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Showing papers in "Journal of analytical and bioanalytical techniques in 2014"


Journal ArticleDOI
TL;DR: X-ray powder diffusion technique has many salient features and advantages that promote its wide range use as discussed by the authors, and has numerous applications that cater to industrial and academic research that ultimately enriches the growth and development of Science and Technology.
Abstract: The review presents a brief overview of advanced X-Ray Powder Diffraction Technique. It is an indispensable method of material investigation, characterization and quality control. It has many salient features and advantages that promote its wide range use. It has numerous applications that cater to industrial and academic research that ultimately enriches the growth and development of Science and Technology.

99 citations


Journal ArticleDOI
TL;DR: This review elaborates the significant uses of GC-MS, a highly effective and versatile analytical techniques with numerous scientific applications to cater the field of applied Sciences and Technology.
Abstract: GC-MS is highly effective and versatile analytical techniques with numerous scientific applications to cater the field of applied Sciences and Technology. This review elaborates the significant uses of this technique. It is a very useful for quality control, analytical research, impurity profiling and maintenance for human welfare and development.

82 citations


Journal ArticleDOI
TL;DR: In this paper, a short review examines the application of amperometric and impedimetric methods to the detection of biomarkers of clinical relevance in both planar and nanofunctionalised interfaces comprising immobilized antibodies/antigens and oligonucleotide receptors.
Abstract: Electroanalyses have brought a huge amount to our understanding of interfaces generally. When applied to surfaces which have been specifically engineered so as to recruit targets from an analytical solution, potent sensors can be derived. These may be based on a multitude of different analytical methods all typified by specific requirements and surface configurations. This short review examines the application of amperometric and impedimetric methods to the detection of biomarkers of clinical relevance. Basic principles are introduced with examples at both planar and “nanofunctionalised” interfaces comprising immobilized antibodies/antigens and oligonucleotide receptors. A particular focus is made of new developments in impedance and impedance derived capacitance spectroscopy.

65 citations


Journal ArticleDOI
TL;DR: This is the first work evaluating different aspects of sample preparation for direct SPME-GC-MS analysis of VOCs and the first method proposed for the analysis of murine and human faecal samples and proposed method can be coupled to the Automated Mass Spectral Deconvolution and Identification System and the R software package, Metab to produce results in a reliable and high-throughput manner.
Abstract: The analysis of volatile organic compounds (VOCs) emitted from biological fluids such as blood, urine, breath and faeces, has been receiving more attention from researchers and clinicians due to their contribution to the metabolome and potential use as diagnostic tools in clinical settings. The faecal metabolome represents the final product of a complex interaction involving the gut microbiota and cell metabolism and an accurate measurement of the faecal volatile organic metabolome enables a better understanding of disease-related metabolic pathways and, eventually, identifying potential biomarkers. However, there is a lack of published evidence evaluating the sample preparation steps for faecal metabolome analysis and no well-defined protocol has been established. Consequently, different research groups employ diverse methodologies, which, ultimately, prevent comparison of results between laboratories. We evaluated different aspects of sample preparation when processing murine and human faecal samples through a pipeline involving solid phase micro-extraction (SPME) coupled to gas chromatography-mass spectrometry (GC-MS). We identified the sample volume, the SPME fibre coating, the extraction conditions and the vial volume that produce the most accurate and reproducible results. Finally, we propose an optimized method for the direct SPME-GC-MS analysis of VOCs in murine and human faecal samples. To the best of our knowledge, this is the first work evaluating different aspects of sample preparation for direct SPME-GC-MS analysis of VOCs and the first method proposed for the analysis of murine and human faecal samples. In addition, our proposed method can be coupled to the Automated Mass Spectral Deconvolution and Identification System (AMDIS) and the R software package, Metab, in order to produce results in a reliable and high-throughput manner.

44 citations


Journal ArticleDOI
TL;DR: In this article, the authors compared the performance of different methods for disaccharides derived from different types of GAGs (dermatan sulfate, heparan sulfates, keratan sulfate and chondroitin sulfate).
Abstract: Glycosaminoglycans (GAGs) are distributed in the whole body and play a variety of important physiological roles associated with inflammation, growth, coagulation, fibrinolysis, lipolysis, and cell-matrix biology. Accumulation of undegraded GAGs in lysosomes gives rise to a distinct clinical syndrome, mucopolysaccharidoses. Measurement of each specific GAG in a variety of specimens is urgently required to understand GAG interaction with other molecules, physiological status of patients, and prognosis and pathogenesis of the disease. We established a highly sensitive and accurate tandem mass spectrometry (LC-MS/MS) method for measurements of disaccharides derived from four specific GAGs [dermatan sulfate (DS), heparan sulfate (HS), keratan sulfate (KS), and chondroitin sulfate (CS)]. Disaccharides were produced by specific enzyme digestion of each GAG, and quantified by negative ion mode of multiple reaction monitoring. Subclasses of HS and GAGs with identical molecular weights can be separated using a Hypercarbcolumn (2.0 mm×50 mm, 5 μm) with an aectonitrile gradient in ammonium acetate (pH 11.0). We also developed a GAG assay by RapidFire with tandem mass spectrometry (RF-MS/MS). The RF system consists of an integrated solid phase extraction robot that binds and de-salts samples from assay plates and directly injects them into a MS/MS detector, reducing sample processing time to ten seconds. RF-MS/MS consequently yields much faster throughput than conventional LC-MS/MS-based methods. However, the RF system does not have a chromatographic step, and therefore, cannot distinguish GAGs that have identical molecular weights. Both methods can be applied to analysis of dried blood spots, blood, and urine specimens. In this article, we compare the assay methods for GAGs and describe their potential applications.

