Screening and Quantitative Confirmatory Method for the Analysis of Glucocorticoids in Bovine Milk Using Liquid Chromatography-Tandem Mass Spectrometry

An LC/MS/MS method was developed and validated for the simultaneous identification, confirmation, and quantification of 12 glucocorticoids in bovine milk. The method was validated in accordance with the criteria defined in Commission Decision 2002/657/EC. The developed method can detect and confirm the presence of dexamethasone, betamethasone, prednisolone, flumethasone, 6 alpha-methylprednisolone, fluorometholone, triamcinolone acetonide, prednisone, cortisone, hydrocortisone, clobetasol propionate, and clobetasol butyrate in bovine milk. Milk samples are extracted with acetonitrile; sodium chloride is subsequently added to aid partition of the milk and acetonitrile mixture. The acetonitrile extract is then subjected to liquid-liquid purification by the addition of hexane. The purified extract is evaporated to dryness and reconstituted in a water acetonitrile mixture, and determination is carried out by LC/MS/MS. The method permits analysis of up to 30 samples in 1 day.

Determination of carazolol residues in porcine tissue by radioreceptor assay

A radioreceptor assay was developed for the determination of the p-blocker carazolol in porcine muscle and kidney. The method involves a simple alkaline extraction procedure using diethyl ether followed by a competitive assay between carazolol residues and [H-3]-dihydroalprenolol ([H-3]-DHA) using solubilised beta2-adrenoceptors isolated from a transfected cell line. The limit of detection (LOD) was determined using 20 reference blank samples of pig kidney and pig muscle. LODs for muscle (0.93 mug kg(-1)) and kidney (1.47 mug kg(-1)) were well below their respective European community maximum residue limits, (MRLs 5 and 25 mug kg(-1), respectively). The assay was used to investigate if carazolol residues persisted in pig tissues for up to 30 h post-intramuscular injection at the recommended dose rate (10 mug carazolol/kg body weight). The highest mean +/- S.D. concentrations were detected at 1 h post-injection in kidney (10.84 +/- 1.3 mug kg(-1)) and muscle (3.59 +/- 0.2 mug kg(-1)) which were less than the respective MRLs. It is concluded that this method offers a robust and rapid alternative to other methods for the screening of carazolol residues in pig meat. (C) 2002 Elsevier Science B.V. All rights reserved.

Environmental and genetic control of arsenic accumulation and speciation in rice grain:comparing a range of common cultivars grown in contaminated sites across Bangladesh, China, and India

The concentration of arsenic (As) in rice grains has been identified as a risk to human health. The high proportion of inorganic species of As (As(i)) is of particular concern as it is a nonthreshold, class 1 human carcinogen. To be able to breed rice with low grain As, an understanding of genetic variation and the effect of different environments on genetic variation is needed. In this study, 13 cultivars grown at two field sites each in Bangladesh, India, and China are evaluated for grain As. There was a significant site, genotype, and site by genotype interaction for total grain As. Correlations were observed only between sites in Bangladesh and India, not between countries or within the Chinese sites. For seven cultivars the As was speciated which revealed significant effects of site, genotype, and site by genotype interaction for percentage As(i). Breeding low grain As cultivars that will have consistently low grain As and low As(i), over multiple environments using traditional breeding approaches may be difficult, although CT9993-5-10-1-M, Lemont, Azucena, and Te-qing in general had low grain As across the field sites.

Ancient manuring practices pollute arable soils at the St Kilda World Heritage Site, Scottish North Atlantic

