LC Evaluation of In Vitro Release of AZT from Microemulsions

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

LC Assay for Ciprofloxacin Hydrochloride Ophthalmic Solution

The objective of the current study was to develop and subsequently validate a simple, sensitive and precise reversed-phase LC method for the determination of ciprofloxacin hydrochloride in ophthalmic solution form. The chromatographic separation of ciprofloxacin hydrochloride was achieved on a Symmetry Waters C(18) column using UV detection at 275 nm. The optimized mobile phase consisted of 2.5% acetic acid solution: methanol:acetonitrile (70:15:15, v/v/v). The proposed method provided linear responses within the concentration range 1.0-6.0 mu g mL(-1) for ciprofloxacin hydrochloride. Correlation coefficient (r) for the ciprofloxacin hydrochloride was 0.9994. The precision of the method was demonstrated using intra- and inter-day assay RSD% values which were less than 5% in all instances. No interference from any components of pharmaceutical dosage forms was observed.

Comparison of Impurity Profiles of Lipiblock (R) vs. Orlistat using HPLC and LC-MS/MS

Comparative HPLC-UV and LC-MS/MS studies of impurity profiles of a reference sample (Xenical (R), F. Hoffmann La Roche Ltd., Switzerland) vs. generic (Lipiblock (R), EMS Sigma Pharma, a generic drug) were carried out with ethanol extracts of commercial samples. The generic formulation contained higher levels of common impurities as well as a considerable number of impurities not found in the reference product. The detected impurity profile of Lipiblock (R) revealed that it most likely is based on fermentation. Since the effect of the impurities is unknown, at this point fully synthetic Xenical (R) appears to offer a better safety margin than Lipiblock (R) which, however, compares quite well to other generic formulations.

Detecção de metamidofós em solos por métodos ecotoxicológico e cromatografia líquida acoplada à espectrometria de massas sequencial (LC-MS/MS)

Soil contamination by pesticides is an environmental problem that needs to be monitored and avoided. However, the lack of fast, accurate and low cost analytical methods for discovering residual pesticide in complex matrices, such as soil, is a problem still unresolved. This problem needs to be solved before we are able to assess the quality of environmental samples. The intensive use of pesticides has increased since the 60s, because the dependence of their use, causing biological imbalances and promoting resistance and recurrence of high populations of pests and pathogens (upwelling). This has contributed to the appearance of new pests that were previously under natural control. To develop analytical methods that are able to quantify residues pesticide in complex environment. It is still a challenge for many laboratories. The integration of two analytical methods one ecotoxicological and another chemical demonstrates the potential for environmental analysis of methamidophos. The aim of this study was to evaluate an ecotoxicological method as "screening" analytical methamidophos in the soil and perform analytical confirmation in the samples of the concentration of the analyte by chemical method LC-MS/MS In this work we tested two soils: a clayey and sandy, both in contact with the kinetic methamidophos model followed pseudo-second order. The clay soil showed higher absorption of methamidophos and followed the Freundlich model, while the sandy, the Langmuir model. The chemical method was validated LC-MS/MS satisfactory, showing all parameters of linearity, range, precision, accuracy, and sensitivity adequate. In chronic ecotoxicological tests with C. dubia, the NOEC was 4.93 and 3.24 for ng L-1 of methamidophos to elutriate assays of sandy and clay soils, respectively. The method for ecotoxicological levels was more sensitive than LC-MS/MS detection of methamidophos, loamy and sandy soils. However, decreasing the concentration of the standard for analytical methamidophos and adjusting for the validation conditions chemical acquires a limit of quantification (LOQ) in ng L-1, consistent with the provisions of ecotoxicological test. The methods described should be used as an analytical tool for methamidophos in soil, and the ecotoxicological analysis can be used as a "screening" and LC-MS/MS as confirmatory analysis of the analyte molecule, confirming the objectives of this work

Bronsted Acid Catalyzed Morita-Baylis-Hillman Reaction: A New Mechanistic View for Thioureas Revealed by ESI-MS(/MS) Monitoring and DFT Calculations

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Phenolic Composition of the Edible Parts (Flesh and Skin) of Bordo Grape (Vitis labrusca) Using HPLC-DAD-ESI-MS/MS

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Venom peptide analysis of Vipera ammodytes meridionalis (Viperinae) and Bothrops jararacussu (Crotalinae) demonstrates subfamily-specificity of the peptidome in the family Viperidae

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Re-examination of the anion derivatives of isoflavones by radical fragmentation in negative electrospray ionization tandem mass spectrometry: experimental and computational studies

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

An LC-DAD Fingerprinting Method for Alkaloids, Flavonoids and Styrylpyrones from Cryptocarya mandioccana

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Determination of carbamate insecticides in apples, pears, and lettuce by LC with UV detector

A simple and rapid method was developed for determination of 8 carbamate insecticides and 10 of their metabolites in apples, pears, and lettuce by liquid chromatography with UV diode array detector. With this method no derivatization is needed. Carbamates not belonging to the N-methylcarbamate class and metabolites without the N-methyl group can also be determined.

New chemical evidence for the ability to generate radical molecular ions of polyenes from ESI and HR-MALDI mass spectrometry

We report here new chemical evidence for the generation of radical molecular ions of compounds with a conjugated pi-system (polyene) in ESI and HR-MALDI mass spectrometry. The oxidation potential of the neutral polyenes was calculated by cyclic-voltammetry and the results compared with those previously published for other complex conjugated compounds that have also been shown to form M.+ in ESI-MS. This study clearly demonstrates the correlation between the oxidation potential and the formation of the M.+ for the polyenes studied.

Multiresidue analysis of pesticides in water from rice cultures by on-line solid phase extraction followed by LC-DAD

An automated on-line solid phase extraction procedure followed by liquid chromatography with diode array detection was investigated for the determination of different classes of pesticides in water samples containing varied amount of humic substances. The different pesticides used were: carbendazin, carbofuran, atrazine, diuron, propanil, molinate, alachlor, parathion-ethyl, diazinon, trifluralin and the degradation products deisopropylatrazine and deethylatrazine. Humic substances extracted from a Brazilian sediment were used from 5 to 80 mg/l and their influence on recoveries was evaluated in neutral and acidic media. Recoveries higher than 70% were obtained for all the pesticides, from the preconcentration of 75 mi of aqueous sample fortified at 2 ng/ml using precolumns packed with PLRP-S. Good recoveries were obtained at neutral pH for most of the analytes up to 40 mg/l of humic acid. Only at 80 mg/l the recoveries were significantly affected, both at acidic and neutral pH. The method was applied to the determination of pesticides in river water spiked at 0.1 to 1 ng/ml. Detection limits obtained for water containing 10 mg/l of humic acid were between 0.05 and 0.3 ng/ml.

A Validated Stability-Indicating LC Method for Orbifloxacin in the Presence of Degradation Products

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)