40 citations


Journal ArticleDOI
TL;DR: In this paper, the potential of activated carbon stems and leaves (ACS, ACL) prepared from dried water hyacinth stems and leaf (DS, DL) by chemical activation with phosphoric acid (1:3) and modified activated carbon stem and leaves with nitric acid(1:1) for the removal of lead from aqueous solution was investigated.
Abstract: In this work, the potential of activated carbon stems and leaves (ACS, ACL) prepared from dried water hyacinth stems and leaves (DS, DL) by chemical activation with phosphoric acid (1:3) and modified activated carbon stems and leaves (MACS, MACL) with nitric acid (1:1) for the removal of lead from aqueous solution was investigated. Carbon samples were produced with a reasonable yield about 75% and have a remarkable surface area (57.46, 71.83, 864.52, 493.78, 381.22, and 265.22 m2/g for DS, DL, ACS, and ACL, MACS and MACL, respectively and well developed pore structure. Batch adsorption experiments were conducted to study the effect of various operating parameters, pH of the solution (1 to 6), initial concentration of lead ions (50 to 400 mg /l), contact time (2-250 min), and temperature (298-323 K). It is obvious that the maximum adsorption of lead at pH 5 is in the order: MACS (175.63 mg/g) > MACL (164.56 mg/g) > DS (90.50 mg/g) > DL (66.60 mg/g) > ACS (36.00 mg/g) > ACL (33.40 mg/g). This may be attributed to the increase in the number of active sites on the modified activated carbon. The equilibrium data were analyzed using Langmuir and Freundlich isotherms. The results showed that the experimental data were fitted well by the Langmuir model. Kinetic results revealed that the adsorption process obeyed a pseudo-second order model and intra-particle diffusion was the rate controlling step. The thermodynamic studies revealed that the adsorption was spontaneous and endothermic process. Desorption of about 90% of the sorbed lead from carbon was achieved using about 0.6 M HCl.

40 citations


Journal ArticleDOI
TL;DR: In this paper, steam activated carbon (SCBACS) was obtained from the carbonized sugarcane bagasse residues in the presence of nitrogen in the temperature range from 700 to 900°C and the structure of the SCBACs was characterized by N2 adsorption at 77 K, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR).
Abstract: Sugarcane bagasse-based activated carbons (SCBACs) with different chemical characteristics appropriate for the removal of phenol in aqueous solutions have been prepared. The steam activated carbon (SCBACS) is obtained from the carbonized sugarcane bagasse residues in the presence of nitrogen in the temperature range from 700 to 900°C. The chemically activated carbon (SCBACN) was obtained from the carbonized sugarcane bagasse residues using NaOH. The structure of the SCBACs was characterized by N2 adsorption at 77 K, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The B.E.T methods are used to deduce the effective surface areas. The parameters, such as initial pH, temperature, initial phenol concentration, biosorbents dosage... etc., affecting the adsorption capacity of SCBACs toward phenol removal from aqueous solutions are investigated using batch experiments. The studies of kinetic models including pseudo first order and pseudo second-order are carried out. Adsorption isotherms are investigated. Equilibrium adsorption data fitted the Langmuir adsorption isotherm. The thermodynamic parameters including ΔG°, ΔH° and ΔS° for the adsorption processes of phenol onto the SCBACs are calculated. The negative values of ΔG° indicated the spontaneous nature of adsorption. The prepared SCBACs are successfully applied to the removal of phenol from different water samples with a recovery % more than 80.0% and a relative standard deviation (RSD) less than 4.0%. Regeneration of the activated carbons can be easily performed using 0.5 M NaOH.

32 citations


Journal ArticleDOI
TL;DR: A liquid chromatography/tandem mass spectrometry (LC-MS/MS) assay was developed for the determination of vancomycin in human plasma, bone and fat tissue.
Abstract: A liquid chromatography/tandem mass spectrometry (LC-MS/MS) assay was developed for the determination of vancomycin in human plasma, bone and fat tissue. For vancomycin in plasma, sample was treated with methanol to precipitate the proteins. After centrifugation, the supernatant was diluted with water, and then injected into the LC-MS/MS system. For vancomycin in bone and fat, the pulverized bone/fat samples were immersed in phosphate buffered saline pH 7.3 at 4°C overnight. After centrifugation, the supernatant of bone/fat tissue suspension was treated in the same way as the plasma samples. Vancomycin and aminopterin, the internal standard, were resolved on a C18(2) column using gradient elution of 0.05% formic acid and methanol. The two compounds were detected using electrospray ionisation in the positive mode. Standard curves were linear over the concentration range 0.05 to 50 mg/L (r2>0.99) in plasma, bone and fat. Bias was ≤ ± 10% from 0.05 to 50 mg/L, intra- and inter-day coefficients of variation (imprecision) were <10%, and the limit of quantification was 0.05 mg/L. The assay has been used successfully in a clinical study to investigate the regional delivery of vancomycin in bone and fat after prophylactic administration of vancomycin through an intraosseous route or systemic route, during total knee arthroplasty.

