localised concentration gradients generated by careful flow control due to the diffusion limited non-turbulent mixing regime within a micro reactor, leads to the observed stereo selectivity for the cis and trans isomers.

Electric field-induced mobilisation of multiphase solution systems based on the nitration of benzene in a micro reactor.

This paper describes the electric field-induced flow characteristics of multiphase solutions in a micro reactor device using the nitration of benzene as a model process. Photolithographic and wet etching techniques were used to fabricate the micro reactor (channels, 200 microns id, 100 microns deep) in a borosilicate glass substrate. The results focus specifically on the flow parameters of reagents/reactants (i.e., voltage, solution concentration and pH ranges and current-voltage relationships) used in this study. The benzene was introduced and mobilised by electroosmotic flow (EOF), as a microemulsion using an appropriate surfactant (sodium dodecyl sulfate), whilst the nitronium ions, produced in situ from mixed H2SO4-HNO3 (the nitrating agent), underwent electrophoretic-induced (electrokinetic) mobility. A co-surfactant, butan-1-ol, was used owing to (a) its relative solubility in the aqueous surfactant solution, (b) its ability to aid the solubilization of benzene, (c) the provision of a water-rich (oil-in-water) rather than oil-rich (water-in-oil) microemulsion system and (d) its lack of significant adverse effects on the EOF. The optimum conditions used for the nitration of benzene within the micro reactor were a run of the microemulsion as main reagent stream, then three 30 s segmented injections of mixed acid, with a 5 s push of the microemulsion into the system after each injection, and then a 60 s stopped-flow reaction time before driving reaction product segments to a collection reservoir.

Tris(2,2'-bipyridine)ruthenium(II) electrogenerated chemiluminescence of alkaloid type drugs with solid phase extraction sample preparation.

An electrogenerated chemiluminescence (ECL) method for the determination of pethidine, atropine, homatropine and cocaine is described. The optimum conditions were found to be similar for all of these compounds although the ECL emission intensity for cocaine was an order of magnitude lower than for pethidine due to their different chemical structures. Linear calibrations were obtained for all the compounds at pH 10 in borate buffer (0.05 mol l-1) at 1.3 V. Limits of detection of 6.8 x 10(-8), 2.2 x 10(-7), 3.2 x 10(-7) and 6.5 x 10(-7) mol l-1, respectively, were achieved for pethidine, atropine, homatropine and cocaine in standard solutions. Solid-phase extraction was used to separate the drugs from their matrix and the method was applied to the determination of spiked urine samples. The limits of quantitation for pethidine, atropine, homatropine and cocaine in urine were 1.0 x 10(-6), 2.0 x 10(-6), 2.0 x 10(-6) and 4.0 x 10(-6) mol l-1, respectively, with recoveries of between 90 and 110%.

The preparation of a series of nitrostilbene ester compounds using micro reactor technology.

The synthesis of stilbene esters using Wittig chemistry has been used to illustrate the generic diversity micro reactors offer in terms of chemical control and rapid method development. The micro reactor consisted of a 'T' design based on channel geometries 200 microns wide and 100 microns deep, etched into borosilicate glass and sealed with a borosilicate top plate using a thermal bonding technique. The movement of the reagent and products was achieved using electroosmotic flow (EOF), assisted by the incorporation of micro porous silica frits within the micro-channels to allow accurate solution control. To optimise the operating conditions methyl 4-formylbenzoate, premixed with sodium methoxide, was reacted with 2-nitrobenzyl-triphenylphosphonium bromide in dry degassed MeOH using flow conditions for both reagents of 0.40 microL min-1 for 20 min. A product yield of 70% (2:1 reaction stoichiometry with the aldehyde in excess) was obtained representing a 10% increase compared with the traditional batch synthesis. To demonstrate the capability of micro reactors to perform atom efficient synthesis a series of experiments based on an injection methodology (optimised to 30 s) were performed in the micro reactor at 1:1 stoichiometry resulting in a yield of 59%. Finally, the capability of micro reactors to perform a series of analogue reactions was investigated. The yields for a further three aldehydes indicated that the technology will be suitable for the development of automated device to support the generation of combinatorial libraries and rapid high throughput synthetic methods.

An investigation of electroosmotic flow and pressure pumped luminol chemiluminescence detection for cobalt analysis in a miniaturised total analytical system.

The luminol chemiluminescence reaction has been investigated for the determination of cobalt in a planar glass micro reactor. Reagents were mobilised within an etched glass chip with 200 microm wide channels using either electrically driven flow with voltages below 200 V cm(-1) or negative pressure pumping. Surfactants were used to assist mobilisation of the luminol for electrically driven flow and this also increased the chemiluminescence intensity in that system. A calibration over seven orders of magnitude was achieved for cobalt(II) nitrate with the negative pressure pumping system, and the limit of detection at the 95% confidence level was 3 x 10(-11) mol l(-1). The limit of detection for the electrokinetic flow was 4 x 10(-11) mol l(-1) and the linear range was between 10(-10) to 10(-6) mol l(-1). The advantages and disadvantages of both mobilisation methods are discussed for this reaction.

Analysis of tricyclic antidepressants using electrogenerated chemiluminescence.

