Transition Ions Research Articles

Theory of coupled ion-electron transfer kinetics

The microscopic theory of chemical reactions is based on transition state theory, where atoms or ions transfer classically over an energy barrier, as electrons maintain their ground state. Electron transfer is fundamentally different and occurs by tunneling in response to solvent fluctuations. Here, we develop the theory of coupled ion-electron transfer, in which ions and solvent molecules fluctuate cooperatively to facilitate non-adiabatic electron transfer. We derive a general formula of the reaction rate that depends on the overpotential, solvent properties, the electronic structure of the electron donor/acceptor, and the excess chemical potential of ions in the transition state. For Faradaic reactions, the theory predicts curved Tafel plots with a concentration-dependent reaction-limited current. For moderate overpotentials, our formula reduces to the Butler–Volmer equation and explains its relevance, not only in the well-known limit of large electron-transfer (solvent reorganization) energy, but also in the opposite limit of large ion-transfer energy. The rate formula is applied to Li-ion batteries, where reduction of the electrode host material couples with ion insertion. In the case of lithium iron phosphate, the theory accurately predicts the concentration dependence of the exchange current measured by in operando X-Ray microscopy without any adjustable parameters. These results pave the way for interfacial engineering to enhance ion intercalation rates, not only for batteries, but also for ionic separations and neuromorphic computing.

Synthesis, Characterization and antibacterial Study of some Complexes Derivatives from1,3,4– Thiadiazole Schiff base

The present study included preparing a new ligand from the thiadiazole derivatives from react between 1,2,5-dihydrazine, 1,3,4-thiadiazol with 4-Dimethyl amino benzaldehyde with a ratio of (1:2) to preparing the ligand (L1) Transition ions complexes (Co+3, Cu+2) were prepared with ligand (L1), the ligand and its complexes were characterized using the elemental analysis (C.H.N.S), Infrared spectrum (FTIR), proton nuclear magnetic resonance spectrum (1H-NMR), Mass spectroscopy, magnetic sensitivity, and molar conductivity, the practical results were exactly in line with the molecular formula and structural formulas for the compounds. The program (Hyper Chem) was used to draw ligands and their complexes and to show the distribution of electron density.The results obtained from the study of magnetic sensitivity and molar conductivity of the prepared ligand complexes confirmed that the geometry shape of [L1CoCl3] is an octahedral complex, while [L1CuCl2] is a square planner complex. The results of molar conductivity also confirmed that the prepared cobalt complex is electrolytic, while the [L1CuCl2] complex is non-electrolytic.The biological activity of the prepared ligand and its complexes were tested against two types of bacteria Staphylococcus aureus and Escherichia Coli in comparison with the standard inhibitor (Ciprofloxacin), the obtained results confirmed the biological activity of the prepared ligand was more than the standard inhibitor (Cipro) against Escherichia coli also the complexes (A1, A2) showed higher biological activity than the standard inhibitor (Cipro) against Escherichia coli (Gram-negative), the ligand and its prepared complexes don’t show biological activity against Staphylococcus aureus(Gram-positive).

Luminescence dynamics of Eu3+ activated and co-activated defect spinel zinc titanate nanophosphor for applications in WLEDs

The luminescence properties of novel Eu3+ doped and (Li+,Ni2+) co-doped ZnTiO3 nanophosphors were reported in this work. The powder samples were fabricated via the facile solution combustion technique. The structural and photoluminescence characteristics of ZnTiO3:0.0075Eu3+ nanophosphor are influenced by calcination temperature and co-doped ions. Under the excitation by near UV and blue light, the red luminescence of prepared nanophosphor appeared owing to strong absorption and efficient energy transfer mechanism. In the developed nanophosphors, the enhancement red emission is only possible in the presence of Li+ and Ni2+ ions. Phase transformation in high temperature form of zinc titanate improves the non-radiative transition and co-dopant ions in phase pure defect spinel can increase the rate of radiative transition. The photometric characterizations hint that the nanophosphor materials proved to be highly beneficial for the red light emission in WLEDs applications.

