RESUMEN
In quantitative analysis of spectral data, noises and background interference always degrade the accuracy of spectral feature extraction. The wavelet transform is multi-scale decomposition used to reduce the noise and improve the analysis precision. On the other hand, the wavelet transform denoising is often followed by destroying the efficiency information. The present research introduced two indexes to control the scale of decomposition, the smoothness index (SI) and the time shift index (TSI). When the parameters satisfied TSI < 0.01 and SI > 0.100 4, the noise of spectral characteristic was reduced. In the meanwhile, the reflection peaks of biochemical components were reserved. Through analyzing the correlation between denoised spectrum and chlorophyll content, some spectral characteristics parameters reflecting the changing tendency of chlorophyll content were chosen. Finally, the partial least squares regression (PLSR) was used to develop the prediction model of the chlorophyll content of tomato leaf. The result showed that the predictiong model, which used the values of absorbance at 366, 405, 436, 554, 675 and 693 nm as input variables, had higher predictive ability (calibration coefficient was 0. 892 6, and validation coefficient was 0.829 7) and better potential to diagnose tomato growth in greenhouse.
Asunto(s)
Clorofila/análisis , Solanum lycopersicum/química , Espectroscopía Infrarroja Corta , Análisis de Ondículas , Calibración , Análisis de los Mínimos Cuadrados , Modelos Teóricos , Hojas de la Planta/químicaRESUMEN
AIM: To develop a near-infrared diffuse reflectance analysis (NIRDRA) method for rapid noninvasive quantitative determination of ambroxol hydrochloride in half-finished product particles and non-blister-packed, blistered tablets. METHODS: All spectra were measured with a Fourier transform spectrometer equipped with a PbS and a InGaAs detector, an external integrating sphere, a rotating sample cup, and a fibre-optic probe for reflectance measurements. All samples were scanned from 12,000 cm-1 to 4,000 cm-1, and each sample spectrum was obtained as an automatic mean of 64 scans. No spectrum pre-processing method was used, and spectral regions, 4,602-4,247, 12,000-7,498 and 6,102-5,446, 12,000-5,446 cm-1 were selected to develope mathematical models by partial least square method for half-finished product particles and non-blister-packed, blistered tablets samples, respectively. RESULTS: The optimal rank and mean square error determined for half-finished product particles and non-blister-packed, blistered tablets samples by cross validation method all was 6 and 0.306, 0.972 and 1.492, respectively, the average recovery was 100%, 100% and 102% respectively; and the RSD was 1.17%, 1.70% and 1.78% respectively. CONCLUSION: Results showed that the NIRDRA method was rapid, simple, noninvasive and sensitive, and it can be applied to assay the content of ambroxol hydrochloride in half-finished product particles non-blister-packed and blistered tablets.
Asunto(s)
Ambroxol/análisis , Expectorantes/análisis , Espectroscopía Infrarroja Corta/métodos , Ambroxol/administración & dosificación , Expectorantes/administración & dosificación , Control de Calidad , ComprimidosRESUMEN
AIM: To determine the molecular weight and first-order structure of somatostatin. METHODS: The molecular weight of somatostatin was determined by electrospray ionization mass spectrometry. Somatostatin was deoxidized by 2-mercaptoethanol. A series of typical fragment ions of deoxidized product were obtained by insource collision-induced dissociation (CID). RESULTS: The m/z of quasi-molecular ion [M + H]+ of somatostatin was 1,637.8 and [M + Na]+ was 1,659.5. The m/z of double-charge ion [M + 2H]2+ was 819.5 and [M + H + Na]2+ was 830.3. It showed that the molecular weight of somatostatin was 1,636.7. The y and b series of fragment ions of deoxidized product were obtained by adjusting the fragmentor voltage. It was determined that the first-order structure of deoxidized product of somatostatin was A-G-C-K-N-F-F-W-K-T-F-T-S-C. CONCLUSION: The molecular weight and first-order structure of somatostatin were confirmed.
Asunto(s)
Somatostatina/química , Espectrometría de Masa por Ionización de Electrospray/métodos , Secuencia de Aminoácidos , Estructura Molecular , Peso Molecular , Somatostatina/análisisRESUMEN
A new reagent, anthraquinone-2-sulfonyl chloride (ASC), has been used for the derivatization of phenols. Several compounds with different polarity were selected to evaluate the new reagent and derivatives of these phenols prepared via a facile pathway. The optimal conditions for analytical derivatization and mechanism of the derivatization reaction are discussed. The derivatization procedure involves an ion-pair extraction of the deprotonated phenols with a tetrabutylammonium counter ion to an organic phase. At the interface of two phases, the derivatization reaction occurs quantitatively at room temperature within 3 min. The derivatives are stable and readily amenable to analysis by normal-phase and reversed-phase high performance liquid chromatography (HPLC). Excellent linearity response was demonstrated over the concentration range of 0.2 mumol/L to 200 mumol/L at 320 nm for normal-phase HPLC, at 256 nm for reversed-phase HPLC. Combined with preconcentration using a Waters Sep-Pak Plus C18 cartridge, detection limits of phenols for water sample analysis were as low as 1 x 10(-9) mol/L (ca. 0.1 microgram/L).
Asunto(s)
Cromatografía Líquida de Alta Presión/instrumentación , Fenoles/análisis , Contaminantes Químicos del Agua/análisis , Abastecimiento de Agua/análisis , Antraquinonas , Cromatografía Líquida de Alta Presión/métodos , Estudios de Evaluación como Asunto , Indicadores y Reactivos , SolventesRESUMEN
AIM: To establish a RP-HPLC method for determination of cyclovirobuxine D. METHODS: Cyclovirobuxine D reacted with a derivative reagent 1-naphthyl isocyanate in chloroform to form fluorescence derivatives, stopped the reaction by adding the mobile phase and then directly injected the solution into the chromatograph to seperate it by RP-HPLC. The analysis was carried out on C18 column, the mobile phase is methanol-water (85:15), the excitation wavelength was set at 305 nm, emission at wavelength 385 nm, and the flow rate was 1 mL.min-1. The effect of several factors including the reaction medium, temperature, time and amount of 1-naphthyl isocyanate on the yield of the derivatization was also investigated systematically. RESULTS: A simple and rapid RP-HPLC method for the simultaneous isolation and analysis of cyclovirobuxine D and its related substances was developed, and the absence of interference between the derivative peak responses of cyclovirobuxine D and its related substances were verified by UV diode array detecter and MS. The linearity was obtained from 0.75 microgram.mL-1 to 2.5 micrograms.mL-1 of cyclovirobuxine D derivatives with a correlation coefficient of 0.9991. The detection limit of cyclovirobuxine D derivative was 1 ng.mL-1, the repeatability of derivatization was good with relative standard derivation no more than 1.2% and derivative was stable within 48 h. The method described conforms to the validation of China Pharmacopiea compendial methods used for pharmaceutical products in general. CONCLUSION: The established method is proved to be reliable quantitative method for the quality control of cyclovirobuxine D.