Food safety problems caused by excessive nitrite addition have been frequently reported and the detection of nitrite in food is particularly important. The standing time during the pretreatment of primary sample has a...Food safety problems caused by excessive nitrite addition have been frequently reported and the detection of nitrite in food is particularly important. The standing time during the pretreatment of primary sample has a great influence on the concentration of nitrite tested by spectrophotometric method. In this context, three kinds of food samples are prepared, including canned mustard, canned fish and home-made pickled water. A series of standing times are placed during the sample pretreatments and the corresponding nitrite contents in these samples are detected by spectrophotometric method based on N-ethylenediamine dihydrochloride. This study aims to find out a reasonable standing time during the pretreatment of food sample, providing influence factor for precise detection of nitrite.展开更多
1,10-phenanthroline and its derivatives can form charge-transfer complexes with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone(DDQ).The absorption spectra and conditions of complex formation,such as the reaction time,the q...1,10-phenanthroline and its derivatives can form charge-transfer complexes with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone(DDQ).The absorption spectra and conditions of complex formation,such as the reaction time,the quantity of DDQ, and the solvents, have been studied.After the HMO calculation of phenanthrolines,the molar absorptivities were found to depend on the substituents on the phenanthroline rings.展开更多
The new catalytic kinetic spectrophotometric method for Au(III) determination was developed and validated. It was based on the catalytic effect of gold on the oxidation of sudan red III by ammonium peroxodisulfate ...The new catalytic kinetic spectrophotometric method for Au(III) determination was developed and validated. It was based on the catalytic effect of gold on the oxidation of sudan red III by ammonium peroxodisulfate ((NH4)2S2O8) with nitrilo triacetic acid as an activator in microemulsion and H2SO4 medium. Under optimum conditions, there was the linearity of the calibration curve in the concentration range from 0 to 20 μg/L Au(Ⅲ) at 520 nm. The relative standard deviation was 3.0% with a correlation coefficient of 0.9986. The detection limit achieved was 9.75 × 10^-5 μg/mL. A new method using a column packed with sulfhydryl dextrose gel (SDG) as a solid-phase extractant has been developed for the preconcentration and separation of Au(Ⅲ) ions. The method has been applied to the determination of trace gold with satisfactory results.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
A new analytical method using Back-Propagation (BP) artificial neural network and kinetic spectrophotometry for simultaneous determination of iron and magnesium in tap water, the Yellow River water and seawater is est...A new analytical method using Back-Propagation (BP) artificial neural network and kinetic spectrophotometry for simultaneous determination of iron and magnesium in tap water, the Yellow River water and seawater is established. By conditional experiments, the optimum analytical conditions and parameters are obtained. Levenberg-Marquart (L-M) algorithm is used for calculation in BP neural network. The topological structure of three-layer BP ANN network architecture is chosen as 15-16-2 (nodes). The initial value of gradient coefficient μ is fixed at 0.001 and the increase factor and reduction factor of μ take the default values of the system. The data are processed by computers with our own programs written in MATLAB 7.0. The relative standard deviation of the calculated results for iron and manganese is 2.30% and 2.67% respectively. The results of standard addition method show that for the tap water, the recoveries of iron and manganese are in the ranges of 98.0%-104.3% and 96.5%-104.5%, and the RSD is in the range of 0.23%-0.98%; for the Yellow River water (Lijin district of Shandong Province), the recoveries of iron and manganese are in the ranges of 96.0%-101.0% and 98.7%-104.2%, and the RSD is in the range of 0.13%-2.52%; for the seawater in Qingdao offshore, the recoveries of iron and manganese are in the ranges of 95.3%-104.8% and 95.3%-104.7%, and the RSD is in the range of 0.14%-2.66%. It is found that 21 common cations and anions do not interfere with the determination of iron and manganese under the optimum experimental conditions. This method exhibits good reproducibility and high accuracy in the determination of iron and manganese and can be used for the simultaneous determination of iron and manganese in tap water and natural water. By using the established ANN- catalytic spectrophotometric method, the iron and manganese concentrations of the surface seawater at 11 sites in Qingdao offshore are determined and the level distribution maps of iron and manganese are drawn.展开更多
