High-Throughput Screening of Antimalarials via Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

The counterfeiting of pharmaceuticals, especially antimalarials, is a well-recognized and growing public health problem. There have been an alarming number of reports of counterfeit antimalarials throughout the world and insufficient regulations and xactivity. Thus there is an urgent need for a rapid and sensitive authentication and screening tool for multiple antimalarials. While many methods have been developed using HPLC, MS, or LC-MS to screen individual antimalarials, no methods are available for the analysis of multiple antimalarial drugs within a single run. In this study, Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) with multiple reaction monitoring (MRM) was used as a selective and rapid way to screen ten common antimalarials. The compounds were first individually analyzed using electrospray ionization mass-spectrometry (ESI-MS). Following this, a corresponding MS/MS spectrum was obtained to enable selection of the optimal unimolecular decay fragmentation ( transition ) of each antimalarial. Finally, these single reaction monitoring (SRM) transitions were combined into a method that utilizes HPLC separation followed by multiple reaction monitoring (MRM) in an ion trap mass analyzer allowing for sequential screening of a mixture of these compounds within a single LC-MS/MS run. This method has both pharmaceutical and medical applications with the capability of providing drug quality control measurements and the detection of many drugs and their metabolites in biological samples.Committee Member/Second Reader: Lyon, L. Andrew; Faculty Mentor: Fernandez, Facundo M

Validação de método multirresíduo para determinação de pesticidas em alimentos empregando QuEChERs e UPLC-MS/MS.

This paper presents a practical and rapid method which was validated for simultaneous quantification and confirmation of 29 pesticides in fruits and vegetables using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The samples were extracted following the method known as QuEChERS. Using the developed chromatographic conditions, the pesticides can be separated in less than 9 min. Two multiple reaction monitoring (MRM) assays were used for each pesticide. Four representative matrices (lettuce, tomato, apple and grapes) were selected to investigate the effect in recoveries and precision. Typical recoveries ranged from 70-120%, with relative standard deviation (RSDs) lower than 20%

DETERMINAZIONE INNOVATIVA DEL ROTENONE NEGLI OLI DI OLIVA DA AGRICOLTURA BIOLOGICA MEDIANTE SPETTROMETRIA DI MASSA TANDEM

Il rotenone, pesticida naturale utilizzato in agricoltura biologica su una grande varietà di colture, è stato determinato quantitativamente mediante Atmosheric Pressure Chemical Ionisation Spettrometria di Massa Tandem (APCI MS/MS) nelle olive e negli oli di oliva ottenuti dopo trattamento in una prova di campo che ha interessato la cv Carolea in Calabria. La tecnica analitica ha previsto la realizzazione di esperimenti “Multiple Reaction Monitoring” (MRM) utilizzando uno standard interno ottenuto per sintesi. Le quantità rilevate sono comprese tra 9 mg/Kg di olio dopo 1 giorno dal trattamento e 0.15 mg/Kg di olio dopo 1 mese circa dal trattamento. Quest’ultimo valore è molto più elevato dei 40 µg/Kg permessi dalla legislazione italiana

Determination of clindamycin in pig plasma after implantation of poly(D,Llactide-co-glycolide)/hydroxyapatite/clindamycin core–shell nanosphere by liquid chromatography-tandem mass spectrometry

Clindamycin was determined in pig plasma by liquid chromatography/tandem mass spectrometry (LC-MS/MS). The multiple reaction monitoring (MRM) mode of precursor-product ion transitions for clindamycin (m/z=421.1/126.1) and the internal standard, caffeine (m/z=192/125) was used. The samples were prepared by two methods: 0.1% formic acid in methanol and 1.5% trichloacetic acid. The recovery for the two preparation methods at 0.05mg/ml (n=6) was found to be for the first 104.3% and for the second method 106.5%, with repeatability RSD 1.1% and RSD 4.34%, respectively. The results of the comparison of the two different preparation methods of samples demonstrated that both methods were satisfactory

Beyond the Western front:targeted proteomics and organelle abundance profiling

The application of westerns or immunoblotting techniques for assessing the composition, dynamics, and purity of protein extracts from plant material has become common practice. While the approach is reproducible, can be readily applied and is generally considered robust, the field of plant science suffers from a lack of antibody variety against plant proteins. The development of approaches that employ mass spectrometry to enable both relative and absolute quantification of many hundreds of proteins in a single sample from a single analysis provides a mechanism to overcome the expensive impediment in having to develop antibodies in plant science. We consider it an opportune moment to consider and better develop the adoption of multiple reaction monitoring (MRM)-based analyses in plant biochemistry

