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    103 results match your criteria Analytical Chemistry Insights [Journal]

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    Comparison of 3 Derivatization Methods for the Analysis of Amphetamine-Related Drugs in Oral Fluid by Gas Chromatography-Mass Spectrometry.
    Anal Chem Insights 2017 24;12:1177390117727533. Epub 2017 Aug 24.
    The Department of Forensic Chemistry, The College of Forensic Sciences, Naif Arab University for Security Sciences, Riyadh, Saudi Arabia.
    The heptafluorobutyric anhydride (HFBA), pentafluoropropionic anhydride (PFPA), and trifluoroacetic anhydride (TFAA) are compared as derivatizing reagents to use as the optimal method for the analysis of 10 amphetamines and cathinones in oral fluid. The target compounds were amphetamine (AMP), methamphetamine (MA), 4-methylamphetamine, 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxy-N-ethylamphetamine (MDEA), cathinone (CAT), methcathinone, mephedrone, and ephedrine. Amphetamine-D5, MA-D5, MDA-D5, MDMA-D5, and MDEA-D5 use as internal standards (IS). Read More

    Quality by Design-Applied Liquid Chromatography-Tandem Mass Spectrometry Determination of Enzalutamide Anti-Prostate Cancer Therapy Drug in Spiked Plasma Samples.
    Anal Chem Insights 2017 28;12:1177390117726776. Epub 2017 Aug 28.
    National Institute of Pharmaceutical Education and Research (NIPER), Kolkata, India.
    This research article presents the Quality by Design (QbD)-finalised conditions for a method that uses liquid chromatography-tandem mass spectrometry for the determination of concentration of enzalutamide (ENZ), an atypical anticancer drug, in a drug formulation and in spiked plasma samples. Critical process attributes (CPA) considered to be the influential parameters in separation, identification, and quantification processes by ultrahigh-performance liquid chromatography-electrospray ionisation-tandem mass spectrometry (UHPLC-ESI-MS/MS) were organic content, buffer strength, pH modifier, flow rate, spray voltage, sheath gas, and auxiliary gas that alter critical analytical attributes, such as retention time (R1) and area (R2). These factors were evaluated first in a factorial design (Taguchi orthogonal array design) and then extensively in a central composite design (CCD) to zero-in on the mobile phase for the quantification of ENZ standard drug and along with its internal standard (ENZIS) in spiked plasma samples and in formulation. Read More

    Synthesis and Optical Properties of Pentamethine Cyanine Dyes With Carboxylic Acid Moieties.
    Anal Chem Insights 2017 30;12:1177390117711938. Epub 2017 May 30.
    Department of Chemistry, Georgia State University, Atlanta, GA, USA.
    Cyanine dyes possessing carboxylic acid groups have been used in many different fields of study. The acid groups can act as handles for bioconjugation or as metal chelators. Several pentamethine cyanine dyes with propionic acid handles were synthesized and their optical properties were studied to determine their usefulness as fluorescent probes. Read More

    Analytical Method Validation of High-Performance Liquid Chromatography and Stability-Indicating Study of Medroxyprogesterone Acetate Intravaginal Sponges.
    Anal Chem Insights 2017 20;12:1177390117690152. Epub 2017 Feb 20.
    Department of Pharmacy, An-Najah National University, Nablus, Palestine.
    Medroxyprogesterone acetate is widely used in veterinary medicine as intravaginal dosage for the synchronization of breeding cycle in ewes and goats. The main goal of this study was to develop reverse-phase high-performance liquid chromatography method for the quantification of medroxyprogesterone acetate in veterinary vaginal sponges. A single high-performance liquid chromatography/UV isocratic run was used for the analytical assay of the active ingredient medroxyprogesterone. Read More

    Review of Current Applications of Immunohistochemistry in Pediatric Nonneoplastic Gastrointestinal, Hepatobiliary, and Pancreatic Lesions.
    Anal Chem Insights 2017 18;12:1177390117690140. Epub 2017 Apr 18.
    Department of Anatomical Pathology, Children's Hospital of Eastern Ontario (CHEO), Ottawa, ON, Canada.
    Immunohistochemical (IHC) stains are widely used by pathologists for a variety of considerations in the diagnostic workup of pediatric nonneoplastic lesions in gastrointestinal (GI), hepatic, biliary, and pancreatic lesions. The pathologic changes cover a wide range and types of presentations, including inflammatory (bacterial and viral), metaplastic, posttransplant lymphoproliferative, autoimmune, metabolic, degenerative, developmental, and genetic conditions, among others. The everyday practical value of IHC stains covers primary identification, confirmation, differential, and/or exclusionary roles in the hands and eyes and minds of the practitioners. Read More

