Derivative Uv Spectroscopic Approaches In Multicomponent Analysis–A Review

The spectrophotometric multi-component analysis involves spectrum recording and mathematical equations. However, spectral interference poses a major limitation when mixture samples are encountered. To overcome this derivative spectrophotometry (DS) has been introduced for the resolution of overlapping peaks. In this review modified methods like derivative quotient spectra, double divisor ratio spectra derivative method, double divisor means centering of ratio spectra method, derivative subtraction coupled with the constant multiplication method (DS-CM), amplitude subtraction (AS), modified amplitude subtraction (MAS), amplitude factor method (P-Factor), amplitude modulation method (AM), amplitude summation method (A-Sum), simultaneous derivative ratio spectrophotometry (S1DD), derivative compensation ratio via regression equation, differential dual wavelength (D1 DWL), differential derivative ratio (D1DR), successive derivative subtraction method (SDS) and derivative transformation (DT) of derivative spectrophotometry theories and applications are reviewed. These methods were applied to solve different complex pharmaceuticals mixtures. These developed methods were simple and cost-effective.

Development and validation of a method for the determination of folic acid in different pharmaceutical formulations using derivative spectrophotometry

ABSTRACT Folic acid is a B complex water-soluble vitamin that is essential to humans, and its deficiency can cause problems including congenital malformations in the fetus as well as heart disease. Most countries affected by diseases associated with a lack of folic acid now supplement foods with the vitamin. There is therefore a need for the development of new analytical procedures able to determine folic acid present in different matrices. This work describes the development of zero order and first order derivative spectrophotometric methods for the determination of folic acid in different pharmaceutical formulations, using 0.1 mol L-1 NaOH as solvent. The methods are shown to be simple, selective, and robust. Good linearity was achieved, with correction coefficients ≥0.9996 and limits of detection and quantification ranging from 0.64 to 0.75 and from 1.80 to 2.85 mg L-1, respectively. Recoveries of 98-104% were obtained in accuracy tests, and precision (as RSD) was between 0.2 and 4.8%. The methods can be used in routine analyses for quality control purposes, offering an alternative to the procedures already reported in the literature

Validation of high performance liquid chromatographic and spectrophotometric methods for the determination of the antiparkinson agent pramipexole dihydrochloride monohydrate in pharmaceutical products

abstract The antiparkinson agent pramipexole dihydrochloride monohydrate was quantified in pharmaceutical products by high performance liquid chromatography (HPLC) and derivative spectrophotometry. The first method was based on HPLC using tamsulosin HCl as an internal standard. In this method, chromatographic separation was achieved using a LiChrospher 60 RP column at 25°C, with a flow rate of 1.0 mL/min at 263 nm. The eluent comprised 0.01 mol/L ammonium acetate (pH 4.4) and acetonitrile (35:65 by volume). The linearity range was found to be 10.0-30.0 µg/mL with a mean recovery of 100.5 ± 1.10. The limit of detection (8 ng/mL) and limit of quantification (50 ng/mL) were calculated. In the second method, the first derivative spectrophotometric technique for the determination of pramipexole dihydrochloride monohydrate was performed by measuring the amplitude at 249 and 280 nm. In the first derivative technique, the absorbance and concentration plot was rectilinear over the 5.0-35.0 µg/mL range with a lower detection limit of 1.5 ng/mL and quantification limit of 4.5 ng/mL. The typical excipients included in the pharmaceutical product do not interfere with the selectivity of either method. The developed methods were validated for robustness, selectivity, specificity, linearity, precision, and accuracy as per the ICH and FDA guidelines (ICH Q2B, 1996; FDA,2000). In conclusion, the developed methods were successful in determining the quantity of the antiparkinson agent pramipexole dihydrochloride monohydrate in pharmaceutical products. The RSD values for the pharmaceutical product used in this study were found to be 0.97% for the HPLC method and 0.00% for the first derivative spectrophotometric method.

