Demonstrating Compliance of a Gel Permeation Chromatography (GPC) Method With the Requirements in a Proposed USP Monograph for Sorbitan Sesquioleate
Abstract
The United States Pharmacopeia (USP) proposed changes to the monograph for sorbitan sesquioleate to udpate assay procedure and add a limit test for organic impurities (USP-PF 50(2)). Both test procedures utilize a GPC method with a refractive index (RI) detector. In this work, the proposed GPC method was run on an Arc™ HPLC System with a strong solvent compatibility kit. The results met all the system suitability specifications and acceptance criteria for both the assay and organic impurities analysis in sorbitan sesquioleate, demonstrating compliance with the USP requirements.
Benefits
- Successful implementation of a proposed USP monograph for sorbitan sesquioleate by demonstrating compliance with all the requirements for system suitability and acceptance criteria for the assay and organic impurities testing
- Reliable GPC analysis using the Arc HPLC System with a strong solvent compatibility kit and RI detector
Introduction
The USP is modernizing monographs for drug substance, drug products, and excipients across the compedia to take advantage of new metholodogies and technogies.1 As part of the initiative, USP proposed updates to the monograph for sorbitan sesquioleate.2 For assay, USP proposed a GPC method for analysis of sorbitan tri-/higher esters, sorbitan diesters, and sorbitan monoester to replace current tests for fatty acids and polyols testing. For impurities, a limit of organic impurities test is added, utilizing similar method as for the assay.
Sorbitan sesquioleate is a non-ionic surfactant and emulsifier used as excipients in cosmetic, food, veterinary products, household items, pharmaceutical ointments, and creams.3–4 It is primarily used to create stable oil-in-water emulsions and improve the texture and appearance of products. As a surfactant, it reduces surface tension and facilitates the spread of liquids. Sorbitan sesquioleate is synthesized by the esterification reaction of sorbitol and oleic acid.4
Herein, the GPC method described for the assay and organic impurities in the proposed USP monograph for sorbitan sesquioleate was run an Arc HPLC System with a strong solvent compatibility kit and RI detector. 2 The results generated by the method were compared against the USP requirements for system suitability and acceptance criteria for assay and limit of organic impurities. The GPC analysis and implementation of a proposed USP monograph for sorbitan monooleate is shown in a previously published Waters™ Application Note.5
Experimental
Solutions preparation and experimental conditions proceeded as described in the proposed USP monograph for sorbitan sesquioleate.
Materials
Tetrahydrofuran (THF) HPLC grade, no preservatives, purchased from Fisher Chemicals, Catalog No: T425–4. Isopropyl alcohol (IPA) purchased from Honeywell, catalog number LC323–4. Sorbitan sesquioleate purchased form Sigma-Aldrich.
Sample Description
Standard Solutions
Standard solution for assay prepared by dissolving each of oleic acid, 1,4-sorbitan, and isosorbide in tetrahydrofuran at 1.0 mg/mL. For limit of organic impurities, proceeded as described in the assay.
Sample Solutions
Sample solution for assay testing prepared by dissolving sorbitan sesquioleate in tetrahydrofuran at 1.0 mg/mL. For limit of organic impurities, proceeded as described in the assay.
Method Conditions
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System: |
Arc HPLC System with quaternary solvent manager (QSM), flow through needle (FTN) sample manager, and strong solvent compatibility kit (p/n: 205002572). Column heater/cooler (p/n: 186179100) |
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Detector: |
Refractive Index (RI) · Flow cell temperature: 30 °C · Sampling rate: 10 pts/sec · Polarity: positive |
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Mobile phase: |
Tetrahydrofuran |
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Separation: |
Isocratic |
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Columns: |
Columns with 7.8 x 300 mm with 5 µm, connected in series, starting with larger pore size using a joining tube (p/n: WAT084080) supplied with columns. 1. Styragel™ HR 1, 100 Å, molecular weight range: 100–5,000 (p/n: WAT044234) 2. Styragel HR 0.5, 50 Å, molecular weight range: 0–1,000 (p/n: WAT044231) |
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Column temperature: |
30 °C |
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Sample temperature: |
25 °C |
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Flow rate: |
0.9 mL/min |
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Injection volume: |
20 µL |
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Run time: |
30 minutes |
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Vials: |
LCMS Maximum Recovery 2 mL volume (p/n: 600000670CV) |
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Wash Solvents: |
Sample manager/purge wash: tetrahydrofuran Seal wash: isopropyl alcohol |
Assay and limit of organic impurities procedures operated under the same chromatographic conditions.