    Colorimetric Detection Based on Localised Surface Plasmon Resonance Optical Characteristics for the Detection of Hydrogen Peroxide Using Acacia Gum-Stabilised Silver Nanoparticles.
    Anal Chem Insights 2017 23;12:1177390116684686. Epub 2017 Feb 23.
    Chemistry Department, College of Science, Taif University, Taif, Kingdom of Saudi Arabia.
    The use of nanoparticles in sensing is attracting the interest of many researchers. The aim of this work was to fabricate Acacia gum-stabilised silver nanoparticles (SNPs) using green chemistry to use them as a highly sensitive and cost-effective localised surface plasmon resonance (LSPR) colorimeter sensor for the determination of reactive oxygen species, such as hydrogen peroxide (H2O2). Silver nanoparticles were fabricated by the reduction of an inorganic precursor silver nitrate solution (AgNO3) using white sugar as the reducing reagent and Acacia gum as the stabilising reagent and a sonication bath to form uniform silver nanoparticles. Read More

    Insight into Biochemical Characterization of Plant Sesquiterpene Synthases.
    Anal Chem Insights 2016 29;11(Suppl 1):1-7. Epub 2016 Sep 29.
    Department of Biotechnology and Biomedicine, Technical University of Denmark, Kongens Lyngby, Denmark.
    A fast and reproducible protocol was established for enzymatic characterization of plant sesquiterpene synthases that can incorporate radioactivity in their products. The method utilizes the 96-well format in conjunction with cluster tubes and enables processing of >200 samples a day. Along with reduced reagent usage, it allows further reduction in the use of radioactive isotopes and flammable organic solvents. Read More

    Development of Hollow-Fiber Liquid-Phase Microextraction Method for Determination of Urinary trans,trans-Muconic Acid as a Biomarker of Benzene Exposure.
    Anal Chem Insights 2016 11;11:65-71. Epub 2016 Sep 11.
    Department of Biostatistics and Epidemiology, School of Public Health and Center of Health Research, Hamedan University of Medical Sciences, Hamedan, Iran.
    For the first time, hollow-fiber liquid-phase microextraction combined with high-performance liquid chromatography-ultraviolet was used to extract trans,trans-muconic acid, in urine samples of workers who had been exposed to benzene. The parameters affecting the metabolite extraction were optimized as follows: the volume of sample solution was 11 mL with pH 2, liquid membrane containing dihexyl ether as the supporter, 15% (w/v) of trioctylphosphine oxide as the carrier, the time of extraction was 120 minutes, and stirring rate was 500 rpm. Organic phase impregnated in the pores of a hollow fiber was extracted into 24 µL solution of 0. Read More

    Stability-Indicating High-Performance Liquid Chromatography Assay for the Determination of Sulthiame in Pharmaceutical Dosage Forms.
    Anal Chem Insights 2016 6;11:59-64. Epub 2016 Sep 6.
    Service de Pharmacie, Hôpital Jean Verdier, APHP, Hôpitaux Universitaires de Paris-Seine-Saint-Denis, Bondy, France.
    A stability-indicating assay by reversed-phase high performance liquid chromatography method was developed and validated for the determination of sulthiame (STM). The chromatographic separation was achieved on a reversed-phase NovaPack C18 column and an isocratic mobile phase consisting of deionized water:methanol (70:30, v/v). The flow rate was 1. Read More

    Extraction of Honey Polyphenols: Method Development and Evidence of Cis Isomerization.
    Anal Chem Insights 2016 10;11:49-57. Epub 2016 Aug 10.
    Laboratory of Biological and Industrial Chemistry, University of Liege-Gembloux Agro-Bio Tech, Passage des Déportés 2, B-5030 Gembloux, Belgium.
    Honey polyphenols have been studied with the objective of relating honeys to their floral sources. Initially synthesized by plant, these polyphenols can be found in the plant's nectar, which are collected by bees, which convert the nectar into honey. Consequently, polyphenols constitute minor components of honey. Read More

    On the Conflicting Estimations of Pigment Site Energies in Photosynthetic Complexes: A Case Study of the CP47 Complex.
    Anal Chem Insights 2016 2;11:35-48. Epub 2016 Jun 2.
    Department of Chemistry, Kansas State University, Manhattan, KS, USA.; Department of Physics, Kansas State University, Manhattan, KS, USA.
    We focus on problems with elucidation of site energies [Formula: see text] for photosynthetic complexes (PSCs) in order to raise some genuine concern regarding the conflicting estimations propagating in the literature. As an example, we provide a stern assessment of the site energies extracted from fits to optical spectra of the widely studied CP47 antenna complex of photosystem II from spinach, though many general comments apply to other PSCs as well. Correct values of [Formula: see text] for chlorophyll (Chl) a in CP47 are essential for understanding its excitonic structure, population dynamics, and excitation energy pathway(s). Read More