Coprecipitation synthesis of Co-doped LiMn1.5Ni0.5O4 material as 5 V cathode of Li-ion batteries with huge rate capability for high power applications

LiMn1.5-yNi0.5-yCo2yO4 (y = 0.05 and 0.1) materials were synthesized at 800 and 900 °C by co-precipitation method. The samples prepared at 800 °C have small particle size (~ 300 nm). The ones at 900 °C showed a double distribution of the particles; one at 800 nm and the other at 1.4 μm. At 1C-rate, the capacity retention after 50 cycles increases from 81% (y = 0.05) and 78% (y = 0.1), for the 800 °C samples, to 98% (y = 0.05) and 95% (y = 0.1), for the 900 °C samples. At high rate capability, the 900 °C samples showed the best electrochemical behavior; the obtained Qdch at 30C-rate were 86.5mAh/g, for LiMn1.45Ni0.45Co0.1O4 and 85mAh/g for LiMn1.4Ni0.4Co0.2O4 with retention of 71.1% and 66.7%, respectively. This good behavior is due to the low electrolyte decomposition, the low metal transition ions dissolution in the electrolyte and the better diffusion and migration of the Li+ in the bulk of the electrodes. The LiMn1.45Ni0.45Co0.1O4 material exhibits the highest rate capability to date with an outstanding power and energy densities of 12.2 kW/kg and 400 Wh/kg. The LiMn1.45Ni0.45Co0.1O4 material is a promising cathode for Li-ion batteries destined to high-power applications.

UHPLC-MS/MS profiling of histidine and bile acid metabolism in human gastric fluid for diagnosis of gastric diseases

Bile acids (BAs) are synthesized in the liver and can mediate homeostasis and various metabolism processes in the human body. Their levels in the gastrointestinal tract are closely related to various gastrointestinal diseases. In particular, farnesoid X receptor activated by free BAs is associated with overexpression of histidine decarboxylase in tumorigenesis. Therefore, comprehensive profiling of histamine (HIST), histidine (His), and BAs in biological samples can provide insight into the pathological mechanisms of gastrointestinal diseases. However, development of an analytical platform to profile HIST, His, and BAs in biological samples has several challenges such as highly different polarities between acidic and basic targets, low physiological concentrations of analytes, and high matrix interference of biological samples. In this study, an ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method combined with serial derivatization was developed to simultaneously determine HIST, His, and 5 BAs (cholic acid, deoxycholic acid, chenodeoxycholic acid, ursodeoxycholic acid, and lithocholic acid) in human gastric fluid. In serial derivatization, benzoyl chloride (BzCl) and N,N-dimethylethylenediamine (DMED) were used to selectively derivatize amino and carboxyl groups of analytes, respectively. After serial derivatization, all target derivatives were determined using a reverse-phase C18 LC column and positive multiple reaction monitoring (MRM) mode, with reasonable chromatographic separation and sensitive MS detection. To accurately quantify target metabolites, 7 stable isotope-labeled internal standards were used. The MS/MS spectra of DMED and Bz derivatives exhibited specific fragments via loss of a neutral molecule (dimethylamine; 45 Da) and inductive cleavage (benzoyl; m/z 105) from protonated molecules, enabling selection of appropriate MRM transition ions for selective and sensitive detection. The developed method was validated with respect to limits of detection and quantification, linearity, precision, accuracy, stability, and matrix effect. The established method was successfully applied to human gastric fluid samples. This method provides reliable quantification of HIST, His, and BAs in human gastric fluid and will be helpful to understand pathophysiological mechanisms of gastric diseases.

