Isosorbide dinitrate is an organic nitrate drug, and its preparation (tablet) is clinically used for the treatment of coronary heart disease and angina pectoris, and is one of the most widely used cardiovascular drugs. In the synthesis process, organic reagents such as acetic acid and ethyl acetate are used, which are harmful to the human body. Acetic acid easily causes decomposition of the main drug in the preparation, and ethyl acetate has a bad odor. Therefore, it is necessary to control the residual amount. Simultaneous determination of three organic solvent residues in isosorbide dinitrate raw materials by chromatography is sensitive, accurate and reliable.
1 Instruments and reagents
Puri GC7800 Gas Chromatograph
, isosorbide dinitrate (Shandong Linuo Pharmaceutical Factory), acetic acid, ethyl acetate and DMF are all analytically pure.
2 Experimental part
2.1 Preparation of the solution
2.1.1 Preparation of standard solution: Take appropriate amount of acetic acid and ethyl acetate, dilute with DMF to contain 0.01 mg per 1 ml, 0.1 mg of ethyl acetate, and shake well to obtain a standard stock solution. Dilute the standard stock solution and double the reference solution.
2.1.2 Preparation of the test solution: Take 1 g of isosorbide dinitrate, accurately weigh it, place it in a 10 ml volumetric flask, add DMF to dissolve and dilute to the mark, and shake it to obtain the test solution.
2.2 Chromatographic conditions and content calculation method
The column was PEG-20M stainless steel column (4m×2mm), the column temperature was programmed, the initial column temperature was maintained at 50°C for 3min, then it was raised to 180°C at 10°C/min for 5min, then at 10°C/min. The rate was increased by 280 ° C for 10 min. FID detector, detector temperature 320 ° C, inlet temperature 320 ° C, nitrogen as carrier gas, flow rate 50 ml / min, hydrogen flow rate 30 ml / min, air flow rate 400 ml / min. The number of theoretical plates is not less than 1600 based on ethyl acetate, and the injection amount of the control and the test solution is 2 μl. The external standard peak area method is used to calculate the content.
3 Results and discussion
3.1 Linear relationship investigation
Precisely weigh the standard stock solution in 0.5, 1.0, 1.5, 2.0, 2.5, 3.0ml to 10ml volumetric flasks, dilute to the mark with DMF, and shake to obtain the series standard solution I-VI. For the injection measurement, the concentration of each solution (C) was plotted on the abscissa, and the corresponding peak area (A) was plotted on the ordinate. Linear regression was performed. The linear equations of ethyl acetate were Y=38.01+3535X, (r=0.9994). , Y=9.51+2926.76X, (r=0.9997), Y=-5.34478+1198.35821X, (r=0.9999), indicating acetic acid and acetic acid in the range of 0.0005-0.003 mg/ml
The ethyl ester concentration was in a good linear relationship in the range of 0.005 to 0.03 mg/ml.
3.2 Precision test
Take 1 part of the reference solution and inject 5 times. The RSD of the peak area is 2.6%, the RSD of the peak area of ​​acetic acid is 3.6%, and the RSD of the peak area of ​​ethyl acetate is 3.9%.
3.3 Recovery test
Weigh accurately the same batch of known residual amount of isosorbide dinitrate sample 0.5g (3 parts), (containing 6.5 × 0.0001mg, containing acetic acid, ethyl acetate each 8.5 × 0.001mg, placed in a 10ml volumetric flask, respectively, precisely added Standard stock solution 0.05ml, 0.10ml, 0.15ml, dissolved in DMF, diluted to the mark, shaken. According to the above chromatographic conditions, the recovery was calculated, and the recovery rates of acetic acid and ethyl acetate were 100.3%, respectively. 98.7% and 100.5%.
3.4 Determination of detection limit
The standard solution in 2.1.1 was gradually diluted and injected according to the above chromatographic conditions. The detection limits (N=3) of acetic acid and ethyl acetate were 30 mg, 50 mg and 100 mg, respectively.
3.5 Sample determination
Precisely take 2μl of the control solution and the test solution, and sample according to the above chromatographic conditions. Calculate the organic residue in each sample according to the peak area according to the external standard method. The results show that the three batches of samples meet the requirements of organic residue standards for human medicine. .
3.6 Selection of experimental conditions
Because of the strong polar substance, the packed column PEG-20M stainless steel column with strong polar fixative is selected; because of the certain difference between the boiling points of acetic acid and ethyl acetate, the constant temperature separation time is long and the peak shape is poor and easy to overlap with the solvent. Therefore, the temperature-programming mode is adopted; and because the experiment requires a lower detection limit and both are carbon-containing compounds, a highly sensitive hydrogen flame detector is used.
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