29 citations


Journal ArticleDOI
TL;DR: In this article, a simple, precise and rapid high performance liquid chromatography method with UV detection has been developed for the determination of saxagliptin and metformin in bulk, the analytes were detected at 225 nm and total run time for the method was 7 min.
Abstract: In this paper a simple, precise and rapid high performance liquid chromatography method with UV detection has been developed for the determination of saxagliptin and metformin in bulk. An Agilent, Zorbax CN (250 × 4.6 mm I.D., 5 μm) column was used with a mobile phase mixture of methanol-50 mM phosphate buffer (pH 2.7) in a gradient elution mode at a flow rate of 1.0 ml min-1. The analytes were detected at 225 nm and total run time for the method was 7 min. The calibration graphs were linear in the range of 5.00-125.00 μg ml-1 for saxagliptin and 2.50-62.50 μg ml-1 for metformin. For stability indicating study, saxagliptin was subjected to acid, neutral and alkali hydrolysis, oxidation and heat stress. The developed method could be used for quality control assay for SAX in tablets and for stability studies as the method separates SAX from its degradation products and tablet excipients.

27 citations


Journal ArticleDOI
TL;DR: The developed method was established for simultaneous identification of flavonoids and other constituents in the rhizomes of three Iris species growing in Kashmir Himalayas, India and demonstrates the developed method could be employed as a rapid and versatile analytical technique for identification of chemical constituents and quality control of Iris samples.
Abstract: Genus Iris has long history of use in various indigenous systems of medicine as alternative aperient, stimulant, cathartic, diuretic, gall bladder diseases, liver complaints, dropsy, purification of blood, venereal infections, fever, ringworms, bilious infections and for a variety of heart diseases. Rhizomes of genus Iris are rich source of secondary metabolites and most of these metabolites are reported to possess anticancer, antiplasmodial, anticholinesterase, enzyme inhibitor and immunomodulatory properties. In our study, high performance liquid chromatography with diode array detector coupled with electrospray ionization mass spectrometry (HPLC-DAD-ESI-MS/MS) method was established for simultaneous identification of flavonoids and other constituents in the rhizomes of three Iris species (Iris crocea, Iris germanica and Iris spuria) growing in Kashmir Himalayas, India. About twenty seven compounds were identified in these Iris species based on chromatographic retention time (tR), UV and MS/MS spectra and compared with those of isolated authentic compounds and literature data. About seven constituents (iridalglycoside 5b, iridalglycoside 7, irisquin B, irilin A, hesperetin, irisolone and irisolodone) were reported for the first time from Iris crocea. Our results demonstrate the developed method could be employed as a rapid and versatile analytical technique for identification of chemical constituents and quality control of Iris samples.

23 citations


Journal ArticleDOI
TL;DR: In this paper, the concentrations of some organochlorine, organophosphorus and pyrethroid pesticide residues in water and sediment samples from river Challawa were investigated using High Performance liquid Chromatography (HPLC) with UV/visible Detector.
Abstract: The concentrations of some organochlorine, organophosphorus and pyrethroid pesticide residues in water and sediment samples from river Challawa were investigated using High Performance liquid Chromatography (HPLC) with UV/visible Detector. The concentrations of organochlorine and organophosphorus pesticide residues were significantly higher in the sediment samples when compared to water samples. According to the concentrations and detection frequency dieldrin and aldrin were the most dominant compounds among the organochlorine pesticide residues, while chlorpyrifos and dichlovos; permethrin and deltamethrin were the dominant compound among the organophosphorus and pyrethroid pesticides respectively. The result also indicates that the water and sediment samples within the study area were contaminated by dichlovos, diazinon, chlorpyrifos, fenitrothion, dieldrin, aldrin, DDT, DDE and DDDs. The results also show that there is still exists a variety of the studied pesticide in the water and sediment from river Challawa. Despite bans and restrictions on the usage of some of these pesticides in Nigeria, the observed concentrations of the studied Organochlorine and organophosphorus and pyrethroid pesticidesin the eight sample points could explain either their persistence in the environment or continued use in the study area.

Journal ArticleDOI
TL;DR: In this paper, the levels of fluoride, cadmium, arsenic, lead and nickel were determined in sachet, tap and ground water in Maiduguri Metropolis of Borno State, Nigeria.
Abstract: This study was conducted in Maiduguri Metropolis of Borno State, Nigeria. The levels of fluoride, cadmium, arsenic, lead and nickel were determined in sachet, tap and ground water. The levels of fluoride and some heavy metals were also determined in blood and urine samples with respect to age groups. The sample collection and preparation were carried out using standard procedures. The concentrations of the heavy metals were determined by using Inductively Coupled Plasma Atomic Emission Spectrophotometer (ICPAES), while fluoride was determined Potentiometrically Using Ion-Selective Electrode. The results of this study showed that the concentration of fluoride was highest in male subject with a value of 1.65 mg/l within the age group of 51-60, while the lowest concentration of 0.02 mg/l was observed in female subject within the age group of 1-10. The concentrations of the metals studied in blood samples from male subject were significantly higher than in the female subject. The concentrations of these metals were significantly higher at an age group of 51-60, while the age group 1-10 showed the lowest concentrations. It was also observed that the concentration of fluoride in urine samples from male subject increased significantly with increase in age (P<0.05). The concentration of fluoride in borehole water from Gamboru, Bolori, Mairi and Gwange ward ranged between 0.02 mg/l and 0.01 mg/l, 0.04 mg/l and 0.11 mg/l Ni, 0.05 mg/l and 0.07 mg/l Cd, while for tap water the concentration of fluoride ranged from (0.034 to 0.73 mg/l), (0.026 to 0.54 mg/l)As, (0.15 to 0.24 mg/l)Pb, (0.08 to 0.22 mg/l)Ni, and (0.12 to 0.31 mg/l)Cd. Similarly for sachet water (Hauwa, Madube, Mustapha and Rahama waters) the concentration of fluoride ranged between 0.01 mg/l and 0.06 mg/l, 0.01 mg/l and 0.03 mg/l As, 0.001 mg/l to 0.05 mg/lPb, 0.01 mg/l and 0.0007 mg/l Ni, 0.01 mg/l to 0.05 mg/l Cd. The highest concentration of Cd in borehole water was observed in Mairi, while the lowest concentration of F was in Gamboru. Similarly, the concentration of F in tap water was significantly higher (P<0.05) in Bolori, while Ni showed the lowest concentration in Gamboru. From the above results, the concentrations of all the metals in the water samples were lower than those of the blood and urine samples, this is possible because; metals can be accumulated and concentrated in human bodies. Hence, it may be concluded that the water samples consumed by these inhabitants might not be responsible for the presence of these studied metal in the blood and urine samples.

