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Abstract Salbutamol sulfate was coordinated with Cu2+ when pH was 10, and the characteristic absorption peak of the complex was generated at 334 nm. The absorption intensity of the complex was in linear relation with the concentration of salbutamol sulfate. The regression equation was A=0.011 ρsalbutamol sulfate -0.123 0, correlation coefficient r=0.999 5, and the detection limit was 4.6 μg/ml. It was used for the determination of salbutamol sulfate samples successfully. The recovery rate was 100.5%-103.0%, and the RSD was 1.5%.
Key words Salbutamol sulfate; UVVIS spectroscopy; Absorption intensity; Content determination
Received: July 21, 2019Accepted: October 28, 2019
Supported by Schoollevel Project of Guangxi University of Chinese Medicine (YB140004); The 2017 Basic Ability Improving Project of Young and Middleaged Teachers by the Education Department of Guangxi (2017KY0284).
Yu LIN (1988-), female, P. R. China, lecturer, devoted to research about pharmaceutical analysis.
*Corresponding author. Email: 734290145@qq.com.
Salbutamol sulfate is mainly used for respiratory diseases such as bronchial asthma or asthmatic bronchitis with bronchospasm. At present, the methods for determining the content of salbutamol sulfate mainly include high performance liquid chromatography［1-4］, fluorescence spectrophotometry［5-6］, flow injection chemiluminescence［7-8］, tetrachloroquinone colorimetry, dynamically modified chromatography［9］, Emerson reagent photometry［10］ and capillary electrophoresisnoncontact conductivity detection method［11］. Each of these methods has its own advantages and disadvantages. High performance liquid chromatography has high sensitivity and stability, but the instrument is expensive. Fluorescence spectrophotometry, Emerson reagent photometry and capillary electrophoresisnoncontact conductivity detection method are simple in operation and strong in specificity, but the sensitivity is not high. The flow injection chemiluminescence method is simple in instrument, but the selectivity is not good. The tetrachloroquinone colorimetry is simple in operation and low in cost, but the accuracy is low.
Since the salbutamol sulfate molecule contains elements O and N with lone pair of electrons, which can coordinate with metal ions to form a cyclic complex. The content of salbutamol sulfate can be determined indirectly by measuring the absorption intensity of the Cu2+salbutamol sulfate complex by the UVVIS method. Experimental Materials
Experimental instruments and equipment
UV1780 UVVis spectrophotometer (Shimadzu Enterprise Management (Japan) Co., Ltd.); HHS4 digital thermostatic water bath (Hetan Medical Instrument); KQ 5200B ultrasonic cleaner (Kunlun Ultrasonic Instrument Co., Ltd. ).
Experimental reagents
Salbutamol sulfate standard (National Institutes for Food and Drug Control); CuSO4·5H2O (AR, Chengdu Jinshan Chemical Reagent Co., Ltd.); Ammonium hydroxide (AR, Sinopharm Chemical Reagent Co., Ltd.); Ammonium Chloride (AR, Sinopharm Chemical Reagent Co., Ltd.).
Solution preparation
1.00×10-3 mol/L salbutamol sulfate standard solution: A certain amount of salbutamol sulfate standard (0.029 1 g) was accurately weighed in a small beaker, dissolved in distilled water and diluted to constant volume in a 50 ml volumetric flask.
1.00×10-3 mol/L CuSO4·5H2O solution: A certain amount of copper sulfate pentahydrate (0.025 0 g) was accurately weighed in a small beaker, dissolved in distilled water and diluted to constant volume in a 100 ml volumetric flask.
Ammoniaammonium chloride buffer with pH=10: A certain amount of ammonium chloride (5.40 g) was weighed, added with 35.00 ml of concentrated ammonia water, and diluted to 100 ml.
Experimental Methods and Results
Experimental methods
Certain amounts of 1.00×10-3 mol/L salbutamol sulfate standard solution, 1.00×10-3 mol/L CuSO4·5H2O solution and ammoniaammonium chloride buffer with pH=10 were accurately pipetted to a 10 ml volumetric flask, and the obtained solution was diluted to the mark line with distilled water, shaken, heated at 50 ℃ for 10 min, and cooled to room temperature. The absorbance A of the test solution was measured at a wavelength of 334 nm using a blank reagent as a reference.