    Removal of 4-Nitrophenol from Water Using Ag-N-P-Tridoped TiO2 by Photocatalytic Oxidation Technique.
    Anal Chem Insights 2016 4;11:29-34. Epub 2016 Apr 4.
    Department of Chemistry, Haramaya University, Dire Dawa, Ethiopia.
    Photocatalytic oxidation using semiconductor nanoparticles is an efficient, eco-friendly, and cost-effective process for the removal of organic pollutants, such as dyes, pesticides, phenols, and their derivatives in water. In the present study, nanosize Ag-N-P-tridoped titanium(IV) oxide (TiO2) was prepared by using sol-gel-synthesized Ag-doped TiO2 and soybean (Glycine max) or chickpea (Cicer arietinum) seeds as nonmetallic bioprecursors. As-synthesized photocatalysts were characterized using X-ray diffraction, Fourier transform infrared, and ultra violet (UV)-visible spectroscopic techniques. Read More

    Quality Issues of Research Antibodies.
    Anal Chem Insights 2016 20;11:21-7. Epub 2016 Mar 20.
    Bundesanstalt für Materialforschung und -prüfung (BAM), Division 1.5 Protein Analysis, Richard-Willstätter-Strasse 11, 12489 Berlin, Germany.
    According to several recent studies, an unexpectedly high number of landmark papers seem to be not reproducible by independent laboratories. Nontherapeutic antibodies used for research, diagnostic, food analytical, environmental, and other purposes play a significant role in this matter. Although some papers have been published offering suggestions to improve the situation, they do not seem to be comprehensive enough to cover the full complexity of this issue. Read More

    Development and Validation of Stability-Indicating RP-HPLC Method for Simultaneous Determination of Metformin HCl and Glimepiride in Fixed-Dose Combination.
    Anal Chem Insights 2016 13;11:13-20. Epub 2016 Mar 13.
    Department of Pharmaceutical Sciences and Technology, Institute of Chemical Technology, Elite Status and Centre of Excellence-Government of Maharashtra, Matunga (E), Mumbai, Maharashtra, India.
    A simple reversed-phase high-performance liquid chromatography method was developed and validated for simultaneous determination of Metformin hydrochloride (MET) and Glimepiride (GLM) in combination and estimation of their principal degradation products. The separation was achieved using JASCO Finepak SIL (250 mm × 4.6 mm i. Read More

    Electrochemical Behavior and Voltammetric Determination of a Manganese(II) Complex at a Carbon Paste Electrode.
    Anal Chem Insights 2016 18;11:1-11. Epub 2016 Jan 18.
    Department of Analytical Chemistry, Aristotle University of Thessaloniki, Panepistimioupoli, Thessaloniki, Greece.
    Investigation of the electrochemical behavior using cyclic voltammetry and detection of [Mn(2+)(thiophenyl-2-carboxylic acid)2 (triethanolamine)] with adsorptive stripping differential pulse voltammetry. The electrochemical behavior of a manganese(II) complex [Mn(2+)(thiophenyl-2-carboxylic acid)2(triethanolamine)] (A) was investigated using cyclic and differential pulse voltammetry in an acetate buffer of pH 4.6 at a carbon paste electrode. Read More

    Sample Preparation of Eggs From Laying Hens Using QuEChERS Dispersive Extraction for the Simultaneous Determination of Melamine and Cyromazine Residues by HPLC-DAD.
    Anal Chem Insights 2015 20;10:53-8. Epub 2015 Dec 20.
    Department of Chemistry, Laboratory of Analytical Chemistry, Aristotle University of Thessaloniki, Thessaloniki, Greece.
    A quick, easy, cheap, effective, rugged, and safe (QuEChERS) dispersive extraction method is proposed herein for the isolation and cleanup of melamine and cyromazine from chicken egg yolk. Analytes are determined by high-performance liquid chromatography using photodiode array detector after separation on a LiChroCART® (250 × 4 mm)-LiChrospher® RP-8e, 5 μm analytical column using a mobile phase of 0.1% trifluoracetic acid and methanol (80:20 v/v) delivered isocratically at a flow rate of 1 mL/minute. Read More

    A High-Performance Thin Layer Chromatography (HPTLC) Method for Simultaneous Determination of Diphenhydramine Hydrochloride and Naproxen Sodium in Tablets.
    Anal Chem Insights 2015 3;10:47-51. Epub 2015 Dec 3.
    Quality Assurance Techniques Department, Dr. D.Y. Patil Institute of Pharmaceutical Sciences and Research, Pimpri, Pune, Maharashtra, India.
    A rapid and simple high-performance thin layer chromatography (HPTLC) method with densitometry at 230 nm was developed and validated for simultaneous determination of diphenhydramine hydrochloride (DPH) and naproxen sodium (NPS) from pharmaceutical preparation. The separation was carried out on aluminum plates precoated with silica gel 60 F254 using mobile phase toluene:methanol:glacial acetic acid (7.5:1:0. Read More

