Tetracycline residues in royal jelly and honey by liquid chromatography tandem mass spectrometry: validation study according to Commission Decision 2002/657/EC

A specific, sensitive and robust liquid chromatography tandem mass spectrometry method for determining oxytetracycline, tetracycline, chlortetracycline and doxycycline in royal jelly and honey samples is presented. Extraction of drug residues was performed by ammonium acetate buffer as extractant followed by a clean-up with metal chelate affinity chromatography and solid-phase extraction. Tetracycline analysis was performed using liquid chromatography–electrospray ionisation–tandem mass spectrometry. The presented method is the first validated for royal jelly and in accordance with the requirements set by Commission Decision 2002/657/EC. Recoveries of the methods, calculated spiking the samples at 5.0, 10.0, 20.0 and 30.0 μg kg⁻¹, were 79% to 90% for honey and 77% to 90% for royal jelly. The intra-day precision (RSD) ranged between 8.1% and 15.0% for honey and from 9.1% to 16.3% for royal jelly, while inter-day precision values were from 10.2% to 17.6% and from 10.6% to 18.4% respectively for honey and royal jelly. Linearity for the four analytes was calculated from 5.0 to 50.0 μg kg⁻¹. The decision limits (CCα) ranged from 6.2 to 6.4 μg kg⁻¹ and from 6.1 to 6.5 μg kg⁻¹ for honey and royal jelly, respectively. Detection capabilities values (CCβ) ranged between 7.2 and 7.7 μg kg⁻¹ and from 7.3 to 7.9 μg kg⁻¹ respectively for honey and royal jelly. The developed method is currently in use for confirmation of the official control analysis of honey and royal jelly samples.     

Determination of fluoroquinolone antibiotics in hospital and municipal wastewaters in Coimbra by liquid chromatography with a monolithic column and fluorescence detection

The main goal of this work was determination of residues of the antibiotics ofloxacin (OFLO), norfloxacin (NOR), ciprofloxacin (CIPRO), and enrofloxacin (ENRO) in wastewater samples. The samples, after acidification to pH 4.5 and addition of EDTA, were extracted on an anion-exchange cartridge in tandem with an Oasis HLB cartridge. The LC–FD method, developed in previous studies, was based on application of a monolithic C₁₈ column. The limit of quantification (LOQ) of the method was 250 ng L⁻¹ for OFLO, 25 ng L⁻¹ for NOR and CIPRO, and 50 ng L⁻¹ for ENRO. Mean recovery ranged between 75 and 121% for OFLO, NOR, CIPRO, and ENRO. A total of 14 wastewater samples were analyzed; these were collected from four hospitals and from influent and effluent from a wastewater-treatment plant in Coimbra, Portugal, during spring and autumn. CIPRO was present in all the samples, NOR was detected second most often, followed by OFLO. ENRO was found at concentrations under the LOQ in five hospital samples, and the highest level was found in influent from the WWTP.     

Determination of fluoroquinolone residues in poultry muscle in Portugal

A total of 98 poultry samples, including chicken and turkey muscle, were analysed, using a sensitive and reliable analytical method based on liquid chromatography (LC) with spectrofluorimetric detection, for simultaneous determination of four fluoroquinolone (FQ) antibiotics, namely enrofloxacin (ENRO), ciprofloxacin (CIPRO), norfloxacin (NOR), and sarafloxacin (SARA). The method involved extraction with 0.15 mol L⁻¹ HCl and clean-up by solid-phase extraction using Oasis HLB cartridges. Chromatographic separation was carried out on a C₁₈ TSK gel column, in isocratic mode, with 0.025 mol L⁻¹ H₃PO₄ solution, adjusted to pH 3.0 with tetrabutylammonium hydroxide-methanol (78:22) as mobile phase. Good linearity over the investigated concentration range was observed, with mean values of correlation coefficients higher than 0.9989 for all the analytes studied. The limits of quantification (LOQ), expressed as the lowest fortification level with acceptable precision were 15 μg kg⁻¹ for ENRO, CIPRO, and NOR, and 30 μg kg⁻¹ for SARA; these values are in compliance with requirements for monitoring of maximum residues levels (MRLs). Overall recoveries from spiked samples ranged from 80% to 92% with relative standard deviations (RSD) lower than 6.1%. Of the chicken and turkey samples analysed, 44.2% and 37.8%, respectively, were contaminated. The levels found in the analysed poultry samples, collected from markets of Oporto and Coimbra, located in the north and central zones of Portugal, respectively, were lower than 114.2 and 87.6 μg kg⁻¹ in chicken and turkey muscle samples, respectively. One positive chicken sample was contaminated with ENRO at levels higher than the MRL.     

