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Abstract This laboratory study aimed to evaluate the influence of endodontic sealer and cervical limit of root filling on the discoloration of root canal treated teeth. Bovine incisors were randomly distributed into six experimental groups and control (n=21/group), according to the endodontic sealer used [AH Plus (AP); MTA Fillapex (MF) and Sealer Plus BC (SPB)] and the cervical limit of root filling [dental cervix (DC) or 2 mm in apical direction (2mm-AD)]. Tooth discoloration (ΔE) was evaluated by a digital spectrophotometer using the CIED2000 method. Color assessments were performed immediately before (baseline), 1 week, 1, 3, 6 months, and 1 year after obturation. Data were analyzed by ANOVA and Tukey's post-hoc tests (α=5%). Teeth filled with the three sealers showed perceptible tooth discoloration (ΔE≥2.7) in 1 week, maintaining similar values over time. There was a significant difference between MF and SPB sealers in the 2mm-AD groups. In addition, 2mm-AD groups promoted significantly lower discoloration than DC groups for AH (3 months) and SPB (1 and 3 months) sealer,s. Teeth filled with AP, MF, and SPB sealers displayed discoloration from 1 week to one year, with differences between MF and SPB sealers. A cervical limit of filling material at 2 mm from the dental cervix seems more advisable, promoting lower crown discoloration.
Resumo O presente estudo laboratorial teve como objetivo avaliar a influência do cimento endodôntico e do limite cervical da obturação radicular na alteração de cor de dentes tratados endodonticamente. Incisivos bovinos foram distribuídos aleatoriamente em seis grupos experimentais e um controle (n=21/grupo), de acordo com o cimento endodôntico utilizado [AH Plus (AP); MTA Fillapex (MF) e Sealer Plus BC (SPB)] e o limite cervical da obturação [Colo dentário (CD) ou 2mm na direção apical (2mm-DA)]. A alteração de cor (ΔE) foi avaliada por um espectofotômetro digital usando o método CIED2000. As avaliações de cor foram realizadas imediatamente antes (baseline), 1 semana, 1, 3, 6 meses e 1 ano após a obturação. Os dados foram analisados pelos testes ANOVA e post-hoc de Tuckey (α=5%). Dentes obturados com os três cimentos apresentaram alteração de cor perceptível (ΔE≥2.7) em 1 semana, mantendo valores semelhantes ao longo do tempo. Houve uma diferença significativa entre os cimentos MF e SPB nos grupos 2mm-DA. Além disso, os grupos 2mm-DA promoveram uma alteração de cor significativamente menor do que o grupos CD para os cimentos AH (3 meses) e SPB (1 e 3 meses). Os dentes obturados com os cimentos AH, MF e SPB apresentaram alteração de cor entre 1 semana a um ano, com diferenças entre os cimentos MF e SPB. O limite cervical do material obturador a 2mm do colo dentário parece mais aconselhável, promovendo menor alteração de cor da coroa dentária.
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Aims@#The utilisation of lignocellulosic biomass for bioethanol production reduces the dependency on fossil fuels as a source of energy and emission of greenhouse gas (GHG). However, studies in this emerging field are hampered by the cost of ethanol quantification methods. Due to the volatile nature of ethanol, the method for the quantification of bioethanol production should be reproducible and rapid to avoid any evaporation loss to the surroundings. Therefore, this study aimed to develop a simple, rapid and precise bioethanol quantification method using a gas chromatographyflame ionisation detector (GC-FID) without having to go through distillation process for ethanol purification.@*Methodology and results@#The bioethanol was produced via consolidated bioprocessing (CBP) using Trichoderma asperellum B1581 and paddy straw. The peak corresponding to ethanol was obtained at 2.347 min with a peak area of 189.66, equating to 0.159% (v/v) or 1.25 g/L ethanol. A comparison between the quantity of ethanol detected by GC-FID and spectrophotometric analysis (340 nm) showed no significant difference (p>0.05) in the amount of ethanol detected by GC analysis, thus validating the accuracy of the GC method.@*Conclusion, significance and impact of study@#This work presents a simple, precise and reliable method to determine the amount of bioethanol in the sample using a GC-FID. Currently, there are many GC-FID methods available for the determination of ethanol/alcohol in a human blood samples or in beverages but not in bioethanol samples. Thus, this method was developed to facilitate the determination of bioethanol in the samples produced from lignocellulosic materials.