[ Objective] To establish the standardized spectrophotometric method to determine boar sperm concentration. [ Method ] The relation- ships between absorbance (A), transmittance (T) and sperm concentration (C) of...[ Objective] To establish the standardized spectrophotometric method to determine boar sperm concentration. [ Method ] The relation- ships between absorbance (A), transmittance (T) and sperm concentration (C) of different wavelengths (450, 550, 650 nm) were compared. [ Result] The maximum sperm concentration detected by absorbance presented an upward trend with the increase of the wavelengths, 202 mitliorVml (450 nm), 224 million/ml (550 nm) and 235 mUlion/ml (650 nm), respectively, but the stability of repeated measurement was decreased. With the increase of sperm dilution times, the stability of repeated measurement of transmittance was reduced, and when dilution times were more than 10 times (450 nm), 6 times (550 nm) and 4 times (650 nm), differences appeared between the observed values of repeated measurement. [ Con- clusion] Wavelength at 450 nm was found to be the most sensitive and reliable, and sperm concentration presented cubic functional regression rela- tionship or power functional regression relationship with absorbance or transmittance, respectively. The regression equation for the standard curve at 450 nm was C400 = 0.48A3 - 0.76A2 + 0.67A - 0.066 ( R = 0.951 ) and C400 = 1.657T -0.108. 8 ( R = 0.940).展开更多
At present, there is no method for identifying meat frozen in a thermal state acceptable for production control. The role of free nucleotides in the processes of refrigeration and storage of meat, affecting the struct...At present, there is no method for identifying meat frozen in a thermal state acceptable for production control. The role of free nucleotides in the processes of refrigeration and storage of meat, affecting the structural and mechanical properties of muscle tissue, the formation of taste and its biological value is known. In this article we compared methods for identifying the thermal state of meat based on the determination of the composition and content of free nucleotides by high-performance liquid chromatography (HPLC) and spectrophotometry [SF]. High-purity reference substances were used: free nucleotides—ATP, ADP, AMP, IMP and nucleosides-inosine and hypoxanthine. It has been experimentally established that the characteristic peaks of the absorption spectra for extracts of free nucleotides of meat frozen depended from thermal state of meat. The content of ATP is 21.8 times higher in meat frozen in a fresh state, and the amount of IMF is 12.3 times lower than in meat frozen after cooling. The results of studies of meat frozen using the HPLC method and the developed SF method show the adequacy of the data obtained by both methods. SF-method based on the determination of the optical density of the extracts of free nucleotides is recommended to justify the choice of technological process meat defrost modes.展开更多
A selective and new spectrophotometric method is described for determination of five 1,4 dihydropyridine drugs (1,4- DHP);namely nifedipine (NIF), nicardipine (NIC), nimodipine (NIM), felodipine (FEL) and amlodipine (...A selective and new spectrophotometric method is described for determination of five 1,4 dihydropyridine drugs (1,4- DHP);namely nifedipine (NIF), nicardipine (NIC), nimodipine (NIM), felodipine (FEL) and amlodipine (AML). The method is based on a coupling reaction between the cited drugs and vanillin reagent in acidic condition. Under optimized conditions, the red coloured products were measured at 500 nm for NIF, NIC, NIM and FEL or at 479 nm for AML. Molar absorptivities were ranged from 0.575 × 104 - 1.065 × 104 l·mol-1·cm-1, Beer’s law was obeyed at 5 - 70 μg/mL concentration range and the limit of detection was ranged from 0.150 - 1.500 μg/mL. The proposed method was successfully extended to pharmaceutical preparations tablets and capsules and comparison by Student’s t-test and variance ratio F-test showed no significant difference.展开更多
