Reverse Phase HPLC For Rapid,Comprehensive Measurement of Nucleotides,Nucleosides and Bases of The Myocardial Adenine Pool

Abstract

A novel reverse phase HPLC method is described for the simultaneous measurement of adenosine tri-, di- and monophosphates (ATP, ADP, AMP), inosine monophosphate (IMP), adenosine, inosine, hypoxanthine, nicotinamide adenine dinucleotide (NAD) and uric acid in cardiac tissues and coronary effluent. The use of a simplified perchloric acid extraction procedure and ODS columns easily modified with Mq⁺⁺, Tris and phosphate buffer, allows considerable saving in analysis time together with extremely good resolution, particularly for ATP and ADP, and provides a very practical tool for the routine assessment of changes in adenine pool metabolites.     

Novel Reaction for Rapid,Simple, and Sensitive Determination of Molybdenum in Various Samples

Abstract

A new sensitive, selective, rapid, and reproducible method is presented for the analysis of trace amounts of molybdenum (VI) (Mo(VI)). The method is based on the reaction of molybdenum (VI) with a new analytical reagent, 6‐(5‐Chloro‐2‐hydroxy‐4‐sulfophenylazo)‐5‐hydroxy‐1‐naphthalenesulfonic acid, disodium salt. Under optimum reaction conditions, molybdenum (VI) forms a red complex with a maximum absorption peak at 589 nm. The color reaction is rapidly completed at room temperature. The apparent molar absorption coefficient and Sandell sensitivity were 1.13×10⁴ L · mol^?1 · cm^?1 and 0.0084 µg · cm^?2, respectively. Beer's law was obeyed up to 8.5 µg · mL^?1. Methods for the determination of Mo(VI) by first‐derivative spectrophtometry have also been proposed at 547 and 625 nm. The proposed methods offer the advantages of sensitivity, rapidity, selectivity, and simplicity without any prior separation or extraction. The methods have been applied to the determination of Mo(VI) in various environmental samples and some alloys; satisfactory results have been obtained.     

A Simple, Rapid and Reagentless Turbidimetric Method for Determination of Light Stabilizer Tinuvin 622 in Polyethylene

This study presents an inexpensive and reagentless turbidimetric technique for the determination of Tinuvin 622 in polyethylene matrix. Tinuvin is dissolved in acetone, and water is added to it. The solubility of the analyte is reduced in the water/acetone mixture and it precipitates in the form of small particles. Different parameters affecting the analysis were studied, and it was found that in a 50:50 mixture of water and acetone high turbidity was obtained. Turbidity increases to 30min and remains constant for at least 1h. Stirring speed and ionic strength are no effective factors in this method. The linear dynamic range is relatively large (10–250mgL^–1) with a limit of detection of 3mgL^–1. The repeatability of the method is good, and the relative standard deviation for six repeated experiments performed on solutions containing 100mgL^–1 is 1.5%. To analyze real samples (polyethylene polymer), the matter is dissolved in hot xylenes, and methanol is added while the solution is being stirred. The precipitated polymer is filtered and the solution evaporated into the rotary. The remaining solids are dissolved in acetone and analyzed as standards. The obtained results were compared with those obtained by gas chromatography (after saponification) and no significant differences were observed.     

Minireview: Whole-cell,Nucleotide, and Enzyme Inhibition-based Biosensors for the Determination of Arsenic

Arsenic is a natural and highly toxic environmental contaminant and is intensely connected with human health. It can cause DNA damage, mutations, neurological disorders, and cancer. In previous few decades, large numbers of biosensors for recognition and identification of arsenic both qualitatively and quantitatively have been developed. The biosensor is a logical device that is usually used for identification of a particular or a group of analytes in samples. This review aims at various advancements made in the improvement of biosensors for arsenic detection such as whole cell-based, nucleotide-based, and enzyme inhibition-based biosensors. The review focuses on the technology used for development of arsenic biosensor along with their advantages and limitations.     