Subject(s)
Chromatography, Gas , Flame Ionization , EthanolABSTRACT
Objective. The aim of this study was the development and validation of an UV-Vis spectrophotometric method for the quantification of oclacitinib in commercial capsule formulation since pharmacopeias have not yet provided an official monograph for this drug. Methods. The parameters linearity, limit of detection, limit of quantitation, specificity, precision, accuracy, and robustness were determined according to Brazilian and international guidelines. Results. Linearity was determined for the analytical range of 5-15 µg/mL, and a limit of detection of 1.18 µg/mL and limit of quantification of 3.58 µg/mL were obtained. The method was selective and the precision was demonstrated through repeatability and intermediate precision, with relative standard deviations of 1.96% and 1.78%, respectively. In its turn, accuracy presented recovery percentages of 98.32-100.91%. All robustness and sample stability (48 h at 25 °C) results revealed no statistical variation among the groups. Conclusions. The presented method is suitable for the quantification of oclacitinib in commercial capsule formulation.
ABSTRACT
Abstract Among fruits and fruit products, oranges and orange juice are the most widely consumed worldwide. However, the effects of pest infestation of oranges on the quality of orange juice are not yet known. To evaluate the effect of the oriental fruit fly Bactrocera dorsalis on the antioxidant activity of orange juice, we measured changes in the vitamin C (Vc) concentration, total phenol content, and antioxidant activity of orange juice after the introduction of fruit fly eggs. Ten days after the eggs were introduced (larvae removed), the concentration of Vc in orange juice was 18.65 µg/mL, which was 9.16 µg/mL lower than that measured in healthy orange juice. In addition, the total phenol content decreased by 46.519 mg Gallic Acid Equivalents (GAE)/g to 9.748 mg GAE/g. Furthermore, the free-radical scavenging activity decreased from 22.297% to 5.393%. Correlation analysis indicated significant correlations between Vc concentration, total phenol content, and antioxidant activity of orange juice after B. dorsalis infestation. The decrease in Vc concentration, total phenol content and free-radical scavenging activity indicated that B. dorsalis changed the quality of orange juice by affecting the antioxidant activity of the juice after the oranges were infested.
Resumo Entre frutas e produtos de frutas, as laranjas e suco de laranja são os mais consumidos em todo o mundo. No entanto, os efeitos da infestação de laranjas sobre a qualidade do suco de laranja ainda não são conhecidos. Para avaliar o efeito da mosca-das-frutas oriental, Bactrocera dorsalis, sobre a atividade antioxidante do suco de laranja, foram medidas as mudanças na concentração de vitamina C (Vc), no teor de fenol total e na atividade antioxidante do suco de laranja após a introdução de ovos da mosca-das-frutas oriental. Dez dias após a introdução dos ovos (larvas removidas), a concentração de Vc no suco de laranja foi de 18,65 µg/mL, que foi 9,16 µg/mL menor do que a medida em suco de laranja saudável. Além disso, o teor total de fenol diminuiu de 46,519 mg em equivalente de ácido gípico (GAE)/g para 9,748 mg de GAE/g. Ademais, a atividade de eliminação de radicais livres diminuiu de 22,297% para 5,393%. A análise de correlação indicou correlações significativas dentre a concentração de Vc, o conteúdo total de fenol e a atividade antioxidante do suco de laranja após a infestação por B. dorsalis. A diminuição na concentração de Vc, o conteúdo total de fenol e a atividade sequestradora de radicais livres indicaram que B. dorsalis alterou a qualidade do suco de laranja, afetando a atividade antioxidante do suco após a infestação das laranjas.