    Organ-on-a-Chip: New Platform for Biological Analysis.
    Anal Chem Insights 2015 29;10:39-45. Epub 2015 Nov 29.
    School of Pharmaceutical Science and Technology, Dalian University of Technology, Dalian, China. ; State Key Laboratory of Fine Chemicals, Department of Chemical Engineering, Dalian University of Technology, Dalian, China.
    Direct detection and analysis of biomolecules and cells in physiological microenvironment is urgently needed for fast evaluation of biology and pharmacy. The past several years have witnessed remarkable development opportunities in vitro organs and tissues models with multiple functions based on microfluidic devices, termed as "organ-on-a-chip". Briefly speaking, it is a promising technology in rebuilding physiological functions of tissues and organs, featuring mammalian cell co-culture and artificial microenvironment created by microchannel networks. Read More

    Spectrophotometric Investigations of Macrolide Antibiotics: A Brief Review.
    Anal Chem Insights 2015 12;10:29-37. Epub 2015 Nov 12.
    Department of Chemistry, R. T. M. Nagpur University, Nagpur, India.
    Macrolides, one of the most commonly used class of antibiotics, are a group of drugs produced by Streptomyces species. They belong to the polyketide class of natural products. Their activity is due to the presence of a large macrolide lactone ring with deoxy sugar moieties. Read More

    Immunohistochemical Markers of Soft Tissue Tumors: Pathologic Diagnosis, Genetic Contributions, and Therapeutic Options.
    Anal Chem Insights 2015 29;10(Suppl 1):1-10. Epub 2015 Oct 29.
    Department of Pathology and Laboratory Medicine, Children's Hospital Los Angeles, Los Angeles, CA, USA. ; Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
    After ~30 years of widespread usage, immunohistochemistry (IHC) has become a standard method of diagnosis for surgical pathology. Because of the plethora of diagnoses and often subtle nature of diagnostic criteria, IHC finds particular utility in soft tissue tumors. The use of progressively small amounts of tissue for diagnosis highlights the importance of this method. Read More

    Organophosphate Hydrolase in Conductometric Biosensor for the Detection of Organophosphate Pesticides.
    Anal Chem Insights 2015 7;10:23-7. Epub 2015 Oct 7.
    Chemistry Department, Faculty of Mathematics and Natural Sciences, Brawijaya University, Malang, Indonesia.
    The research has developed an enzyme biosensor for the detection organophosphate pesticide residues. The biosensor consists of a pair of screen-printed carbon electrode (SPCEs). One of electrodes contains immobilized organophosphate hydrolase (OPH) on a chitosan membrane by cross-linking it with glutaraldehyde. Read More

    Determination and Validation of a Solid-phase Extraction Gas Chromatography-mass Spectrometry for the Quantification of Methadone and Its Principal Metabolite in Human Plasma.
    Anal Chem Insights 2015 26;10:17-22. Epub 2015 Aug 26.
    Department of Forensic Laboratory, Jean Verdier Hospital-APHP, University Hospitals of Paris Seine Saint-Denis, Bondy, France. ; Department of Pharmacy, Jean Verdier Hospital-APHP, University Hospitals of Paris Seine Saint-Denis, Bondy, France.
    This study aimed to develop a solid-phase extraction gas chromatography-selected ion monitoring-mass spectrometry method for the determination of methadone (MDN) and 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) in human plasma. The linear response was obtained over the concentration range from 10 to 2000 ng/mL for MDN and EDDP. The absolute recoveries of MDN and EDDP were 95. Read More

    Spectrophotometric Determination of Cefixime Trihydrate in Pharmaceutical Formulations Based on Ion-Pair Reaction with Bromophenol Blue.
    Anal Chem Insights 2015 27;10:11-6. Epub 2015 Jul 27.
    Department of Chemistry, R. T. M. Nagpur University, Nagpur, India.
    Cefixime trihydrate is a broad spectrum cephalosporin antibiotic, effective against gram-positive and gram-negative bacterial infections. Simple and rapid method has been developed for the determination of cefixime trihydrate in bulk and pharmaceutical formulations. This method was based on the formation of bluish-green ion-pair complex of cefixime trihydrate with bromophenol blue in dimethyl sulfoxide (DMSO)-acetonitrile medium. Read More