Cleanup strategies and advantages in the determination of several therapeutic classes of pharmaceuticals in wastewater samples by SPE–LC–MS/MS

This work describes the development and validation of an offline solid-phase extraction with simultaneous cleanup capability, followed by liquid chromatography–(electrospray ionisation)–ion trap mass spectrometry, enabling the concurrent determination of 23 pharmaceuticals of diverse chemical nature, among the most consumed in Portugal, in wastewater samples. Several cleanup strategies, exploiting the physical and chemical properties of the analytes vs. interferences, alongside with the use of internal standards, were assayed in order to minimise the influence of matrix components in the ionisation efficiency of target analytes. After testing all combinations of adsorbents (normal-phase, ion exchange and mixed composition) and elution solvents, the best results were achieved with the mixed-anion exchange Oasis MAX cartridges. They provided recovery rates generally higher than 60%. The precision of the method ranged from 2% to 18% and 4% to 19% (except for diclofenac (22%) and simvastatin (26%)) for intra- and inter-day analysis, respectively. Method detection limits varied between 1 and 20 ng L⁻¹, while method quantification limits were <85 ng L⁻¹ (both excluding ibuprofen). This analytical method was applied to gather preliminary results on influents and effluents of two wastewater treatment plants (WWTPs) located in the urban region of Porto (Portugal). Typically, paracetamol, hydrochlorothiazide, furosemide, naproxen, ibuprofen, diclofenac and bezafibrate were detected in concentrations ranging from 1 to 20 μg L⁻¹, while gemfibrozil, simvastatin, ketoprofen, azithromycin, bisoprolol, lorazepam and paroxetine were quantified in levels below 1 μg L⁻¹. These WWTPs were given particular attention since they discharge their effluents into the Douro river, where water is extracted for the production of drinking water. Some sampling spots in this river were also analysed.     

Simultaneous extraction of polycyclic aromatic hydrocarbons and polychlorinated biphenyls in agricultural soils by pressurized liquid extraction and determination by gas chromatography coupled to tandem mass spectrometry

A simple and rapid method based on pressurized liquid extraction has been validated for the simultaneous extraction of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) from agricultural soil samples. Effective extraction was carried out in less than 17 min for all the studied compounds, and good recoveries were obtained for PAHs and PCBs, ranging from 70% to 112%, when blank samples were spiked at 2.5 μg kg⁻¹, except for naphthalene with recoveries close to 40%. The separation and determination were performed by gas chromatography coupled to tandem mass spectrometry using a triple quadrupole mass analyzer. The target compounds were detected by electron impact with selected reaction monitoring, and mass spectrometric conditions were optimized in order to increase selectivity and sensitivity. The developed method was validated, and matrix-matched calibration was used for quantification purposes. Repeatability and interday precision ranged from 0.9% to 16.8% and from 1.6% to 22.3%, respectively. Limits of quantification ranged from 0.07 to 2.50 μg kg⁻¹. The proposed method was applied to the analysis of agricultural soil samples collected from Almeria (Spain), and PAHs and PCBs were detected in some samples at concentrations ranging from 0.1 to 210 μg kg⁻¹.     

Comparative study of inorganic elements determination in whole blood from Crioula breed horse by EDXRF and NAA analytical techniques