resumo O fármaco antiparkinsoniano, dicloridrato de pramipexol monoidratado, foi quantificado no produto farmacêutico por cromatografia líquida de alta eficiência (CLAE) e espectrofotometria derivada. No primeiro método baseado na CLAE, o cloridrato de tansulosina foi usado como padrão interno. Nesse método, a separação cromatográfica foi realizada usando uma coluna Lichrosper 60 RP a 25 °C e acetato de amônio 0,01 mol/L (pH:4.4): acetonitrila (35:65 em volume) como eluente com fluxo de 1,0 mL /min a 263 nm. A faixa de linearidade foi de 10.0-30.0 µg/mL com média da recuperação 100.5 ± 1.10. O limite de detecção (8 ng/mL) e o limite de quantificação (50 ng/mL) foram calculados. Por outro lado, a primeira técnica de espectrofotometria derivada para a determinação de dicloridrato de pramipexol monoidratado foi realizada através da medida da amplitude a 249 e 280 nm. Na técnia da primeira derivada, a absorvância e a plotagem da concentração foi retilínea na faixa de 5.0-35.0 µg/mL com limite inferior de detecção de 1.5 ng/mL e limite de quantificação de 4.5 ng/mL. Os excipientes típicos incluídos no produto farmacêutico não interferem com a seletividade dos métodos. Os métodos desenvolvidos foram validados quanto à robustez, seletividade, especificidade, linearidade, precisão e exatidão de acordo com as diretrizes do ICH e FDA (ICH Q2B,1996; FDA,2000). Concluindo, os métodos propostos foram aplicados com sucesso para a determinação quantitativa do agente antiparkinsoniano dicloridrato de pramipexol monoidrato em produtos farmacêuticos. Os valores de RSD para o produto farmacêutico utilizado neste estudo foi 0.97% para a CLAE e 0.00% para o método de espectrofotometria de primeira derivada.

Desenvolvimento de nanopartículas de poli (n-butil-cianoacrilato) com zidovudina revestidas por ácido hialurônico para veiculação em gel de uso transdérmico / Development nanoparticles poly (n -butyl cyanoacrylate) zidovudine coated with hyaluronic acid to serve transdermal gel using

A zidovudina (AZT) ainda é o fármaco mais empregado no tratamento da AIDS, isoladamente ou em associação a outros antirretrovirais, porém é um fármaco administrado em altas doses e que apresenta efeitos adversos que comprometem a adesão do paciente ao tratamento. Assim, um novo sistema de liberação de zidovudina composto por nanopartículas de poli (n-butil-cianoacrilato) (PBCA) revestidas por ácido hialurônico (AH) foi desenvolvido e caracterizado com o objetivo de prolongar a liberação do fármaco e diminuir sua toxicidade. As nanopartículas têm sido amplamente estudadas como veículo para fármacos por permanecer na circulação por um tempo maior e, portanto, liberar o fármaco de forma prolongada. Para polimerização e, portanto, obtenção das nanopartículas, n-butil-cianoacrilato e Dextran® foram adicionados a HCl 0,1 M (pH 2,5), sob agitação a 800 rpm, por 1 h. O AZT foi adicionado e o processo foi neutralizado com adição de NaOH 0,1M após mais 3 h de agitação. Após filtração as partículas foram revestidas pela adição de uma dispersão aquosa de ácido hialurônico (AH) a baixa rotação. O diâmetro hidrodinâmico médio das nanopartículas não revestidas foi de 152,3 nm, com um índice de polidispersividade médio igual a 0,055. O potencial zeta médio dessas partículas foi -0,678 mV. O diâmetro hidrodinâmico médio das nanopartículas revestidas com AH obtido foi de 196,9 nm, com um índice de polidispersividade médio igual a 0,440. O potencial zeta médio dessas partículas foi de -25,6 mV. Os valores resultantes dessas análises são indicativos da estabilidade das nanopartículas obtidas e da boa reatividade dos monômeros dos cianoacrilatos. Ainda, pelos resultados é possível confirmar a ocorrência do revestimento. Assim, a eficiência do processo de revestimento das nanopartículas pode ser comprovada por meio dos resultados das análises de calorimetria exploratória diferencial (DSC) e pelos resultados das análises de espectroscopia de absorção na região do infravermelho. Para quantificar o fármaco associado às nanopartículas, um método empregando espectrofotometria derivada (ED1) no UV aplicando a técnica do ponto de anulação foi desenvolvido e validado. Tal método possibilitou a eliminação da interferência dos excipientes, o que permitiu a quantificação do AZT na suspensão de nanopartículas com precisão e exatidão adequadas. A porcentagem de fármaco associado às nanoestruturas obtidas pelo método foi de 64%, considerado satisfatório. As nanopartículas foram incorporadas a uma formulação base de gel de Carbopol® 940 que, apresentou estabilidade após ser submetida a diferentes condições de armazenamento, com incidência de luz e variação da temperatura

