A comparison between the high-temperature catalytic oxidation method (HTCO) and the UV/persulphate method for the determination of dissolved organic carbon (DOC)in seawater is presented in this paper. In seawater samp...A comparison between the high-temperature catalytic oxidation method (HTCO) and the UV/persulphate method for the determination of dissolved organic carbon (DOC)in seawater is presented in this paper. In seawater sample chloride ion can affect the oxidation efficiency of the UV/persulphate method if the asymptotic concentration of persulphate is not reached.During HTCO analysis, blanks that appear to originate mainly from the catalyst are high and far from constant.If the blanks are well estimated and correction is made, the difference of determined DOC values between the UV/persulphatemethod and the HTCO mehod is small, the HTCO values being slightly higher.展开更多
The application of cross flow ultrafiltration(CFF) techniques to separate colloidal organic carbon(COC) from truly dissolved organic carbon(TDOC) was investigated; COC and TDOC were determined by the high temperature ...The application of cross flow ultrafiltration(CFF) techniques to separate colloidal organic carbon(COC) from truly dissolved organic carbon(TDOC) was investigated; COC and TDOC were determined by the high temperature combustion method(HTC) and UV/persulphate method. It was found that CFF can quantitatively separate COC from seawater. The determination results by the HTC and UV/persulphate method for COC and TDOC showed little difference, which suggested that the oxidation efficiency of the two methods are identical. Colloidal particles have no remarkable influence on the oxidation efficiency of the UV/persulphate method.展开更多
A new method using high-performance liquid chromatography coupled with ultra violet detection(HPLC–UV)was developed and validated for the simultaneous quantification of atazanavir,dolutegravir,darunavir,efavirenz,etr...A new method using high-performance liquid chromatography coupled with ultra violet detection(HPLC–UV)was developed and validated for the simultaneous quantification of atazanavir,dolutegravir,darunavir,efavirenz,etravirine lopinavir,raltegravir,rilpivirine and tipranavir in human plasma.For the first time we reported here the development and validation of an HPLC–UV assay to quantify the frequently administered 9antiretroviral compounds including dolutegravir and rilpivirine.A simple solid phase extraction procedure was applied to 500 μL aliquots of plasma.The chromatographic separation of the drugs and internal standard(quinoxaline) was achieved with a gradient of acetonitrile and sodium acetate buffer on a C_(18) reverse-phase analytical column with a 25 min analytical run time.Calibration curves were optimised according to the therapeutic range of drug concentrations in patients,and the coefficient of determination(r^2) was higher than0.99 for all analytes.Mean intraday and interday precisions(RSD) for all compounds were less than 15.0%,and the mean accuracy(% deviation from nominal concentration) was also found to be less than 15.0%.Extraction recovery range was between 80% and 120% for all drugs analysed.The solid phase extraction and HPLC–UV method enable a specific,sensitive,and reliable simultaneous determination of nine antiretroviral agents in plasma.Good extraction efficiency and low limit of HPLC–UV quantification make this method suitable for use in clinical trials and therapeutic drug monitoring.展开更多
Baking meat by wrapping them in Aluminum (Al) foil is common in many countries. The excessive use of Al foil in baking and the disagreement about using Al foils were the motivation to do this study especially after th...Baking meat by wrapping them in Aluminum (Al) foil is common in many countries. The excessive use of Al foil in baking and the disagreement about using Al foils were the motivation to do this study especially after the 2007 WHO/FDA Report. In this investigation, a gravimetric and a UV-Vis spectrophotometric method are used to estimate Aluminum (Al) leaching into meat baked by wrapping in Al foil. Three kinds of meat were used fish, cow stakes and chicken. The importance of Al exposure area was neglected by many studies. Five factors affecting Al leaching into meat are studied (baking temperature, baking time, additives, Al exposure area and weight of meat). The effect of cooking times (20, 40, 60 minutes) at 180℃ and cooking temperatures (160℃, 180℃, 200℃) at 60 minutes on the amount of Al leaching were evaluated. It was found that Al leaching into meat increased with increasing temperature, baking time, additives and Al exposure area. Moreover, Al exposure area was more effective than the weight of the meat. The Al leaching was highest in fish and lowest in chicken. Comparing the present results with the Provisional Tolerance Weekly Intake of Al approved by WHO/FDA, it shows that Al leaching into meat baked by wrapping in Al foil may add considerable doses into the diet. Continuous monitoring of Al foil used for baking meat is recommended.展开更多