Screening of metal ions for complexing
In order to investigate the complexation of salbutamol sulfate with metal ions, a certain amount of 1.00×10-3 mol/L salbutamol sulfate standard solution was accurately transferred. Cu2+, Al3+, Ca2+, Cd3+, Ni2+ and Fe3+ were added, respectively, under the same condition.
The experiments showed that the complexation of salbutamol sulfate with Cu2+ was better, and there was no obvious characteristic absorption with Ni2+. Other metal ions can form certain characteristic absorption with salbutamol sulfate, but the absorption was weak and the sensitivity was low. Therefore, Cu2+ was chosen for research. Absorption spectrum
With distilled water as a reference, the absorption spectra of different solutions were determined (Fig. 1). The results showed that at λ=334 nm, curve 1 had obvious characteristic absorption peaks, while curves 2 and 3 had no obvious absorption, indicating that salbutamol sulfate formed a new complex with Cu2+. Fig. 2 shows the absorption spectra of different concentrations of complexes. It can be seen from the figure that with other conditions fixed, the absorption intensity of the complex increased with the concentration of salbutamol sulfate at λ=334 nm.
1. 1.00×10-4 mol/L salbutamol sulfate standard solution+ammoniaammonium chloride buffer with pH=10+5.00×10-5 mol/L Cu2+; 2. 1.00×10-4 mol/L salbutamol sulfate standard solution+ammoniaammonium chloride buffer with pH=10; 3. 5.00×10-5 mol/L Cu2++ammoniaammonium chloride buffer with pH=10.
Methodological evaluation of determination
Investigation of detection limit and linear relation
Under the optimized experimental conditions, different concentrations of salbutamol sulfate were determined according to "Experiment methods", and the absorbance A was plotted against ρsalbutamol sulfate (μg/ml), obtaining a linear regression equation: A=0.011ρsalbutamol sulfate -0.123 0, correlation coefficient r=0.999 5. According to IUPAC, blank reagent was used as a reference, which was measured in parallel at 334 nm, and the detection limit of the method was obtained to be 4.6 μg/ml.
1. 1.00×10-4 mol/L salbutamol sulfate+ammoniaammonium chloride buffer with pH=10+1.00×10-4 mol/L Cu2+; 2. 2.00×10-4 mol/L salbutamol sulfate+ammoniaammonium chloride buffer with pH=10+1.00×10-4 mol/L Cu2+; 3. 3.00×10-4 mol/L salbutamol sulfate+ammoniaammonium chloride buffer with pH=10+1.00×10-4 mol/L Cu2+; 4. 4.00×10-4 mol/L salbutamol sulfate+ammoniaammonium chloride buffer with pH=10+1.00×10-4 mol/L Cu2+; 5. 5.00×10-4 mol/L salbutamol sulfate+ammoniaammonium chloride buffer with pH=10+ 1.00×10-4 mol/L Cu2+.
Fig. 2 Absorption spectra of different concentrations of complex
Precision test
Certain amounts of 1.00×10-3 mol/L salbutamol sulfate standard solution, 1.00×10-3 mol/L CuSO4·5H2O solution and ammoniaammonium chloride buffer with pH=10 were accurately pipetted to a 10 ml volumetric flask, and 10 groups were prepared in parallel according to "Experiment methods". The absorbance was measured, respectively, and the RSD of the absorbance was 1.5%, indicating that the precision of the instrument was good. Recovery test
Twenty salbutamol sulfate tablets (each containing 2 mg of salbutamol sulfate) were taken from different manufacturers, respectively. The salbutamol sulfate tablets from each manufacturer were accurately weighed and ground. Each salbutamol sulfate powder (equivalent to 29.1 mg of salbutamol sulfate) was accurately weighed, dissolved in distilled water and diluted to constant volume in a 50 ml volumetric flask. Each solution was shaken and filtered.
Sample 1: salbutamol sulfate (Jiangsu Yabang Epson Pharmaceutical Co., Ltd., SFDA approval number: H32024535, specification: 2 mg/tablet); Sample 2: salbutamol sulfate (Suzhou Hongsen Pharmaceutical Co., Ltd., SFDA approval number: H32024129, specification: 2 mg/tablet).
