Method for detecting light liquid paraffin residue in soft capsule dosage form

Abstract

The invention relates to a method for detecting light liquid paraffin residue in a soft capsule dosage form, which adopts high performance liquid chromatography based on an evaporative light-scattering detector for detection, and comprises the following steps: (1) setting conditions of the high performance liquid chromatography; (2) dissolving an n-octadecane reference substance in dichloromethane to prepare n-octadecane reference substance linear solutions with different gradient concentrations between 28g / mL and 210g / mL, drawing detection results of the high performance liquid chromatography into a standard curve, and fitting to obtain the standard curve; (3) taking the solution in a plurality of soft capsules, putting the solution in a measuring flask, adding dichloromethane for dissolving, and filtering with a 0.22 m filter membrane for later use; and (4) sampling the test solution, then sampling the n-octadecane reference substance solution, comparing the logarithm values of the chromatogram peak areas of the test solution and the reference substance solution, and calculating the concentration of n-octadecane in the sample by an external standard method, thereby obtaining the residual concentration of light liquid paraffin.

Description

Technical Field

[0001] The invention relates to the technical field of chemical component detection, and in particular to a method for detecting light liquid paraffin residue in a soft capsule dosage form. Background Art

[0002] Light liquid paraffin refers to paraffin containing normal alkanes obtained by using kerosene or diesel fractions as raw materials and dewaxing isopropanol-urea through molecular sieve adsorption or separation. It is called light liquid paraffin because it is a transparent colorless or light yellow liquid at room temperature. Light liquid paraffin is a colorless, odorless viscous liquid that is soluble in chloroform, ether and hydrocarbon compounds; slightly soluble in ethanol (95%), and almost insoluble in water.

[0003] Light liquid paraffin is often used as a lubricant in the soft capsule process. After washing, it may remain on the surface of the soft capsule. The low molecular weight compounds decomposed by light liquid paraffin can easily cause gastrointestinal disorders and diarrhea in the human body. Long-term intake can reduce immune function. Therefore, in the quality research of soft capsules, light liquid paraffin is controlled as an impurity.

[0004] The currently commonly used chemical composition detection methods are not suitable for the detection of light liquid paraffin residues in soft capsule dosage forms. They lack specificity, cannot prove that trace amounts of light liquid paraffin can be detected, and cannot be accurately quantified.

[0005] According to the concept of impurity spectrum control, the drug quality standard requires that the analytical method used has a sufficiently low detection limit to ensure the detection of the trace amount of light liquid paraffin actually present in the drug. Therefore, it is very necessary to accurately detect light liquid paraffin, which is conducive to effectively controlling the quality of soft capsule products. Summary of the invention

[0006] In view of the above situation, it is necessary to provide a method for detecting light liquid paraffin residue in a soft capsule dosage form in view of the problems in the prior art.

[0007] The present invention discloses a method for detecting light liquid paraffin residue in a soft capsule dosage form, which adopts a high performance liquid chromatography method based on an evaporative light scattering detector for detection, and comprises the following steps: (1) Setting the HPLC conditions: An amino column was used, with dichloromethane and acetonitrile as the mobile phase; gradient elution, the gradient elution flow rate was 0.5-1.0 ml / min; The evaporative light scattering detector has a drift tube temperature of 20 to 30°C and a nebulizer temperature of 20 to 30°C; (2) The n-octadecane reference substance was dissolved in dichloromethane to prepare a linear solution of the n-octadecane reference substance with different gradient concentrations between 28µg / mL and 210µg / mL. The solution was filtered through a 0.22µm filter membrane and tested. The logarithmic value of the chromatographic peak area was used as the ordinate, and the logarithmic value of the concentration of the n-octadecane reference substance linear solution was used as the abscissa. The results of the HPLC test were plotted into a standard curve and fitted to obtain the standard curve equation: Y=KX+b, where: Y represents the logarithmic value of the chromatographic peak area, X represents the logarithmic value of the n-octadecane concentration, and K and b are constants; (3) Prepare the test solution: take the solution in several soft capsules, place it in a volumetric bottle, add dichloromethane to dissolve it, let it stand after ultrasonication, take the extract, and filter it with a 0.22 µm filter membrane for later use; (4) Sample testing: Inject the test solution and then inject the n-octadecane reference solution. Compare the logarithmic values ​​of the chromatogram peak areas of the test solution and the reference solution. Calculate the concentration of n-octadecane in the test solution by the external standard method to obtain the residual concentration of light liquid paraffin.

