A method for detecting the residue of light liquid paraffin in soft capsule dosage form

Abstract

A method for detecting the residue of light liquid paraffin in soft capsule dosage form, which is detected by high performance liquid chromatography based on evaporative light scattering detector, includes the steps: (1) setting the conditions of high performance liquid chromatography; (2) dissolving n-octadecane reference substance in dichloromethane to prepare n-octadecane reference substance linear solutions with different gradient concentrations between 28 μg / mL and 210 μg / mL, plotting the detection results of high performance liquid chromatography into a standard curve and then fitting it to obtain the standard curve; (3) taking the solutions in multiple soft capsules, placing them in a volumetric flask, dissolving with dichloromethane, and filtering with a 0.22 μm filter membrane for standby; (4) injecting the test solution, and then injecting the n-octadecane reference substance solution, comparing the logarithmic values of the peak areas of the chromatograms of the test solution and the reference substance solution, and calculating the concentration of n-octadecane in the sample by the external standard method, that is, obtaining the residue concentration of light liquid paraffin.

Description

Technical Field

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

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

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

[0004] Currently, the commonly used chemical composition detection methods are not applicable to the detection of light liquid paraffin residues in soft capsule dosage forms, lack pertinence, cannot prove that trace amounts of light liquid paraffin can be detected, and cannot accurately quantify.

[0005] According to the concept of impurity profile control, in drug quality standards, it is required that the analytical methods used have a sufficiently low detection limit to ensure the detection of trace amounts of light liquid paraffin actually present in drugs. Therefore, it is very necessary to accurately detect light liquid paraffin, which is beneficial 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 the residue of light liquid paraffin in soft capsule dosage forms for the problems in the prior art.

[0007] The present invention discloses a method for detecting the residue of light liquid paraffin in soft capsule dosage forms, which uses high performance liquid chromatography based on an evaporative light scattering detector for detection, including the steps:

[0008] (1) Set the conditions of high performance liquid chromatography:

[0009] Use an amino chromatographic column, with dichloromethane and acetonitrile as the mobile phase; perform gradient elution, and the gradient elution flow rate is 0.5 - 1.0 ml / min;

[0010] For the evaporative light scattering detector, the drift tube temperature is 20 - 30°C, and the nebulizer temperature is 20 - 30°C;

[0011] (2) Dissolve the n-octadecane reference substance in dichloromethane to prepare a linear solution of the n-octadecane reference substance with different gradient concentrations ranging from 28 μg / mL to 210 μg / mL. After filtering through a 0.22 μm filter membrane, perform the detection. Use the logarithm of the chromatographic peak area as the ordinate and the logarithm of the concentration of the n-octadecane reference substance linear solution as the abscissa. Plot the detection results of high-performance liquid chromatography to form a standard curve and then perform fitting to obtain the standard curve equation: Y = KX + b, where: Y represents the logarithm of the chromatographic peak area, X represents the logarithm of the n-octadecane concentration, and K and b are constants;

[0012] (3) Prepare the test solution: Take the solution inside multiple soft capsules, place it in a volumetric flask, dissolve it with dichloromethane, ultrasonicate and then let it stand. Take the extract and filter it through a 0.22 μm filter membrane for standby;

[0013] (4) Sample detection: Inject the test solution, and then inject the n-octadecane reference substance solution. Compare the logarithm of the chromatographic peak area of the test solution and the reference substance solution chromatograms, and calculate the concentration of n-octadecane in the test solution by the external standard method, that is, obtain the residual concentration of light liquid paraffin.

[0014] Further, in the above method for detecting the residual amount of light liquid paraffin in the soft capsule dosage form, the gradient elution flow rate is 0.8 ml / min.

[0015] Further, in the above method for detecting the residual amount of light liquid paraffin in the soft capsule dosage form, the drift tube temperature is 25 °C and the nebulizer temperature is 25 °C.

[0016] Further, in the above method for detecting the residual amount of light liquid paraffin in the soft capsule dosage form, for the amino chromatographic column, its column temperature is 15 - 30 °C, and the particle size of the chromatographic column packing is 3 μm - 5 μm.

[0017] Further, in the above method for detecting the residual amount of light liquid paraffin in the soft capsule dosage form, for the amino chromatographic column, its column temperature is 15 °C, and the particle size of the chromatographic column packing is 5 μm.