Subject(s)
Animals , Female , Tephritidae , Citrus sinensis , Oviposition , Fruit , AntioxidantsABSTRACT
Estimation of plasma protein binding (PPB) is of paramount importance in the pharmacokinetics characterization of drugs, as it can cause significant change in volume of distribution, clearance and half-life of the drug. Ampicillin (α-amino benzyl penicillin) is most commonly used drug in equine practice. This study was conducted to determine the extent of PPB of ampicillin in apparently healthy horses (n=6). A simple spectrophotometric method was applied for the determination of ampicillin at 320 nm wavelength, based on acid degradation product of penicillin at 75°C in presence of citrate buffer (pH 5.2) and traces of copper salt. In the study, it was observed that this method permits the detection of ampicillin to a level not beyond 1.0 μg/ml. Various concentrations of ampicillin (3.125, 6.25, 12.5, 25, 50, 100 μg/ml) were prepared in triplicate in pooled plasma collected from healthy animals. In vitro binding of ampicillin to plasma proteins was determined by employing the equilibrium dialysis technique. The study revealed that the plasma protein binding of ampicillin was to the extent of 12.8 ± 0.07 %. Binding capacity of ampicillin to plasma protein (βi) and dissociation rate constant of protein-drug complex (Kβ) in the present study were 0.34 × 10-6 ± 0.02 × 10-6 mol.gm-1 and 0.003 × 10-9 ± 0.0003 × 10-9 mol, respectively in horses. Hence, the study concluded that usage of spectrophotometric method helps in quick, cost effective and efficient results in estimation of PPB for ampicillin
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Objective: To develop and validate novel more sensitive analytical methods for the concurrent quantification of metformin-canagliflozin and metformin-gliclazide in their bulk forms and in their pharmaceutical preparations. Methods: Two methods were developed based on several chemometric assisted spectrophotometric methods and a Reversed-Phase High-Performance Liquid Chromatography (RP-HPLC). The first method applies different spectrophotometric chemometric assisted methods, including ratio difference, derivative ratio and extended ratio subtraction method, while the second method describes a RP-HPLC separation of metformin hydrochloride-canagliflozin and metformin hydrochloride-gliclazide binary mixtures using a C18 column with a mobile phase consisting of acetonitrile: potassium dihydrogen phosphate (adjusted to pH 3) with sodium lauryl sulphate as additive in the ratio of 30:70 (%v/v) in isocratic elution mode at 1 ml/min. Results: The proposed methods were able to quantify each of the studied drugs in their binary mixtures with high percentage recoveries in both methods. The spectrophotometric methods were able to quantify each of metformin, canagliflozin and gliclazide in the ranges of 2.0-20.0 μg/ml, 1.5-40.0 μg/ml and 2.0-30.0 μg/ml, respectively. The RP-HPLC method produced well-resolved peaks at a retention time of 3.92, 6.92 and 9.10 min in the concentration ranges of 50.0-300.0 μg/ml, 5.0-50.0 μg/ml and 10.0-100.0 μg/ml for metformin, canagliflozin and gliclazide, respectively. The proposed methods were optimized and validated in accordance to the International Conference of Harmonisation (ICH) guidelines in terms of linearity, LOD, LOQ, precision and accuracy. Conclusion: The developed methods were found to be sensitive and reproducible methods for the simultaneous determination of anti-diabetic binary mixtures; metformin hydrochloride-canagliflozin and metformin hydrochloride-gliclazide. And thus were successfully employed for the quality control analysis of the pharmaceutical formulations of the studied binary mixtures.