Investigation of vacuum ultraviolet photoionization of methylcyclohexane in energy region of 9−15.5 eV

Vacuum ultraviolet (VUV) photoionization and photodissociation of methylcyclohexane have been studied utilizing a reflectron time-of-flight mass spectrometer (RTOF-MS) with synchrotron radiation source. Photoionization efficiency curves (PIEs) of molecule ion C7H14+ and fragment ions C7H13+, C6H11+, C6H10+, C5H10+, C5H9+, C4H8+, C4H7+, and C3H5+ were observed. The ionization energy of methylcyclohexane was measured to be (9.80±0.03) eV, and appearance energies of fragment ions were determined from the PIEs. Optimized structures of transitional states, intermediates and product ions were characterized at the B3LYP/6-31G(d) level and the energies were calculated using G3B3 method. Formation channels of dominating fragment ions were proposed. Intramolecular hydrogen migrations and carbon ring-opening were the foremost processes in fragmentation pathways of methylcyclohexane.

Formation of Samin Diastereomers by Acid-Catalyzed Transformation of Sesamolin with Hydrogen Peroxide.

The conversion of sesame lignans is of interest because the derived products may have potential applications. Here, in investigating the transformation of sesamin and sesamolin, main endogenous sesame lignans in sesame seeds, in both acidic aqueous and anhydrous systems, 7R,7'S-samin was identified as one of the major products of sesamolin in both systems catalyzed with common inorganic acids, but sesaminol was not generated. In investigating the effect of different oxidizing agents on the acid-catalyzed conversion of sesame lignans, 7R,7'S-samin was still the major product of sesamolin, whereas sesamolin as well as 7R,7'S-samin stereoselectively rendered 7R,7'R-samin in the presence of hydrogen peroxide. Hydrogen peroxide may play a role in stabilizing the transitional oxonium ions, derived from acid hydrolysis of sesamolin or 7R,7'S-samin by forming a seven-membered ring intermediate through hydrogen bonding, to consequently produce 7R,7'R-samin as the final product.

Mapping Magnetic Properties and Relaxation in Vanadium(IV) Complexes with Lanthanides by Electron Paramagnetic Resonance.

Vanadium(IV) complexes are actively studied as potential candidates for molecular spin qubits operating at room temperatures. They have longer electron spin decoherence times than many other transition ions, being the key property for applications in quantum information processing. In most cases reported to date, the molecular complexes were optimized through the design for this purpose. In this work, we investigate the relaxation properties of vanadium(IV) ions incorporated in complexes with lanthanides using electron paramagnetic resonance (EPR). In all cases, the VO6 moieties with no nuclear spins in the first coordination sphere are addressed. We develop and implement the approaches for facile diagnostics of relaxation characteristics in individual VO6 moieties of such compounds. Remarkably, the estimated relaxation times are found to be close to those of other vanadium-based qubits obtained previously. In the future, a synergistic combination of qubit-friendly properties of vanadium ions with single-molecule magnetism and luminescence of lanthanides can be pursued to realize new functionalities of such materials.

Matrix-assisted photochemical vapor generation for determination of trace bismuth in Fe[sbnd]Ni based alloy samples by inductively coupled plasma mass spectrometry

As the impurities in alloy may affect its mechanical and physical properties, the determination of trace elements is important to ensure the quality of alloy. However, accurate determination of trace impurities in alloy samples is a big challenge due to their complicated matrix and low concentrations. In this work, matrix-assisted photochemical vapor generation (PVG) was developed for the determination of impurity in alloy samples by inductively coupled plasma mass spectrometry (ICPMS). Bismuth was selected as the target element, which is detrimental to the strength of alloy even at very low concentration. The transition ions existed in alloy worked as the “sensitizers” for the efficient PVG of bismuth, and only formic acid and acetic acid were required for the analysis of alloy samples after digestion. This largely reduced the risks of sample contamination and analyte loss in multiple sample pretreatment involved in conventional analytical methods. The PVG efficiency of bismuth was greatly enhanced, making the sensitive and simple determination of trace analytes in alloy samples feasible. The limit of detection (LOD, 3σ) for Bi was found to be 0.4 ng L−1 corresponding to 0.54 ng g−1 for analysis of 0.5 g of alloy sample. A relative standard deviation (RSD) of 1.1% was obtained from seven replicate measurements of 0.5 μg L−1 Bi3+ in sample matrix. The proposed method was successfully applied for the determination of Bi in two certified reference materials (FeNi based alloys GBW01621 and GBW01622).