[0008] Furthermore, in the above-mentioned method for detecting light liquid paraffin residue in the soft capsule dosage form, the gradient elution flow rate is 0.8 ml / min.

[0009] Furthermore, in the above-mentioned method for detecting light liquid paraffin residue in the soft capsule dosage form, the drift tube temperature is 25°C and the nebulizer temperature is 25°C.

[0010] Furthermore, in the above-mentioned method for detecting light liquid paraffin residue in the soft capsule dosage form, the column temperature of the amino chromatographic column is 15 to 30° C., and the particle size of the chromatographic column filler is 3 µm to 5 µm.

[0011] Furthermore, in the above-mentioned method for detecting light liquid paraffin residue in the soft capsule dosage form, the column temperature of the amino chromatographic column is 15° C., and the particle size of the chromatographic column filler is 5 µm.

[0012] Furthermore, in the above-mentioned method for detecting light liquid paraffin residue in the soft capsule dosage form, the gradient elution conditions of the mobile phase include: 0min, the content of dichloromethane in the mobile phase was 100%, and the content of acetonitrile was 0%; 5 min, the mobile phase contained 100% dichloromethane and 0% acetonitrile; 5.1 min, dichloromethane content 0%, acetonitrile content 100% in the mobile phase; 10 min, 0% dichloromethane and 100% acetonitrile in the mobile phase; 10.1 min, the mobile phase contained 100% dichloromethane and 0% acetonitrile; 18min, the mobile phase contained 100% dichloromethane and 0% acetonitrile.

[0013] The present invention relates to a method for detecting light liquid paraffin residue in a soft capsule dosage form, which adopts a pretreatment method of organic solvent extraction and detects the content of light liquid paraffin in the soft capsule dosage form based on an HPLC-ELSD detection method. The method has the advantages of high sensitivity, good specificity, simple operation, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The chromatogram of the reference substance solution in Example 2 of the present invention; Figure 2 The chromatogram of the test solution in Example 2 of the present invention. DETAILED DESCRIPTION

[0015] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0016] With reference to the following description and accompanying drawings, embodiments of the present invention will be clear. In these descriptions and accompanying drawings, some specific implementations of the embodiments of the present invention are specifically disclosed to represent some ways of implementing the principles of the embodiments of the present invention, but it should be understood that the scope of the embodiments of the present invention is not limited thereto. On the contrary, embodiments of the present invention include all changes, modifications and equivalents that fall within the spirit and connotation of the appended claims.

[0017] Example 1 (1) Instrument conditions: Chromatographic column: Ultimate XB-NH2 4.6ⅹ250mm, 5µm; sample chamber temperature: 5℃; injection volume: 20µl, column temperature: 15℃, flow rate: 0.8ml / min, dichloromethane as mobile phase A, acetonitrile as mobile phase B; ELSD (evaporative light scattering detector): drift tube temperature: 25 °C, nebulizer temperature: 25 °C, nebulizer gas: N2, nebulizer gas flow rate: 1.2 SLM, gain: 3.0; The elution procedure is:

[0018] (2) Solution preparation Mobile phase A: dichloromethane.

[0019] Mobile phase B: acetonitrile.

[0020] n-Octadecane reference stock solution: Take 0.35 g of n-Octadecane reference, weigh accurately, place in a 100 ml volumetric flask, add dichloromethane to dissolve it and dilute to the scale, shake well, and prepare a reference stock solution with a concentration of 3.5 mg / ml.

[0021] Preparation of n-octadecane reference solution: Accurately measure 1.0 ml of n-octadecane reference stock solution, place it in a 25 ml volumetric flask, dilute to the mark with dichloromethane, shake well, and obtain a n-octadecane reference solution with a concentration of 140 µg / ml.

[0022] Linear solution of n-octadecane reference substance: Accurately measure 0.4ml, 1.0ml, 2.0ml, 2.4ml and 3.0ml of n-octadecane reference substance stock solution and place them in different 50ml volumetric flasks, dilute them to the scale with dichloromethane, shake well, and obtain linear solutions of n-octadecane reference substance with concentrations of 28µg / ml, 70µg / ml, 140µg / ml, 168µg / ml and 210µg / ml, respectively.