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Objective: To develop and validate new, selective spectrophotometric colorimetric analytical methods for the quantification of methimazole in its pure form and in its pharmaceutical preparations. Methods: Method A is based on the oxidation of methimazole with potassium permanganate in alkaline medium, the manganate ion produced was measured at λmax= 610 nm. Method B is a kinetic determination of methimazole using fixed-time method based on the oxidation of methimazole using known excess of cerium (IV) nitrate in acidic medium and assessing the unreacted Ce (IV) by adding a fixed amount of methyl orange and measuring the absorbance of the resultant solution at λmax=507 nm which is equivalent to the unreacted methyl orange. The reaction conditions and analytical parameters are investigated and optimized. Method validation was carried out according to ICH guidelines in terms of linearity, LOD, LOQ, precision, and accuracy. Results: Beer’s law is obeyed in the range of 1.50–15.00 μg/ml for method A and 0.25–3.00 μg/ml for method B. The developed methods were subjected to the detailed validation procedure. The proposed spectrophotometric methods were applied for the determination of the methimazole in its pure form and in its pharmaceutical formulation. The percentage recoveries were found to be 100.82 % and 99.85 % in the pharmaceutical formulation for the two proposed methods, respectively. Conclusion: Both developed spectrophotometric methods, considered as green analytical chemistry, were found to be novel, highly selective and can be applied for the quality control of methimazole in its pure form and in its pharmaceutical formulation based on the simplicity, applicability of the parameters, accessibility of the reagents employed and reasonably low time of analysis.
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This study was performed with an objective of developing and validating an UV-spectroscopic method for estimating contents of prulifloxacin in simulated intestinal fluid (SIF) i.e. phosphate- buffer media with a pH of 6.8 as per ICH guidelines. The λmax for prulifloxacin in phosphate- buffer media pH 6.8 was found to be 272 nanometer. The calibration curve of drug followed linearity in-between 1-9 μg/ml concentration range and correlation co-efficient value was found equal to 0.9995. We tested this proposed method onto the bulk and marketed pharmaceutical formulation (tablets) also in order to find out contents of drug. Using developed method for estimation of prulifloxacin in SIF, drug was found to be in-between 101.91 and 104.02 % in marketed tablets which shows a good agreement with that of the claimed level. Accuracy of developed method was established through recovery experimentation, performed for three spiked percent concentrations- 75%, 100%, and 125%. The % recovery was found to be in between 97.27 and 101.82%. Low values of % RSD supported accuracy as well as the reproducibility of developed method. Precision of developed method was established by good in-limit intraday and interday experimental variations and through repeatability tests. Values of % RSD less than 2 confirmed about precision of developed method. The ruggedness of the developed method was validated by performing drug estimation by two different performers. This proposed spectroscopic method has proved to be a rapid and successful method for routine analysis of prulifloxacin in simulated intestinal fluid.
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Capecitabine is a fluoropyrimidine carbamate, designed as 'pro-drug' to the cytotoxic agent 5-fluorouracil (5-FU) meant to be administered orally. Capecitabine is used as first line monotherapy for metastatic colorectal cancer. In the present study simple, rapid, accurate UV spectrophotometric methods were developed and validated for the estimation of capecitabine in bulk and its formulations as per ICH guidelines. Three solvent systems viz., 0.1N NaOH, 0.1N HCl and Methanol: Water (1:3) were tried. The results suggest that the developed methods shows linearity over the concentration range of 2-24μg/ml with a correlation coefficient of 0.9999. All the developed methods were statistically validated for accuracy, precision, linearity, robustness, and ruggedness as per ICH guidelines. The % RSD values for validated methods were found to be less than 1.5 and methods will find application in routine analysis of drug formulations containing capecitabine.
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A sensitive, simple, and economic spectrophotometric method was developed and validated for the determination ofgabapentin in pure form and pharmaceutical preparations. The method is based on Schiff base condensation reaction ofthe primary amino group of gabapentin with salicylaldehyde reagent in the presence of acetate solution at 45°C for 20minutes. The obtained yellow-colored derivative in methanolic medium showed absorption maxima at 403 nm. Underthe optimum conditions, Beer’s law was obeyed in the concentration range of 6 to 100 μg/ml with correlation coefficientvalue of 0.9961. Limit of detection and limit of quantification were found to be 1.16 and 3.48 μg/ml, respectively. Thevalidity of the described method was assessed according to the International Conference on Harmonization guidelines.The mean percentage recoveries ± SD were 100.57 ± 1.5 by applying the standard addition technique. The method wasrepeatable and precise (RSD ≤ 0.61% and ≤ 1.34%, respectively) and was successfully applied for the determinationof the investigated drug in its pharmaceutical dosage form without detectable interference from the additives, hence,can be suggested for routine analysis of the gabapentin.