The impact of ancient fertilization practices on the biogeochemistry of arable soils on the remote Scottish island of Hirta, St Kilda was investigated. The island was relatively unusual in that the inhabitants exploited seabird colonies for food, enabling high population densities to be sustained on a limited, and naturally poor, soil resource. A few other Scottish islands, the Faeroes and some Icelandic Islands, had similar cultural dependence on seabirds. Fertilization with human and animal waste streams (mainly peat ash and bird carcases) on Hirta over millennia has led to over-deepened, nutrient-rich soils (plaggen). This project set out to examine if this high rate of fertilization had adversely impacted the soil, and if so, to determine which waste streams were responsible. Arable soils were considerably elevated in Pb and Zn compared to non-arable soils. Using Pb isotope signatures and analysis of the waste streams, it was determined that this pollution came from peat and turf ash (Pb and Zn) and from bird carcases (Zn). This was also confirmed by (13)C and (15)N analysis of the profiles which showed that soil organic matter was highly enriched in marine-derived C and N compared to non-arable soils. The pollution of such a remote island may be typical of other 'bird culture' islands, and peat ash contamination of marginal arable soils at high latitudes may be widespread in terms of geographical area, but less intense at specific locations due to lower population densities than on Hirta.

An ecotoxicological approach to assessing the impact of tanning industry effluent on river health

A study was conducted to investigate the sediment health and water quality of the River Sagana, Kenya, as impacted by the local tanning industry. Chemical analysis identified the main chemical pollutants (pentachlorophenols and chromium) while a bioassay addressed pollutant bioavailability. The bioassay, exploiting the luminescence response of a lux marked bacterial biosensor, was coupled to a dehydrogenase and Dapnia magna test to determine toxicity effects on sediments. Results highlighted the toxicity of the tannery effluent to the sediments at the point of discharge (64% of control bioluminescence) with gradual improvement downstream. There was a significant increase in dehydrogenase downstream, with the enzyme activity attaining a peak at 600 m, also indicating a gradual reduction of toxicity. Biological oxygen demand (19.56 mg L(-1)) dissolved oxygen (3.97 mg L(-1)) and high lethal dose value (85%) of D. magna also confirmed an initial stress at the point of discharge and recovery downstream. Optical density of surface water demonstrated an increase in suspended particulates and colour after the discharge point, eventually decreasing beyond 400 m. In conclusion, the study highlighted the importance of understanding the biogeochemistry of river systems impacted by industries discharging effluent into them and the invaluable role of a biosensor-based ecotoxicological approach to address effluent hazards, particularly in relation to river sediments.

An in situ spatially resolved analytical technique to simultaneously probe gas phase reactions and temperature within the packed bed of a plug flow reactor

This paper reports the detailed description and validation of a fully automated, computer controlled analytical method to spatially probe the gas composition and thermal characteristics in packed bed systems. As an exemplar, we have examined a heterogeneously catalysed gas phase reaction within the bed of a powdered oxide supported metal catalyst. The design of the gas sampling and the temperature recording systems are disclosed. A stationary capillary with holes drilled in its wall and a moveable reactor coupled with a mass spectrometer are used to enable sampling and analysis. This method has been designed to limit the invasiveness of the probe on the reactor by using the smallest combination of thermocouple and capillary which can be employed practically. An 80 mu m (O.D.) thermocouple has been inserted in a 250 mu m (O.D.) capillary. The thermocouple is aligned with the sampling holes to enable both the gas composition and temperature profiles to be simultaneously measured at equivalent spatially resolved positions. This analysis technique has been validated by studying CO oxidation over a 1% Pt/Al2O3 catalyst and the spatial resolution profiles of chemical species concentrations and temperature as a function of the axial position within the catalyst bed are reported.

Development of a planar waveguide microarray for the monitoring and early detection of five harmful algal toxins in water and cultures