    Determination of Chlorophenoxy Acid Methyl Esters and Other Chlorinated Herbicides by GC High-resolution QTOFMS and Soft lonization.
    Anal Chem Insights 2015 9;10:1-9. Epub 2015 Feb 9.
    Agilent Technologies, Santa Clara, CA, USA.
    Gas chromatography with quadrupole time-of-flight mass spectrometry (GC-QTOFMS) and soft ionization generated by a rare-gas plasma is described here for the determination of various chlorophenoxy acid methyl esters and a few chlorinated herbicides. This plasma-based, wavelength-selectable ionization source, which can use Xe, Kr, Ar, Ne, or He as the plasma gas, enables ionization of GC-amenable compounds with ionization energies below 8.4, 10, 11. Read More

    A Study of Method Development, Validation, and Forced Degradation for Simultaneous Quantification of Paracetamol and Ibuprofen in Pharmaceutical Dosage Form by RP-HPLC Method.
    Anal Chem Insights 2014 18;9:75-81. Epub 2014 Nov 18.
    Drug Analysis and Research Laboratory, Centre for Advanced Research in Sciences, University of Dhaka, Dhaka, Bangladesh.
    A rapid and stability-indicating reversed phase high-performance liquid chromatography (RP-HPLC) method was developed for simultaneous quantification of paracetamol and ibuprofen in their combined dosage form especially to get some more advantages over other methods already developed for this combination. The method was validated according to United States Pharmacopeia (USP) guideline with respect to accuracy, precision, specificity, linearity, solution stability, robustness, sensitivity, and system suitability. Forced degradation study was validated according to International Conference on Harmonisation (ICH). Read More

    A Continuous Flow System for the Measurement of Ambient Nitrogen Oxides [NO + NO2] Using Rhodamine B Hydrazide as a Chemosensor.
    Anal Chem Insights 2014 17;9:67-73. Epub 2014 Aug 17.
    PG-Department of Chemistry, NMKRV College for Women, Jayanagar, Bangalore-560011, India.
    A new chemosensor has been used to monitor atmospheric nitrogen oxides [NO + NO2] at parts per billion (ppb) level. It is based on the catalytic reaction of nitrogen oxides with rhodamine B hydrazide (RBH) to produce a colored compound through the hydrolysis of the amide bond of the molecule. A simple colorimeter has been used to monitor atmospheric nitrogen dioxide at ppb level. Read More

    Preliminary development of a fiber optic sensor for measuring bilirubin.
    Anal Chem Insights 2014 1;9:59-65. Epub 2014 Jul 1.
    Applied Physics Laboratory, Johns Hopkins University, Laurel, MD, USA.
    Preliminary development of a fiber optic bilirubin sensor is described, where an unclad sensing portion is used to provide evanescent wave interaction of the transmitted light with the chemical environment. By using a wavelength corresponding to a bilirubin absorption peak, the Beer-Lambert Law can be used to relate the concentration of bilirubin surrounding the sensing portion to the amount of absorbed light. Initial testing in vitro suggests that the sensor response is consistent with the results of bulk absorption measurements as well as the Beer-Lambert Law. Read More

    Determination of xanthine in the presence of hypoxanthine by adsorptive stripping voltammetry at the mercury film electrode.
    Anal Chem Insights 2014 9;9:49-55. Epub 2014 Jun 9.
    Department of Chemistry, Pontifícia Universidade Católica, Rua Marquês de São Vicente, Rio de Janeiro, Brazil. ; Facultad Quimica, Quimica Analitica, Universidad de La Habana, Cuba.
    A stripping method for the determination of xanthine in the presence of hypoxanthine at the submicromolar concentration levels is described. The method is based on controlled adsorptive accumulation at the thin-film mercury electrode followed by a fast linear scan voltammetric measurement of the surface species. Optimum experimental conditions were found to be the use of 1. Read More

    Kinetic Study of the Alkaline Degradation of Oseltamivir Phosphate and Valacyclovir Hydrochloride using Validated Stability Indicating HPLC.
    Anal Chem Insights 2014 27;9:41-8. Epub 2014 May 27.
    National Organization for Drug Control and Research (NODCAR), Dokki, Giza, Egypt.
    Aqueous alkaline degradation was performed for oseltamivir phosphate (OP) and valacyclovir hydrochloride (VA). Isocratic stability indicating the use of high-performance liquid chromatography (HPLC) was presented for each drug in the presence of its degradation product. The separations were performed using the Nucleosil ODS column and a mobile phase consisting of phosphate buffer (pH = 7), acetonitrile, and methanol 50:25:25 (v/v/v) for OP. Read More

    A UPLC-MS Method for the Determination of Ofloxacin Concentrations in Aqueous Humor.
    Anal Chem Insights 2014 5;9:27-32. Epub 2014 May 5.
    Department of Ophthalmology, Medical School, University of Patras, Patras, Greece.
    A rapid, simple, and specific method based on ultra performance liquid chromatography (UPLC) with mass spectrometry detection has been developed for quantitative analysis of ofloxacin in human aqueous humor using tobramycin as internal standard (IS). Chromatographic separation was achieved on a Waters Acquity UPLC BEH C18 Shield column (150 × 2.1 mm, 1. Read More