Physical Properties of Lead Arsenate Glass System

My Present work is lead arsenate composite material ions, study the properties of the pbo As2O3 glass system doped with Transition metal ions, scanning electron micros copy, EDS, X-RD and Optical absorption peaks readings wave length rangeis 300-1200 nm for identification of various electronic transitions metal ions. Lead Arsenate pure glasses doped with various composites of iron ionswerepreserved. study the samples characterized by XRD studies and SEM studies reveal the existence of (Fe2Pb)As2O6glassypoints are also detected. The optical absorption bands ofthis glass have presented 3 absorption peaks on 670,560nm. the observed gradually growth trendy the strength of the peacks due to Fe+2transition ions at the expenditure of the peaks due to Fe+3transition ions up to 0.6 mol% .the amorphous Fe2O3 glasses in the range of frequency 102 Hz to 105 Hz and temperature is 77 k to 450 k.

Effects of reaction atmosphere on physico-chemical properties of V-doped FeNb11O29

FeNb11O29, pure or doped with metal transition ions, is a very promising material with advanced multifunctionalities and interesting applicative perspectives. It is isostructural with Nb12O29, one of the rare compounds in which Nb displays a local magnetic moment and shows both antiferromagnetic ordering and metallic conductivity at low temperatures. In this work we have synthesized and studied Fe0.8V0.2Nb11O29 monoclinic powders. In particular we monitored the effects on structural, electronic and magnetic properties in samples produced in different atmospheres to stabilize cations with different oxidation states.We have demonstrated that the reaction atmosphere influences the phase homogeneity, the crystallite size and the amount of paramagnetic centres, with a transformation of Fe3+ in Fe2+ when an inert atmosphere is used, as proved by the absence, in this case, of any electron paramagnetic resonance signal. Also the Raman spectra result to be affected due to the change of coordination polyhedra. Subsequent re-oxidation of reduced powders brings to the monophasic iron niobate again containing Fe3+ demonstrating the reversibility of redox process. This reversibility is accompanied by a complete restoring of monoclinic structure evidenced by X-ray diffraction data and by Raman measurements, which allowed also to follow in situ the spectral changes induced by laser heating.

Preparation, Characterization and Biological Study of New Derivatives of 1, 3, 4 - Thiadiazoleand Its Complexes with Some Transitional Element Ions.

Preparation, Characterization and Biological Study of New Derivatives of 1, 3, 4 - Thiadiazoleand Its Complexes with Some Transitional Element Ions.

Structural studies of transition metal ions doped in biomass ash as silica source for glass production in Thailand

(55-x)SiO2-13B2O3-1.0Al2O3-4.5BaO-6.3CaO-0.2Sb2O3-20Na2O-XMO (X = 0.0, 0.1, 0.2, 0.4, 0.6, 0.8, 1.0 and M = NiO, CoO, CuO and Fe2O3) were prepared by conventional melt quenching technique. In this research, glass productions from rice husk ash (RHA) and the effect of CoO, CuO, NiO, and Fe2O3 on structural properties were investigated. The local RHA in Nakhon Pathom Province, Thailand was used as a silica source for glass matrices. FTIR and RAMAN analysis were performed. FTIR reveled Si—O—Si antisymmetric vibrations of bridging oxygens for all transition ion doped glasses. Vibrations of transitional metal ions were observed in the lower wavenumber (˂1000cm−1) region in RAMAN spectra.