Zidovudine (AZT) is still the most widely used drug in the treatment of AIDS, alone or in combination with other antiretroviral drugs, however it is indicated in high doses and has adverse effects that compromise patient compliance to treatment. Thus, a new zidovudine delivery system made of poly (n-butyl-cyanoacrylate) nanoparticles coated with hyaluronic acid (HA) was developed and characterized in order to extend the drug release and reduce its toxicity. The nanoparticles have been widely studied as drug carriers once they remain in circulation for a longer period and, consequently, release the drug gradually. For the polymerization, and, therefore synthesis of nanoparticles, n-butyl-cyanoacrylate and Dextran® were added to 0.1 M HCl (pH 2.5) and stirred at 800 rpm for 1 hour. AZT was added and the reaction was neutralized by the addition of 0.1 M NaOH after 3 more hours of agitation. After filtration the particles were coated by addition of an aqueous dispersion of hyaluronic acid (HA) at low revs. The mean hydrodynamic diameter of non-coated nanoparticles was 152.3 nm with an average polydispersity index of 0.055. The average zeta potential of these particles was -0.678 mV. The average hydrodynamic diameter of the coated nanoparticles was 196.9 nm, presenting an average polydispersity index of 0.440. The average zeta potential of these particles was -25.6 mV. The resulting values of these tests are indicative not only of the stability of the obtained nanoparticles but also the good reactivity of the monomers of cyanoacrylates. Moreover, the results can confirm the occurrence of coating. Thus, the efficiency of the coating process of the nanoparticles can be demonstrated by the results of the analysis of differential scanning calorimetry (DSC) and the results of the absorption spectroscopy in the infrared region. In order to quantify the drug associated with the nanoparticles, a method employing derivative spectrophotometry (ED1) UV applying the zero-crossing technique was developed and validated. This method allowed the elimination of interference of excipientes, allowing the quantification of AZT nanoparticles in suspension with adequate accuracy and precision. The percentage of the drug associated with the obtained nanostructures by the method was 64%. The nanoparticles were incorporated into a Carbopol® 940 gel formulation, which was stable after being subjected to different storage conditions, with incidence of light and temperature variation

Development and Validation of First Derivative Spectrophotometric Method for Quantification of Darunavir in Tablets.

Aims: Darunavir is widely used in HIV/AIDS therapy. It is a HIV protease inhibitor that has excellent efficacy against the virus. The aim of this study is to develop and validate an analytical method fast and free of interferences for determination of darunavir ethanolate as raw material and tablet dosage form. Methodology: As the formulation excipients show high interference in darunavir determination by a direct UV absorption measurement a derivative spectrophotometry was applied. A selective, easy and fast method was achieved employing simple and cheap instrumentation by using first-order derivative spectrophotometry. Results: The first-derivation of spectrum of the drug measured between 200 and 400 nm allowed identification of the analyte and showed absence of placebo interference. The assay was based on the absorbance at 276nm. The linear concentration range was established from 11 to 21 μg/mL. The intra-day and inter-day precision expressed as RSD was 0.06% and 3.75% respectively with mean recovery of 99.84%. Conclusion: The proposed analytical method is able to quantify darunavir as raw material and tablets and can be used routinely by any laboratory applying a spectrophotometer with a derivative accessory. The great difference of the method proposed here is that it proves to be free of placebo interferences as well as simple, fast and low cost.

Spectrophotometric methods for determination of tapentadol hydrochloride.

Two simple, fast, environmental friendly and reliable spectrophotometric methods were developed for determination of tapentadol hydrochloride in bulk and synthetic mixture containing the possible excipients. The first method is based on measuring the first derivative values of aqueous solution of the drug at 228 nm (method I) and the second method based on measuring the second derivative values at 235 nm (method II). Calibration graphs constructed at their wavelengths of determination were linear in the concentration range of tapentadol 5- 60 μg.ml-1 for both methods. The proposed methods have been extensively validated as per ICH guidelines. The developed spectrophotometric methods in this study are simple, accurate, precise, specific and reproducible and can be directly applied to pharmaceutical dosage form.