Journal ArticleDOI
TL;DR: The proof of applicability of this methodology allowed the successful measurement of prop ofol and its non-conjugated metabolites in plasma and solid tissues from seven New Zealand White rabbits that were submitted to a long-term anaesthesia protocol with a continuous infusion of propofol.
Abstract: Propofol is an important compound used for anaesthetic purposes in clinical practice. Nevertheless, in the recent years, the use of propofol has also been reported for recreational, abusive or even for suicidal and criminal purposes. So far, there is a lack of practical techniques validated for simultaneous quantification of propofol and its non-conjugated metabolites (2,6-diispropyl-1,4-quinol and 2,6-diispropyl-1,4-quinone) in plasma and organs, to optimize therapeutics, to prevent undesired effects, and for application in forensic settings. A simple gas chromatography/ Ion trap – mass spectrometry method was optimized for the detection and quantification of propofol and its non-conjugated metabolites in plasma and organ (liver, heart, kidney and lungs) samples. All compounds were simultaneously extracted from 0.5 mL of plasma and 0.2 g of each organ, following a straightforward and rapid procedure using thymol as internal standard. This method was validated according to international guidelines for analytical methods. The standard curve ranged from 0.005 to 100 μg/mL for propofol and 0.005 to 50 μg/mL for the non-conjugated metabolites. Intra and inter-assay variability for propofol and its metabolites was less than 15% and the average recovery was greater than 90%. The proof of applicability of this methodology allowed the successful measurement of propofol and its non-conjugated metabolites in plasma and solid tissues from seven New Zealand White rabbits that were submitted to a long-term anaesthesia protocol with a continuous infusion of propofol ranging from 20 to 60 mg/kg/h. This optimized and validated assay may also be suitable in the monitoring of sedated or anaesthetised animals and humans with continuous infusions of propofol and for use in pharmacokinetic and toxicological studies.

Journal ArticleDOI
TL;DR: This work has shown that 4% w/v is the optimal concentration of the TCA solution for protein precipitation that is visualized by SDS-PAGE analysis, and provides optimal condition for protein purification and analysis of any xenobiotic compound like tenofovir.
Abstract: For low protein concentrations containing biological samples (in proteomics) and for non proteinaceous compound assays (in bioanalysis), there is a critical need for a simple, fast, and cost-effective protein enrichment or precipitation method. However, 2,2,2-trichloroacetic acid (TCA) is traditionally used for protein precipitation at ineffective concentrations for very low protein containing samples. It is hypothesized that response surface methodology, can be used to systematically identify the optimal TCA concentration for protein precipitation in a wider concentration range. To test this hypothesis, a central composite design is used to assess the effects of two factors (X1 = volume of aqueous solution of protein, and X2 = volume of TCA solution 6.1N) on the optical absorbance of the supernatant (Y1), and the percentage of protein precipitated (Y2). Using either bovine serum albumin (BSA) as a model protein or human urine (with 20 ppm protein content), 4% w/v (a saddle point) is the optimal concentration of the TCA solution for protein precipitation that is visualized by SDS-PAGE analysis. At this optimal concentration, the Y2-values range from 76.26 to 92.67% w/w for 0.016 to 2 mg/mL of BSA solution. It is also useful for protein enrichment and xenobiotic analysis in protein-free supernatant as applied to tenofovir (a model HIV microbicide). In these conditions, the limit of detection and limit of quantitation of tenofovir are respectively 0.0014 mg/mL and 0.0042 mg/mL. This optimal concentration of TCA provides optimal condition for protein purification and analysis of any xenobiotic compound like tenofovir.

Journal ArticleDOI
TL;DR: In this special issue on PDT-Cancer, PDT scientists and experts worldwide contributed seven peer-reviewed articles that broadly cover the use and applications of PDT for cancer, for infections and for inflammatory conditions.
Abstract: ISSN: 2155-9872 JABT, an open access journal Photodynamic Therapy-Cancer J Anal Bioanal Tech Photodynamic therapy (PDT) is a treatment modality involving photoactivatable chemicals (called photosensitizers), light and tissue oxygen [1-6]. PDT has clinical applications in the treatment of a variety of solid cancers [4,7-21], including but not limited to those of lung, skin, breast, head and neck, digestive tract, pancreas, liver, bladder, ovary, prostate and brain. In addition, there are many clinical applications of PDT for treatment of a wide range of non-cancerous conditions, such as bacterial and fungal infections; hyperproliferative or inflammatory conditions, such as macular degeneration or psoriasis; and premalignant conditions, such as actinic keratosis [22] and Barrett’s esophagus [23]. To achieve better therapeutic efficacy, new photosensitizers and novel light sources are continuously being developed, and the mechanisms of action are becoming better understood [24,25]. To achieve improved tumor selectivity and to reduce side effects in the treatment of cancer, the concept of targeted photodynamic therapy has been successfully developed by attaching specific functionalities to the photosensitizer, such as antibodies recognizing tumor antigens [26,27], or ligands and peptides to recognize receptors [28], which could be selectively expressed on one of the two major tumor compartments, either on the malignant cells or on tumor neovasculature. To achieve better efficacy than PDT that is targeted to a single tumor compartment (stPDT), a recent editorial [29] in this Journal summarized a new PDT approach (Figure 1), which was designed for dual targeting of photosensitizers (dtPDT) to both malignant cells and neovasculature [30,31] by conjugating photosensitizers to a protein, factor VII, the natural ligand for tissue factor. This approach allows for dual targeting of malignant cells and of tumor neovasculature, both of which either overexpress or selectively express tissue factor [30-33], respectively. In this special issue on PDT-Cancer, PDT scientists and experts worldwide contributed seven peer-reviewed articles. These review and research articles broadly cover the use and applications of PDT for cancer, for infections and for inflammatory conditions.