<strong>Context:</strong> Substandard and falsified medicines are circulating in low-income countries mostly without any control. We availed a simple and not expensive UV-Vis spectroscopic method to evalua...<strong>Context:</strong> Substandard and falsified medicines are circulating in low-income countries mostly without any control. We availed a simple and not expensive UV-Vis spectroscopic method to evaluate the quality of tramadol in Kisangani before and during the Covid-19 period. <strong>Methods:</strong> For the analytical quantitative method, an experimental design was applied to set up the optimal levels of the selected factors, namely, pH of dissolution medium, type of cuvette, and wavelength. Taking into account the capsule pharmaceutical formulation within 80 - 120 μg·mL<sup>-1</sup> concentration range, we analyzed 89 tramadol samples from pharmacies and hospitals of the six Kisangani municipalities. <strong>Results:</strong> pH showed a significant effect on absorbance, whereas quartz cuvette and wavelength did not. A typical 100 μg·mL<sup>-1</sup> tramadol solution gave an absorbance of 0.64 at 272 nm. Validation highlighted a matrix effect observed with a 6% bias. A correction factor of 0.9372 allowed to improve the accuracy profile, which were then totally included within the 10% acceptance limits. Quality control revealed that 25 samples out of 89 were not compliant in terms of manufacturing license, registration status in DRC and content as well. <strong>Conclusion:</strong> This study showed that the strengthening of analytical strategy in Kisangani is a need.展开更多
In the framework of fighting against the poor quality medicines sold in developing countries using classical analytical methods easily accessible in those countries, four UV-Visible spectrophotometric methods for one ...In the framework of fighting against the poor quality medicines sold in developing countries using classical analytical methods easily accessible in those countries, four UV-Visible spectrophotometric methods for one antimalarial (quinine) and two antibiotics (amoxicillin and metronidazole) have been developed and validated according to the total error strategy using the accuracy profiles as a decision tool. The dosing range was 2 - 10 μg/mL (for quinine sulfate in tablet), 4 - 12 μg/mL (for quinine bichlorhydrate in oral drop-metronidazole benzaote in oral suspension) and 15 - 35 μg/mL (for amoxicillin trihydrate in capsule). The validated methods were then applied in determining the content of some analogous medicines sold in the Democratic Republic of Congo. Thus, the proposed UV-Visible spectrophotometric methods are simple and suitable to quantify quinine, amoxicillin and metronidazole in different pharmaceutical forms.展开更多
Nicotine and cotinine in hair are good biomarkers for assessing long-term exposure to smoking. However, analytical devices such as GC/MS are associated with high cost and are not widely used. HPLC/UV is used widely in...Nicotine and cotinine in hair are good biomarkers for assessing long-term exposure to smoking. However, analytical devices such as GC/MS are associated with high cost and are not widely used. HPLC/UV is used widely in laboratories, but is unsuitable for measurement of minor constituents, except when using the column-switching method. Thus, we aimed to establish a simple, inexpensive and sensitive method based on HPLC/UV with column switching for measuring nicotine and cotinine in hair. First, we compared the presence and absence of a column selection unit. We then measured amounts of nicotine and cotinine in hair samples collected from the general population, and compared both the corresponding levels and the detection limits with those in previous studies. Finally, initial and running costs of HPLC/UV were compared with other analytical methods. As one of the results, the areas of nicotine and cotinine measured by HPLC/UV with column-switching method were 12.9 and 16.9 times greater, respectively, than those without the column-switching method. The amount of nicotine and cotinine in hair was significantly correlated to number of cigarettes smoked per day (r = 0.228, p = 0.040). In addition, the HPLC/UV method showed similar sensitivity and detection limit (nicotine, 0.10 ng/mg;cotinine, 0.08 ng/mg) as reported in previous studies. The cost of the HPLC/UV method is lower than that of other analytical methods. We were able to establish a low-cost method with good sensitivity for measuring nicotine and cotinine in hair. The HPLC/UV with a column-switching method will be useful as a first step in screening surveys in order to better understand the effects of smoking exposure.展开更多
In this paper, the kind of remanent small molecules in unsaturated polyester res(?) (UP resin) , the best extractant and the best suitalbe extractive time for measuring the content of these small molecules were studie...In this paper, the kind of remanent small molecules in unsaturated polyester res(?) (UP resin) , the best extractant and the best suitalbe extractive time for measuring the content of these small molecules were studied using ultraviolet- visible spectrophotometry ( UV-VIS method). According to the principle of additivity lightness absorption for mixid solution, the contents of samll molecules in several kinds of cured UP resin were measured. It is pointed out that the UV-VIS method in the assay quality of food grade GRP products is more suitable to China.展开更多