Extraction and purification technology for different extracts from Lamiophlomis rotata in industrialization / 中草药

Objective: The macroporous adsorptive resin chromatographic column combining with polyamide chromatographic column was used to separate the flavonoides, phenylethanoidglycosides, iridoid glycosides, and high polarity ingredients (such as alkaloid salts and sugars) in industrialization. Methods: Water extract from Lamiophlomis rotata (WELR) was separated and enriched by series and parallel method of polyamide and macroporous adsorptive resins and CCPP serial laminar analysis, and was ultrafiltrated by LM-125 ultrafiltration apparatus, then was dried under the reduced pressure by JYT-50 LN multipurpose kinesis back flow extract concentration subassembly. WELR, 70% ethanol solution eluate I (70% ethanol solution eluted polyamide column), 70% ethanol solution eluate II (70% ethanol solution eluting macroporous resin column), and ultrafiltration matter. The total flavonoids and total phenylethanoid glycosides were determined by aluminum nitrate-sodium nitrite UV spectrophotometry. The total iridoid glycosides were determined by the first derivative spectrophotometry. Shanzhiside methylester and 8-O-acetyl shanzhiside methylester were determined and the changes of total iridoid glycosides ingredients were investigated in the different elution requirement by HPLC. Results: Ethanol (70%) was used as dissolvent. Using the "introduction from superior surface" sample introduction mode and "introduction from superior surface" eluting mode in polyamide chromatographic column, the "introduction from inferior surface" sample introduction mode and "introduction from superior surface" eluting mode in the macroporous adsorptive resin chromatographic column, yields of 70% ethanol solution eluate I, 70% ethanol solution eluate II, and ultrafiltration matter were 2.43%, 20.80%, and 82.60%, respectively. Conclusion: This production technology may transform the experimental achievement to industrial production successfully.

Derivative Spectrophotometric Methods for the Determination of Zolpidem Tartrate in Tablets.

Two simple, precise and accurate first derivative spectrophotometric methods were developed for the determination of Zolpidem Tartrate in pharmaceutical formulations in phosphate buffer pH 6.8 and acetate buffer pH 4.0. Beer’s law was obeyed over the concentration range 0.5-20 μg/ml in both phosphate buffer (pH 6.8) (Method A) and acetate buffer (pH 4.0) (Method B). The regression equations were found to be y = 0.101x+0.012 (r2 = 0.999) and y = 0.064x+0.009 (r2 = 0.999) in Method A and B respectively. The % RSD in precision studies was found to be 0.28-0.69 (Intra-day) and 0.31-0.73 (Inter-day) for Method A and 0.25-0.82 (Intra-day) and 0.26-0.57 (Inter-day) for Method B respectively. The % RSD in accuracy studies was also found to be 0.14-0.19 (Method A) and 0.18-0.23 (Method B) with percentage recovery 98.67-99.78 and 98.56-99.83 Method A and B respectively.

Simultaneous determination of pioglitazone and glimepiride in their pharmaceutical formulations.

Four sensitive and precise spectrophotometric methods were developed and validated for the simultaneous determination of pioglitazone hydrochloride (PGZ) and glimepiride (GLM) in their pharmaceutical formulations. Among the methods adopted were direct absorbance, firstderivative (1D), second-derivative (2D) and first-derivative of ratio spectra (1DD). The selectivity of the proposed methods was checked using laboratory prepared mixtures. The proposed methods were successfully applied to the analysis of GLM and PGZ in their mixture and in pharmaceutical dosage forms without interference from other additives.

Validated stability indicating methods for determination of nitazoxanide in presence of its degradation products / 药物分析学报

Three sensitive,selective and reproducible stability-indicating methods are presented for determination of nitazoxanide (NTZ),a new anti-protozoal drug,in presence of its degradation products.Method A utilizes the first derivative of ratio spectra spectrophotometry by measurement of the amplitude at 364.4 nm using one of the degradation products as a divisor.Method B is a chemometric-assisted spectrophotometry,where principal component regression (PCR) and partial least squares (PLS) were applied.These two approaches were successfully applied to quantify NTZ in presence of degradation products using the information included in the absorption spectra in the range 260-360 nm.Method C is based on the separation of NTZ from its degradation products followed by densitometric measurement of the bands at 254 nm.The separation was carried out on silica gel 60F254,using chloroform-methanol-ammonia solution-glacial acetic acid (95∶5∶1∶1 by volume,pH=5.80) as a developing system.These methods are suitable as stability-indicating methods for the determination of NTZ in presence of its degradation products either in bulk powder or in pharmaceutical formulations.Statistical analysis of the results has been carried out revealing high accuracy and good precision.