A Simple,Rapid, and Sensitive HPTLC Method for the Estimation of Clarithromycin: Application to Single Dose Clinical Study

JPC – Journal of Planar Chromatography – Modern TLC - Clarithromycin used for the treatment of respiratory tract infection. Anew alternative simple, rapid, sensitive, and selective...     

Simple High-Performance Liquid Chromatographic Assay, with Post-Column Derivatization, for Simultaneous Determination of Mycophenolic Acid and its Glucuronide Metabolite in Human Plasma and Urine

Two simple high-performance liquid chromatographic (HPLC) methods have been established for simultaneous determination of mycophenolic acid (MPA) and its glucuronide metabolite (MPAG) in human urine, and of their total and unbound forms in human plasma. For total MPA and MPAG analysis sample preparation entailed precipitation of protein with acetonitrile and isolation of the free analytes from the plasma by ultrafiltration. For urine samples, fivefold dilution with water was used. MPAG was determined by UV detection whereas MPA was quantified by fluorescence detection after post-column derivatization with 0.2 M sodium hydroxide solution. For plasma, response was found to be linearly dependent on concentration over the ranges 0.1–40 μg mL^-1 and 0.01–1 μg mL^-1 for total and free MPA, respectively, and 10–200 μg mL^-1 and 2.5–100 μg mL^-1 for total and free MPAG, respectively. For urine, linearity was observed from 0.1 to 50 μg mL^-1 for MPA and 10 to 500 μg mL^-1 MPAG in the urine before dilution. The methods reported were found to be accurate and reproducible for quantifying the level of MPA and MPAG and can thus be used for clinical pharmacokinetic studies and for therapeutic drug monitoring. Contributed equally to this work An erratum to this article is available at .     

Development of a Simple,Underivatized Method for Rapid Determination of Free Amino Acids in Honey Using Dilute-and-Shoot Strategy and Liquid Chromatography-Tandem Mass Spectrometry

A simple, fast and reliable analytical method was developed for 20 free amino acids (FAAs) determination in honey samples through a dilute-and-shoot strategy and hydrophilic interaction liquid chromatography tandem mass spectrometry. Compared with previous reports, direct dilution by water has significantly reduced the matrix effect and facilitated full extraction of FAAs. Further, a 5 min determination method was established with an acetonitrile–water mobile phase system with 0.1% formic acid addition. The established method was validated and demonstrated several advantages including short detection time, wide linear range over 3–4 orders of magnitude, high sensitivity down to 0.1 ng/mL and negligible matrix effect. Twenty FAAs were determined in 10 honey samples from different botanical origins by this method, and 19 FAAs were found. This general applicable method was also promising for fast determination of FAAs in other practical samples.     

Simple and sensitive HPLC method for determination of amrubicin and amrubicinol in human plasma: application to a clinical pharmacokinetic study

A simple and sensitive high‐performance liquid chromatographic (HPLC) method was developed for determination of amrubicin and its metabolite amrubicinol in human plasma. After protein precipitation with methanol without evaporation procedure, large volume samples were injected and separated by two monolithic columns with a guard column. The mobile phase consisted of tetrahydrofuran–dioxane–water (containing 2.3 mM acetic acid and 4 mM sodium 1‐octanesulfonate; 2:6:15, v/v/v). Wavelengths of fluorescence detection were set at 480 nm for excitation and 550 nm for detection. Under these conditions, linearity was confirmed in the 2.5–5000 ng/mL concentration range of both compounds. The intra‐ and inter‐day precision and intra‐ and inter‐day accuracy for both compounds were less than 10%. The method was successfully applied to a clinical pharmacokinetic study of amrubicin and amrubicinol in cancer patients. Copyright © 2009 John Wiley & Sons, Ltd.     