The World Health Organization states that envenomation is responsible for a high number of deaths per year, especially in equatorial areas. The only effective specific treatment is the use of hyperimmune serum (antivenom). In Brazil, Crioula breed horses are used for antivenom production, with great importance in the maintenance of public health programs. A strict biochemical and metabolic control is required to attain specificity in antiserum. Inorganic elements represent only a small fraction of whole blood. Nonetheless, they play important roles in mammalian metabolism, being responsible for controlling enzymatic reactions, respiratory and cardiac functions and ageing. In this work, whole blood samples from Crioula breed horses were analyzed by EDXRF technique. The reference interval values were determined for the elements Na (1955–2013 μg g⁻¹), Mg (51–75 μg g⁻¹), P (523–555 μg g⁻¹), S (1628–1730 μg g⁻¹), Cl (2388–2574 μg g⁻¹), K (1649–1852 μg g⁻¹), Ca (202–213 μg g⁻¹), Cu (4.1–4.5 μg g⁻¹) and Zn (2.4–2.8 μg g⁻¹) and a comparative study with NAA results was outlined. The samples were obtained from Instituto Butantan. Both techniques showed to be appropriate for whole blood sample analyses and offer a new perspective in Veterinary Medicine.     

Multisyringe flow injection spectrophotometric determination of uranium in water samples

A multisyringe flow injection analysis method for the determination of uranium in water samples was developed. The methodology was based on the complexation reaction of uranium with arsenazo (III) at pH 2.0. Uranium concentrations were spectrophotometrically detected at 649 nm using a light emitting diode. Under the optimized conditions, a linear dynamic range from 0.1 to 4.0 μg mL⁻¹, a 3σ detection limit of 0.04 μg mL⁻¹, and a 10σ quantification limit of 0.10 μg mL⁻¹ were obtained. The reproducibility (%) at 0.5, 2.5, and 4.0 μg mL⁻¹ was 2.5, 0.9, and 0.6%, respectively (n = 10). The interference effect of some ions was tested. The proposed method was successfully applied to the determination of uranium in water samples.     

Analysis of captan, folpet, and captafol in apples by dispersive liquid–liquid microextraction combined with gas chromatography

A novel method was developed for the determination of captan, folpet, and captafol in apples by dispersive liquid–liquid microextraction (DLLME) coupled with gas chromatography–electron capture detection (GC–ECD). Some experimental parameters that influence the extraction efficiency, such as the type and volume of the disperser solvents and extraction solvents, extraction time, and addition of salt, were studied and optimized to obtain the best extraction results. Under the optimum conditions, high enrichment factors for the compounds were achieved ranging from 824 to 912. The recoveries of fungicides in apples at spiking levels of 20.0 μg kg⁻¹ and 70.0 μg kg⁻¹ were 93.0–109.5% and 95.4–107.7%, respectively. The relative standard deviations (RSDs) for the apple samples at 30.0 μg kg⁻¹ of each fungicide were in the range from 3.8 to 4.9%. The limits of detection were between 3.0 and 8.0 μg kg⁻¹. The linearity of the method ranged from 10 to 100 μg kg⁻¹ for the three fungicides, with correlation coefficients (r ²) varying from 0.9982 to 0.9997. The obtained results show that the DLLME combined with GC–ECD can satisfy the requirements for the determination of fungicides in apple samples. Figure Dispersive liquid–liquid microextraction (DLLME) coupled with gas chromatography–electron capture detection (GC–ECD) allows satisfactory determination of fungicides in apple samples     

Production of Lipids Containing High Levels of Docosahexaenoic Acid by a Newly Isolated Microalga, <Emphasis Type="Italic">Aurantiochytrium</Emphasis> sp. KRS101

In the present study, a novel oleaginous Thraustochytrid containing a high content of docosahexaenoic acid (DHA) was isolated from a mangrove ecosystem in Malaysia. The strain identified as an Aurantiochytrium sp. by 18S rRNA sequencing and named KRS101 used various carbon and nitrogen sources, indicating metabolic versatility. Optimal culture conditions, thus maximizing cell growth, and high levels of lipid and DHA production, were attained using glucose (60 g l⁻¹) as carbon source, corn steep solid (10 g l⁻¹) as nitrogen source, and sea salt (15 g l⁻¹). The highest biomass, lipid, and DHA production of KRS101 upon fed-batch fermentation were 50.2 g l⁻¹ (16.7 g l⁻¹ day⁻¹), 21.8 g l⁻¹ (44% DCW), and 8.8 g l⁻¹ (40% TFA), respectively. Similar values were obtained when a cheap substrate like molasses, rather than glucose, was used as the carbon source (DCW of 52.44 g l⁻¹, lipid and DHA levels of 20.2 and 8.83 g l⁻¹, respectively), indicating that production of microbial oils containing high levels of DHA can be produced economically when the novel strain is used.     