Sensitive spectrophotometric determination of thorium (IV) using diacetyl monoxime isonicotinoyl hydrazone (DMIH).

Thorium (IV) forms a yellow Coloured water soluble complex with Diacetyl Monoxime Isonicotinoyl hydrazone (DMIH) reagent in acidic buffer of PH 5.0 with λ max at 352 nm. The molar absorptivity and sandell’s sensitivity are 2.265 X 10 4 L mol -1 cm -1 and 0.0022μg /cm2 respectively. The Beer’s law validity range 1.16–13.92 μg / mL. Thorium (IV) forms (M: L) 1:1 complex with DMIH and stability constant of the complex is 7.0265 X 10 6.The derivative spectrophotometric determination of Th (IV)) was carried out by measuring peak height method. The developed derivative spectrophotometric method was employed for the determination of Thorium (IV) in synthetic samples of alloy. The effect of various diverse ions was also studied.

Direct and derivative spectrophotometric determination of gold (iii) using 3,5-dimethoxy-4-hydroxybenzaldehyde benzoylhydrazone(dmbbh) in presence of micellar medium.

A simple and sensitive spectrophotometric method has been developed for the determination of Gold (III) using 3,5-Dimethoxy-4-hydroxy benzaldehyde benzoylhydrazone (DMBBH) in a neutral surfactant of Triton X-100(5%) (micellar medium). Gold (III) forms an wine red coloured water soluble complex with the reagent in acidic medium pH 5.0. The molar absorptivity and Sandell’s sensitivity of coloured species are 2.32 x 104 L.mol-1 cm-1 and 0.00862 mg/cm2 respectively. Beer’s law is obeyed in the range 0.4925-5.91 mg/ml of Au(III) at lmax at 380 nm. The developed derivative spectrophotometric method was employed for the determination of gold (III). This method has been satisfactorily applied for the determination of gold (III) in water samples and pharmaceutical samples.

Serum paraquat concentration detected by spectrophotometry in patients with paraquat poisoning / 世界急诊医学杂志（英文）

BACKGROUND: Paraquat (PQ) is a world-wide used herbicide and also a type of common poison for suicide and accidental poisoning. Numerous studies have proved that the concentration of serum PQ plays an important role in prognosis. Spectrophotometry, including common spectrophotometry and second-derivative spectrophotometry, is commonly used for PQ detection in primary hospitals. So far, lack of systematic research on the reliability of the method and the correlation between clinical features of patients with PQ poisoning and the test results has restricted the clinical use of spectrophotometry. This study aimed to evaluate the reliability and value of spectrophotometry in detecting the concentration of serum PQ. METHODS: The wavelengths for detecting the concentration of serum PQ by common and second-derivative spectrophotometry were determined. Second-derivative spectrophotometry was applied to detect the concentration of serum PQ. The linear range and precision for detection of PQ concentration by this method were confirmed. The concentration of serum PQ shown by second-derivative spectrophotometry and HPLC were compared in 8 patients with PQ poisoning. Altogether 21 patients with acute poisoning 4 hours after PQ ingestion treated in the period of October 2008 to September 2010 were retrospectively reviewed. The patients were divided into higher and lower than 1.8 μg/mL groups based on their concentrations of serum PQ measured by second-derivative spectrophotometry on admission. The severity of clinical manifestations between the two groups were analyzed with Student's t test or Fisher's exact test. RESULTS: The absorption peak of 257 nm could not be found when common spectrophotometry was used to detect the PQ concentration in serum. The calibration curve in the 0.4–8.0 μg/mL range for PQ concentration shown by second-derivative spectrophotometry obeyed Beer's law with r=0.996. The average recovery rates of PQ were within a range of 95.0％ to 99.5％, relative standard deviation (RSD) was within 1.35％ to 5.41％ (n=6), and the lower detection limit was 0.05 μg/mL. The PQ concentrations in serum of 8 patients with PQ poisoning shown by second-derivative spectrophotometry were consistent with the quantitative determinations by HPLC (r=0.995, P<0.0001). The survival rate was 22.2％ in patients whose PQ concentration in serum was more than 1.8 μg/mL, and the incidences of acidosis, oliguria and pneumomediastinum in these patients were 55.6％, 55.6％and 77.8％, respectively. These clinical manifestations were different significantly from those of the patients whose PQ concentration in serum was less than 1.8 μg/mL (P<0.05). CONCLUSIONS: For common spectrophotometry, the wavelength at 257 nm was not suitable for detecting serum PQ as no absorbance was shown. Second-derivative spectrophotometry was reliable for detecting serum paraquat concentration. Serum PQ concentration detected by second-derivative spectrophotometry could be used to predict the severity of clinical manifestations of patients with PQ poisoning, and PQ content higher than 1.8 μg/mL 4 hours after ingestion could be an important predictive factor for poor prognosis.