Quantitative authenticity testing of buffalo mozzarella via alpha(s1)-Casein using multiple reaction monitoring mass spectrometry

We address the detection and quantitation of bovine milk in 'buffalo' mozzarella cheese using multiple reaction monitoring (MRM) mass spectrometry (MS). Focussing on the abundant protein alpha(s1)-casein, present in both species but with 10 amino acid sequence differences, we extract a list of marker peptides specific to each species. 'Identical' peptides, exactly the same in both species, are used for relative quantitation of alpha(s1)-casein in each milk type, whereas 'similar' peptides, present in both species but differing typically by one amino acid, are used to demonstrate relative quantitation in binary cheese mixtures. In addition, we report a pilot survey of UK supermarket and restaurant products labelled as 'buffalo mozzarella', finding that 2/3 of restaurant meals and supermarket pizzas are either mislabelled or adulterated

Sample pretreatment and analytical method development for detecting strobilurin pesticides in aqueous matrices

In this study a method development is presented focusing on the measurement of strobilurin pesticides with GC-MS/MS after a Solid Phase Extraction (SPE) preconcentration step. The analysed pesticides were azoxystrobin, dimoxystrobin, famoxadone, fenamidone, fluoxastrobin, kresoxim-methyl, E-metominostrobin, orysastrobin, picoxystrobin, pyraclostrobin and trifloxystrobin. GC parameter optimization, MS Full Scan, Daughter mode and finally Multiple Reaction Monitoring (MRM) analysis had been done to have perfect separation and characteristic transitions. Calibration curves, repeatability and recovery values were determined to describe reliability of the method. During the SPE method development spiked bottled drinking water was used. Four types of cartridges were tested. STRATA-X had been chosen for further analysis with different elution solvents and with different volumes. PDMS/DVB 65 pm SPME fiber had also been chosen amongst three fibers. Parameter optimization such as extraction and desorption time, pH and NaCl dependence were done. Linearity and repeatability tests were carried out

Bioanalytical Method Development and Validation of Memantine in Human Plasma by High Performance Liquid Chromatography with Tandem Mass Spectrometry: Application to Bioequivalence Study

A simple, sensitive, and rapid HPLC-MS/MS method was developed and validated for quantitative estimation of memantine in human plasma. Chromatography was performed on Zorbax SB-C18 (4.6 × 75 mm, 3.5 μm) column. Memantine (ME) and internal standard Memantine-d6(MED6) were extracted by using liquid-liquid extraction and analyzed by LC-ESI-MS/MS using multiple-reaction monitoring (MRM) mode. The assay exhibited a linear dynamic range of 50.00–50000.00 pg/ml for ME in human plasma. This method demonstrated an intra- and interday precision within the range of 2.1–3.7 and 1.4–7.8%, respectively. Further intra- and interday accuracy was within the range of 95.6–99.8 and 95.7–99.1% correspondingly. The mean recovery of ME and MED6 was 86.07 ± 6.87 and 80.31 ± 5.70%, respectively. The described method was successfully employed in bioequivalence study of ME in Indian male healthy human volunteers under fasting conditions

Determination of dextromethorphan in rabbit plasma by LC-MS/MS and its application to pharmacokinetic study

A highly sensitive liquid chromatographic tandem mass spectrometric (LC-MS/MS) method for determination of dextromethorphan in rabbit plasma using triazolam as the internal standard (IS) was developed. Plasma samples were extracted with ethyl acetate and separated on a SB-C18 column with a mobile phase of acetonitrile-water 60:40 (v/v) at a flow of 0.3 mL/min. Detection is carried out by multiple reaction monitoring (MRM) on a ion-trap LC-MS/MS system with an electrospray ionization interface. The lower limit of quantification (LLOQ) was 1 ng/mL. After intravenous administration of a single dose of dextromethorphan 2 mg/kg, the main pharmacokinetic parameters were as follows: AUC0→t 636.13 ± 47.13 (ng/mL·h); CL 2.60 ± 0.24 (L/h), Cmax 874 ± 67.16 (ng/mL), Vz 1.58 ± 0.11 (L/kg), T1/2 2.41 ± 0.35 (h), MRT 1.26 ± 0.08 (h).Colegio de Farmacéuticos de la Provincia de Buenos Aire