A novel method has been investigated for the selective and sensitive determination of a range of tricyclic antidepressants including amitriptyline, doxepin, nortriptyline, promazine, chlorpromazine, imipramine, clomipramine, desipramine, protriptyline and trimipramine using electrogenerated chemiluminescence (ECL). The ECL mechanism is based on the reaction between tris(2,2'-bipyridyl)ruthenium(II) [Ru(bpy)3(2+)] and the tertiary amino groups on the antidepressants. After selecting the best operating parameters calibration curves were obtained over three orders of magnitude for amitriptyline, doxepin, nortriptyline, promazine and chlorpromazine. Linear calibrations were used to obtain limits of detection in the range 0.09-0.24 microgram ml-1 with relative standard deviations below 4% for five replicate samples. Rapid depression in the signal was observed with repeat analysis of imipramine, clomipramine, protriptyline, desipramine and trimipramine due to electrode fouling by the oxidation product of the reaction. Use of a lower concentration of the compound was found to alleviate the problem. Finally the concentration of doxepin was determined in a pharmaceutical preparation.

Evidence of the subperiosteal origin of osteoid osteomas in tubular bones: analysis by CT and MR imaging.

OBJECTIVE: A large series of patients with pathologically proven osteoid osteoma of tubular bones was reviewed to determine the frequency of a subperiosteal site of origin. MATERIALS AND METHODS: Thirty-eight cases that were included met two criteria: the tumor was located in a tubular bone, and the lesion had been evaluated by CT scanning or MR imaging, or both. The location of the osteoid osteoma was categorized as intracortical, sub-periosteal, endosteal, or medullary. RESULTS: Among the 38 cases, 19 were imaged with CT scanning, 14 with MR imaging, and five with both techniques. The most common affected sites were the femur (n = 13), tibia (n = 15), and humerus (n = 4). Among these 38 cases, 18 were intracortical, two were intramedullary, and 18 were subperiosteal. CONCLUSION: Osteoid osteomas occurring in a subperiosteal or surface location are not rare. Indeed, many osteoid osteomas arising in a tubular bone possibly originate in a subperiosteal site and later appear as an intracortical lesion. This site of origin appears to relate principally to continual remodeling of bone with subperiosteal deposition and endosteal erosion.

Osteochondral defect of the glenoid fossa: cross-sectional imaging features.

PURPOSE: To evaluate the cross-sectional imaging features of osteochondral defects (OCDs) of the glenoid fossa and to elicit a more detailed analysis of the trauma, if any, that may cause this injury. MATERIALS AND METHODS: Eight patients (seven male patients, one female patient; age range, 15-42 years; mean age, 27 years) with an OCD in the glenoid fossa were identified. Conventional computed tomography (CT), CT arthrography, or magnetic resonance (MR) imaging was performed. Surgical correlation was available in six patients. RESULTS: Six patients had a history of anterior dislocation or subluxation, one patient had an acromioclavicular joint separation, and one patient had chronic pain. Seven patients had anterior labral tears, and four had a redundant capsular insertion. A glenoid OCD appeared as either a multiloculated cyst in the subchondral bone mimicking a subchondral cyst (six patients) or a single osteochondral fragment (two patients). The lesion ranged from 8 mm to 2.0 cm in diameter. Three patients had an intraarticular body. Surgery confirmed an OCD in six of six patients. CONCLUSION: A glenoid OCD occurs most often as a result of acute trauma and has a high association with instability, labral tear, and intraarticular bodies.

On-line sample preparation for the determination of riboflavin and flavin mononucleotides in foodstuffs.

An on-line sample preparation method is described for the determination of riboflavin and flavin mononucleotide (FMN) in milk and cereal samples by high-performance liquid chromatography (HPLC) with fluorescence detection. The on-line system consists of microwave extraction followed by dialysis and trace enrichment with a C18 mini-column. Sample preparation was minimal, with milk samples being directly introduced into the system and cereal only needing to be ground prior to analysis. Results were obtained for a range of samples and these were found to be in agreement with the Association of Official Analytical Chemists (AOAC) method and a previously reported HPLC method. Recoveries were between 94 and 106% for a range of different samples and the relative standard deviation for ten samples was in the range 1.2-2.0%. During the microwave extraction all the flavin adenine dinucleotide (FAD) was converted into FMN and 15% of FMN was converted into riboflavin. The full analysis time on the ground samples was about 20 min.

Myelofibrosis associated with prominent periosteal bone apposition. Report of two cases.

Myelofibrosis is a myeloproliferative disorder that is characterized by splenomegaly and bone marrow replacement by fibrous tissue. The predominant radiographic feature is osteosclerosis; however, in rare instances, periosteal bone apposition or periostitis is apparent in the metaphysis of the distal femura and proximal tibiae. It has been suggested that periostitis, when associated with fever and bone pain, is indicative of more aggressive disease. We report this unusual radiographic finding and its similar appearance to hypertrophic osteoarthropathy in two patients with myelofibrosis. In our patients, the presence of periosteal bone apposition did not correlate with increased disease aggressiveness.

MR appearance of idiopathic synovial osteochondromatosis.

OBJECTIVE: A retrospective review of the MR examinations in 21 patients with idiopathic synovial osteochondromatosis (ISO) was performed to determine its MRI characteristics. MATERIALS AND METHODS: Twenty-one patients diagnosed with ISO had undergone MRI prior to surgery. The MR images were retrospectively evaluated for configuration and extent of lesion as well as for signal characteristics. RESULTS: Three distinct MR patterns were seen in ISO: A--lobulated homogeneous intraarticular signal isointense to slightly hyperintense to muscle on T1-weighted images and hyperintense on T2-weighted images (n = 3); B--pattern A plus foci of signal void on all pulse sequences (n = 17); and C--features of pattern A and B plus foci of peripheral low signal surrounding central fat-like signal (n = 2). The foci of signal void in pattern B and C corresponded to areas of calcification and the foci of peripheral low signal surrounding central fat-like signal in pattern C corresponded to areas of ossification. CONCLUSION: The MR appearance of ISO appears sufficiently unique to allow its differentiation from other causes of intraarticular pathology.