Agricultural Biotechnology2019
Discussion
Optimization of solution pH
The absorbance of the complex at different pH was investigated. Certain amounts of 1.00×10-3 mol/L salbutamol sulfate standard solution (4.00 ml) and 1.00×10-3 mol/L Cu2+ (2.00 ml) were accurately transferred to 10 ml volumetric flasks, and the pH values were adjusted with 0.1 mol/L hydrochloric acid solution and 0.1 mol/L sodium hydroxide solution, respectively. According to "Experiment methods", the results showed that when pH<7, there was almost no obvious characteristic absorption; when pH=7, the complex had certain characteristic absorption at λ=334 nm, but the absorbance was lower; when pH>7 , the absorbance of the complex increased with the concentration of salbutamol sulfate increasing; when pH=10, the peak shape of the complex was stable, and the absorbance was the largest and stable; and when pH>10, the complex absorption decreased. Therefore, pH=10 was chosen.
Certain amounts of 1.00×10-3 mol/L salbutamol sulfate standard solution (4.00 ml) and 1.00×10-3 mol/L Cu2+ (2.00 ml) were accurately transferred to 10 ml volumetric flasks, and different amounts of ammoniaammonium chloride buffer with pH=10 were added into the volumetric flasks, respectively. The results showed that when Vbuffer<0.10 ml, the absorbance of the complex increased with the increase of the buffer amount, and the buffer capacity was not strong due to insufficient buffer amount; when Vbuffer=0.10 ml, the absorbance value was the largest; and when Vbuffer>0.10 ml, the absorbance of the complex decreased, which might be due to the buffer amount was excessive, and the excess buffer solution and salbutamol sulfate competed for Cu2+ , resulting in a decrease in Cu2+ reacted with salbutamol sulfate. Therefore, in this experiment, 0.10 ml of ammoniaammonium chloride buffer solution with pH=10 was used to adjust the pH value. Effect of reaction temperature
Multiple solutions were prepared in parallel according to the experimental method. The prepared solutions were placed in water baths at different temperatures, respectively, rapidly cooled to room temperature and immediately measured. The results showed that when T<50 ℃, the absorbance of the complex increased with the increase of T; when T=50 ℃, the absorbance of the complex was the largest and stable, and the peak shape was better; and when T>50 ℃, it might be because of the toohigh temperature, the complex decomposed, and the peak shape deteriorated. In summary, the reaction temperature was chosen to be 50 ℃.
Optimization on addition sequence of reagents
According to "Experiment methods", with amounts of various reagents fixed, their addition sequence were set as: ① salbutamol sulfate standard solution, ammoniaammonium chloride buffer solution, Cu2+ solution, ② salbutamol sulfate standard solution, Cu2+ solution, ammoniaammonium chloride buffer liquid, and ③ Cu2+ solution, ammoniaammonium chloride buffer, salbutamol sulfate standard solution. The strength A of each complex was measured, and their values ranked from large to small as: ①>③>②. Therefore, the three solutions could be added following the order of salbutamol sulfate standard solution, ammoniaammonium chloride buffer and Cu2+ solution.
Interference test
When determining the content of salbutamol sulfate, the effects of other interfering substances must be considered. Under the above optimized conditions, the same concentration of salbutamol sulfate solution was measured. The relative error was of ±5%, and the coexisting substances in Table 3 did not affect the measurement. The results showed that magnesium stearate, dextrin and lactose had less interference to the complexation reaction, but glucose, CMCNa and starch had a greater interference with the experimental determination. The salbutamol sulfate preparation contained no glucose and CMCNa, and starch can be removed by filtration, so there is no interference to the experiment.
Discussion on reaction mechanism
The structural formula of salbutamol sulfate is shown in Fig. 3. The hydroxyl group O atom and the amino group N atom on the molecule both contain a lone pair of electrons, which can coordinate with Cu2+ to form a complex. The structural formula of the complex is shown in Fig. 4.