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ABSTRACT Dysphania ambrosioides (L.) Mosyakin and Clemants (Syn: Chenopodium ambrosioides L.), Amaranthaceae, is a plant with antibacterial, antifungal, antioxidant, antiparasitic and antitumor properties that is commonly used in Brazilian folk medicine. In this work we performed the optimization of ultrasound-assisted extraction of flavonoids in the aerial parts of D. ambrosioides. The flavonoid concentrations, as rutin equivalents, were quantified with the aid of a validated spectrophotometric method. The Box-Behnken (33) design with response surface methodology, for the independent variables, extraction time, temperature, and ethanol content, were used for the optimization of ultrasound-assisted extraction. The analytical method was selective, linear, without matrix interference, accurate, precise and robust. The best conditions for the ultrasound-assisted extraction of flavonoids were: time of 60 min, temperature of 57 °C and ethanol content of 57% (w/w). The methods of extracting and quantifying flavonoids developed in the present study have provided be eco-friendly, simple, and useful to determine the flavonoid content, expressed as rutin equivalents, in the aerial parts of D. ambrosioides.
ABSTRACT
A sensitive, simple, and economic spectrophotometric method was developed and validated for the determination ofgabapentin in pure form and pharmaceutical preparations. The method is based on Schiff base condensation reaction ofthe primary amino group of gabapentin with salicylaldehyde reagent in the presence of acetate solution at 45°C for 20minutes. The obtained yellow-colored derivative in methanolic medium showed absorption maxima at 403 nm. Underthe optimum conditions, Beer’s law was obeyed in the concentration range of 6 to 100 μg/ml with correlation coefficientvalue of 0.9961. Limit of detection and limit of quantification were found to be 1.16 and 3.48 μg/ml, respectively. Thevalidity of the described method was assessed according to the International Conference on Harmonization guidelines.The mean percentage recoveries ± SD were 100.57 ± 1.5 by applying the standard addition technique. The method wasrepeatable and precise (RSD ≤ 0.61% and ≤ 1.34%, respectively) and was successfully applied for the determinationof the investigated drug in its pharmaceutical dosage form without detectable interference from the additives, hence,can be suggested for routine analysis of the gabapentin.
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Objective: The aim of the present work was to develop and validate a simple UV spectroscopic method for the determination of duloxetine, which is a thiophene derivative and a selective neurotransmitter reuptake inhibitor for serotonin, norepinephrine, and to lesser degree dopamine. Methods: The UV Spectrophotometric analysis was performed using Shimadzu UV-1800 and Shimadzu UV-1700 spectrophotometer by using solvent system acetonitrile and water in the ratio of 8:2. Detection was performed at a wavelength of 290 nm. Method validation was carried out according to ICH Q2R1 guidelines by taking the parameters linearity, accuracy, precision, ruggedness, and robustness, LOD and LOQ. Results: The UV Spectrophotometric method was found linear in the range of 10-50 μg/ml. The method was rugged and robust with % relative standard deviation less than 2. The extraction recoveries were found to be higher than 99% in all experimental conditions. Conclusion: Based upon the performance characteristics, the proposed method was found accurate, precise and rapid and suitable for the determination of Duloxetine for routine analysis.
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Objective To optimize the color conditions of spectrophotometric determination of total saponins in Fructus Trichosanthis. Methods Several factors affecting the content determination of total saponins in Fructus Trichosanthis were studied, including the color temperature, color time, 5% vanillin-acetic acid dosage, as well as the amount of perchloric acid. The analysis conditions were optimized by Box-Behnken response surface method. Results The optimized conditions were: temperature 60°C, the col or time 25 min, 5% vanillin-acetic acid 0.1 ml and perchloric 0.6 ml. The color was stable and the determination results were accurate. Conclusion The color conditions determined by Box-Behnken response surface method can be used for content determination of total saponins in Fructus Trichosanthis.