Eco-Friendly,Simple, Fast,and Sensitive UPLC-MS/MS Method for Determination of Pexidartinib in Plasma and Its Application to Metabolic Stability

Pexidartinib is the first drug approved by the U.S. Food and Drug Administration specifically to treat the rare joint tumor tenosynovial giant cell tumor. In the current study, a validated, selective, and sensitive UPLC-MS/MS assay was developed for the quantitative determination of pexidartinib in plasma samples using gifitinib as an internal standard (IS). Pexidartinib and IS were extracted by liquid-liquid extraction using methyl tert-butyl ether and separated on an acquity BEH C₁₈ column kept at 40 °C using a mobile phase of 0.1% formic acid in acetonitrile: 0.1% formic acid in de-ionized water (70:30). The flow rate was 0.25 mL/min. Multiple reaction monitoring (MRM) was operated in electrospray (ESI)-positive mode at the ion transition of 418.06 > 165.0 for the analyte and 447.09 > 128.0 for the IS. FDA guidance for bioanalytical method validation was followed in method validation. The linearity of the established UPLC-MS/MS assay ranged from 0.5 to 1000 ng/mL with r > 0.999 with a limit of quantitation of 0.5 ng/mL. Moreover, the metabolic stability of pexidartinib in liver microsomes was estimated.     

Reactions of Various Nucleophiles with d-Glucal over Keggin-Type Heteropoly Compounds: A Simple,Rapid, and Expedient Method for the Synthesis of Pseudoglycals

The reaction of benzyl alcohol with 3,4,6-tri-O-acetyl-d-glucal has been investigated with several heteropoly compounds, and the optimal catalyst is 12-tungstophosphoric acid supported on carbon. In the presence of this catalyst, various alcohols gave the corresponding alkyl and aryl 2,3-unsaturated glycopyranosides in excellent yields and good anomeric selectivity under solvent-free condition. 4,6-Di-O-acetyl-2,3-dideoxy-α-d-erythro-hex-2-enopyranosyl cyanide and ethyl 4,6-di-O-acetyl-2,3-dideoxy-1-thio-α-d-erythro-hex-2-enopyranoside have also been prepared with trimethylsilyl cyanide and ethanthiol as nucleophiles, respectively. The catalyst could be easily recovered and reused several times with slight loss of activity. The selectivity to give α-anomers predominantly did not show any change in all runs.     

Direct Analysis of Beer by ICP-AES: A Very Simple Method for the Determination of Cu, Mn and Fe

A very simple method for determination of trace amount of Cu, Mn and Fe in beer by inductively coupled plasma spectrometry (ICP-AES) was developed. The beer was directly introduced into the plasma, without dilution or adding of reagents, via a conventional V-groove nebulizer. The only sample preparation used was degassing of the beer to remove CO₂. By optimizing the ICP-AES parameters (RF power and Nebulizer gas flow rate) and by the appropriate choice of wavelengths for measurements, sufficient accuracy for the determination of the trace metals was obtained. Various types of beers were analysed by the direct ICP-AES method and for comparison, also with two other methods: by GFAAS and ICP-AES after decomposition. No significant difference was found for Cu and Mn (ANOVA, 95% confidence level) using the three methods. This was normally also the case for Fe; only in one case did the result of Fe by the direct method deviate from the other methods (10% lower results). The limit of detection for the direct method was estimated to 1.1, 0.3, and 1.1 ng mL⁻¹ for Cu, Mn, and Fe, respectively.     

A Simple,Efficient and Ultrasensitive Gold Nanourchin Based Electrochemical Sensor for the Determination of an Antimalarial Drug: Mefloquine

Mefloquine (MQ) is a quinoline based antimalarial drug, which is potent against multiple drug‐resistant Plasmodium falciparum . It is widely prescribed for the prophylactic treatment of malaria. Due to extensive usage of MQ, constant monitoring of the drug level in human body is of paramount importancein order to ensure that optimum drug exposure is achieved. The present work describes a gold nanourchins (AuNUs) based electrochemical sensor for the determination of MQ.AuNUs were synthesized via seed‐mediated method and characterized using ultraviolet‐visible spectroscopy, energy‐dispersive X‐ray spectroscopy, field emission scanning electron microscopy, zeta‐sizer and electrochemical techniques (electrochemical impedance spectroscopy and cyclic voltammetry). Fabrication of the sensor was done by drop‐coating the synthesized AuNUs onto a glassy carbon electrode. The fabricated sensor exhibited enhanced voltammetric response, which was attributed to the excellent conductivity and high surface area of AuNUs. Under optimum square wave voltammetric conditions, the sensor displayed two linear response ranges (from 2.0×10⁻⁹ to 1.0×10⁻⁶ M and from 1.0×10⁻⁶ to 1.0×10⁻³ M) with a detection limit of 1.4 nM. The electrode demonstrated good reproducibility, stability and selectivity over common interferents. The utility of the sensor was successfully assessed for quantification of the drug in pharmaceutical preparation and spiked human urine sample. Thus, the present study demonstrates a promising approach for determination of MQ with practical utility in quality control and clinical analysis.     