[0023] The linear solutions of n-octadecane reference substance (L1 to L5, respectively) were injected and tested according to the instrument conditions. The logarithm of the chromatographic peak area was used as the ordinate, and the logarithm of the concentration of the linear solution of n-octadecane reference substance was used as the abscissa. The results of the high performance liquid chromatography were plotted into a standard curve and then fitted to obtain the standard curve equation. The linear results are shown in Table 1.

[0024] Table 1 Linearity results

[0025] Conclusion: The linear equation of n-octadecane is y = 1.9622x + 2.8276, and the correlation coefficient r is 0.9998, indicating good linearity.

[0026] Example 2 n-Octadecane reference stock solution: Take 0.35 g of n-Octadecane reference, weigh accurately, place in a 100 ml volumetric flask, add dichloromethane to dissolve it and dilute to the scale, shake well, and prepare a reference stock solution with a concentration of 3.5 mg / ml.

[0027] Preparation of n-octadecane reference solution: Accurately measure 1.0 ml of n-octadecane reference stock solution, place it in a 25 ml volumetric flask, dilute to the mark with dichloromethane, shake well, and obtain a n-octadecane reference solution with a concentration of 140 µg / ml.

[0028] Test solution: Take 4 soft capsules, pierce the capsule shell with a syringe needle to obtain the solution, place it in a 50ml volumetric flask, add dichloromethane to dissolve and dilute to the scale, ultrasonicate for 15 minutes, let it stand for 5 minutes, take the extract, filter it with a 0.22µm filter membrane, and obtain a test solution with a concentration of 140mg / ml.

[0029] Spiked test solution: Take 4 soft capsules in three times, puncture the capsule shell with a syringe needle to take the solution, place them in three 50ml volumetric flasks, add dichloromethane to dissolve, ultrasonicate for 15 minutes, let it stand for 5 minutes, add 1ml, 2ml, and 3ml of n-octadecane reference solution at the limit of 50%, 100%, and 150%, respectively, dilute to the scale with dichloromethane, shake well, take the extract, filter with a 0.22µm filter membrane, and obtain the spiked test solution for accuracy detection.

[0030] The n-octadecane reference solution and the test solution were injected and tested according to the instrument conditions described in Example 1, and the chromatograms obtained were as follows: Figure 1 and Figure 2 Compare the logarithmic values ​​of the chromatogram peak area of ​​the test solution and the n-octadecane reference solution, substitute the logarithmic value of the chromatogram peak area of ​​n-octadecane in the test solution into the above standard curve, and calculate the concentration of n-octadecane in the test solution by the external standard method.

[0031] The spiked test solution was sampled and tested according to the instrument conditions of Example 1, and the concentration of n-octadecane was calculated by the external standard method. The accuracy results are shown in Table 2.

[0032] Table 2 Accuracy results

[0033] Conclusion: The mean recoveries of n-octadecane in solutions at concentration levels of 50%, 100%, and 150% were all between 80.0% and 120.0%, and the relative standard deviations (RSDs) of the recoveries at each concentration level and the total recovery were all less than 15.0%, indicating that the method had good accuracy.

[0034] Example 3 Preparation of n-octadecane reference solution: same as in Example 2.

[0035] Spiked test solution: Take 4 soft capsules, pierce the capsule shell with a syringe needle to take the solution, put it in a 50ml volumetric bottle, add an appropriate amount of dichloromethane, ultrasonicate for 15 minutes, let it stand for 5 minutes, add 2ml of n-octadecane reference solution according to the limit of 100%, dilute to the scale with dichloromethane, and shake well. Take the extract 6 times, filter with a 0.22µm filter membrane, and obtain 6 spiked test solutions for repeatability experiments (respectively, items REP-1 to REP-6). The repeatability results are shown in Table 3.

[0036] The n-octadecane reference solution and the spiked test solution were sampled and tested according to the instrument conditions of Example 1, the obtained chromatogram peak area logarithms were compared, and the concentration of n-octadecane in the sample was calculated by the external standard method.

[0037] Table 3 Repeatability results

[0038] Conclusion: The relative standard deviation (RSD) of n-octadecane content calculated in 6 repeatability experiments was less than 15.0%, indicating that the method had good repeatability.