Direct and derivative spectrophotometric determination of mercury (II) using diacetylmonoxime benzoylhydrazone (DMBH).

A simple and derivative spectrophotometric method has been developed for the determination of mercury (II) using Diacetylmonoxime benzoylhydrazone (DMBH). Mercury (II) forms an orange coloured water soluble complex with the reagent in basic medium (pH 10.5).The molar absorptivity and Sandell’s sensitivity of coloured species are 2.01 x 104 L.mol-1 cm-1 and 0.0099 mg/cm2 respectively. Beer’s law is obeyed in the range 1.0029 – 12.0354 mg/ml of Hg (II) at lmax 361 nm. The developed derivative spectrophotometric method was employed for the determination of mercury (II). This method has been satisfactorily applied for the determination of mercury (II) in different environmental water samples and biological samples.

Espectrofotometria derivada: uma contribuição prática para o desenvolvimento de métodos / A contribution to the derivative spectrophotometry method

A espectrofotometria derivada (ED) tem sido utilizada como uma importante ferramenta no controle de qualidade de medicamentos para a determinação simultânea de fármacos em sistemas multicomponentes. Esta técnica oferece uma alternativa para melhorar a sensibilidade e a seletividade na análise de misturas e está acessível à maioria dos laboratórios. O procedimento é simples, rápido e não necessita extração prévia da amostra. Este trabalho tem como objetivo fornecer subsídios para o desenvolvimento de método por espectrofotometria derivada, utilizando a técnica do ponto de anulação, visando utilizá-la como um método alternativo no controle de qualidade de fármacos associados e, em especial, nos estudos de dissolução. Muitos subsídios foram retirados da literatura, outros de experiências vivenciadas no laboratório durante o desenvolvimento do método por ED aplicado na análise de dois inibidores da protease do vírus da imunodeficiência humana. Várias ordens de derivadas, diferentes valores de lambda delta e diferentes velocidades de varredura foram avaliados.

Derivative spectrophotometry has been successfully used as a quality control tool in pharmaceutical analysis for the simultaneous determination of drugs in multicomponent formulations. This technique, accessible to most laboratories, offers an alternative means of enhancing the sensitivity and specificity in mixture analysis. The procedure is simple, rapid and does not require any preliminary separations or treatment of the samples. The aim of this study is to provide pointers for the development of methods of analysis by derivative spectrophotometry (DS), using the zerocrossing technique, and to encourage professionals and researchers to use DS as an alternative method for quality control of drug combinations, especially in the study of dissolution. Much information, extracted from the literature, has been assembled here, together with the laboratory experience gained while developing a DS method to analyze a combination of two human immunodeficiency virus protease inhibitors. Various orders of derivatives, values of delta lambda and scan speeds were tested.

Validação intralaboratorial de metodologia quantitativa para determinação de L-fenilalanina em farinha de trigo por espectrofotometria derivada segunda / Single-laboratory validation of a quantitative methodology for determination of L-phenylalanine in wheat flour by second derivative spectrophotometry