Journal ArticleDOI
TL;DR: In this article, the analysis of 20 organochlorine pesticides has been carried out in surface water samples collected from Peshawar, KPK, Pakistan, using SPME-GC-ECD method.
Abstract: The analysis of 20 organochlorine pesticides has been carried out in surface water samples collected from Peshawar, KPK, Pakistan, using SPME-GC-ECD method. This method showed good liner response with R2 values in the range of 0.9933 to 0.9999 for all pesticides. Percent recoveries at 1 μg L-1 for all the pesticides ranged from 89.9 to 106.1%. A total of 59 surface water samples were tasted for 20 organochlorin pesticides residues, of which, 37 samples were found contaminated with γ-BHC, 12 samples with β-BHC, 25 samples with heptachlor and 25 samples with aldrin with a maximum concentration of 0.092, 0.053, 0.089 and 0.036 μg L-1, respectively. However other pesticides were found in lesser no. of water samples. The Gamma irradiation decomposition of monocrotophos aqueous solution at various concentrations (60-150 mg L-1) was carried out and their removal efficiency was investigated. Gamma irradiation showed 100% degradation for a 60 mg L-1 solution at an absorbed dose of 1200 Gy. The dose constants investigated in this study ranged from 1.4×10-3 to 3.0×10-3 Gy-1. The effect of saturated solutions of N2 and N2O, and radical scavengers such as tert-butanol and iso-propanol, on the degradation of monocrotophos were also studied. The results showed that degradation of monocrotophos mainly proceeded through oxidative •OH radical. The inorganic by-products NO3-, NH4+ and PO43- were quantitatively determined by ion chromatography. A detail mechanism pathway of monocrotophos degradation by irradition has been developed.

Journal ArticleDOI
TL;DR: In this article, a ringdown breath analyzer has been validated using gas chromatography-mass spectrometry (GC-MS), which is typically referred to as the golden standard method for trace gas analysis.
Abstract: Acetone in exhaled breath is a potential biomarker of diabetes mellitus (DM) and elevated breath acetone concentrations have been observed in DM patients. One of the near real-time and online breath acetone analysis techniques is cavity ringdown spectroscopy (CRDS) that has been demonstrated for breath acetone measurements in human subjects including diabetic patients in a clinic. In this work, we have constructed a ringdown breath acetone analyzer for the purpose of instrument validation. Its detection capabilities, such as limit of detection, baseline stability, detection sensitivity, and reproducibility, were investigated. For the first time, a ringdown acetone breath analyzer has been validated using gas chromatography-mass spectrometry (GC-MS), which is typically referred to as the golden standard method for trace gas analysis. The GC-MS validation challenged the analyzer’s response to various breath acetone concentrations and its quantitative measurement accuracy. Subsequently, 25 subjects including 19 healthy and 6 diabetic people were tested using the validated ringdown breath acetone analyzer. Comparison of the testing results shows that this ringdown breath acetone analyzer can be used for reliable real-time, online breath acetone analysis in a clinic.

Journal ArticleDOI
TL;DR: An LC-MS/MS method specifically designed for monitoring MPA and progesterone levels in human serum yields results with precision and accuracy suitable for clinical use.
Abstract: Medroxyprogesterone (MPA) is widely used as a contraceptive or for hormone replacement therapy after menopause. The use of MPA, specifically in adolescent girls, is linked to excess weight gain and decreases in bone mineral density. Metabolism and clearance of MPA is highly variable making this agent a candidate for individualized dosing strategies which could possibly decrease unwanted side effects. MPA has been measured in animal tissues and fluids for many years as a contaminant resulting from the use of growth hormones in food animals. MPA has been measured by radioimmunoassay, gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS/MS). LC-MS/MS techniques have proven to be both more specific than radioimmunoassay and required much simpler sample preparation techniques than GC-MS. Here we describe an LC-MS/MS method specifically designed for monitoring MPA and progesterone levels in human serum. The technique in this report involves minimal sample preparation and yields results with precision and accuracy suitable for clinical use

Journal ArticleDOI
TL;DR: In this article, the activity concentrations of 210Po and 210Pb in atmospheric particulate samples collected in South Italy (Taranto) in Nov 2008 and in May 2009 were determined.
Abstract: The activity concentrations of 210Po and 210Pb in atmospheric particulate samples collected in South Italy (Taranto) in Nov 2008 and in May 2009 were determined. The corrected activity concentrations of 210Pb and 210Po in sampling time were in the range of 11.9-122 μBq m-3 and of 300-1105 μBq m-3, respectively. The 210Po/210Pb activity concentration ratios were in the range of 0.0273-0.174. Based on the 210Po/210Pb activity concentration ratios in air particulates, the atmospheric residence times of aerosol in South Italy were estimated, which are ranged from 8.89 to 49.7 days. The calculated residence times are very useful for simulating and modeling the atmosphere transport process of the inorganic and organic pollutants in air in the studied region.