Conclusions
In this study, the content of salbutamol sulfate is determined by molecular spectroscopy using Cu2+ as a medium. The content of salbutamol sulfate was determined indirectly by measuring the absorption intensity of Cu2+salbutamol sulfate complex. The method is efficient, environmentally friendly and low in consumption, and can be used for the determination of salbutamol sulfate with good accuracy and reproducibility. Agricultural Biotechnology2019
References
［1］ MI Y, FANG ZZ, WANG JJ, et al. Determination of salbutamol sulfate oral colontargeted sustainedrelease tablet［J］. Journal of Tianjin Medical University, 2008, 14(4): 460-462, 465. (in Chinese)
［2］ WANG JJ, XU YK. Content Determination of salbutamol sulfate oral colontargeted sustainedrelease capsule［J］. Journal of North Pharmacy, 2012, 9(8): 4-5. (in Chinese)
［3］ YAN M, GUO T, ZHOU JP, et al. Determination of the content of salbutamol sulfate pulsatile tablets and related substances by RPHPLC method［J］. Pharmaceutical Journal of Chinese Peoples Liberation Army, 2009, 1(25): 73-76. (in Chinese)
［4］ LI ZX, ZHANG FX. Preparation and invitro release of salbutamol sulfate as a chronotherapy agent for asthma［J］. China Medical Herald, 2009, 6(24):43-45. (in Chinese)
［5］ XU X, QIU YH. Determination of the content of salbutamol sulfate injection with fluorospectrophotometry［J］. China Pharmaceuticals, 2005, 14(11): 33. (in Chinese)
［6］ HUANG XP, HUANG XX, XIE SX, et al. Determination of the content of salbutamol sulfate tablet with fluorospec trophotometry［J］. Modern Preventive Medicine, 2005, 32(5): 562-577. (in Chinese)
［7］ WENG W. Determination of salbutamol sulfate by chemiluminescence with ruthenium (IV) and rhodamine B［C］∥Proceedings of the 8th national symposium on luminescence analysis and dynamics analysis of the Chinese Chemical Society. Chinese Chemical Society, 2005: 1. (in Chinese)
［8］ LI SJ. Application of flowinjection chemiluminescence method in combination with PLS in drug analysis［D］. Zhengzhou: Zhengzhou University, 2011. (in Chinese)
［9］ HAN J, XU YC. Determination of metronidazole cholorhexidine acetate and miconzole nitrate in Kangtaizuo Washing Solution by HPLC［J］. Chinese Journal of Pharmaceutical Analysis, 1997, 17(1): 11-14. (in Chinese)
［10］ PANG ZH, LI QB, QIU X, et al. Determination of salbutamol sulfate with Emerson reagent by spectrophotometry in pharmaceuticals［J］.Chemical Reagents, 2014, 36(9): 815-818. (in Chinese)
［11］ CHEN CG, LI H, FAN YJ, et al. Determination of salbutamol sulfate in medicaments by capillary electrophoresis with contactless conductivity detection［J］. Chinese Journal of Chromatography, 2011, 29(2): 137-140. (in Chinese)
Key words Salbutamol sulfate; UVVIS spectroscopy; Absorption intensity; Content determination
Received: July 21, 2019Accepted: October 28, 2019
Supported by Schoollevel Project of Guangxi University of Chinese Medicine (YB140004); The 2017 Basic Ability Improving Project of Young and Middleaged Teachers by the Education Department of Guangxi (2017KY0284).
Yu LIN (1988-), female, P. R. China, lecturer, devoted to research about pharmaceutical analysis.
*Corresponding author. Email: 734290145@qq.com.
Salbutamol sulfate is mainly used for respiratory diseases such as bronchial asthma or asthmatic bronchitis with bronchospasm. At present, the methods for determining the content of salbutamol sulfate mainly include high performance liquid chromatography［1-4］, fluorescence spectrophotometry［5-6］, flow injection chemiluminescence［7-8］, tetrachloroquinone colorimetry, dynamically modified chromatography［9］, Emerson reagent photometry［10］ and capillary electrophoresisnoncontact conductivity detection method［11］. Each of these methods has its own advantages and disadvantages. High performance liquid chromatography has high sensitivity and stability, but the instrument is expensive. Fluorescence spectrophotometry, Emerson reagent photometry and capillary electrophoresisnoncontact conductivity detection method are simple in operation and strong in specificity, but the sensitivity is not high. The flow injection chemiluminescence method is simple in instrument, but the selectivity is not good. The tetrachloroquinone colorimetry is simple in operation and low in cost, but the accuracy is low.
Since the salbutamol sulfate molecule contains elements O and N with lone pair of electrons, which can coordinate with metal ions to form a cyclic complex. The content of salbutamol sulfate can be determined indirectly by measuring the absorption intensity of the Cu2+salbutamol sulfate complex by the UVVIS method. Experimental Materials
Experimental instruments and equipment
UV1780 UVVis spectrophotometer (Shimadzu Enterprise Management (Japan) Co., Ltd.); HHS4 digital thermostatic water bath (Hetan Medical Instrument); KQ 5200B ultrasonic cleaner (Kunlun Ultrasonic Instrument Co., Ltd. ).