Rapid residue analysis of four triazolopyrimidine herbicides in soil, water, and wheat by ultra-performance liquid chromatography coupled to tandem mass spectrometry

A sensitive and effective method for simultaneous determination of triazolopyrimidine sulfonamide herbicide residues in soil, water, and wheat was developed using ultra-performance liquid chromatography coupled with tandem mass spectrometry. The four herbicides (pyroxsulam, flumetsulam, metosulam, and diclosulam) were cleaned up with an off-line C18 SPE cartridge and detected by tandem mass spectrometry using an electrospray ionization source in positive mode (ESI+). The determination of the target compounds was achieved in <2.0 min. The limits of detection were below 1 μg kg⁻¹, while the limits of quantification did not exceed 3 μg kg⁻¹ in different matrices. Quantitation was determined from calibration curves of standards containing 0.05–100 μg L⁻¹ with r ² > 0.997. Recovery studies were conducted at three spiked levels (0.2, 1, and 5 μg kg⁻¹ for water; 5, 10, and 100 μg kg⁻¹ for soil and wheat). The overall average recoveries for this method in water, soil, wheat plants, and seeds at three levels ranged from 75.4% to 106.0%, with relative standard deviations in the range of 2.1–12.5% (n = 5) for all analytes.     

Determination of tetracycline residues in soil by pressurized liquid extraction and liquid chromatography tandem mass spectrometry

An optimized extraction and cleanup method for the analysis of chlortetracycline (CTC), doxycycline (DC), oxytetracycline (OTC) and tetracycline (TC) in soil is presented. Soil extraction in a pressurized liquid extraction system, followed by extract clean up using solid-phase extraction (SPE) and tetracycline determination by liquid chromatography tandem mass spectrometry (LC-MS/MS) provided appropriate efficiency and reproducibility. Different dispersing agents and solvents for soil extraction and several SPE cartridges for cleanup were compared. The best extraction results were obtained using ethylenediamine tetraacetic acid-treated sand as dispersing agent, and water at 70 °C. The most effective cleanup was obtained using Strata-X^TM sorbent in combination with a strong anion exchange cartridge. Recoveries ranged from 71% to 96% and precision, as indicated by the relative standard deviations, was within the range of 8–15%. The limits of quantification (LOQs) by using LC-MS/MS, based on signal-to-noise ratio (S/N) of 10, ranged from 1 μg kg⁻¹ for TC to 5 μg kg⁻¹ for CTC. These results pointed out that this technique is appropriate to determine tetracyclines in soils. Analysis of 100 samples taken in the Valencian Community revealed that, in soil, up to 5 μg kg⁻¹ CTC, 15 μg kg⁻¹ OTC, 18 μg kg⁻¹ TC, and 12 μg kg⁻¹ DC could be detected. Detection of the analytes in several samples, which typify great part of the Spanish agricultural soils, should be outlined as most important result of this study. Electronic supplementary material  The online version of this article (doi: ) contains supplementary material, which is available to authorized users.     

Studies on uranium recovery from inlet stream of Effluent Treatment Plant by novel “In-House” sorbent

A fast and simple multisyringe flow injection analysis (MSFIA) method for routine determination of thorium in water samples was developed. The methodology was based on the complexation reaction of thorium with arsenazo (III) at pH 2.0. Thorium concentrations were spectrophotometrically detected at 665 nm. Under optimal conditions, Beer’s law was obeyed over the range from 0.2 to 4.5 μg mL⁻¹ thorium, a 3σ detection limit of 0.05 μg mL⁻¹, and a 10σ quantification limit of 0.2 μg mL⁻¹ were obtained. The relative standard deviations (RSD, %) at 0.5, 2.5 and 4.5 μg mL⁻¹ was 2.8, 1.5 and 0.8%, respectively (n = 10). It was found that most of the common metal ions and anions did not interfere with the thorium determination. The proposed method was successfully applied to its analysis in various water samples.     