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Objective To optimize the color conditions of spectrophotometric determination of total saponins in Fructus Trichosanthis. Methods Several factors affecting the content determination of total saponins in Fructus Trichosanthis were studied , including the color temperature,color time,5%vanillin-acetic acid dosage,as well as the amount of perchloric acid. The analysis con-ditions were optimized by Box-Behnken response surface method. Results The optimized conditions were:temperature 60℃,the col-or time 25 min,5%vanillin-acetic acid 0.1 ml and perchloric 0.6 ml. The color was stable and the determination results were accurate. Conclusion The color conditions determined by Box-Behnken response surface method can be used for content determination of total saponins in Fructus Trichosanthis.
ABSTRACT
Abstract Among fruits and fruit products, oranges and orange juice are the most widely consumed worldwide. However, the effects of pest infestation of oranges on the quality of orange juice are not yet known. To evaluate the effect of the oriental fruit fly Bactrocera dorsalis on the antioxidant activity of orange juice, we measured changes in the vitamin C (Vc) concentration, total phenol content, and antioxidant activity of orange juice after the introduction of fruit fly eggs. Ten days after the eggs were introduced (larvae removed), the concentration of Vc in orange juice was 18.65 µg/mL, which was 9.16 µg/mL lower than that measured in healthy orange juice. In addition, the total phenol content decreased by 46.519 mg Gallic Acid Equivalents (GAE)/g to 9.748 mg GAE/g. Furthermore, the free-radical scavenging activity decreased from 22.297% to 5.393%. Correlation analysis indicated significant correlations between Vc concentration, total phenol content, and antioxidant activity of orange juice after B. dorsalis infestation. The decrease in Vc concentration, total phenol content and free-radical scavenging activity indicated that B. dorsalis changed the quality of orange juice by affecting the antioxidant activity of the juice after the oranges were infested.
Resumo Entre frutas e produtos de frutas, as laranjas e suco de laranja são os mais consumidos em todo o mundo. No entanto, os efeitos da infestação de laranjas sobre a qualidade do suco de laranja ainda não são conhecidos. Para avaliar o efeito da mosca-das-frutas oriental, Bactrocera dorsalis, sobre a atividade antioxidante do suco de laranja, foram medidas as mudanças na concentração de vitamina C (Vc), no teor de fenol total e na atividade antioxidante do suco de laranja após a introdução de ovos da mosca-das-frutas oriental. Dez dias após a introdução dos ovos (larvas removidas), a concentração de Vc no suco de laranja foi de 18,65 µg/mL, que foi 9,16 µg/mL menor do que a medida em suco de laranja saudável. Além disso, o teor total de fenol diminuiu de 46,519 mg em equivalente de ácido gípico (GAE)/g para 9,748 mg de GAE/g. Ademais, a atividade de eliminação de radicais livres diminuiu de 22,297% para 5,393%. A análise de correlação indicou correlações significativas dentre a concentração de Vc, o conteúdo total de fenol e a atividade antioxidante do suco de laranja após a infestação por B. dorsalis. A diminuição na concentração de Vc, o conteúdo total de fenol e a atividade sequestradora de radicais livres indicaram que B. dorsalis alterou a qualidade do suco de laranja, afetando a atividade antioxidante do suco após a infestação das laranjas.
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ABSTRACT This work presents the development of a methodology based on the formation of a charge transfer complex between quinalizarin and rosuvastatin, allowing for the spectrophotometric determination of rosuvastatin at 579 nm. The factors involved in the sensitivity of the technique were studied (nature and proportion of the solvent, reaction time, pH of aqueous phase and quinalizarin concentration). The proposed spectrophotometric procedures were validated with respect to linearity, ranges, precision, accuracy, detection and quantification limits. Calibration curves of the formed color products showed good linear relationships over the concentration range of 6-15 mg L-1. The proposed method has been successfully applied, which can be confirmed by interference test (comparison between the standard curves and addition of analyte), method precision (RSD 2.3% to 6 mg L-1), and by accuracy (statistically equivalent results between the proposed method and a chromatographic method of reference).