Experimental reagents
Salbutamol sulfate standard (National Institutes for Food and Drug Control); CuSO4·5H2O (AR, Chengdu Jinshan Chemical Reagent Co., Ltd.); Ammonium hydroxide (AR, Sinopharm Chemical Reagent Co., Ltd.); Ammonium Chloride (AR, Sinopharm Chemical Reagent Co., Ltd.).
Solution preparation
1.00×10-3 mol/L salbutamol sulfate standard solution: A certain amount of salbutamol sulfate standard (0.029 1 g) was accurately weighed in a small beaker, dissolved in distilled water and diluted to constant volume in a 50 ml volumetric flask.
1.00×10-3 mol/L CuSO4·5H2O solution: A certain amount of copper sulfate pentahydrate (0.025 0 g) was accurately weighed in a small beaker, dissolved in distilled water and diluted to constant volume in a 100 ml volumetric flask.
Ammoniaammonium chloride buffer with pH=10: A certain amount of ammonium chloride (5.40 g) was weighed, added with 35.00 ml of concentrated ammonia water, and diluted to 100 ml.
Experimental Methods and Results
Experimental methods
Certain amounts of 1.00×10-3 mol/L salbutamol sulfate standard solution, 1.00×10-3 mol/L CuSO4·5H2O solution and ammoniaammonium chloride buffer with pH=10 were accurately pipetted to a 10 ml volumetric flask, and the obtained solution was diluted to the mark line with distilled water, shaken, heated at 50 ℃ for 10 min, and cooled to room temperature. The absorbance A of the test solution was measured at a wavelength of 334 nm using a blank reagent as a reference.
Screening of metal ions for complexing
In order to investigate the complexation of salbutamol sulfate with metal ions, a certain amount of 1.00×10-3 mol/L salbutamol sulfate standard solution was accurately transferred. Cu2+, Al3+, Ca2+, Cd3+, Ni2+ and Fe3+ were added, respectively, under the same condition.
The experiments showed that the complexation of salbutamol sulfate with Cu2+ was better, and there was no obvious characteristic absorption with Ni2+. Other metal ions can form certain characteristic absorption with salbutamol sulfate, but the absorption was weak and the sensitivity was low. Therefore, Cu2+ was chosen for research. Absorption spectrum
With distilled water as a reference, the absorption spectra of different solutions were determined (Fig. 1). The results showed that at λ=334 nm, curve 1 had obvious characteristic absorption peaks, while curves 2 and 3 had no obvious absorption, indicating that salbutamol sulfate formed a new complex with Cu2+. Fig. 2 shows the absorption spectra of different concentrations of complexes. It can be seen from the figure that with other conditions fixed, the absorption intensity of the complex increased with the concentration of salbutamol sulfate at λ=334 nm.
1. 1.00×10-4 mol/L salbutamol sulfate standard solution+ammoniaammonium chloride buffer with pH=10+5.00×10-5 mol/L Cu2+; 2. 1.00×10-4 mol/L salbutamol sulfate standard solution+ammoniaammonium chloride buffer with pH=10; 3. 5.00×10-5 mol/L Cu2++ammoniaammonium chloride buffer with pH=10.
Methodological evaluation of determination
Investigation of detection limit and linear relation
Under the optimized experimental conditions, different concentrations of salbutamol sulfate were determined according to "Experiment methods", and the absorbance A was plotted against ρsalbutamol sulfate (μg/ml), obtaining a linear regression equation: A=0.011ρsalbutamol sulfate -0.123 0, correlation coefficient r=0.999 5. According to IUPAC, blank reagent was used as a reference, which was measured in parallel at 334 nm, and the detection limit of the method was obtained to be 4.6 μg/ml.
1. 1.00×10-4 mol/L salbutamol sulfate+ammoniaammonium chloride buffer with pH=10+1.00×10-4 mol/L Cu2+; 2. 2.00×10-4 mol/L salbutamol sulfate+ammoniaammonium chloride buffer with pH=10+1.00×10-4 mol/L Cu2+; 3. 3.00×10-4 mol/L salbutamol sulfate+ammoniaammonium chloride buffer with pH=10+1.00×10-4 mol/L Cu2+; 4. 4.00×10-4 mol/L salbutamol sulfate+ammoniaammonium chloride buffer with pH=10+1.00×10-4 mol/L Cu2+; 5. 5.00×10-4 mol/L salbutamol sulfate+ammoniaammonium chloride buffer with pH=10+ 1.00×10-4 mol/L Cu2+.