New simple and sensitive spectrophotometric determination of fluoride in drinking groundwater has been developed using aluminium-resorcin blue complex. The method is based on the reaction of fluoride with the coloured...New simple and sensitive spectrophotometric determination of fluoride in drinking groundwater has been developed using aluminium-resorcin blue complex. The method is based on the reaction of fluoride with the coloured complex to produce colourless aluminium fluoride complex and releasing of the free ligand. The relationship of the reaction of flu-oride with the complex is sixth-order polynomial function. The reaction reaches equilibrium at fluoride concentration of 0.054 mM. The equilibrium constant (Keq) was calculated as 1.12 × 1014. Beer-Lambert law is obeyed in the range 0.0 - 0.024 mM of fluoride (0.0 - 1.0 mg·L-1). The molar absorptivity at 502 nm is 6.45 × 103 L·mol-1·cm-1. Fluoride concentration higher than 1.0 mg·L-1 can be measured after proper dilution. The sensitivity, detection limit, quantitation limit, and the percentage recovery of 0.75 mg·L-1 fluoride for the method were found to be 0.357 μg·ml-1., 0.07 mg·L-1, 0.2 mg·L-1, and 101.1 respectively.展开更多
An alternative spectrophotometric method was optimized and validated for the estimation of mercury using diethyldithiocarbamate (DDTC), a common reagent, widely used for the preconcentration and isolation of metal ion...An alternative spectrophotometric method was optimized and validated for the estimation of mercury using diethyldithiocarbamate (DDTC), a common reagent, widely used for the preconcentration and isolation of metal ions in complex matrices followed by their estimation by varied techniques. Diethyldithiocarbamate forms yellow Cu(DDTC)2 with copper and white Hg(DDTC)2 with mercury (having d10 system) which are extracted in CCl4. The UV-visible spectrum of Cu(DDTC)2 is very stable at pH 5.0 and has a maximum absorption (λmax) at 435 nm. Hg(DDTC)2 is more stable than Cu(DDTC)2. Estimation of mercury is based on a quantitative displacement of Cu(II) of Cu(DDTC)2 with the addition of mercury followed by the measurement of reduced absorbance. Primarily, method was optimized and validated for the estimation of copper. Therefore, simultaneous determination of Cu(II) and Hg(II) in mixture is proposed fractionating the extract. The molar specific coefficient (ε) for the mercury was 1.4 × 104 mol﹣1·L·cm﹣1 and for copper was 3.16 × 105 mol﹣1·L·cm﹣1 at 435 nm. The detection limits of Cu2+ and Hg2+ were 0.023 μg·mL﹣1 and 0.029 μg·mL﹣1, respectively. The calibration curve shows good linearity of 0.02 - 12.0 and 0.02 - 15.0 μg·mL﹣1 for the Cu2+ and Hg2+ determination, respectively. Proposed technique was applied to food, biological and pharmaceutical samples for the determination of Cu(II) and Hg(II).展开更多
A spectrophotometric method for the assay of lamivudine in pure form and in dosage form was developed in this study. The method was based on charge-transfer complex formation between the drug, which acted as n-donor w...A spectrophotometric method for the assay of lamivudine in pure form and in dosage form was developed in this study. The method was based on charge-transfer complex formation between the drug, which acted as n-donor while chloranilic acid and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) acted as a p-acceptor in a non-aqueous solvent in each case. Chloranilic acid was found to form a charge-transfer complex in a 1:1 stoichiometry with lamuvudine (lamivudine-chloranilic acid) with a maximium absorption band at 521 nm. Also, DDQ was found to form a charge-transfer complex in a 1:1 stoichiometry with lamivudine (lamivudine-DDQ) with a maximium absorption band at 530 nm. The pH was obeyed at acid range. The complexes obeyed Beer’s law at a concentration range of 0.04 - 0.28 mg/ml. The thermodynamic parameters calculated at different temperatures included the molar absorptivity, association constant, free energy change, enthalpy and entropy. The proposed method has been conveniently applied in the analysis of commercially available lamivudine tablet with good accuracy and precision.展开更多
Spectrophotometric method was used to evaluate the kinetic of the complex formation from the reaction between H[Ru(III)Cl2(H2EDTA)] and the modifier agent [3-(2-aminoethyl)aminopropyl] trimethoxysilane (AEATS) (μ = 0...Spectrophotometric method was used to evaluate the kinetic of the complex formation from the reaction between H[Ru(III)Cl2(H2EDTA)] and the modifier agent [3-(2-aminoethyl)aminopropyl] trimethoxysilane (AEATS) (μ = 0.50 mol.dm-3 with NaCF3COO, 298.15 K), in pseudo-first order conditions. These studies showed that the reactions are successives producing several species influenced by the concentrations ratio. The electronics spectrum of all solutions showed a band in 457 nm with variable molar absorptivity (ε).展开更多