Two new selective, precise, and accurate methods were developed for the determination of fenofibrate in the presence of its basic degradation product. In the first method fenofibrate was determined using an algorithm ...Two new selective, precise, and accurate methods were developed for the determination of fenofibrate in the presence of its basic degradation product. In the first method fenofibrate was determined using an algorithm bivariate calibration derivative method, in which an optimum pair of wavelengths was chosen for the determination of different binary mixtures. In the second method (HPLC), separation was achieved on RESTEK Pinnacle II phenyl column (5 μm, 250 × 4.6 mm) and Pinnacle II phenyl (5 μm, 10 × 4 mm) guard cartridge using a mobile phase consisting of methanol –0.1% phosphoric acid (60:40, v/v) at a flow rate 2 mL●min–1, and the column oven temperature was set at 50°C. The UV detector was time programmed at 302 nm and 289 nm for the internal standard (I.S.) and fenofibrate, respectively. The proposed methods were successfully applied for the determination of fenofibrate and its degradation product in the laboratory-prepared mixture and in pharmaceutical formulation. The assay results obtained using the bivariate method were statistically compared to those of the HPLC method and good agreement was observed.展开更多
Nickel nanoparticles （〈10 nm） were success fully synthesized using a reductive method of nickel chloride with sodium borohydride in the ethanol/poly vinylpyrrolidone （PVP） system. The effects of three fac tors, s...Nickel nanoparticles （〈10 nm） were success fully synthesized using a reductive method of nickel chloride with sodium borohydride in the ethanol/poly vinylpyrrolidone （PVP） system. The effects of three fac tors, such as the concentration of the nickel ions, the time of reaction, and the amount of PVP （surfactant）, were discussed. The possible growth process of the particles and optimum reactive conditions was also investigated. The result of transmission electron microscopy （TEM） reveals that these nickel nanoparticles are spherical. The average diameter could be controlled as 25 nm under selected conditions. Highresolution TEM and energydispersive spectroscopy results indicates that the nickel nanoparticles are pure. The UVvisible light absorption spectrum shows that the peaks of nickel nanoparticles moves toward the short wavelength along with the decrease of sizes.展开更多
The research work was carried out for establishing a new Ultra Violet (UV)— Visible spectroscopy and Reverse phase-Ultra Fast Liquid Chromatography (RP-UFLC) method for the analysis and quantification of a biosimilar...The research work was carried out for establishing a new Ultra Violet (UV)— Visible spectroscopy and Reverse phase-Ultra Fast Liquid Chromatography (RP-UFLC) method for the analysis and quantification of a biosimilar drug, Filgrastim. Filgrastim or recombinant methionyl granulocyte colony stimulating factor (rGCSF) is a glycoprotein. It has a biological action essential for proliferation and differentiation of hematopoetic and progenitor cells. The UV and RP-UFLC work was carried on a Shimadzu UV1800 Spectrophotometer and Shimadzu Prominence LC-20AD UFLC systems, respectively. The <i>λ</i><sub>max</sub> of filgrastim was found to be 215 nm. The correlation coefficient by UV spectroscopy was found to be 0.9994 for the concentration range of 1 to 3 μg/ml in double distilled water. The Reverse phase UFLC was done by using Phenomenex C4 (25 cm × 0.46 cm internal diameter) 15 μ, 300 A° analytical column. The optimized mobile phase for binary elution was Acetonitrile and double distilled water (80:20) with a flow rate of 1 ml/min. The retention time of drug was at 3.2 min. It was observed that the response of the detector was linear in the range of 5 - 15 μg/ml with correlation coefficient value of 0.999. After developing the methods, it was assured for the intended use by validation of the analytical parameters like linearity, accuracy, precision, limit of detection, limit of quantitation, ruggedness and robustness. The results of all the parameters for both the methods were found to be within the acceptance criteria as per the International Council for Harmonisation (ICH) guidelines.展开更多
文摘A comparison between the high-temperature catalytic oxidation method (HTCO) and the UV/persulphate method for the determination of dissolved organic carbon (DOC)in seawater is presented in this paper. In seawater sample chloride ion can affect the oxidation efficiency of the UV/persulphate method if the asymptotic concentration of persulphate is not reached.During HTCO analysis, blanks that appear to originate mainly from the catalyst are high and far from constant.If the blanks are well estimated and correction is made, the difference of determined DOC values between the UV/persulphatemethod and the HTCO mehod is small, the HTCO values being slightly higher.