    Spectrophotometric and spectrofluorimetric studies on azilsartan medoxomil and chlorthalidone to be utilized in their determination in pharmaceuticals.
    Anal Chem Insights 2014 7;9:33-40. Epub 2014 May 7.
    Department of Chemistry, Georgia State University, Atlanta, GA, USA.
    The recently approved angiotensin II receptor blocker, azilsartan medoxomil (AZL), was determined spectrophotometrically and spectrofluorimetrically in its combination with chlorthalidone (CLT) in their combined dosage form. The UV-spectrophotometric technique depends on simultaneous measurement of the first derivative spectra for AZL and CLT at 286 and 257 nm, respectively, in methanol. The spectrofluorimetric technique depends on measurement of the fourth derivative of the synchronous spectra intensities of AZL in presence of CLT at 298 nm in methanol. Read More

    Application of Nanofiber-packed SPE for Determination of Urinary 1-Hydroxypyrene Level Using HPLC.
    Anal Chem Insights 2014 22;9:17-25. Epub 2014 Apr 22.
    Department of Chemistry, Rhodes University, Grahamstown, South Africa.
    It is always desirable to achieve maximum sample clean-up, extraction, and pre-concentration with the minimum possible organic solvent. The miniaturization of sample preparation devices was successfully demonstrated by packing 10 mg of 11 electrospun polymer nanofibers into pipette tip micro column and mini disc cartridges for efficient pre-concentration of 1-hydroxypyrene in urine samples. 1-hydroxypyrene is an extensively studied biomarker of the largest class of chemical carcinogens. Read More

    Buprenorphine and norbuprenorphine determination in mice plasma and brain by gas chromatography-mass spectrometry.
    Anal Chem Insights 2014 10;9:9-16. Epub 2014 Mar 10.
    Laboratoire de toxicologie de médecine légale, Hôpital Jean Verdier - APHP, Bondy, France.
    A gas chromatography tandem mass spectrometry method for quantification of buprenorphine (BUP) and norbuprenorphine (NBUP) in brain and plasma samples from mice was developed and validated. Analytes were extracted from the brain or plasma by solid phase extraction and quantified within 20 minutes. Calibration was achieved by linear regression with a 1/x weighting factor and d4-buprenorphine internal standard. Read More

    Synthesis and Characterization of Maillard Reaction Products of Salbutamol and Terbutaline with Lactose and Development and Validation of an LC Method for the Determination of Salbutamol and Terbutaline in the Presence of These Impurities.
    Anal Chem Insights 2014 2;9:1-7. Epub 2014 Mar 2.
    Pharmaceutical Chemistry Department, Faculty of Pharmacy, Cairo University, Cairo, Egypt.
    Being secondary amines, both salbutamol (SLB) and terbutaline (TRB) react by Maillard reaction (MR) with lactose, which is added as an inactive ingredient in tablets. The Amadori rearrangement products were synthesized, isolated, and characterized by mass spectrometry. In addition, a simple, selective, and precise reversed-phase liquid chromatography (LC) method was developed and validated for the determination of SLB and TRB in tablets, each in the presence of its MR impurity. Read More

    Simultaneous determination of amlodipine besylate and atorvastatin calcium in binary mixture by spectrofluorimetry and HPLC coupled with fluorescence detection.
    Anal Chem Insights 2013 4;8:107-15. Epub 2013 Nov 4.
    Pharmaceutical Chemistry Department, Faculty of Pharmacy, Cairo University, Cairo, Egypt.
    Caduet tablets are novel prescription drug that combines amlodipine besylate (AM) with atorvastatin calcium (AT). A spectrofluorimetric and an HPLC-fluorescence detection methods were developed for simultaneous determination of both drugs in tablets. In the spectrofluorimetric method, native fluorescence of AM and AT were measured in methanol at 442 and 369 nm upon excitation at 361 and 274 nm, respectively. Read More

    Development and Validation of RP-LC Method for the Determination of Cinnarizine/Piracetam and Cinnarizine/Heptaminol Acefyllinate in Presence of Cinnarizine Reported Degradation Products.
    Anal Chem Insights 2013 7;8:99-106. Epub 2013 Oct 7.
    National Organization for Drug Control and Research (NODCAR), Agouza, Giza, Egypt.
    Specific stability indicating reverse-phase liquid chromatography (RP-LC) assay method (SIAM) was developed for the determination of cinnarizine (Cinn)/piracetam (Pira) and cinnarizine (Cinn)/heptaminol acefyllinate (Hept) in the presence of the reported degradation products of Cinn. A C18 column and gradient mobile phase was applied for good resolution of all peaks. The detection was achieved at 210 nm and 254 nm for Cinn/Pira and Cinn/Hept, respectively. Read More