Data Mangement
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Chromatography software: |
Empower™ 3 Feature Release 5 Service Release 5 (FR5 SR3) for data acquisition and analysis. |
Results and Discussion
The procedures for assay and a limit test of organic impurities described in the proposed USP monograph for sorbitan sesquioleate operate under the same GPC method conditions using the Waters Styragel HR 0.5 and HR 1 columns.2 Additionally, both procedures follow the same preparation scheme for standard and sample solutions.
Peak Assignment
The relative retention times (RRT) provided in the proposed USP monograph are designed to aid peak assignment for the assay and organic impurities testing (Table 1). Therefore, identification of peaks in the chromatographic analysis of standard and sample solutions on an Arc HPLC System with the strong solvent compatibility kit was performed following the USP specification (Figure 1).
Table 1. Relative retention time (RRT) to aid in peak assignment for assay and limit of organic impurities testing according to the proposed USP monograph for sorbitan sesquioleate.2
Figure 1. GPC separation of standard solution (A) and sorbitan sesquioleate sample (B) using an Arc HPLC System with a strong solvent compatibility kit and RI detector. RT ratio in Empower: relative retention time (RRT).
System Suitability
System suitability determination performed as instructed in the proposed USP monograph for sorbitan sesquioleate, under assay and limit of organic impurities.2 Both standard and sample solutions were used for assay procedure, while standard solution for a limit testing of organic impurities. Six replicate injections of standards solutions showed excellent relative standard deviations (RSD) for peak areas and retention times of ≤0.68 % and ≤0.01 %, respectively (Figure 2). Overall, the system suitability results generated by the GPC method met all the USP requirements specified for the assay and limit of organic impurities (Table 2).
Figure 2. Results for six replicate injections of standard solution. RT: retention time, RSD: relative standard deviation.
Table 2. System suitability for assay and organic impurities of sorbitan sesquioleate. USP requirements and results generated by the GPC method. 2
Assay: analysis of sorbitan tri-/higher esters, sorbitan diesters, and sorbitan monoesters
The percentage (%) of each sorbitan ester component in the sorbitan sesquioleate sample was calculated by area normalization as instructed by the USP.2 Area of individual peak was divided by the sum of the relevant peak areas and multiplied by 100. The results generated by the GPC method for the sorbitan tri-/higher esters, sorbitan diesters, and sorbitan monoesters met the USP acceptance criteria ranges (Table 3).
Table 3. GPC results for assay of sorbitan tri-/higher esters, sorbitan diesters, and sorbitan monoesters in sorbitan sesquioleate sample (n=6).
Limit of Organic Impurities
The percentage (%) of each individual impurity in the sorbitan sesquioleate sample was determined by comparing area of each peak to the sum of the relevant peaks. The GPC results met the USP limits for organic impurities content (Table 4).
Table 4. GPC results for organic impurities content in sorbitan monooleate sample (n=6). NMT: not more than.
Conclusion
The GPC method described in the proposed USP monograph for sorbitan sesquioleate demonstrated excellent performance on the Arc HPLC System with a strong solvent compatibility kit and refractive index detector. The USP requirements for system suitability, and acceptance criteria for assay and limit of organic impurities testing were met. The GPC system delivered reliable and reproducible results, which is critical to assure compliance with the USP requirements.
References
- United States Pharmacopeia and National Formulary (USP-NF), https://www.uspnf.com/notices/retired-compendial-notices/usp-monograph-modernization-initiative.
- United States Pharmacopeia—National Formulary/ Pharmacopeial Forum (USP–NF/PF) Revision Abstract to Monograph for Sorbitan Sesquioleate, USP 50(2), 2024. https://doi.usp.org/USPNF/USPNF_M77616_30101_01.html.
- Sorbitan Sesquioleate, chemotechnique.se.
- Sorbitan Sesquioleate, https://www.huanachemical.com/products/sorbitan-sesquioleate/
- Maziarz M. Performance Verification of a Proposed USP Monograph for Sorbitan Monooleate Using a Gel Permeation Chromatography (GPC) Method With Refractive Index (RI) Detection. Waters Application Note. 720008502. September 2024.
720008613, November 2024