文摘The application of cross flow ultrafiltration(CFF) techniques to separate colloidal organic carbon(COC) from truly dissolved organic carbon(TDOC) was investigated; COC and TDOC were determined by the high temperature combustion method(HTC) and UV/persulphate method. It was found that CFF can quantitatively separate COC from seawater. The determination results by the HTC and UV/persulphate method for COC and TDOC showed little difference, which suggested that the oxidation efficiency of the two methods are identical. Colloidal particles have no remarkable influence on the oxidation efficiency of the UV/persulphate method.
基金supported by “Ministero della Salute” “Ricerca corrente 2015” grant to E.C.
文摘A new method using high-performance liquid chromatography coupled with ultra violet detection(HPLC–UV)was developed and validated for the simultaneous quantification of atazanavir,dolutegravir,darunavir,efavirenz,etravirine lopinavir,raltegravir,rilpivirine and tipranavir in human plasma.For the first time we reported here the development and validation of an HPLC–UV assay to quantify the frequently administered 9antiretroviral compounds including dolutegravir and rilpivirine.A simple solid phase extraction procedure was applied to 500 μL aliquots of plasma.The chromatographic separation of the drugs and internal standard(quinoxaline) was achieved with a gradient of acetonitrile and sodium acetate buffer on a C_(18) reverse-phase analytical column with a 25 min analytical run time.Calibration curves were optimised according to the therapeutic range of drug concentrations in patients,and the coefficient of determination(r^2) was higher than0.99 for all analytes.Mean intraday and interday precisions(RSD) for all compounds were less than 15.0%,and the mean accuracy(% deviation from nominal concentration) was also found to be less than 15.0%.Extraction recovery range was between 80% and 120% for all drugs analysed.The solid phase extraction and HPLC–UV method enable a specific,sensitive,and reliable simultaneous determination of nine antiretroviral agents in plasma.Good extraction efficiency and low limit of HPLC–UV quantification make this method suitable for use in clinical trials and therapeutic drug monitoring.
文摘Baking meat by wrapping them in Aluminum (Al) foil is common in many countries. The excessive use of Al foil in baking and the disagreement about using Al foils were the motivation to do this study especially after the 2007 WHO/FDA Report. In this investigation, a gravimetric and a UV-Vis spectrophotometric method are used to estimate Aluminum (Al) leaching into meat baked by wrapping in Al foil. Three kinds of meat were used fish, cow stakes and chicken. The importance of Al exposure area was neglected by many studies. Five factors affecting Al leaching into meat are studied (baking temperature, baking time, additives, Al exposure area and weight of meat). The effect of cooking times (20, 40, 60 minutes) at 180℃ and cooking temperatures (160℃, 180℃, 200℃) at 60 minutes on the amount of Al leaching were evaluated. It was found that Al leaching into meat increased with increasing temperature, baking time, additives and Al exposure area. Moreover, Al exposure area was more effective than the weight of the meat. The Al leaching was highest in fish and lowest in chicken. Comparing the present results with the Provisional Tolerance Weekly Intake of Al approved by WHO/FDA, it shows that Al leaching into meat baked by wrapping in Al foil may add considerable doses into the diet. Continuous monitoring of Al foil used for baking meat is recommended.