Fig. 2 Absorption spectra of different concentrations of complex
Precision test
Certain amounts of 1.00×10-3 mol/L salbutamol sulfate standard solution, 1.00×10-3 mol/L CuSO4·5H2O solution and ammoniaammonium chloride buffer with pH=10 were accurately pipetted to a 10 ml volumetric flask, and 10 groups were prepared in parallel according to "Experiment methods". The absorbance was measured, respectively, and the RSD of the absorbance was 1.5%, indicating that the precision of the instrument was good. Recovery test
Twenty salbutamol sulfate tablets (each containing 2 mg of salbutamol sulfate) were taken from different manufacturers, respectively. The salbutamol sulfate tablets from each manufacturer were accurately weighed and ground. Each salbutamol sulfate powder (equivalent to 29.1 mg of salbutamol sulfate) was accurately weighed, dissolved in distilled water and diluted to constant volume in a 50 ml volumetric flask. Each solution was shaken and filtered.
Sample 1: salbutamol sulfate (Jiangsu Yabang Epson Pharmaceutical Co., Ltd., SFDA approval number: H32024535, specification: 2 mg/tablet); Sample 2: salbutamol sulfate (Suzhou Hongsen Pharmaceutical Co., Ltd., SFDA approval number: H32024129, specification: 2 mg/tablet).
Agricultural Biotechnology2019
Discussion
Optimization of solution pH
The absorbance of the complex at different pH was investigated. Certain amounts of 1.00×10-3 mol/L salbutamol sulfate standard solution (4.00 ml) and 1.00×10-3 mol/L Cu2+ (2.00 ml) were accurately transferred to 10 ml volumetric flasks, and the pH values were adjusted with 0.1 mol/L hydrochloric acid solution and 0.1 mol/L sodium hydroxide solution, respectively. According to "Experiment methods", the results showed that when pH<7, there was almost no obvious characteristic absorption; when pH=7, the complex had certain characteristic absorption at λ=334 nm, but the absorbance was lower; when pH>7 , the absorbance of the complex increased with the concentration of salbutamol sulfate increasing; when pH=10, the peak shape of the complex was stable, and the absorbance was the largest and stable; and when pH>10, the complex absorption decreased. Therefore, pH=10 was chosen.
Certain amounts of 1.00×10-3 mol/L salbutamol sulfate standard solution (4.00 ml) and 1.00×10-3 mol/L Cu2+ (2.00 ml) were accurately transferred to 10 ml volumetric flasks, and different amounts of ammoniaammonium chloride buffer with pH=10 were added into the volumetric flasks, respectively. The results showed that when Vbuffer<0.10 ml, the absorbance of the complex increased with the increase of the buffer amount, and the buffer capacity was not strong due to insufficient buffer amount; when Vbuffer=0.10 ml, the absorbance value was the largest; and when Vbuffer>0.10 ml, the absorbance of the complex decreased, which might be due to the buffer amount was excessive, and the excess buffer solution and salbutamol sulfate competed for Cu2+ , resulting in a decrease in Cu2+ reacted with salbutamol sulfate. Therefore, in this experiment, 0.10 ml of ammoniaammonium chloride buffer solution with pH=10 was used to adjust the pH value. Effect of reaction temperature
Multiple solutions were prepared in parallel according to the experimental method. The prepared solutions were placed in water baths at different temperatures, respectively, rapidly cooled to room temperature and immediately measured. The results showed that when T<50 ℃, the absorbance of the complex increased with the increase of T; when T=50 ℃, the absorbance of the complex was the largest and stable, and the peak shape was better; and when T>50 ℃, it might be because of the toohigh temperature, the complex decomposed, and the peak shape deteriorated. In summary, the reaction temperature was chosen to be 50 ℃.