Rapid Capillary Electrophoresis Method for Simultaneous Determination of Abemaciclib,Ribociclib, and Palbociclib in Pharmaceutical Dosage Forms: A Green Approach

Advances in the treatment of HR+/HER2- breast cancer phenotype have been made with the introduction of abemaciclib, ribociclib, and palbociclib, inhibitors of cyclin D dependent kinases 4 and 6 (CDK4/6). Here, a novel, fast, cheap, and green CE method for the simultaneous determination of these three CDK4/6 inhibitors in less than 4 min is proposed for the first time. Separation was achieved by capillary zone electrophoresis in an acidic medium, in accordance with the structures of the analytes and their pKa values. The optimal pH of the running buffer was found to be 2.9. The optimal method conditions were 27.5 kV separation voltage, 30 °C, 5 s injection time under 50 mbar pressure, and 50 mM phosphate background buffer with benzimidazole as an internal standard. The developed method was validated with respect to robustness, selectivity, accuracy, precision, linearity, and limits of detection. The method was shown to be linear in the range of 10 to 100 µg mL⁻¹ with correlation coefficients higher than 0.9981. A greenness assessment of the proposed method was performed, and the method was shown to be green. The validated method was successfully applied to pharmaceutical dosage forms of all CDK4/6 inhibitors.     

Chiral HPLC analysis of donepezil, 5-O-desmethyl donepezil and 6-O-desmethyl donepezil in culture medium: application to fungal biotransformation studies

An high performance liquid chromatography (HPLC) method for the enantioselective determination of donepezil (DPZ), 5-O-desmethyl donepezil (5-ODD), and 6-O-desmethyl donepezil (6-ODD) in Czapek culture medium to be applied to biotransformation studies with fungi is described for the first time. The HPLC analysis was carried out using a Chiralpak AD-H column with hexane/ethanol/methanol (75:20:5, v/v/v) plus 0.3 % triethylamine as mobile phase and UV detection at 270 nm. Sample preparation was carried out by liquid-liquid extraction using ethyl acetate as extractor solvent. The method was linear over the concentration range of 100-10,000 ng mL(-1) for each enantiomer of DPZ (r ≥ 0.9985) and of 100-5,000 ng mL(-1) for each enantiomer of 5-ODD (r ≥ 0.9977) and 6-ODD (r ≥ 0.9951). Within-day and between-day precision and accuracy evaluated by relative standard deviations and relative errors, respectively, were lower than 15 % for all analytes. The validated method was used to assess DPZ biotransformation by the fungi Beauveria bassiana American Type Culture Collection (ATCC) 7159 and Cunninghamella elegans ATCC 10028B. Using the fungus B. bassiana ATCC 7159, a predominant formation of (R)-5-ODD was observed while for the fungus C. elegans ATCC 10028B, DPZ was biotransformed to (R)-6-ODD with an enantiomeric excess of 100 %.     