文摘Food safety problems caused by excessive nitrite addition have been frequently reported and the detection of nitrite in food is particularly important. The standing time during the pretreatment of primary sample has a great influence on the concentration of nitrite tested by spectrophotometric method. In this context, three kinds of food samples are prepared, including canned mustard, canned fish and home-made pickled water. A series of standing times are placed during the sample pretreatments and the corresponding nitrite contents in these samples are detected by spectrophotometric method based on N-ethylenediamine dihydrochloride. This study aims to find out a reasonable standing time during the pretreatment of food sample, providing influence factor for precise detection of nitrite.
基金Supported by the National Natural Science Funds.
文摘1,10-phenanthroline and its derivatives can form charge-transfer complexes with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone(DDQ).The absorption spectra and conditions of complex formation,such as the reaction time,the quantity of DDQ, and the solvents, have been studied.After the HMO calculation of phenanthrolines,the molar absorptivities were found to depend on the substituents on the phenanthroline rings.
文摘The new catalytic kinetic spectrophotometric method for Au(III) determination was developed and validated. It was based on the catalytic effect of gold on the oxidation of sudan red III by ammonium peroxodisulfate ((NH4)2S2O8) with nitrilo triacetic acid as an activator in microemulsion and H2SO4 medium. Under optimum conditions, there was the linearity of the calibration curve in the concentration range from 0 to 20 μg/L Au(Ⅲ) at 520 nm. The relative standard deviation was 3.0% with a correlation coefficient of 0.9986. The detection limit achieved was 9.75 × 10^-5 μg/mL. A new method using a column packed with sulfhydryl dextrose gel (SDG) as a solid-phase extractant has been developed for the preconcentration and separation of Au(Ⅲ) ions. The method has been applied to the determination of trace gold with satisfactory results.
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A new analytical method using Back-Propagation (BP) artificial neural network and kinetic spectrophotometry for simultaneous determination of iron and magnesium in tap water, the Yellow River water and seawater is established. By conditional experiments, the optimum analytical conditions and parameters are obtained. Levenberg-Marquart (L-M) algorithm is used for calculation in BP neural network. The topological structure of three-layer BP ANN network architecture is chosen as 15-16-2 (nodes). The initial value of gradient coefficient μ is fixed at 0.001 and the increase factor and reduction factor of μ take the default values of the system. The data are processed by computers with our own programs written in MATLAB 7.0. The relative standard deviation of the calculated results for iron and manganese is 2.30% and 2.67% respectively. The results of standard addition method show that for the tap water, the recoveries of iron and manganese are in the ranges of 98.0%-104.3% and 96.5%-104.5%, and the RSD is in the range of 0.23%-0.98%; for the Yellow River water (Lijin district of Shandong Province), the recoveries of iron and manganese are in the ranges of 96.0%-101.0% and 98.7%-104.2%, and the RSD is in the range of 0.13%-2.52%; for the seawater in Qingdao offshore, the recoveries of iron and manganese are in the ranges of 95.3%-104.8% and 95.3%-104.7%, and the RSD is in the range of 0.14%-2.66%. It is found that 21 common cations and anions do not interfere with the determination of iron and manganese under the optimum experimental conditions. This method exhibits good reproducibility and high accuracy in the determination of iron and manganese and can be used for the simultaneous determination of iron and manganese in tap water and natural water. By using the established ANN- catalytic spectrophotometric method, the iron and manganese concentrations of the surface seawater at 11 sites in Qingdao offshore are determined and the level distribution maps of iron and manganese are drawn.