O objetivo deste trabalho foi validar um método quantitativo para determinação de L-fenilalanina (Fen) em farinha de trigo por espectrofotometria derivada segunda. A amostra de farinha de trigo, na quantidade de 0,525g, foi submetida à hidrólise ácida com HCl a 5,7 mol/L, a 110 °C, por 24 h. O material hidrolisado foi reconstituído para 50 mL com tampão fosfato de sódio a 0,1 mol/L, pH 7,0. As soluções preparadas a partir dessa amostra foram submetidas às leituras de absorvância, entre 230 nm e 280 nm, em espectrofotômetro UV/VIS. Os espectros de derivada segunda foram traçados e os valores das áreas dos picos negativos foram utilizados para estimar os teores de Fen. A linearidade do método foi demonstrada na faixa de 0,010 mg/mL a 0,035 mg/mL (correspondente a teores de 251 mg/100g a 877 mg/100g de Fen em farinha de trigo). Efeitos de matriz foram observados. A determinação de Fen não sofreu interferência de compostos como L-tirosinae L-triptofano. As porcentagens de recuperação variaram de 81% a 118% e os desvios padrão relativos de repetitividade e reprodutibilidade parcial foram respectivamente 11% e 15%, para amostras contendo 354 mg/100g, demonstrando adequada recuperação e precisão do método. Os limites de detecção e quantificação foram, respectivamente, 63 mg/100ge 175 mg/100g. Os parâmetros de desempenho estudados indicaram adequação do método para o monitoramento e controle de teores de Fen em farinha de trigo.

Determination of optimum wavelength and derivative order in spectrophotometry for quantitation of hydroquinone in creams

UV derivative spectrophotometry was used for quantitative determination of hydroquinone in creams. The aim of this work was to investigate optimum wavelength and order of derivative, and to validate the proposed spectrophotometric method. The results of standard curves were calculated and statistically analyzed through the least squares method in the interval from 10.0 to 26.0 µg/mL, in the first, second, third and fourth order derivatives. The quantitative determination was carried out by using the zero-crossing (Z-C) and zero-peak (Z-P) methods. The proposed method is simple, of low cost and provides reliable results in order to be used in quality control of creams containing hydroquinone as active substance.

A espectrofotometria derivada no UV foi usada para a determinação quantitativa de hidroquinona em cremes. O objetivo desta pesquisa foi investigar o melhor comprimento de onda e a ordem da derivada, bem como validar o método proposto. Os resultados das curvas analíticas foram analisados estatisticamente pelo método dos mínimos quadrados no intervalo de 10,0 a 26,0 µg/mL, na primeira, segunda, terceira e quarta ordens da derivada. As determinações quantitativas foram realizadas utilizando os métodos "zero-crossing (Z-C)" e zero-pico (Z-P). O método proposto é simples, de baixo custo e fornece resultados confiáveis podendo ser usado no controle de qualidade de cremes contendo hidroquinona como substância ativa.

Determination of the Main Component of Captopril Tablets by Derivative Spectrophotometry / 中国药房

OBJECTIVE:To establish derivative spectrophotometry for the determination of the main component of Captopril tablets.METHODS:Under the alkaline condition of sodium hydroxide,2,4-dinitrofluorobenzene was used as derivatization reagent to react with captopril at 40 ℃ in the water bath.Then UV spectrophotometry was adopted to detect the content of captopril with detection wavelength set at 342 nm.RESULTS:The linear range of captopril was 1.0～14.0 ?g?mL-1(r=0.999 9) with an average recovery of 99.61%(RSD=1.27%,n=9).The RSD of intra-day and inter-day both were less than 2%.CONCLUSION:This method is stable,reliable,rapid and simple for the determination of the main components of Captopril tablets.

Determination of the Content of Vitamin E in Muyan Capsule by First-Derivative Spectrophotometry / 中国药房

OBJECTIVE:To determine vitamin E in muyan capsule.METHODS:The content of vitamin E in muyan capsule was determined by first-derivative spectrophotometry with detection wavelength at 230nm.RESULTS:The linear range of vitamin E was 14.98 ～ 24.96? g? mL-1(r=0.999 8).The average recovery of vitamin E was 100.1%(RSD=0.26%).CONCLUSION:The method is simple,rapid and accurate,and applicable for the determination of vitamin in muyan capsule.

Study on Dissolution Test Methods for Diclofenac Sodium Suppository / 中国药房

OBJECTIVE:To establish a good method for determining the dissolution rates of diclofenac sodium suppository METHODS:The dissolution method Ⅰ and Ⅱ of ChP(2000) were compared,the first derivative spectrophotometry was used and the parameters(T50,Td,m) obtained from these samples were brought for correlation analysis RESULTS:The dissolution rate of diclofenac sodium suppository from the dissolution method Ⅰ and Ⅱ were remarkably different,and the dissolution method Ⅱ was better than Ⅰ CONCLUSION:The method established by this study is suitable for the quality control of diclofenac sodium suppository,and the percentage of dissolution of diclofenac sodium suppository in 45min more than 80% is the standard of quality control