Production of Fumaric Acid by <Emphasis Type="BoldItalic">Rhizopus oryzae</Emphasis>: Role of Carbon–Nitrogen Ratio

Cytosolic fumarase, a key enzyme for the accumulation of fumaric acid in Rhizopus oryzae, catalyzes the dehydration of l-malic acid to fumaric acid. The effects of carbon–nitrogen ratio on the acid production and activity of cytosolic fumarase were investigated. Under nitrogen limitation stress, the cytosolic fumarase could keep high activity. With the urea concentration decreased from 2.0 to 0.1 g l⁻¹, the cytosolic fumarase activity increased by 300% and the production of fumaric acid increased from 14.4 to 40.3 g l⁻¹ and l-malic acid decreased from 2.1 to 0.3 g l⁻¹. Cytosolic fumarase could be inhibited by substrate analog 3-hydroxybutyric acid. With the addition of 3-hydroxybutyric acid (50 mM) in the fermentation culture, fumaric acid production decreased from 40.3 to 14.1 g l⁻¹ and l-malic acid increased from 0.3 to 5.4 g l⁻¹.     

Voltammetry and amperometric detection of tetracyclines at multi-wall carbon nanotube modified electrodes

The voltammetric behaviour and amperometric detection of tetracycline (TC) antibiotics at multi-wall carbon nanotube modified glassy carbon electrodes (MWCNT-GCE) are reported. Cyclic voltammograms of TCs showed enhanced oxidation responses at the MWCNT-GCE with respect to the bare GCE, attributable to the increased active electrode surface area. Hydrodynamic voltammograms obtained by flow-injection with amperometric detection at the MWCNT-GCE led us to select a potential value E _det = +1.20 V. The repeatability of the amperometric responses was much better than that achieved with bare GCE (RSD ranged from 7 to 12%), with RSD values for i _p of around 3%, thus demonstrating the antifouling capability of MWCNT modified electrodes. An HPLC method with amperometric electrochemical detection (ED) at the MWCNT-GCE was developed for tetracycline, oxytetracycline (OTC), chlortetracycline and doxycycline (DC). A mobile phase consisting of 18:82 acetonitrile/0.05 mol L⁻¹ phosphate buffer of pH 2.5 was selected. The limits of detection ranged from 0.09 μmol L⁻¹ for OTC to 0.44 μmol L⁻¹ for DC. The possibility to carry out multiresidue analysis is demonstrated. The HPLC-ED/MWCNT-GCE method was applied to the analysis of fish farm pool water and underground well water samples spiked with the four TCs at 2.0 × 10⁻⁷ mol L⁻¹. Solid-phase extraction was accomplished for the preconcentration of the analytes and clean-up of the samples. Recoveries ranged from 87 ± 6 to 99 ± 3%. Under preconcentration conditions, limits of detection in the water samples were between 0.50 and 3.10 ng mL⁻¹.     

Iodine determination in food by inductively coupled plasma mass spectrometry after digestion by microwave-induced combustion

Iodine determination in food samples was performed by inductively coupled plasma mass spectrometry (ICP-MS) after digestion by microwave-induced combustion (MIC). Sample masses up to 500 mg of bovine liver, corn starch, milk powder, or wheat flour were completely combusted using the MIC system. Ammonium nitrate (6 mol l⁻¹ solution, 50 μl) was used as an aid for ignition and vessels were charged with 15 bar of O₂. The use of H₂O, 0.9 mmol l⁻¹ H₂O₂, 10 to 50 mmol l⁻¹ (NH₄)₂CO₃ and 56 mmol l⁻¹ tetramethylammonium hydroxide was investigated as absorbing solutions, as well as the suitability of performing a reflux step after the combustion process. Digestion of food samples by pressurized microwave-assisted acid digestion, microwave-assisted extraction and conventional extraction of iodine in alkaline solution were also evaluated. Iodine recoveries higher than 99% were obtained using MIC and 50 mmol l⁻¹ (NH₄)₂CO₃ or 56 mmol l⁻¹ tetramethylammonium hydroxide as absorbing solution and with 5 min for the reflux step. Accuracy was evaluated using certified reference materials (bovine muscle, corn bran, and milk powder) and agreement better than 97% was obtained. The limit of quantification by MIC and further ICP-MS determination was 0.002 μg g⁻¹. Blanks were always low and no memory effects were observed. Digestion by MIC allowed the processing of up to eight samples by each run in 25 min with high efficiency of digestion (residual carbon content lower than 1%) providing a suitable medium for further iodine determination by ICP-MS.     