[0039] Example 4 Preparation of n-octadecane reference solution: same as in Example 2.

[0040] Preparation of test solution: same as in Example 2.

[0041] Detection limit solution: Accurately measure 1.0 ml of n-octadecane reference solution, place it in a 10 ml volumetric flask, dilute to the mark with dichloromethane, and shake well (concentration is about 14 µg / ml).

[0042] Quantitation limit solution: Accurately measure 5.0 ml of n-octadecane reference solution, place it in a 25 ml volumetric flask, dilute to the mark with dichloromethane, and shake well (concentration is about 28 µg / ml).

[0043] The n-octadecane reference solution, the detection limit solution and the quantification limit solution were sampled and tested according to the instrument conditions of Example 1, and the obtained chromatogram peak area logarithms were compared, and the concentration of n-octadecane in the sample was calculated by the external standard method. The detection limit (LOD) and quantification limit (LOQ) test results are shown in Table 4.

[0044] Table 4 Results of detection limit

[0045] Conclusion: The concentration of n-octadecane in the detection limit solution is 14.24µg / ml, the concentration of n-octadecane in the quantification limit solution is 28.47µg / ml, and the RSD of the quantification limit peak area is 3.7%, which is less than 15.0%, meeting the requirements.

[0046] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0047] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for detecting light liquid paraffin residue in a soft capsule dosage form, characterized in that: The detection was performed by high performance liquid chromatography with an evaporative light scattering detector, comprising the steps of: (1) Setting the HPLC conditions: An amino column was used, with dichloromethane and acetonitrile as the mobile phase; gradient elution, the gradient elution flow rate was 0.5-1.0 ml / min; The evaporative light scattering detector has a drift tube temperature of 20 to 30°C and a nebulizer temperature of 20 to 30°C; (2) The n-octadecane reference substance was dissolved in dichloromethane to prepare a linear solution of the n-octadecane reference substance with different gradient concentrations between 28 µg / mL and 210 µg / mL. The solution was filtered through a 0.22 µm filter membrane and tested. The logarithmic value of the chromatographic peak area was used as the ordinate and the logarithmic value of the concentration of the n-octadecane reference substance linear solution was used as the abscissa. The results of the HPLC test were plotted into a standard curve and fitted to obtain the standard curve equation. (3) Prepare the test solution: take the solution in several soft capsules, place it in a volumetric bottle, add dichloromethane to dissolve it, let it stand after ultrasonication, take the extract, and filter it with a 0.22 µm filter membrane for later use; (4) Sample testing: Inject the test solution and then inject the n-octadecane reference solution. Compare the logarithmic values ​​of the chromatogram peak areas of the test solution and the reference solution. Calculate the concentration of n-octadecane in the test solution by the external standard method to obtain the residual concentration of light liquid paraffin.

2. The method for detecting light liquid paraffin residue in a soft capsule dosage form according to claim 1, characterized in that: The gradient elution flow rate was 0.8 ml / min.

3. The method for detecting light liquid paraffin residue in the soft capsule dosage form according to claim 1, characterized in that: The drift tube temperature was 25 °C and the nebulizer temperature was 25 °C.

4. The method for detecting light liquid paraffin residue in a soft capsule dosage form according to claim 1, characterized in that: The amino chromatographic column has a column temperature of 15 to 30° C. and a particle size of the chromatographic column filler of 3 μm to 5 μm.

5. The method for detecting light liquid paraffin residue in a soft capsule dosage form according to claim 4, characterized in that: The amino chromatographic column has a column temperature of 15°C and a particle size of the chromatographic column filler of 5µm.

6. The method for detecting light liquid paraffin residue in a soft capsule dosage form according to claim 1, characterized in that: The gradient elution conditions of the mobile phase included: 0min, the content of dichloromethane in the mobile phase was 100%, and the content of acetonitrile was 0%; 5 min, the mobile phase contained 100% dichloromethane and 0% acetonitrile; 5.1 min, dichloromethane content 0%, acetonitrile content 100% in the mobile phase; 10 min, 0% dichloromethane and 100% acetonitrile in the mobile phase; 10.1 min, the mobile phase contained 100% dichloromethane and 0% acetonitrile; 18min, the mobile phase contained 100% dichloromethane and 0% acetonitrile.

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