    The evaluation of two commercially available, portable Raman systems.
    Anal Chem Insights 2013 Sep 10;8:83-97. Epub 2013 Sep 10.
    SPAWAR Systems Center Pacific, San Diego, CA.
    Raman spectroscopy and surface enhanced Raman spectroscopy (SERS) have many attributes that make them attractive for field detection of environmental contaminants, industrial process control, as well as materials detection/identification in agriculture, pharmaceuticals, law enforcement/first responders, geology, and archeology. However, portable, robust, inexpensive Raman systems are required for these applications. In this communication, the performances of two commercially available, portable Raman systems are evaluated. Read More

    RP-LC and TLC Densitometric Determination of Paracetamol and Pamabrom in Presence of Hazardous Impurity of Paracetamol and Application to Pharmaceuticals.
    Anal Chem Insights 2013 5;8:73-81. Epub 2013 Sep 5.
    National Organization for Drug Control and Research, Giza, Egypt.
    Two simple, accurate and reproducible methods were developed and validated for the simultaneous determination of paracetamol (PARA) and pamabrom (PAMB) in pure form and in tablets. The first method was based on reserved-phase high-performance liquid chromatography, on a Thermo Hypersil ODS column using methanol:0.01 M sodium hexane sulfonate:formic acid (67. Read More

    Development of Methods for the Determination of pKa Values.
    Anal Chem Insights 2013 8;8:53-71. Epub 2013 Aug 8.
    Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Eindhoven, The Netherlands.
    The acid dissociation constant (pKa) is among the most frequently used physicochemical parameters, and its determination is of interest to a wide range of research fields. We present a brief introduction on the conceptual development of pKa as a physical parameter and its relationship to the concept of the pH of a solution. This is followed by a general summary of the historical development and current state of the techniques of pKa determination and an attempt to develop insight into future developments. Read More

    Biochemical characteristics of organic matter in a guano concretion of late miocene or pliocene age from manchester parish in Jamaica.
    Anal Chem Insights 2013 18;8:41-52. Epub 2013 Jun 18.
    International Centre for Environmental and Nuclear Sciences, University of the West Indies, Mona, Kingston 7, Jamaica.
    The biogeochemical fate of organic matter (OM) entering soils is an important issue that must be examined to better understand its roles in nitrogen cycling and as a natural modulator of soil-atmospheric carbon fluxes. Despite these critical roles, there are uncertainties in estimating the contribution of this feedback mechanism due in part to a lack of molecular-level information regarding the origin and labile and refractory inventories of OM in soils. In this study, we used a multi-analytical approach to determine molecular-level information for the occurrence and stabilization of OM in a bird guano concretion of the Late Miocene or Pliocene age in Jamaica. Read More

    Evidence for the Presence of 1,3-Dimethylamylamine (1,3-DMAA) in Geranium Plant Materials.
    Anal Chem Insights 2013 6;8:29-40. Epub 2013 Jun 6.
    ENVIRON International Corp., Tampa, Florida.
    1,3-Dimethylamylamine (1,3-DMAA) is an aliphatic amine with stimulant properties that are reportedly found naturally only in geranium plants (Pelargonium graveolens). The presence of 1,3-DMAA in geranium plants was first reported in a paper published in 1996, but some have questioned the identification of 1,3-DMAA in that study. Since then, a number of additional studies have been published, largely reporting the absence of 1,3-DMAA in geranium plants and commercial geranium oils. Read More

    Determination of the antiretroviral drug acyclovir in diluted alkaline electrolyte by adsorptive stripping voltammetry at the mercury film electrode.
    Anal Chem Insights 2013 20;8:21-8. Epub 2013 May 20.
    Department of Chemistry, Pontifícia Universidade Católica do Rio de Janeiro, Rio de Janeiro, RJ, Brazil. ; Facultad de Quimica, Química Analítica, Universidad de La Habana, Cuba.
    This paper describes a stripping method for the determination of acyclovir at the submicromolar concentration level. This method is based on controlled adsorptive accumulation of acyclovir at thin-film mercury electrode, followed by a linear cyclic scan voltammetry measurement of the surface species. Optimal experimental conditions include a NaOH solution of 2. Read More

    Utility of Experimental Design in Pre-Column Derivatization for the Analysis of Tobramycin by HPLC-Fluorescence Detection: Application to Ophthalmic Solution and Human Plasma.
    Anal Chem Insights 2013 16;8:9-20. Epub 2013 Apr 16.
    Pharmaceutical Chemistry Department, Faculty of Pharmacy, Cairo University, Kasr El-Aini St., Cairo, Egypt.
    A novel, selective, and sensitive reversed phase high-performance liquid chromatography (HPLC) method coupled with fluorescence detection has been developed for the determination of tobramycin (TOB) in pure form, in ophthalmic solution and in spiked human plasma. Since TOB lacks UV absorbing chromophores and native fluorescence, pre-column derivatization of TOB was carried out using fluorescamine reagent (0.01%, 1. Read More