Rapid determination of anilines in water samples by dispersive liquid-liquid microextraction based on solidification of floating organic drop prior to gas chromatography-mass spectrometry

A rapid, sensitive and environmentally friendly method for the analysis of 14 anilines in water samples by dispersive liquid–liquid microextraction based on solidification of floating organic drop (DLLME-SFO) prior to gas chromatography–mass spectrometry (GC-MS) was developed and optimized. In the proposed method, cyclohexane was used as the extraction solvent as its toxicity was much lower than that of the solvent usually used in dispersive liquid–liquid microextraction (DLLME). In the optimized conditions, the method exhibited good analytical performance. Based on a signal-to-noise ratio of 3, limits of detection for anilines were in the range of 0.07 to 0.29 μg L⁻¹, and the linear range was 0.5–200 μg L⁻¹ with regression coefficients (r ²) higher than 0.9977. It was efficient for qualitative and quantitative analysis of anilines in water samples. The relative standard deviations varied from 2.9 to 8.6 % depending on different compounds indicating good precision. Tap water and river water were selected for evaluating the application to real water samples. The relative recoveries of anilines for the two real samples spiked with 10 μg L⁻¹ anilines were in the scope of 78.2–114.6 % and 77.3–115.6 %, respectively.     

Determination of antibacterials in animal feed by pressurized liquid extraction followed by online purification and liquid chromatography-electrospray tandem mass spectrometry

A fully automated method has been developed for analysis of eighteen antibacterial compounds, including penicillins, cephalosporins and sulfonamides, in animal feed with limits of quantification in the range 0.25–5.79 μg kg⁻¹. The method is based on pressurized liquid extraction of 3 g homogenized feed with water and online clean-up of 500 μL of the extract with C₁₈HD cartridges. The purified sample was directly analysed by liquid chromatography–electrospray tandem mass spectrometry (SPE–LC–ESI-MS–MS). Chromatographic separation was achieved within 10 min by use of a C₁₂ Phenomenex Hydro-RP reversed-phase analytical column and a mobile phase gradient (water + 0.1% formic acid–methanol + 0.1% formic acid). The method was validated, revealing capability for detection of concentrations as low as 0.09 μg kg⁻¹, decision limits (CCα) and detection capabilities (CCβ) in the range 10–174 μg kg⁻¹ and 22–182 μg kg⁻¹, respectively, and inter-day precision ranging from 0.7 to 8.3%. Recovery, with internal standard correction, was in the range 93–134% for all analytes. The method was then applied to analysis of fifteen feed samples, nine of which contained at least one antimicrobial at concentrations between 0.006 and 1.526 mg kg⁻¹. The performance data and results from the method were compared with those from a previous method developed by our group, using offline SPE, by analyzing the same set of samples by both methods. The online SPE approach resulted in slightly improved sensitivity, with LODs of 0.09–2.12 μg kg⁻¹ compared with 0.12–3.94 μg kg⁻¹ by the offline approach. In general, better recovery was achieved by use of online purification (for 72% of the analytes) and the correlation between the two methods was good. The main advantages of the new online method are rapid and automated sample pre-treatment, and reduction of sample manipulation, enabling high-throughput analysis and highly accurate results. Because of all these characteristics, the proposed method is applicable and could be deemed necessary within the field of food control and safety.     

Development of a liquid chromatography-mass spectrometry method for the determination of ursolic acid in rat plasma and tissue: application to the pharmacokinetic and tissue distribution study