文摘[ Objective] To establish the standardized spectrophotometric method to determine boar sperm concentration. [ Method ] The relation- ships between absorbance (A), transmittance (T) and sperm concentration (C) of different wavelengths (450, 550, 650 nm) were compared. [ Result] The maximum sperm concentration detected by absorbance presented an upward trend with the increase of the wavelengths, 202 mitliorVml (450 nm), 224 million/ml (550 nm) and 235 mUlion/ml (650 nm), respectively, but the stability of repeated measurement was decreased. With the increase of sperm dilution times, the stability of repeated measurement of transmittance was reduced, and when dilution times were more than 10 times (450 nm), 6 times (550 nm) and 4 times (650 nm), differences appeared between the observed values of repeated measurement. [ Con- clusion] Wavelength at 450 nm was found to be the most sensitive and reliable, and sperm concentration presented cubic functional regression rela- tionship or power functional regression relationship with absorbance or transmittance, respectively. The regression equation for the standard curve at 450 nm was C400 = 0.48A3 - 0.76A2 + 0.67A - 0.066 ( R = 0.951 ) and C400 = 1.657T -0.108. 8 ( R = 0.940).
文摘At present, there is no method for identifying meat frozen in a thermal state acceptable for production control. The role of free nucleotides in the processes of refrigeration and storage of meat, affecting the structural and mechanical properties of muscle tissue, the formation of taste and its biological value is known. In this article we compared methods for identifying the thermal state of meat based on the determination of the composition and content of free nucleotides by high-performance liquid chromatography (HPLC) and spectrophotometry [SF]. High-purity reference substances were used: free nucleotides—ATP, ADP, AMP, IMP and nucleosides-inosine and hypoxanthine. It has been experimentally established that the characteristic peaks of the absorption spectra for extracts of free nucleotides of meat frozen depended from thermal state of meat. The content of ATP is 21.8 times higher in meat frozen in a fresh state, and the amount of IMF is 12.3 times lower than in meat frozen after cooling. The results of studies of meat frozen using the HPLC method and the developed SF method show the adequacy of the data obtained by both methods. SF-method based on the determination of the optical density of the extracts of free nucleotides is recommended to justify the choice of technological process meat defrost modes.
文摘A selective and new spectrophotometric method is described for determination of five 1,4 dihydropyridine drugs (1,4- DHP);namely nifedipine (NIF), nicardipine (NIC), nimodipine (NIM), felodipine (FEL) and amlodipine (AML). The method is based on a coupling reaction between the cited drugs and vanillin reagent in acidic condition. Under optimized conditions, the red coloured products were measured at 500 nm for NIF, NIC, NIM and FEL or at 479 nm for AML. Molar absorptivities were ranged from 0.575 × 104 - 1.065 × 104 l·mol-1·cm-1, Beer’s law was obeyed at 5 - 70 μg/mL concentration range and the limit of detection was ranged from 0.150 - 1.500 μg/mL. The proposed method was successfully extended to pharmaceutical preparations tablets and capsules and comparison by Student’s t-test and variance ratio F-test showed no significant difference.