[0018] Further, in the above method for detecting the residual amount of light liquid paraffin in the soft capsule dosage form, the gradient elution conditions of the mobile phase include:

[0019] At 0 min, the content of dichloromethane in the mobile phase is 100% and the content of acetonitrile is 0%;

[0020] At 5 min, the content of dichloromethane in the mobile phase is 100% and the content of acetonitrile is 0%;

[0021] At 5.1 min, the content of dichloromethane in the mobile phase is 0% and the content of acetonitrile is 100%;

[0022] 10 min, the content of dichloromethane in the mobile phase is 0%, and the content of acetonitrile is 100%;

[0023] 10.1 min, the content of dichloromethane in the mobile phase is 100%, and the content of acetonitrile is 0%;

[0024] 18 min, the content of dichloromethane in the mobile phase is 100%, and the content of acetonitrile is 0%.

[0025] The present invention relates to a method for detecting the residue of light liquid paraffin in soft capsule dosage forms. It adopts a pretreatment method of extraction with organic solvents and is based on the HPLC-ELSD detection method to detect the content of light liquid paraffin in soft capsule dosage forms. This method has the advantages of high sensitivity, good specificity, and simple operation. Description of the Drawings

[0026] Figure 1 It is the chromatogram of the reference solution in Example 2 of the present invention;

[0027] Figure 2 It is the chromatogram of the test solution in Example 2 of the present invention. Detailed Embodiments

[0028] The embodiments of the present invention are described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation to the present invention.

[0029] Referring to the following description and drawings, the embodiments of the present invention will be clear. In these descriptions and drawings, some specific embodiments in the embodiments of the present invention are specifically disclosed to represent some ways of implementing the principles of the embodiments of the present invention. However, it should be understood that the scope of the embodiments of the present invention is not limited thereto. On the contrary, the embodiments of the present invention include all changes, modifications, and equivalents falling within the spirit and connotation of the appended claims.

[0030] Example 1

[0031] (1) Instrument conditions:

[0032] Chromatographic column: Ultimate XB-NH 2 4.6 × 250 mm, 5 µm; Sample chamber temperature: 5 °C; Injection volume: 20 µl, Column temperature: 15 °C, Flow rate: 0.8 ml / min. Dichloromethane is used as mobile phase A, and acetonitrile is used as mobile phase B;

[0033] ELSD (Evaporative Light Scattering Detector): Drift tube temperature: 25 °C, Nebulizer temperature: 25 °C, Nebulizing gas: N 2, atomization air flow rate: 1.2 SLM, gain: 3.0;

[0034] The elution procedure is as follows:

[0035]

[0036] (2) Solution preparation

[0037] Mobile phase A: dichloromethane.

[0038] Mobile phase B: acetonitrile.

[0039] n-Octadecane reference stock solution: Take 0.35 g of n-octadecane reference substance, accurately weigh it, place it in a 100 ml volumetric flask, add dichloromethane to dissolve it and dilute to the mark, shake well to prepare a reference stock solution with a concentration of 3.5 mg / ml.

[0040] Preparation of n-octadecane reference solution: Accurately measure 1.0 ml of the n-octadecane reference stock solution, place it in a 25 ml volumetric flask, dilute to the mark with dichloromethane, and shake well to obtain an n-octadecane reference solution with a concentration of 140 μg / ml.

[0041] n-Octadecane reference linear solution: Accurately measure 0.4 ml, 1.0 ml, 2.0 ml, 2.4 ml, and 3.0 ml of the n-octadecane reference stock solution, place them in different 50 ml volumetric flasks respectively, dilute to the mark with dichloromethane respectively, and shake well to obtain n-octadecane reference linear solutions with concentrations of 28 μg / ml, 70 μg / ml, 140 μg / ml, 168 μg / ml, and 210 μg / ml respectively.

[0042] Inject the n-octadecane reference linear solutions (L1 to L5 respectively) for detection according to the described instrument conditions. Take the logarithm of the chromatographic peak area as the ordinate and the logarithm of the concentration of the n-octadecane reference linear solution as the abscissa, plot the detection results of high performance liquid chromatography into a standard curve and then fit it to obtain the standard curve equation. The linear results are shown in Table 1.

[0043] Table 1 Linear results

[0044]

[0045] Conclusion: The linear equation of n-octadecane is y = 1.9622x + 2.8276, the correlation coefficient r is 0.9998, and the linearity is good.

[0046] Example 2

[0047] n-Octadecane reference stock solution: Weigh accurately 0.35 g of n-octadecane reference substance, place it in a 100 ml volumetric flask, add dichloromethane to dissolve and dilute to the mark, shake well to prepare a reference stock solution with a concentration of 3.5 mg / ml.