Optimization on addition sequence of reagents
According to "Experiment methods", with amounts of various reagents fixed, their addition sequence were set as: ① salbutamol sulfate standard solution, ammoniaammonium chloride buffer solution, Cu2+ solution, ② salbutamol sulfate standard solution, Cu2+ solution, ammoniaammonium chloride buffer liquid, and ③ Cu2+ solution, ammoniaammonium chloride buffer, salbutamol sulfate standard solution. The strength A of each complex was measured, and their values ranked from large to small as: ①>③>②. Therefore, the three solutions could be added following the order of salbutamol sulfate standard solution, ammoniaammonium chloride buffer and Cu2+ solution.
Interference test
When determining the content of salbutamol sulfate, the effects of other interfering substances must be considered. Under the above optimized conditions, the same concentration of salbutamol sulfate solution was measured. The relative error was of ±5%, and the coexisting substances in Table 3 did not affect the measurement. The results showed that magnesium stearate, dextrin and lactose had less interference to the complexation reaction, but glucose, CMCNa and starch had a greater interference with the experimental determination. The salbutamol sulfate preparation contained no glucose and CMCNa, and starch can be removed by filtration, so there is no interference to the experiment.
Discussion on reaction mechanism
The structural formula of salbutamol sulfate is shown in Fig. 3. The hydroxyl group O atom and the amino group N atom on the molecule both contain a lone pair of electrons, which can coordinate with Cu2+ to form a complex. The structural formula of the complex is shown in Fig. 4.
Conclusions
In this study, the content of salbutamol sulfate is determined by molecular spectroscopy using Cu2+ as a medium. The content of salbutamol sulfate was determined indirectly by measuring the absorption intensity of Cu2+salbutamol sulfate complex. The method is efficient, environmentally friendly and low in consumption, and can be used for the determination of salbutamol sulfate with good accuracy and reproducibility. Agricultural Biotechnology2019
References
［1］ MI Y, FANG ZZ, WANG JJ, et al. Determination of salbutamol sulfate oral colontargeted sustainedrelease tablet［J］. Journal of Tianjin Medical University, 2008, 14(4): 460-462, 465. (in Chinese)
［2］ WANG JJ, XU YK. Content Determination of salbutamol sulfate oral colontargeted sustainedrelease capsule［J］. Journal of North Pharmacy, 2012, 9(8): 4-5. (in Chinese)
［3］ YAN M, GUO T, ZHOU JP, et al. Determination of the content of salbutamol sulfate pulsatile tablets and related substances by RPHPLC method［J］. Pharmaceutical Journal of Chinese Peoples Liberation Army, 2009, 1(25): 73-76. (in Chinese)
［4］ LI ZX, ZHANG FX. Preparation and invitro release of salbutamol sulfate as a chronotherapy agent for asthma［J］. China Medical Herald, 2009, 6(24):43-45. (in Chinese)
［5］ XU X, QIU YH. Determination of the content of salbutamol sulfate injection with fluorospectrophotometry［J］. China Pharmaceuticals, 2005, 14(11): 33. (in Chinese)
［6］ HUANG XP, HUANG XX, XIE SX, et al. Determination of the content of salbutamol sulfate tablet with fluorospec trophotometry［J］. Modern Preventive Medicine, 2005, 32(5): 562-577. (in Chinese)
［7］ WENG W. Determination of salbutamol sulfate by chemiluminescence with ruthenium (IV) and rhodamine B［C］∥Proceedings of the 8th national symposium on luminescence analysis and dynamics analysis of the Chinese Chemical Society. Chinese Chemical Society, 2005: 1. (in Chinese)
［8］ LI SJ. Application of flowinjection chemiluminescence method in combination with PLS in drug analysis［D］. Zhengzhou: Zhengzhou University, 2011. (in Chinese)
［9］ HAN J, XU YC. Determination of metronidazole cholorhexidine acetate and miconzole nitrate in Kangtaizuo Washing Solution by HPLC［J］. Chinese Journal of Pharmaceutical Analysis, 1997, 17(1): 11-14. (in Chinese)
［10］ PANG ZH, LI QB, QIU X, et al. Determination of salbutamol sulfate with Emerson reagent by spectrophotometry in pharmaceuticals［J］.Chemical Reagents, 2014, 36(9): 815-818. (in Chinese)
［11］ CHEN CG, LI H, FAN YJ, et al. Determination of salbutamol sulfate in medicaments by capillary electrophoresis with contactless conductivity detection［J］. Chinese Journal of Chromatography, 2011, 29(2): 137-140. (in Chinese)