Determination of the g-factors measured by EPR based on theoretical crystal field and superposition model analyses for lanthanide-based magnetically concentrated crystals – case study: double tungstates and molybdates

ABSTRACTThe methods developed for theoretical determination of g-factors measured by electron paramagnetic resonance (EPR) for single transition ions are extended to lanthanide-based magnetically concentrated crystals. The crystal field (CF) and superposition model (SPM) analyses are employed for optoelectronic materials: double tungstates and molybdates. Using the crystallographic data for Nd3+ ions in RbNd(WO4)2 and Yb3+ ions in KYb(MoO4)2 as input for SPM modelling, the CF parameters (CFPs) are predicted for the respective ions. The matrix for g tensor is calculated by the complete diagonalisation method. By matching three principal g values (gxx, gyy, gzz) to those measured by EPR, three adjustable SPM intrinsic parameters:, and are obtained. The reliability of the related CFPs is verified by comparative analysis of available data. The results demonstrate that the methods suitable for single lanthanide ions in crystal can be successfully applied to magnetically concentrated systems. The predicted g tensor anisotropy enables consideration of EPR linewidths arising from dipolar broadening in ALn(MO4)2 (A = alkali ions, Ln = lanthanide ions, M = W or Mo) systems based on the moment method, which requires accurate g-factors. The model parameters determined here may be utilised for SPM/CFP calculations for Nd3+ and Yb3+ ions in single-molecule magnets and single-ion magnets.

Simultaneous determination of sarcosine and its related metabolites by gas chromatography-tandem mass spectrometry for prostate cancer diagnosis.

Shortly after sarcosine was delineated as a potential biomarker for prostate cancer in 2009, a variety of analytical methods for clinical application were developed. Moreover, higher uptake of glycine in the mitochondria also played a role in cancer proliferation. A major constraint in the accurate quantification of sarcosine was the interference of the two isomers, α-alanine and β-alanine, using chromatographic separation techniques. Accordingly, we aimed to develop an analytical method for determining sarcosine and its related metabolites (α- and β-alanine, glycine and creatinine) under the same conditions by gas chromatography-tandem mass spectrometry (GC-MS/MS). BSTFA + 1 % TMCS was used for silylation, and GC-MS/MS conditions were optimized for the target analytes. The unique transition ions of sarcosine, α- and β-alanine, glycine and creatinine set up in MRM acquisition were m/z 116 → 73, 190 → 147, 176 → 147, 176 → 147 and 100 → 73, respectively. This newly developed method was successfully validated to apply in clinical settings with low limits of detection (0.01 - 0.03 µg•mL-1), high correlations (R2 > 0.99), great accuracy (88 - 110 % recovery), and notable precision (RSD < 10 %). All TMS derivatives were > 80 % stable for up to 2 h after derivatization and analyzing during this period promises to achieve an accurate result. Monitoring the five-substance profile could enhance prospects for early diagnosis of prostate cancer.

A Gas Chromatography-Triple Quadrupole Mass Spectrometry Assay for the Quantification of Opiates in Human Blood Samples.

A simplified protein precipitation method in combination with gas chromatography-triple quadrupole mass spectrometry (GC-MS-MS) analysis was developed and validated for the simultaneous determination of codeine, morphine, 6-acetylmorphine (6-MAM), hydrocodone and hydromorphone in human blood samples. A protein precipitation with 10% trichloroacetic acid followed by solid-phase extraction using a mixed-mode cartridge was used to separate the analyte from the blood samples. A BSTFA + 1% TMCS was used for derivatization of opiates prior to the analysis. Codeine-D3, morphine-D3, 6-acetylmorphine-D3 and hydrocodone-D6 were used as internal standards. The GC-MS-MS was operated under multiple-reaction monitoring mode using electron ionization technique. The transition ions used for quantitation were 371 → 234 for codeine, 429 → 146 for morphine, 399 → 287 for 6-MAM, 299 → 228 for hydrocodone and 357 → 314 for hydromorphone. The method was linear over the concentration range 2.5-1000 ng/mL for all analytes, except hydrocodone which was linear over 5-1000 ng/mL with a correlation coefficient (r2) = 0.99. The limit of detection was 1.0 ng/mL for all compounds except hydrocodone which was 2.5 ng/mL. The limit of quantitation was 2.5 ng/mL for all compounds except hydrocodone which was 5.0 ng/mL. The precision (% RSD) was within 1.26-14.81 and the accuracy (% Bias) was within -6.29-10.93% for all compounds. The method successfully analyzed morphine (305 ng/mL) and 6-acetylmorphine (6-MAM) (2.3 ng/mL) in a human blood sample received from an opiate user.