[0048] Preparation of n-octadecane reference solution: Pipette accurately 1.0 ml of the n-octadecane reference stock solution into a 25 ml volumetric flask, dilute to the mark with dichloromethane, shake well to obtain an n-octadecane reference solution with a concentration of 140 μg / ml.

[0049] Test solution: Take 4 soft capsules, pierce the capsule shells with a syringe needle to obtain the solution, place it in a 50 ml volumetric flask, add dichloromethane to dissolve and dilute to the mark, sonicate for 15 minutes, let stand for 5 minutes, take the extract, filter it through a 0.22 μm filter membrane to obtain a test solution with a concentration of 140 mg / ml.

[0050] Spiked test solution: Take soft capsules three times, 4 capsules each time, pierce the capsule shells with a syringe needle to obtain the solution, place them in three 50 ml volumetric flasks respectively, add dichloromethane to dissolve, sonicate for 15 minutes, let stand for 5 minutes, add 1 ml, 2 ml, and 3 ml of n-octadecane reference solution according to 50%, 100%, and 150% of the limit respectively, dilute to the mark with dichloromethane, shake well, take the extract, filter it through a 0.22 μm filter membrane to obtain a spiked test solution for accuracy detection.

[0051] Inject the n-octadecane reference solution and the test solution for detection under the instrument conditions described in Example 1, and the obtained chromatograms are respectively as Figure 1 and Figure 2 shown. Compare the logarithm of the peak areas of the chromatograms of the test solution and the n-octadecane reference solution. Substitute the logarithm of the peak area of the n-octadecane chromatographic peak 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.

[0052] Inject the spiked test solution for detection under the instrument conditions of Example 1, and calculate the concentration of n-octadecane by the external standard method. The accuracy results are shown in Table 2.

[0053] Table 2 Accuracy Results

[0054]

[0055] Conclusion: The average recovery rates of n-octadecane in the solutions at the concentration levels of 50%, 100%, and 150% are all between 80.0% and 120.0%. The relative standard deviations (RSD) of the recovery rates at each concentration level and the total recovery rate are all less than 15.0%, indicating that the accuracy of this method is good.

[0056] Example 3

[0057] Preparation of n-octadecane reference solution: same as Example 2.

[0058] Spiked test sample solution: Take 4 soft capsules, puncture the capsule shells with a syringe needle to obtain the solution, place it in a 50 ml volumetric flask, add an appropriate amount of dichloromethane, ultrasonicate for 15 minutes, let stand for 5 minutes, add 2 ml of n-octadecane reference solution according to 100% of the limit, dilute to the mark with dichloromethane, and shake well. Take the extract 6 times and filter through a 0.22 µm filter membrane to obtain 6 portions of spiked test sample solutions for the repeatability experiment (respectively designated as items REP-1 to REP-6), and the repeatability results are shown in Table 3.

[0059] Inject the n-octadecane reference solution and the spiked test sample solution for detection under the instrument conditions described in Example 1. Compare the logarithm values of the chromatogram peak areas obtained, calculate the concentration of n-octadecane in the sample, and obtain it by the external standard method.

[0060] Table 3 Repeatability results

[0061]

[0062] Conclusion: The relative standard deviation (RSD) of the calculated n-octadecane content in the 6 repeatability experiments is less than 15.0%, indicating that the method has good repeatability.

[0063] Example 4

[0064] Preparation of n-octadecane reference solution: same as Example 2.

[0065] Preparation of test sample solution: same as Example 2.

[0066] Limit of detection 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).

[0067] Limit of quantitation 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).

[0068] Inject the n-octadecane reference solution, the limit of detection solution and the limit of quantitation solution for detection under the instrument conditions described in Example 1. Compare the logarithm values of the chromatogram peak areas obtained, and calculate the concentration of n-octadecane in the sample by the external standard method. The detection limit (LOD) and limit of quantitation (LOQ) detection results are shown in Table 4.

[0069] Table 4 Detection limit and limit of quantitation results

[0070]

[0071] Conclusion: The concentration of n-octadecane in the detection limit solution is 14.24 μg / ml, and the concentration of n-octadecane in the quantitation limit solution is 28.47 μg / ml. The RSD of the peak area at the quantitation limit is 3.7%, which is less than 15.0%, meeting the requirements.

[0072] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0073] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent for the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention shall be subject to the appended 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 detection: inject the test solution, and then inject the n-octadecane reference solution, compare the logarithmic values ​​of the chromatogram peak area of ​​the test solution and the 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 to obtain the residual concentration of light liquid paraffin; 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.

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.

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