文摘<strong>Context:</strong> Substandard and falsified medicines are circulating in low-income countries mostly without any control. We availed a simple and not expensive UV-Vis spectroscopic method to evaluate the quality of tramadol in Kisangani before and during the Covid-19 period. <strong>Methods:</strong> For the analytical quantitative method, an experimental design was applied to set up the optimal levels of the selected factors, namely, pH of dissolution medium, type of cuvette, and wavelength. Taking into account the capsule pharmaceutical formulation within 80 - 120 μg·mL<sup>-1</sup> concentration range, we analyzed 89 tramadol samples from pharmacies and hospitals of the six Kisangani municipalities. <strong>Results:</strong> pH showed a significant effect on absorbance, whereas quartz cuvette and wavelength did not. A typical 100 μg·mL<sup>-1</sup> tramadol solution gave an absorbance of 0.64 at 272 nm. Validation highlighted a matrix effect observed with a 6% bias. A correction factor of 0.9372 allowed to improve the accuracy profile, which were then totally included within the 10% acceptance limits. Quality control revealed that 25 samples out of 89 were not compliant in terms of manufacturing license, registration status in DRC and content as well. <strong>Conclusion:</strong> This study showed that the strengthening of analytical strategy in Kisangani is a need.
文摘In the framework of fighting against the poor quality medicines sold in developing countries using classical analytical methods easily accessible in those countries, four UV-Visible spectrophotometric methods for one antimalarial (quinine) and two antibiotics (amoxicillin and metronidazole) have been developed and validated according to the total error strategy using the accuracy profiles as a decision tool. The dosing range was 2 - 10 μg/mL (for quinine sulfate in tablet), 4 - 12 μg/mL (for quinine bichlorhydrate in oral drop-metronidazole benzaote in oral suspension) and 15 - 35 μg/mL (for amoxicillin trihydrate in capsule). The validated methods were then applied in determining the content of some analogous medicines sold in the Democratic Republic of Congo. Thus, the proposed UV-Visible spectrophotometric methods are simple and suitable to quantify quinine, amoxicillin and metronidazole in different pharmaceutical forms.
文摘Nicotine and cotinine in hair are good biomarkers for assessing long-term exposure to smoking. However, analytical devices such as GC/MS are associated with high cost and are not widely used. HPLC/UV is used widely in laboratories, but is unsuitable for measurement of minor constituents, except when using the column-switching method. Thus, we aimed to establish a simple, inexpensive and sensitive method based on HPLC/UV with column switching for measuring nicotine and cotinine in hair. First, we compared the presence and absence of a column selection unit. We then measured amounts of nicotine and cotinine in hair samples collected from the general population, and compared both the corresponding levels and the detection limits with those in previous studies. Finally, initial and running costs of HPLC/UV were compared with other analytical methods. As one of the results, the areas of nicotine and cotinine measured by HPLC/UV with column-switching method were 12.9 and 16.9 times greater, respectively, than those without the column-switching method. The amount of nicotine and cotinine in hair was significantly correlated to number of cigarettes smoked per day (r = 0.228, p = 0.040). In addition, the HPLC/UV method showed similar sensitivity and detection limit (nicotine, 0.10 ng/mg;cotinine, 0.08 ng/mg) as reported in previous studies. The cost of the HPLC/UV method is lower than that of other analytical methods. We were able to establish a low-cost method with good sensitivity for measuring nicotine and cotinine in hair. The HPLC/UV with a column-switching method will be useful as a first step in screening surveys in order to better understand the effects of smoking exposure.
文摘In this paper, the kind of remanent small molecules in unsaturated polyester res(?) (UP resin) , the best extractant and the best suitalbe extractive time for measuring the content of these small molecules were studied using ultraviolet- visible spectrophotometry ( UV-VIS method). According to the principle of additivity lightness absorption for mixid solution, the contents of samll molecules in several kinds of cured UP resin were measured. It is pointed out that the UV-VIS method in the assay quality of food grade GRP products is more suitable to China.