A comprehensive LC–MS/MS method validation for the quantitative investigation of 37 fingerprint phytochemicals in Achillea species: A detailed examination of A. coarctata and A. monocephala

The current study aims to optimize and validate a comprehensive LC–MS/MS method for the quantification of 37 phytochemicals (15 phenolic acids, 17 flavonoids, 3 non-phenolic organic acids, 1 phenolic aldehyde and 1 benzopyrene) in Achillea species. Though Achillea species were chosen as real life samples, the current method is applicable to a wide range of plant species. The developed method was fully validated in terms of linearity, accuracy (recovery), inter-day and intra-day precision (repeatability), limits of detection and quantification (LOD/LOQ) and relative standard uncertainty (U% at 95% confidence level (k = 2)). Reversed-phase ultrahigh performance liquid chromatography was optimized to achive optimum separation for 37 phytochemical compounds and to overcome the suppression effects. MS detection was performed using a triple quadrupole mass spectrometer and negative or positive ionization modes were optimized for each analyte. Multiple reaction monitoring (MRM) was used to quantify the analytes, related molecular ions and transition ions were optimized. Phytochemical screening of ethanol and methanol-chloroform extracts of root and aerial parts of A. coarctata and A. monocephala were performed by using the developed and validated LC–MS/MS method. Root and aerial parts of both species have considerable amounts of certain phenolic-nonphenolic acids (quinic, malic, fumaric, chlorogenic and vanillic acids) and flavonoids (rutin, hesperidin, isoquercitrin, apigetrin, luteolin, apigenin). Additionally, total phenolic and flavonoid amounts, antioxidant (DPPH free radical scavenging assay, ABTS radical cation decolorization assay, β-carotene lipid peroxidation test system and CUPRAC cupper reduction capacity methods), anticholinesterase, tyrosinase, urease inhibition and cytotoxic activities (on HeLa (Human Cervical Carcinoma Cell Line) of A. coarctata and A. monocephala were also investigated. It has been determined that the studied Achillea species, that are rich in total phenolic-flavonoid and chlorogenic acid contents, have high antioxidant and cytotoxic potential at the same time. According to the results of LC–MS/MS, antioxidant and cytotoxic activity studies, after detailed chemical investigation and toxicity studies on these species, A. coarctata and A. monocephala may be promoted as promising sources of natural agents and used for the development of nutraceuticals or functional food ingredients in future.

Current state and recommendations for harmonization of serum/plasma 17-hydroxyprogesterone mass spectrometry methods

Abstract Background: Mass spectrometry (MS)-based 17-hydroxyprogesterone (17OHP) methods show considerable variation in results in external quality assurance (EQA) programs. An understanding of the current status of MS-based serum/plasma 17OHP quantification is important to facilitate harmonization. Methods: A 50-item e-survey related to (1) laboratory characteristics, (2) pre-analytical considerations and (3) analysis of 17OHP was developed and circulated to clinical MS laboratories via professional associations in Asia Pacific, Europe and North America. Results: Forty-four laboratories from 17 countries completed the survey. Sample preparation varied between laboratories with protein precipitation and liquid-liquid extraction being the most common processes. Analyte separation was most commonly achieved by liquid chromatography (LC) using a C18 column and mobile phases of water, methanol and formic acid. The ions selected for quantification were 331&gt;97 m/z or 331&gt;109 m/z. Alternative transition ions were used as qualifiers. Twenty-seven of 44 respondents reported preparing their calibrators in-house and variations in material purity and matrix were evident. Nine of 44 laboratories did not participate in an EQA program, and half did not know if their method separated out isobars. The reference intervals, and also their partitioning, reported by the laboratories were highly discrepant, in some cases, by multiple folds. Conclusions: Although MS-based methods are similar in many facets, they are highly disparate. Five recommendations have been developed as an outcome of this survey to support the continued improvement of analysis of serum/plasma 17OHP by MS.