A fast and sensitive liquid chromatography–mass spectrometry method was developed for the determination of ursolic acid (UA) in rat plasma and tissues. Glycyrrhetinic acid was used as the internal standard (IS). Chromatographic separation was performed on a 3.5 μm Zorbax SB-C18 column (30 mm × 2.1 mm) with a mobile phase consisting of methanol and aqueous 10 mM ammonium acetate using gradient elution. Quantification was performed by selected ion monitoring with (m/z)⁻ 455 for UA and (m/z)⁻ 469 for the IS. The method was validated in the concentration range of 2.5 − 1470 ng mL⁻¹ for plasma samples and 20 − 11760 ng g⁻¹ for tissue homogenates. The intra- and inter-day assay of precision in plasma and tissues ranged from 1.6% to 7.1% and 3.7% to 9.0%, respectively, and the intra- and inter-day assay accuracy was 84.2 − 106.9% and 82.1 − 108.1%, respectively. Recoveries in plasma and tissues ranged from 83.2% to 106.2%. The limits of detections were 0.5 ng mL⁻¹ or 4.0 ng g⁻¹. The recoveries for all samples were >90%, except for liver, which indicated that ursolic acid may metabolize in liver. The main pharmacokinetic parameters obtained were T _max = 0.42 ± 0.11 h, C _max = 1.10 ± 0.31 μg mL⁻¹, AUC = 1.45 ± 0.21 μg h mL⁻¹ and K _a = 5.64 ± 1.89 h⁻¹. The concentrations of UA in rat lung, spleen, liver, heart, and cerebellum were studied for the first time. This method is validated and could be applicable to the investigation of the pharmacokinetics and tissue distribution of UA in rats.     

Rapid and interference free determination of ultra trace level of uranium in potable water originating from different geochemical environments by ICP-OES

Direct determination of uranium in the concentration range of 8 μg L⁻¹ to mg L⁻¹ in water samples originating from different geochemical environments has been done using Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES). Uranium detection with 2–3% RSD (relative standard deviation) has been achieved in water samples by optimizing the plasma power, argon and sheath gas flow. These parameters were optimized for three different emission lines of uranium at 385.958, 409.014 and 424.167 nm. Interference arising due to the variation in concentration of bicarbonate, sodium chloride, calcium chloride, Fe and dissolved organic carbon (DOC) on the determination of uranium in water samples was also cheeked as these are the elements which vary as per the prevailing geochemical environment in groundwater samples. The concentration of NaHCO₃, CaCl₂ and NaCl in water was varied in the range 0.5–2.0%; whereas Fe ranged between 1 and 10 μg mL⁻¹ and DOC between 0.1–1%. No marked interference in quantitative determination of uranium was observed due to elevated level of NaHCO₃, CaCl₂ and NaCl and Fe and DOC in groundwater samples. Concentration of uranium was also determined by other techniques like adsorptive striping voltametry (AdSv); laser fluorimetry and alpha spectrometry. Results indicate distinct advantage for uranium determination by ICP-OES compare to other techniques.     

Anabolic, doping, and lifestyle drugs, and selected metabolites in wastewater—detection, quantification, and behaviour monitored by high-resolution MS and MS n before and after sewage treatment

Municipal wastewater has been examined for steroids, β₂-agonists, stimulants, diuretics, and phosphodiesterase type V inhibitors (PDE type V inhibitors), which are “dual-use-drugs” applied either as anabolic, doping, and lifestyle drugs or for treatment of diverse diseases. To identify their origin, fitness centre discharges under suspicion of being point sources and sewage-treatment plant feed and effluents were sampled and concentrations determined. Sensitive and selective methods for determination and quantification based on solid-phase extraction (SPE) followed by high-performance liquid chromatography–high resolution mass and tandem mass spectrometry (HPLC–(HR)MS and HPLC–MS–MS) were developed and established for analysis of these compounds in wastewater and to assess their effect on the environment. The methods developed enabled quantification at trace concentrations (limit of quantification (LOQ): 5 ng L⁻¹). Of the steroids and stimulants under investigation, testosterone, methyltestosterone, and boldenone or ephedrine, amphetamine, and MDMA (3,4-methylendioxy-N-methylamphetamine) were observed at up to 5 μg L⁻¹ (ephedrine). Of the β₂-agonists salbutamol only, and of the diuretics furosemide and hydrochlorothiazide were confirmed in the extracts. Quite high concentrations of the PDE type V inhibitors sildenafil, tadalafil, and vardenafil and their metabolites were confirmed in fitness centre discharges (sildenafil: 1,945 ng L⁻¹) whereas their concentrations in municipal wastewater did not exceed 35 ng L⁻¹. This study identified anabolic and doping drugs in wastewater for the first time. Results obtained from wastewater treatment plant effluents proved that these “dual-use-drugs”, with the exception of hydrochlorothiazide, were mostly eliminated.