    A Rapid Stability-Indicating RP-HPLC Method for the Determination of Betaxolol Hydrochloride in Pharmaceutical Tablets.
    Anal Chem Insights 2013 11;8:1-7. Epub 2013 Mar 11.
    Unit of Pharmacy, Hôpital Jean Verdier (APHP), Bondy, France.
    A stability-indicating reversed-phase high performance liquid chromatography (RP-HPLC) method was developed for the determination of betaxolol hydrochloride, a drug used in the treatment of hypertension and glaucoma. The desired chromatographic separation was achieved on a Nucleosil C18, 4 μm (150 × 4.6 mm) column, using isocratic elution at a 220 nm detector wavelength. Read More

    Evaluation of matrix-assisted laser desorption/ionization mass spectrometry for second-generation lignin analysis.
    Anal Chem Insights 2012 13;7:79-89. Epub 2012 Dec 13.
    Unit of Biological and Industrial Chemistry, Gembloux Agro-Bio Tech, University of Liege, Gembloux, Belgium.
    Matrix-Assisted Laser Desorption/Ionization time-of-flight (MALDI-TOF) mass spectrometry is evaluated as an elucidation tool for structural features and molecular weights estimation of some extracted herbaceous lignins. Optimization of analysis conditions, using a typical organic matrix, namely α-cyano-4-hydroxycinnamic acid (CHCA), in combination with α-cyclodextrin, allows efficient ionization of poorly soluble lignin materials and suppression of matrix-related ions background. Analysis of low-mass fragments ions (m/z 100-600) in the positive ion mode offers a "fingerprint" of starting lignins that could be a fine strategy to qualitatively identify principal inter-unit linkages between phenylpropanoid units. Read More

    Analysis and Confirmation of 1,3-DMAA and 1,4-DMAA in Geranium Plants Using High Performance Liquid Chromatography with Tandem Mass Spectrometry at ng/g Concentrations.
    Anal Chem Insights 2012 8;7:59-78. Epub 2012 Nov 8.
    Department of Chemistry, The University of Memphis, Memphis, TN, USA.
    1,3-Dimethylamylamine (1,3-DMAA) is a stimulant commercially sold in a variety of dietary supplements as a chemical species derived from geranium plants (Pelargonium graveolens). Whether 1,3-DMAA naturally occurs in geranium plants or other dietary ingredients, it has important regulatory and commercial ramifications. However, the analysis of 1,3-DMAA in geranium plants is not trivial due to low concentrations and a complex environmental matrix, requiring high selectivity and sensitivity. Read More

    Identification and quantification of dimethylamylamine in geranium by liquid chromatography tandem mass spectrometry.
    Anal Chem Insights 2012 6;7:47-58. Epub 2012 Aug 6.
    Intertek-AAC Labs, 711 Parkland Court, Champaign, Illinois, 61821.
    A sensitive and reliable method of liquid chromatography-electrospray ionization/tandem mass spectrometry (LC-ESI/MS/ MS) was developed and validated for determining 1,3-dimethylamylamine (1,3-DMAA) and 1,4-dimethylamylamine (1,4-DMAA) in geranium plants (Pelargonium graveolens). The sample was extracted with 0.5 M HCl and purified by liquid-liquid partition with hexane. Read More

    Simultaneous determination of sitagliptin and metformin in pharmaceutical preparations by capillary zone electrophoresis and its application to human plasma analysis.
    Anal Chem Insights 2012 30;7:31-46. Epub 2012 Jul 30.
    Department of Chemistry, Georgia State University, PO Box 4098, Atlanta, Georgia 30302-4098, USA.
    A novel, quick, reliable and simple capillary zone electrophoresis CZE method was developed and validated for the simultaneous determination of sitagliptin (SG) and metformin (MF) in pharmaceutical preparations. Separation was carried out in fused silica capillary (50.0 cm total length and 43. Read More

    A calculation model for serum ionized calcium based on an equilibrium equation for complexation.
    Anal Chem Insights 2012 4;7:23-30. Epub 2012 Jul 4.
    Faculty of Health Sciences, Kobe University Graduate School of Health Sciences, Kobe, Japan.
    Measurement of ionized calcium is more important than measurement of total calcium in serum samples. In the present study, equations were derived from complexation and acid dissociation equilibrium equations, and were used to determine the concentration of ionized calcium from the observed serum concentrations of total calcium, albumin, total protein, and inorganic phosphate. The ionized calcium concentration was calculated in 67 serum samples from healthy subjects and 34 outpatients previously identified as having abnormal serum calcium levels. Read More

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