Preparation, Characterization and Biological Study of New Derivatives of 1, 3, 4 - Thiadiazoleand Its Complexes with Some Transitional Element Ions.

The current study involved preparation of ligand [2,5-bis-(2-(diphenyl methylene) hydrazineyl)-1,3,4-thiadiazole] (L1) from reacting between thiadiazole derivative [ (2,5-dihydrazineyl-1,3,4 -thiadiazol) and Benzphenone by the ratio (1:2) . Attended the transitional elements ions complexes [Cr+3, Fe+3, Co+3, Ni+2, Cu+2] with ligand (L1) Complexes were diagnosed using the precision analysis of elements (C.H.N), Infrared spectrum (FTIR), Spectrum of Nuclear Magnetic Resonance proton (1H-NMR), Mass spectroscopy, measurement magnetic sensitivity and measurement molar conductivity the results were practical exactly matching with the molecular and structural formulas of the proposed compound .Hyperchem was used to draw ligand (L1) and its complexes and to show the distribution of electronic density. Data obtained indicates that the stereochemistry figure of the complexes [Cr+3, Fe+3, Co+3] was octahedral , the proposed stereochemistry figure of the complexes [Ni+2, Cu+2] is square planer. A study was conducted testing the biological activity for the prepared ligand (L1) and its complexes against two types of bacteria staphylococcus aureus and Escherichia coli compared to the standard inhibitor (Cipro.), the results obtained confirmed that ligand(L1) and their complexes did not show any biological activity towards the bacteria aureus staphylococcus aureus, while the ligand(L1) and their complexes showed different activity twards the second type of bacteria Escherichia coli, some showed greater activity than the standard inhibitor and some showed less activity than the standard inhibitor

Simultaneous Quantitation of Methamphetamine, Ketamine, Opiates and their Metabolites in Urine by SPE and LC-MS-MS.

Heroin, methamphetamine and ketamine have been the most commonly abused drugs in Taiwan. The presence of these drugs and their metabolites in postmortem specimens has been routinely monitored in our laboratory mostly by gas chromatographic-mass spectrometric methods. This study aimed to evaluate a more effective approach to simultaneously quantify these analytes (i.e., amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxymethamphetamine (MDMA), morphine, codeine, 6-acetylmorphine, 6-acetylcodeine, ketamine and norketamine) in postmortem urine and blood specimens by liquid chromatography-tandem mass spectrometry (LC-MS-MS). Samples (1 mL) were extracted via solid-phase extraction, evaporated and reconstituted in the mobile phase for injection into the LC-MS-MS system. Respective deuterated analogs of these analytes were used as internal standards. Chromatographic separation was achieved by an Agilent Zorbax SB-Aq analytical column at 50°C. Mass spectrometric analysis was performed by electrospray ionization in positive-ion dynamic multiple reaction monitoring mode with optimized collision energy for respective precursor ion selected for each analyte, and the monitoring of two transition ions. Performance characteristics were assessed using drug-free samples that were fortified with 50-1,000 ng/mL of the 10 analytes. Analytical parameters evaluated and resulting data are as follows: (i) average extraction recoveries (n= 3) were better than 80%, except for MDMA (71%) and morphine (74%); (ii) inter-day and intra-day precision ranges (%CV) were 1.59-8.80% and 0.57-3.89%, respectively; (iii) calibration linearity (r2), detection limit and quantitation limit for all analytes were >0.999, 1 and 5 ng/mL, respectively; (iv) matrix effects (ion suppression) were observed for three analytes, but were satisfactorily compensated for by the deuterated internal standards adopted in the analytical protocol. This method was successfully applied to the analysis of specimens collected from unknown death cases from various district prosecutors' offices in Taiwan, and was also found helpful to understanding whether the detected opiates were derived from heroin or legal morphine/codeine-containing medications.