Development and Validation of an HPLC–UV Method for the Determination of Insulin in Rat Plasma: Application to Pharmacokinetic Study

A simple, sensitive high performance liquid chromatographic method with UV detection was developed and validated for determination of insulin in rat plasma, using methyl paraben as an internal standard. Insulin was extracted from plasma by a liquid–liquid extraction with a mixture of dichloromethane and n-hexane (1:1, v/v) followed by an acidic back extraction. Chromatographic separation was achieved isocratically with a Phenomenex® C₁₈ analytical column (150 × 4.6 mm ID, 5 μm) at ambient room temperature. The calibration curves were linear within a concentration range of 0.7–8.4 μg mL^?1 (r ² = 0.9994). The inter-day and intra-day accuracy and precision were ≤3.33 and ≤5.55%. The limit of detection (LOD) and limit of quantification (LOQ) were 0.35 and 0.7 μg mL^?1. The average recovery was 87.86% for insulin and 83.52% for methyl paraben. Insulin containing plasma samples were stable at ?20 °C for 7 days. Validated HPLC method was successfully applied to a pharmacokinetic study of insulin in streptozotocin induced diabetic rats.     

A Simple UPLC/MS-MS Method for Simultaneous Determination of Lenvatinib and Telmisartan in Rat Plasma,and Its Application to Pharmacokinetic Drug-Drug Interaction Study

Lenvatinib is a multi-targeted tyrosine kinase inhibitor that inhibits tumor angiogenesis, but hypertension is the most common adverse reaction. Telmisartan is an angiotensin receptor blocker used to treat hypertension. In this study, a simple ultra-performance liquid chromatography-tandem mass spectrometry method was developed for the simultaneous determination of lenvatinib and telmisartan, and it was applied to the pharmacokinetic drug interaction study. Plasma samples were treated with acetonitrile to precipitate protein. Water (containing 5 mM of ammonium acetate and 0.1% formic acid) and acetonitrile (0.1% formic acid) were used as the mobile phases to separate the analytes with gradient elution using a column XSelect HSS T3 (2.1 mm × 100 mm, 2.5 μm). Multiple reaction monitoring in the positive ion mode was used for quantification. The method was validated and the precision, accuracy, matrix effect, recovery, and stability of this method were reasonable. The determination of analytes was not interfered with by other substances in the blank plasma, and the calibration curves of lenvatinib and telmisartan were linear within the range of 0.2–1000 ng/mL and 0.1–500 ng/mL, respectively. The results indicate that lenvatinib decreased the systemic exposure of telmisartan. Potential drug interactions were observed between lenvatinib and telmisartan.     

A Rapid Tandem Mass Spectrometric Assay for Determination of Ursolic Acid – Application to Analysis of Ursolic Acid in Four Species of Staphylea L. and Leaves of Staphylea Pinnata L. Gathered During Ontogenesis

Plant extracts of Staphylea L. exhibit a number of biological activities which are presumably attributed to ursolic acid. A rapid and specific tandem mass spectrometric (MS-MS) assay for the quantification of ursolic acid in the leaves of four species of Staphylea L. (Bladdernut) and in the leaves of S. pinnata L. during ontogenesis, was developed and validated. The samples were analyzed by flow injection analysis without chromatographic separation using a transport liquid of methanol/water/formic acid (80:20:0.1 v/v/v) at a flow-rate of 0.2 mL min⁻¹. The run cycle time was ~2-3 min injection-to-injection. Quantification was achieved using multiple reaction monitoring at MRM transition m/z 439 > 203. Calibration curves were linear over the concentration range of 2–20 μg mL⁻¹ with a lower limit of quantification of 2 μg mL⁻¹ (1.8 ± 0.297, RSD: 0.165). Validation data showed that the RSD% values were in the range of 1.8 to 6.8%, whereas the % DEVs ranged from −18 to −2% indicating reasonable and acceptable precision and accuracy, respectively. A recovery percent of 106.8 ± 10.3 of ursolic acid from spiked extracts samples, indicated the specificity and reliability of tandem mass procedure for determination of ursolic acid in the plant extracts. The derived data of sample analysis showed different contents of ursolic acid among various Staphylea species. The highest content of ursolic acid was found in the leaves extract of S. pinnata L. Additionally, the highest amount of ursolic acid accumulated in the leaves of S. pinnata L. was in the August /September period of the year. Smaller amounts of ursolic acid were found in samples collected before and after that time. The results obtained serve as a justification of determining the most appropriate time for collecting plant material as a source of ursolic acid.