Subject(s)
Spectrophotometry/methods , Drug Compounding/statistics & numerical data , Rosuvastatin Calcium/analysis , Chromatography, High Pressure Liquid/statistics & numerical data , Methodology as a SubjectABSTRACT
Drug counterfeiting and production of substandard drug is a global problem. Substandard or counterfeit drugs are threat for the effective treatment of diseases and highly worsen the quality of life of patients. This study was aimed to assess the pharmaceutical quality of ranitidine hydrochloride tablets manufactured in Bangladesh. Tablets were collected from different parts of Bangladesh and quality parameters were evaluated according to the United States Pharmacopoeia and the British Pharmacopoeial methods. The potency of tablets was measured spectrophotometrically. Weight variation and disintegration time were performed according to pharmaceutical monographs. Among 43 brands tested, 8 failed to comply with the USP specification (active ingredient: 90±10%) due to containing of less amount of ranitidine of which 6 brands were spurious and 2 were substandard in nature. Two brands did not comply with the specification for weight variation of tablets whereas all brands passed disintegration time test. The findings clearly demonstrate the production of substandard ranitidine tablets in Bangladesh. The drug control authority of Bangladesh should take effective steps to prevent the production of substandard drugs to secure public health.
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A cadmium column reduction-azo dyes spectrophotometric method based on micro sequential injection lab-on-valve was established for the determination of total nitrogen in seawater. The experimental parameters were optimized, and the interference experiment was carried out. The results showed that the interference of the main components and salinity in sea water could be eliminated by using a series of standard solution prepared by national standard seawater with certain salinity. The concentration of total nitrogen in seawater was linear with the absorbance in the range of 0 . 03-1 . 00 mg/L with a correlation coefficient of 0. 9993. When determining the national standard seawater at nitrogen concentration of 0. 20 mg/L, the relative standard deviation (RSD) was 4. 9%, the detection limit was 0. 010 mg/L, and the recoveries were 99. 5%-101 . 1%. There were not significance differences between the results of this method and national standard method in the t-test analysis. The method is suitable for the determination of total nitrogen in seawater.
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RESUMONesse trabalho são apresentados os resultados dos ensaios espectrofotométricos realizados nas amostras retiradas das águas do Rio Guaraguaçú localizado no litoral Paranaense. Esses ensaios foram realizados para quantificar o elemento fósforo pelo método do azul de molibdênio e o elemento nitrogênio pelos métodos de Griess e indofenol. Com esses resultados foi possível avaliar que o referido rio vem sofrendo com a atividade antrópica no seu entorno. Os resultados de fosfato estão acima dos valores estabelecidos pela Resolução 357/2005 do CONAMA, sendo que esses resultados, quando comparados com os obtidos em outro rio da região, são similares, daí observa-se que esse fato não é provocado por atividade antrópica. Já os resultados das concentrações dos íons amônio, nitrato e nitrito indicam que os valores obtidos estão abaixo dos valores máximos estabelecidos pela referida resolução, denota-se então que a presença desses dois últimos íons em águas superficiais ocorre onde a atividade antrópica está em expansão.
ABSTRACTIn this paper are present the results of spectrophotometric tests performed on water samples taken from the Guaraguaçú River located on the coast of Paraná State, Brazil. These tests were conducted to quantify the element phosphorus by the blue molybdenum method and the element nitrogen by Griess and indophenol methods. With these results it was possible to assess that this river has been suffering with anthropic activity in your surroundings. The results of phosphate are above the levels established in Resolution 357/2005 of CONAMA, and these results compared with those obtained in other river in the region are similar, hence we observe that this fact is not caused by human activity. Since the results of the concentrations of ammonium, nitrate and nitrite indicate that the values obtained are below the maximums established by that resolution, then we denote that the presence of the latter two ions in surface water occurs where anthropic activity is expanding.