文摘Two new selective, precise, and accurate methods were developed for the determination of fenofibrate in the presence of its basic degradation product. In the first method fenofibrate was determined using an algorithm bivariate calibration derivative method, in which an optimum pair of wavelengths was chosen for the determination of different binary mixtures. In the second method (HPLC), separation was achieved on RESTEK Pinnacle II phenyl column (5 μm, 250 × 4.6 mm) and Pinnacle II phenyl (5 μm, 10 × 4 mm) guard cartridge using a mobile phase consisting of methanol –0.1% phosphoric acid (60:40, v/v) at a flow rate 2 mL●min–1, and the column oven temperature was set at 50°C. The UV detector was time programmed at 302 nm and 289 nm for the internal standard (I.S.) and fenofibrate, respectively. The proposed methods were successfully applied for the determination of fenofibrate and its degradation product in the laboratory-prepared mixture and in pharmaceutical formulation. The assay results obtained using the bivariate method were statistically compared to those of the HPLC method and good agreement was observed.
基金supported by the National Natural Science Foundation of China(Nos.51272025 and 50872011)the National Key Basic Research Development Plan(973 Program)(No.2007CB613608)the New Century Excellent Researcher Award Program from Ministry of Education of China(No.NCET-08-0732)
文摘Nickel nanoparticles （〈10 nm） were success fully synthesized using a reductive method of nickel chloride with sodium borohydride in the ethanol/poly vinylpyrrolidone （PVP） system. The effects of three fac tors, such as the concentration of the nickel ions, the time of reaction, and the amount of PVP （surfactant）, were discussed. The possible growth process of the particles and optimum reactive conditions was also investigated. The result of transmission electron microscopy （TEM） reveals that these nickel nanoparticles are spherical. The average diameter could be controlled as 25 nm under selected conditions. Highresolution TEM and energydispersive spectroscopy results indicates that the nickel nanoparticles are pure. The UVvisible light absorption spectrum shows that the peaks of nickel nanoparticles moves toward the short wavelength along with the decrease of sizes.
文摘The research work was carried out for establishing a new Ultra Violet (UV)— Visible spectroscopy and Reverse phase-Ultra Fast Liquid Chromatography (RP-UFLC) method for the analysis and quantification of a biosimilar drug, Filgrastim. Filgrastim or recombinant methionyl granulocyte colony stimulating factor (rGCSF) is a glycoprotein. It has a biological action essential for proliferation and differentiation of hematopoetic and progenitor cells. The UV and RP-UFLC work was carried on a Shimadzu UV1800 Spectrophotometer and Shimadzu Prominence LC-20AD UFLC systems, respectively. The <i>λ</i><sub>max</sub> of filgrastim was found to be 215 nm. The correlation coefficient by UV spectroscopy was found to be 0.9994 for the concentration range of 1 to 3 μg/ml in double distilled water. The Reverse phase UFLC was done by using Phenomenex C4 (25 cm × 0.46 cm internal diameter) 15 μ, 300 A° analytical column. The optimized mobile phase for binary elution was Acetonitrile and double distilled water (80:20) with a flow rate of 1 ml/min. The retention time of drug was at 3.2 min. It was observed that the response of the detector was linear in the range of 5 - 15 μg/ml with correlation coefficient value of 0.999. After developing the methods, it was assured for the intended use by validation of the analytical parameters like linearity, accuracy, precision, limit of detection, limit of quantitation, ruggedness and robustness. The results of all the parameters for both the methods were found to be within the acceptance criteria as per the International Council for Harmonisation (ICH) guidelines.
文摘以正硅酸乙酯和常用的有机硅为原料,采用溶胶-凝胶法制备了可紫外光(UV)固化的有机硅/SiO2杂化涂料.研究了有机硅用量对杂化漆膜性能的影响,并用FTIR和固体29Si-NMR对杂化涂料进行了表征,测定了UV固化C C的转化率和硅氧烷的缩聚度.结果表明:杂化涂料的有机与无机网络间以共价键的方式结合,在UV固化240 s时双键转化率可达81.0%,硅氧烷的平均缩聚度为89.5%;由于采用了改进的溶胶-凝胶法,在高度交联的SiO2网络结构中引入线性Si O Si链段,使得漆膜既有高硬度又有良好的柔韧性,当TEOS/MPTMS/DDS摩尔比为6∶2∶3时膜的综合性能最佳.