Journal ArticleDOI
TL;DR: The speciation diagrams for dynamic redox systems are perceived as a reasonable alternative to (static) Pourbaix diagrams as the law of the matter conservation, as the general law of Nature.
Abstract: The Generalized Approach to Electrolytic Systems (GATES), based on physical (charge conservation), physicochemical (conservation of elements) and chemical (mass action) laws is the best theory applicable for computer simulation of equilibrium, non-equilibrium and metastable, mono- and polyphase electrolytic redox and non-redox systems. The Generalized Electron Balance (GEB) concept, related to electrolytic redox systems, is put in context with the principle of conservation of all elements in electrolytic redox systems, with aqueous, non-aqueous or mixedsolvent media. Two equivalent approaches to GEB are presented, and termed as the Approach I and Approach II to GEB. The GEB, that enters GATES as GATES/GEB, is fully compatible with charge and concentration balances and completes the set of equations necessary for thermodynamic resolution of redox systems. Computer simulation of such systems is based on all attainable physicochemical knowledge involved in the related algorithm, solvable with use of an iterative computer program, and then presented graphically. This paper is referred mainly to dynamic redox systems, realized according to titrimetric mode. The speciation diagrams for dynamic redox systems are perceived as a reasonable alternative to (static) Pourbaix diagrams. The GEB concept, unknown before 1992, is perceived as the law of the matter conservation, as the general law of Nature. From the GATES viewpoint, the stoichiometric reactions are only the basis to formulate the related equilibrium constants. GATES is also the basis for Generalized Equivalence Mass (GEM) concept, formulated with none relevance to the stoichiometry of chemical reaction notation. From the GATES viewpoint, the stoichiometry is a superfluous concept.

Journal ArticleDOI
TL;DR: The results suggest that experimental design and Monte Carlo simulation can be effectively used to reduce the DR of a process and to optimize the chromatographic conditions for the analysis of bio-active agents as applied in this study.
Abstract: This study intended to determine if experimental design and Monte Carlo simulation methods can be utilized to optimize the liquid chromatography (LC) analysis of active molecules. The method was applied for the simultaneous analysis of two topical microbicides, stampidine (STP) and HI443 in bulk and nanoformulations. The Plackett-Burman design was used for screening; whereas, Box-Behnken design was used to evaluate the main and interaction effects of the selected factors on the responses, namely peak area of STP (Y 1 ), HI443 (Y 2 ), tailing of STP (Y 3 ), and HI443 (Y4). The Monte Carlo simulation was applied to get the minimum defect rate (DR) of the process. The optimized LC conditions were found to be X 1 ; flow rate: 0.6 mL/min, X 2 ; injection volume: 18 µL, and X 3 ; initial gradient acetonitrile ratio: 92% v/v with a minimal DR of 0.077%. The optimized method was applied to determine the percent encapsulation efficiency (%EE) and in vitro release profile of STP and HI443 from solid lipid nanoparticles (SLNs). The %EE of STP and HI443 in SLNs was found to be 30.56 ± 9.44 and 94.80 ± 21.90% w/w, respectively, (n=3). It was observed that the release kinetics of STP followed the first order, whereas, HI443 followed the Peppas kinetic model in SLNs. The LC method was also applied for the estimation of molar extinction coefficients (e 270 ) of both drugs for the first time. These values were estimated to be 7,569.03 ± 217.96 and 17,823.67 ± 88.12 L/mol/cm for STP and HI443, respectively, (n=3). The results suggest that experimental design and Monte Carlo simulation can be effectively used to reduce the DR of a process and to optimize the chromatographic conditions for the analysis of bio-active agents as applied in this study.

Journal ArticleDOI
TL;DR: In this article, a polyaniline and graphene composite modified glassy carbon electrode (PAN/Gr/GCE) was used for the determination of doripenem (DPM) and meropenem metabolites (MPM) in human urine and serum samples.
Abstract: The theme of this study was the preparation, characterization, and application of a polyaniline (PAN) and graphene composite modified glassy carbon electrode (PAN/Gr/GCE) for the voltammetric determination of doripenem (DPM) and meropenem metabolites (MPM) in human urine and serum samples. The morphological study of the PAN/ Gr/GCE composite was examined by scanning electron microscopy (SEM) and cyclic voltammetry (CV). The electrochemical behaviour of DPM and MPM at the PAN/Gr/GCE were investigated using cyclic voltammetry in Ag/ AgCl/KCl supporting electrolyte at pH 2.0-10.0 in phosphate buffer solution. The linear dependence of current versus concentration was reached in a wide concentration range from 2.5×10-7 M to 3.5×10-4 M using cyclic voltammetry and differential pulse voltammetric methods. In acidic media a non-reversible diffusion controlled reduction involving two protons and two electrons occurs at carbon and nitrogen double bond (C=N) in the metabolites. The best electroanalytical performances of this composite electrode were achieved with the detection limits 3.6×10-9 M and 1.75×10-9 M for DPM and MPM respectively. The simplicity of preparation, high sensitivity and stability of this composite electrode should open novel avenues and applications for fabricating robust sensors for detection of DPM and MPM in human urine and serum samples.

