RESUMO
A first-order derivative spectrophotometric (1D-UV) method was developed and validated for simultaneous determination of delapril (DEL) and manidipine (MAN) in tablets. The 1D-UV spectra were obtained using change lambda = 4.0 nm and wavelength set at 228 nm for DEL and 246 nm for MAN. The method was validated in accordance with the ICH requirements, involving the specificity, linearity, precision, accuracy, robustness and limits of detection and quantitation. The method showed high specificity in the presence of two drugs and formulation excipients and was linear over the concentration range of 18-54 microg mL(-1) (r2 = 0.9994) for DEL and 6-18 microg mL(-1) (r2 = 0.9981) for MAN with adequate results for the precision (< or = 1.47%) and accuracy (98.98% for DEL and 100.50% for MAN). Moreover, the method proved to be robust by a Plackett-Burman experimental design evaluation. The proposed 'D-UV method was successfully applied for simultaneous analysis of DEL and MAN in tablets and can be used as alternative green method to separation techniques. The results were compared with the validated liquid chromatography, capillary electrophoresis and liquid chromatography-tandem mass spectrometry methods, showing non-significant difference.
Assuntos
Inibidores da Enzima Conversora de Angiotensina/análise , Bloqueadores dos Canais de Cálcio/análise , Di-Hidropiridinas/análise , Indanos/análise , Espectrofotometria Ultravioleta/métodos , Cromatografia Líquida , Limite de Detecção , Nitrobenzenos , Piperazinas , Reprodutibilidade dos Testes , Espectrometria de Massas em TandemRESUMO
An automatic method, based on flow-batch (FB), for determining glycerol in biodiesel was developed. The FB systems draw upon the useful features of flow, batch and multi-commutation approaches. The standards and samples preparation, as well as, derivatization and analysis were fully automated. For that purpose, a homemade chamber was built. The proposed method is based on liquid-liquid extraction of glycerol and simultaneous oxidation with periodate, generating formaldehyde that reacts with acetylacetone. A fluorescent product of 3,5-diacetyl-1,4-dihydrolutidine was obtained. The fluorescence signal was recorded at λ(ex) =417 nm and λ(em) = 514 nm. A linear response was observed from 0.10 to 5.00 mg L(-1) glycerol, variation coefficient 1.5%, sampling rate 14 h(-1) and detection limit 0.036 mg L(-1) glycerol. The procedure was successfully applied to the analysis of biodiesel samples, and the results agreed with the reference method (ASTM D6584-07) at 95% confidence level.
Assuntos
Biocombustíveis/análise , Di-Hidropiridinas/análise , Glicerol/análise , Espectrometria de Fluorescência/métodos , Automação Laboratorial , Fluorescência , Formaldeído/química , Limite de Detecção , Extração Líquido-Líquido/métodos , Oxirredução , Pentanonas/química , Ácido Periódico/química , Espectrometria de Fluorescência/instrumentaçãoRESUMO
The fragmentation of dihydropyridine calcium-channel antagonists are compared by electrospray ionization (ESI) and atmospheric pressure photonization (APPI). The results demonstrate that in ESI the preferred ionization process is in positive mode, with the mass spectra of [M+H]+ showing base peak ions probably formed by loss of alcohols from carboxyl groups. Conversely, in APPI, a high intense peak is observed in negative mode due to deprotonated molecule [M-H]- after two serial 1, 2-hydride shifts leading to a rearranged deprotonated molecule [M-H]-. These ions undergo another 1,2-hydride shifts to produce a nitro-phenyl product ion of m/z 122. The APPI is also used to develop a method for the quantitation of dihydropyridines (e.g., nifedipine) in human plasma.
Assuntos
Bloqueadores dos Canais de Cálcio/análise , Di-Hidropiridinas/análise , Espectrometria de Massas/métodos , Espectrometria de Massas por Ionização por Electrospray/métodos , Bloqueadores dos Canais de Cálcio/química , Di-Hidropiridinas/química , Estrutura Molecular , Reprodutibilidade dos TestesRESUMO
EI mass spectra of products of the dihydropyridine Hantzsch synthesis using hydroxy and methoxy aldehydes as starting materials are reported. The reaction products (C-4 hydroxy- and methoxyphenyl-1,4-dihydropyridines and chromeno[3,4,c]-pyridines) were derivatized with N-methyl-N-(trimethylsilyl)-trifluoracetamide to be analyzed by gas chromatographic techniques. Fragmentation pathways for 1,4-dihydropyridines and chromeno-pyridines are proposed. The study provides (mainly through MS-MS technique) useful data for the confirmation of the structure of the compounds and also is a valuable tool for further analytical purposes to follow both photostability and reactivity studies with free radicals for these types of compounds.
Assuntos
Aldeídos/análise , Bloqueadores dos Canais de Cálcio/análise , Di-Hidropiridinas/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Espectrometria de Massas em Tandem/métodos , Aldeídos/química , Bloqueadores dos Canais de Cálcio/química , Di-Hidropiridinas/química , Cromatografia Gasosa-Espectrometria de Massas/instrumentação , Estrutura MolecularRESUMO
An HPLC reversed phase method using both UV (356 nm) and electrochemical (1000 mV) detection was developed in order to determine lercanidipine in commercial tablets. Repeatability and reproducibility were adequate. For quantification we have used the calibration plot method for lercanidipine concentration ranging between 1 x 10(-5) and 1 x 10(-4) M. Also, the proposed method is sufficiently selective to distinguish the parent drug and the degradation products after hydrolysis, photolysis or chemical oxidation. Furthermore, the typical excipients included in the drug formulation (talc, lactose, cornstarch, microcrystalline cellulose, carboxymethylcellulose and magnesium stearate) do not interfere with the selectivity of the method. Finally, the proposed chromatographic method was successfully applied to the quantitative determination of lercanidipine in commercial tablets.