A novel multiplex microarray has been developed for the detection of five groups of harmful algal and cyanobacterial toxins found in marine, brackish, and freshwater environments including domoic acid (DA), okadaic acid (OA, and analogues), saxitoxin (STX, and analogues), cylindrospermopsin (CYN) and microcystins (MC, and analogues). The sensitivity and specificity were determined and feasibility to be used as a screening tool investigated. Results for algal/cyanobacterial cultures (n = 12) and seawater samples (n = 33) were compared to conventional analytical methods, such as high performance liquid chromatography (HPLC) and liquid chromatography tandem mass spectrometry (LC-MS/MS). Detection limits for the 15 min assay were 0.37, 0.44, 0.05, 0.08, and 0.40 ng/mL for DA, OA, STX, CYN, and MC, respectively. The correlation of data obtained from the microarray compared to conventional analysis for the 12 cultures was r(2) = 0.83. Analysis of seawater samples showed that 82, 82, 70, 82, and 12% of samples were positive (>IC20) compared to 67, 55, 36, 0, and 0% for DA, OA, STX, CYN, and MC, respectively, for conventional analytical methods. The discrepancies in results can be attributed to the enhanced sensitivity and cross-reactivity profiles of the antibodies in the MBio microarray. The feasibility of the microarray as a rapid, easy to use, and highly sensitive screening tool has been illustrated for the five-plex detection of biotoxins. The research demonstrates an early warning screening assay to support national monitoring agencies by providing a faster and more accurate means of identifying and quantifying harmful toxins in water samples.

When are total concentrations not total? Factors affecting geochemical analytical techniques for measuring element concentrations in soil

Inductively coupled plasma (ICP) following aqua regia digestion and X-ray fluorescence (XRF) are both geochemical techniques used to determine ‘total’ concentrations of elements in soil. The aim of this study is to compare these techniques, identify elements for which inconsistencies occur and investigate why they arise. A study area (∼14,000 km2) with a variety of total concentration controls and a large geochemical dataset (n = 7950) was selected. Principal component analysis determined underlying variance in a dataset composed of both geogenic and anthropogenic elements. Where inconsistencies between the techniques were identified, further numerical and spatial analysis was completed. The techniques are more consistent for elements of geogenic sources and lead, whereas other elements of anthropogenic sources show less consistency within rural samples. XRF is affected by sample matrix, while the form of element affects ICP concentrations. Depending on their use in environmental studies, different outcomes would be expected from the techniques employed, suggesting the choice of analytical technique for geochemical analyses may be more critical than realised.

On-site monitoring and cartographical mapping of heavy metals

This paper presents a portable electrochemical instrument capable of real-time in situ detection and automatic identification of heavy metals. The instrument is equipped with an embedded Geographical Position System and is capable of storing the geographical position of the sample under test. Software has been developed to combine pollutant results with geographical position, in order to produce a cartographical presentation of the pollution of an area. The electrochemical instrument provides the facilities found in a traditional lab based instrument in a portable design for on-site measurements. The instrument is capable of detecting lead, cadmium, zinc, nickel, mercury, and copper with good sensitivity and precision. The system is reliable, easy to use, safe, and it may be used in a variety of situations to help environmental assessment and control.

The frequency of Environmental Quality Standard (EQS) exceedance for chlorinated organic pollutants in rivers of the Humber catchments

The southern industrial rivers (Aire, Calder, Don and Trent) feeding the Humber estuary were routinely monitored for a range of chlorinated micro- organic contaminants at least once a week over a 1.5-year period. Environmental Quality Standards (EQSs) for inland waters were set under the European Economic Community for a limited number of problematic contaminants (18). The results of the monitoring program for seven classes of chlorinated pollutants on the EQS list are presented in this study. All compounds were detected frequently with the exception of hexachlorobutadiene (where only one detectable measurement out of 280 individual samples occurred). In general, the rivers fell into two classes with respect to their contamination patterns. The Aire and Calder carried higher concentrations of micro- pollutants than the Don and Trent, with the exception of hexachlorobenzene (HCB). For Σ hexachlorocyclohexane (HCH) isomers (α + γ) and for dieldrin, a number of samples (~ 5%) exceeded their EQS for both the Aire and Calder. Often, ΣHCH concentrations were just below the EQS level. Levels of p,p'- DDT on occasions approached the EQS for these two rivers, but only one sample (out of 140) exceeded the EQS. No compounds exceeded their EQS levels on the Don and Trent. Analysis of the ratio of γ HCH/αHCH indicated that the source of HCH for the Don and Trent catchments was primarily lindane (γHCH) and, to a lesser extent, technical HCH (mixture of HCH isomers, dominated by α HCH), while the source(s) for the Aire and Calder had a much higher contribution from technical HCH.