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TL;DR: In this paper, a simple and fast method is presented to analyze the concentrations of the sugars sucrose, glucose and fructose in cigarettes, after an extraction step, the diluted samples are applied to an isocratic HPLC system with detection by evaporated light scattering.
Abstract: Simple sugars are an important constituent of tobacco, varying between almost 0 and 20% on weight of tobacco. Some manufacturers add sugars to the natural content in tobacco. In the present report, a simple and fast method is presented to analyze the concentrations of the sugars sucrose, glucose and fructose in cigarettes. After an extraction step, the diluted samples are applied to an isocratic HPLC system with detection by evaporated light scattering (ELSD). The method is very stable and sensitive with a good reproducibility. In one working day 80 samples of cigarettes can be processed and prepared for overnight HPLC analysis by one technician. The average total sugar content in 58 commercial cigarette brands is 17.4% (w/w) with a range of 1.9 to 18.3%.

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TL;DR: In this article, a high performance liquid chromatography method for the determination of fenofibric acid (FA), the active form of Fenofibrate (FBT) in human plasma was developed and validated with 500 μL of human plasma using 4'-chloro-5-fluro-2-hydroxybenzophenone (CFHB) as internal standard (IS).
Abstract: A high performance liquid chromatography method for the determination of fenofibric acid (FA), the active form of fenofibrate (FBT) in human plasma was developed and validated with 500 μL of human plasma using 4’-chloro- 5-fluro-2-hydroxybenzophenone (CFHB) as internal standard (IS). The assay procedure involved a simple one step liquid/liquid extraction of FA and IS from human plasma into ethyl acetate. The organic layer was separated and evaporated under a gentle stream of nitrogen at 40°C. The residue was reconstituted in the mobile phase and injected on a Symmetry ShieldRP18 (150×4.60 mm) 5 μm column. Separation of FA and IS was achieved with a mobile phase consisting of acetonitrile: 0.02 M phosphoric acid (50:50 v/v) at a flow rate of 1 mL/min. Nominal retention times of FA and IS were 6.1 and 9.1 ± 0.5 min, respectively. Absolute recovery of FA using a single step liquid/liquid method was 79.8%. A calibration curve was established for a range of concentrations 0.05 to 10.0 μg/mL with a regression coefficient (r2) of 0.9988. The lower limit of quantification (LLOQ) of FA was 0.05 μg/mL. The intraand inter-day precision for the measurement of FA quality control samples (0.05, 0.12, 1.20 and 8.20 μg/mL), were in the range 4.6-16.9% and 4.4-17.2% relative standard deviations respectively. The accuracy in the measurement of QC samples for FA was in the range of 82.0-104.3% (intra-day) to 95.0-104.9% (inter-day). The method developed was successfully used to investigate the pharmacokinetics and bioequivalence between a micronized Lipidil-Micro™ capsule formulation and a nanonised fenofibrate Lipidil-EZ™ tablet formulation.

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TL;DR: In this article, the authors describe the challenges and some of the techniques to validate the analytical procedures used to identify and quantify these medications and substances and develop a proposed test menu using data obtained from testing over one million specimens.
Abstract: Background: Laboratory urine drug testing of patients on chronic opioid therapy requires providing a large test menu of medications commonly prescribed for this population as well as metabolites and illicit substances. It has been shown that liquid chromatography-tandem mass spectrometry (LC-MS/MS) is the preferred method to analyze urine specimens for these substances. Purpose of the study: To describe the challenges and some of the techniques to validate the analytical procedures used to identify and quantify these medications and substances. Methods: Using data obtained from testing over one million specimens, the authors developed a proposed test menu. Potential isobaric interferences were established by using literature references. A list of potentially interfering medications was obtained by using the proposed test menu and the most commonly prescribed medications. Finally, criteria were designed to detect possible carryover. Results: The LC-MS/MS instrumentation eliminated all potential interferences and provided quantitative data over the test range needed to monitor these patients. Carryover could be eliminated by setting the carryover thresholds for each analyte. Conclusions: Reference laboratories utilizing LC-MS/MS technology to conduct urine drug testing for pain clinicians should employ specific techniques described in this study to develop an optimal test menu and validate procedures that include isolating retention times for isobaric compounds, identifying interfering substances including impurities in medicinal and illicit substance preparations, monitoring ion suppression, and avoiding carryover.

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TL;DR: In this article, the potential of ATR FT/IR techniques to provide rapid quantitative analyses of suspect tablet formulations is reported, which can therefore identify counterfeit tablets rapidly without the need for solvents.
Abstract: Counterfeit medicines are now a global public health problem. In developed countries up to 1% of medicines are reported to be counterfeit whilst in developing countries the level is ~30-40%. In this research the potential of Attenuated Total Reflection (ATR) FT/IR techniques to provide rapid quantitative analyses of suspect tablet formulations is reported. Unlike conventional tablet analyses where several tablets are crushed and solvent extracted, ATR FT/IR methods require that only a single tablet be crushed prior to analysis. This provides a considerable time saving over the solvent extraction protocols cited in the British Pharmacopoeia. Reference ATR FT/IR spectra of the active pharmaceutical ingredient (API) and excipients, from crushed tablets, were recorded for identification purposes. Quantitative data was obtained from ATR FT/IR spectra of calibrated mixtures of the API in the excipients. Tablet samples from various countries, India, Africa, China, Belgium and the UK were examined. Initial results showed the API could be identified down to ca 5% w/w of the tablet. Quantification was linear with selected characteristic peak areas for each API/excipient mixture. The analysis of the tablet samples generally showed good agreement with expectation. This was confirmed by conventional extractive analyses followed by UV quantification. ATR FT/IR can therefore identify counterfeit tablets rapidly without the need for solvents. Whilst LCMS/ MS and NMR techniques may be the ‘gold standards’ of the analytical world they are of much reduced value in sub-Saharan African countries whereas a portable ATR FT/IR may prevent the use of counterfeit antimalarial tablets and contribute to improvements in patient health.