文摘New simple and sensitive spectrophotometric determination of fluoride in drinking groundwater has been developed using aluminium-resorcin blue complex. The method is based on the reaction of fluoride with the coloured complex to produce colourless aluminium fluoride complex and releasing of the free ligand. The relationship of the reaction of flu-oride with the complex is sixth-order polynomial function. The reaction reaches equilibrium at fluoride concentration of 0.054 mM. The equilibrium constant (Keq) was calculated as 1.12 × 1014. Beer-Lambert law is obeyed in the range 0.0 - 0.024 mM of fluoride (0.0 - 1.0 mg·L-1). The molar absorptivity at 502 nm is 6.45 × 103 L·mol-1·cm-1. Fluoride concentration higher than 1.0 mg·L-1 can be measured after proper dilution. The sensitivity, detection limit, quantitation limit, and the percentage recovery of 0.75 mg·L-1 fluoride for the method were found to be 0.357 μg·ml-1., 0.07 mg·L-1, 0.2 mg·L-1, and 101.1 respectively.
文摘An alternative spectrophotometric method was optimized and validated for the estimation of mercury using diethyldithiocarbamate (DDTC), a common reagent, widely used for the preconcentration and isolation of metal ions in complex matrices followed by their estimation by varied techniques. Diethyldithiocarbamate forms yellow Cu(DDTC)2 with copper and white Hg(DDTC)2 with mercury (having d10 system) which are extracted in CCl4. The UV-visible spectrum of Cu(DDTC)2 is very stable at pH 5.0 and has a maximum absorption (λmax) at 435 nm. Hg(DDTC)2 is more stable than Cu(DDTC)2. Estimation of mercury is based on a quantitative displacement of Cu(II) of Cu(DDTC)2 with the addition of mercury followed by the measurement of reduced absorbance. Primarily, method was optimized and validated for the estimation of copper. Therefore, simultaneous determination of Cu(II) and Hg(II) in mixture is proposed fractionating the extract. The molar specific coefficient (ε) for the mercury was 1.4 × 104 mol﹣1·L·cm﹣1 and for copper was 3.16 × 105 mol﹣1·L·cm﹣1 at 435 nm. The detection limits of Cu2+ and Hg2+ were 0.023 μg·mL﹣1 and 0.029 μg·mL﹣1, respectively. The calibration curve shows good linearity of 0.02 - 12.0 and 0.02 - 15.0 μg·mL﹣1 for the Cu2+ and Hg2+ determination, respectively. Proposed technique was applied to food, biological and pharmaceutical samples for the determination of Cu(II) and Hg(II).
文摘A spectrophotometric method for the assay of lamivudine in pure form and in dosage form was developed in this study. The method was based on charge-transfer complex formation between the drug, which acted as n-donor while chloranilic acid and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) acted as a p-acceptor in a non-aqueous solvent in each case. Chloranilic acid was found to form a charge-transfer complex in a 1:1 stoichiometry with lamuvudine (lamivudine-chloranilic acid) with a maximium absorption band at 521 nm. Also, DDQ was found to form a charge-transfer complex in a 1:1 stoichiometry with lamivudine (lamivudine-DDQ) with a maximium absorption band at 530 nm. The pH was obeyed at acid range. The complexes obeyed Beer’s law at a concentration range of 0.04 - 0.28 mg/ml. The thermodynamic parameters calculated at different temperatures included the molar absorptivity, association constant, free energy change, enthalpy and entropy. The proposed method has been conveniently applied in the analysis of commercially available lamivudine tablet with good accuracy and precision.
文摘Spectrophotometric method was used to evaluate the kinetic of the complex formation from the reaction between H[Ru(III)Cl2(H2EDTA)] and the modifier agent [3-(2-aminoethyl)aminopropyl] trimethoxysilane (AEATS) (μ = 0.50 mol.dm-3 with NaCF3COO, 298.15 K), in pseudo-first order conditions. These studies showed that the reactions are successives producing several species influenced by the concentrations ratio. The electronics spectrum of all solutions showed a band in 457 nm with variable molar absorptivity (ε).