Heavy metals as markers for assessing environmental pollution from chemical warehouse and plastics fires

Case histories of large, accidental fires are presented to illustrate that heavy metals may be used as markers to assess the extent of localized environmental contamination resulting from fires. Due to the complexity of fire chemistry with respect to organic pollutants, determination of organic pollutants in the environment following a fire would be time consuming and expensive. Using heavy metals as markers on the other hand is much cheaper and can be done very rapidly. © 1995.

Advanced materials for recognition and capture of whole cells and microorganisms

Selective cell recognition and capture has recently attracted significant interest due to its potential importance for clinical, diagnostic, environmental, and security applications. Current methods for cell isolation from complex samples are largely dependent on cell size and density, with limited application scope as many of the target cells do not exhibit appreciable differences in this respect. The most recent and forthcoming developments in the area of selective recognition and capture of whole cells, based on natural receptors, as well as synthetic materials utilising physical and chemical properties of the target cell or microorganism, are highlighted. Particular focus is given to the development of cell complementary surfaces using the cells themselves as templating agents, by means of molecular imprinting, and their combination with sensing platforms for rapid cell detection in complex media. The benefits and challenges of each approach are discussed and a perspective of the future of this research area is given.

Separation Science and Technology - Theory

I have completed 80% of a teaching text book (text and graphics) on Separation Science and Technology - Theory. The book's content is what I've learned over many years of practice and teaching with an emphasis on clarifying and explaining the nuances within the theories associated with various practical approaches to chemical and biochemical separations.

The book is divided into self-contained Chapters with many worked examples and practice questions. It very much aligns with my teaching on CHM3005D, CHM2010, CHM2007 and is ideal for PMY8105 and the new proposed MSci in Analytical Chemistry Programme. The book brings together diverse material in single space and will be a valuable pedagogical resource for the teaching of this key discipline within QUB and elsewhere.

Analytical strategies for the early quality and safety assurance in the global feed chain. Approaches for nitrogen adulterants in soybean meal and mineral and transformer oils in vegetable oils.

In the past decade, several major food safety crises originated from problems with feed. Consequently, there is an urgent need for early detection of fraudulent adulteration and contamination in the feed chain. Strategies are presented for two specific cases, viz. adulterations of (i) soybean meal with melamine and other types of adulterants/contaminants and (ii) vegetable oils with mineral oil, transformer oil or other oils. These strategies comprise screening at the feed mill or port of entry with non-destructive spectroscopic methods (NIRS and Raman), followed by post-screening and confirmation in the laboratory with MS-based methods. The spectroscopic techniques are suitable for on-site and on-line applications. Currently they are suited to detect fraudulent adulteration at relatively high levels but not to detect low level contamination. The potential use of the strategies for non-targeted analysis is demonstrated.

A generalized fuzzy linguistic model for predicting component concentrations in an optical gas sensing system

Motivated by environmental protection concerns, monitoring the flue gas of thermal power plant is now often mandatory due to the need to ensure that emission levels stay within safe limits. Optical based gas sensing systems are increasingly employed for this purpose, with regression techniques used to relate gas optical absorption spectra to the concentrations of specific gas components of interest (NO_x, SO₂ etc.). Accurately predicting gas concentrations from absorption spectra remains a challenging problem due to the presence of nonlinearities in the relationships and the high-dimensional and correlated nature of the spectral data. This article proposes a generalized fuzzy linguistic model (GFLM) to address this challenge. The GFLM is made up of a series of “If-Then” fuzzy rules. The absorption spectra are input variables in the rule antecedent. The rule consequent is a general nonlinear polynomial function of the absorption spectra. Model parameters are estimated using least squares and gradient descent optimization algorithms. The performance of GFLM is compared with other traditional prediction models, such as partial least squares, support vector machines, multilayer perceptron neural networks and radial basis function networks, for two real flue gas spectral datasets: one from a coal-fired power plant and one from a gas-fired power plant. The experimental results show that the generalized fuzzy linguistic model has good predictive ability, and is competitive with alternative approaches, while having the added advantage of providing an interpretable model.