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TL;DR: This method is sensitive, specific and reproducible for the determination of free and deconjugated testosterone and epitestosterone in rat serum and urine and can be used for in vivo analysis in studies monitoring endocrine dysfunctions and doping.
Abstract: Testosterone and epitestosterone are mainly excreted as glucuronides. The aim of this study was to develop and validate a method using liquid chromatography tandem mass spectrometry (LC-MS/MS) to analyse testosterone and epitestosterone in rat serum and urine to assist in vivo studies on steroid metabolism. The method was developed by spiking charcoal stripped rat plasma and urine with the analytes. The developed method was then applied to serum (n=6) and urine samples (n=6) from young male brown Norway rats to determine testosterone and epitestosterone concentrations. The assay showed linearity within quantification range coefficient (r2) values above 0.991. Optimum conditions were determined for the deconjugation of glucuronidated testosterone and epitestosterone along with the internal standard stanozolol D3. Accuracy, precision and extraction recovery for both compounds was satisfactory in both matrices. The method was capable of quantifying 0.250 ng/mL concentrations of testosterone and epitestosterone in 100 μL of serum and urine. The average concentrations of free and deconjugated testosterone and epitestosterone found in the rat samples were: urine–201.68 ± 90.16 ng/mL and 85.37 ± 21.20 ng/mL; serum– 363.40 ± 11.615 ng/mL and 1.75 ± 0.118 ng/mL, respectively. This method is sensitive, specific and reproducible for the determination of free and deconjugated testosterone and epitestosterone in rat serum and urine. The method can be used for in vivo analysis for further investigations of testosterone and epitestosterone concentrations in studies monitoring endocrine dysfunctions and doping.

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TL;DR: In this article, a new accurate, reliable and robust ion chromatography based method was developed to measure levels of nitrate and nitrite in beetroot juice, concentrated beetroot and spinach powder.
Abstract: Following the discovery of nitrite and nitrate as pro-drugs of the vasorelaxant nitric oxide, many studies have reported enhanced athletic performance following intake of these ions either intravenously or as a food supplement. The primary aim of this study was to develop a new accurate, reliable and robust ion chromatography based method. The newly developed method was applied to selected foodstuffs in powdered and/or juice form to measure levels of nitrate and nitrite. In addition to the commonly used beetroot juice, an initial HPLC-based screen of a range of foods identified spinach powder with very high nitrate and nitrite content. As a result of the initial screening, branded beetroot juice, concentrated beetroot juice and spinach powder were analysed using a new extraction method followed by a newly developed and validated ion chromatographic determination of nitrate and nitrite levels. The new ion chromatography based assay showed higher efficiency and better recovery than the HPLC approach. Significant inter-batch variations were found in levels of nitrate and nitrite in the beetroot juice and concentrated beetroot juice samples tested. In contrast spinach powder could provide a homogenous source of nitrate and nitrate for physiological studies. In summary, the new assay is rapid and efficient facilitating rigorous analyses of nitrate and nitrite levels prior to investigations requiring intake of foodstuffs containing these nitric oxide precursors.

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TL;DR: In this article, the first report of the harmonized collaborative validation study of a simultaneous and multiple determination method for both type A and B trichothecenes along with zearalenone by LC-MS/MS was presented.
Abstract: Harmonized collaborative validation of a simultaneous and multiple determination method for nivalenol, deoxynivalenol, T-2 toxin, HT-2 toxin, and zearalenone in wheat and barley by liquid chromatography tandem mass spectrometry (LC-MS/MS) was conducted by participants from 12 laboratories. The fortified samples of wheat and barley at three different levels and one naturally contaminated wheat sample were extracted, consecutively purified through a Presep C18 (ODS) solid phase extraction column and a Bond Elut Mycotoxin multifunctional column, and were analyzed by LC-MS/MS. The employment of internal standards (verrucarol and zearalanone) was apparently effective to ensure repeatability and reproducibility with sufficient recovery of each mycotoxin. This is the first report of the harmonized collaborative validation study of a simultaneous and multiple determination method for both type A and B trichothecenes along with zearalenone by LC-MS/MS. The validated method should be practical for monitoring of the major Fusarium mycotoxins contained in wheat and barley.

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TL;DR: In this paper, Inductively coupled plasma mass spectrometry (ICP-MS) is used for the determination of elements at the trace and ultratrace level along with the isotope ratios.
Abstract: Mass spectrometry is a versatile technique that is used for the determination of elements at the trace and ultratrace level along with the isotope ratios. The accuracy in the quantification of isotope ratios of radionuclides is essential for environmental monitoring, migration studies, dating, determination of burn-up of fuel, nuclear material accounting and radioactive waste control. Inductively coupled plasma mass spectrometry (ICP-MS) is advantageous due to its outstanding sensitivity, precision and good accuracy for isotope ratio measurements and enhanced figures of merit for the determination of isotope ratio measurements. These advantages can be enhanced by various other variations of ICP-MS like the use of a multiple ion collector device (MC-ICP-MS). The review gives an idea of the various applications in the nuclear field and touches upon some of the important elements used in nuclear industry.