Modernizing the USP Monograph for Acetaminophen

Transcription

1 Modernizing the USP Monograph for cetaophen pplication Note Small Molecule Pharmaceuticals and Generics uthor Rongjie Fu gilent Technologies (Shanghai) Co. Ltd bstract new HPLC method was developed for detering the related compounds p-aophenol and p-chloroacetanilide in the drug acetaophen. The new method allows deteration of less than.% p-aophenol and.% p-chloroacetanilide in acetaophen, which are required by USP for its analysis []. The method was developed on traditional -µm columns, including gilent ZORX XD C and gilent ZORX Eclipse Plus C, with a gradient using phosphate buffer and acetonitrile as the mobile phase. The method was transferred to superficially porous gilent Poroshell columns, which deliver significant time and solvent savings. Several phases of Poroshell were compared.

2 Introduction The United States Pharmacopeia (USP) has embarked on a global initiative to modernize many current monographs across all compendia []. Many of the methods in existing monographs apply traditional methods, including spectrophotometry, thinlayer chromatography (TLC) and other techniques for deteration of impurities, related compounds or assay analysis. However, HPLC is an effective technique for pharmaceutical analysis, and more and more HPLC methods are included in USP. In the USP method for acetaophen, the related compound p-aophenol is detered using spectrophotometry while another related compound, p-chloroacetanilide, is detered using TLC. We developed a new HPLC method to analyze both compounds in acetaophen simultaneously using -µm columns, including ZORX Eclipse XD C and ZORX Eclipse Plus C. The methods were then transferred to.7-µm superficially porous columns, which have efficiencies similar to that of sub- µm totally porous particles. This is attributed primarily to a shorter mass-transfer distance and a narrower particle size distribution. Furthermore, the larger particle size results in lower backpressure, allowing these columns to be used on virtually any LC system. The benefits of transferring from larger particle columns include very significant time and cost savings, because superficially porous particles are optimally run at faster flow rates and achieve similar resolution with a much shorter column length. The method was run on several Poroshell phases of different selectivity. The results easily met the requirements of the USP monograph for acetaophen. Materials and Methods ll reagents and solvents were HPLC or analytical grade. Standards of p-aophenol, acetaophen, and p-chloroacetanilide were purchased from USP. Sodium dihydrogen phosphate, disodium hydrogen phosphate and acetonitrile were purchased from J&K Scientific Ltd, eijing, China. The test solution was mg/ml acetaophen in the mobile phase. The standard solution was µg/ml p-aophenol, acetaophen, and p-chloroacetanilide in the mobile phase, corresponding to.% in mg/ml acetaophen. Conditions for Figures and Columns: gilent ZORX XD C,. mm, µm (p/n ), gilent Eclipse Plus C,. mm, µm (p/n ) Mobile phase: : mm phosphate buffer,.7 g Na HPO.H O and. g NaH PO.H O; : acetonitrile Gradient time () % Stop time: Temperature: C Flow rate:. ml/ Injection volume: µl Detection: UV, nm Conditions for Figures, and Columns: gilent Poroshell EC-C,. 7 mm,.7 µm (p/n ), gilent Poroshell EC-C,. 7 mm,.7 µm (p/n ), gilent Poroshell S-C,. x 7 mm,.7 µm (p/n 797-9) Mobile phase: : mm phosphate buffer, as before : acetonitrile Gradient: time () %.. Stop time: Flow rate:. ml/ Column temperature: C Injection volume: µl Detector: UV, nm Conditions for Figures and 7 Columns: gilent Poroshell onus-rp,. mm,.7 µm (p/n 99-), gilent Poroshell Phenyl-Hexyl,.7 µm (p/n 997-) Mobile phase: : mm phosphate buffer, as before : acetonitrile Gradient: time () % Stop time: Flow rate:. ml/ Temperature: C Injection volume:. µl Detector: UV, nm The HPLC analysis was performed with an gilent Infinity Series Rapid Resolution LC system including a G gilent inary Pump SL, G7C gilent utomatic Liquid Sampler SL, G gilent Thermostatted Column Compartment SL, and GC gilent Diode rray Detector SL.

3 Results and Discussion The European Pharmacopoeia (EP). includes an HPLC method for deteration of related substances in acetaophen (paracetamol) []. n isocratic method with an EP-recommended C column is used for separation of impurities in acetaophen. The isocratic method allows a very long analysis time with a broadening peak of p-chloroacetanilide, which leads to low sensitivity. gradient method using phosphate buffer and acetonitrile was developed on. mm, -µm columns for separating p-aophenol, acetaophen, and p-chloroacetanilide at µg/ml. The three compounds were well separated. The resolution between p-aophenol and acetaophen was sufficient for limit of detection (LOD) of p-aophenol in a high concentration of acetaophen. The signal-to-noise (S/N) of p-chloroacetanilide at µg/ml was also sufficient for LOD. oth columns, the ZORX Eclipse XD-C and ZORX Eclipse Plus C, were appropriate for deteration of the two related compounds, but the ZORX Eclipse XD-C column resolved more impurities around utes, as shown in Figure and Figure.. p-aophenol. acetaophen. chloroacetanilide mg/ml acetaophen Figure. System suitability and test solution for USP acetaophen analysis using gilent ZORX XD C. Standards, corresponding to ppm (), test solution ().. p-aophenol. acetaophen. chloroacetanilide mg/ml acetaophen Figure. System suitability and test solution for USP acetaophen analysis using gilent ZORX Eclipse Plus C. Standards, corresponding to ppm (), test solution ().

4 The method was then transferred to. 7 mm,.7 µm Poroshell EC-C, Poroshell EC-C, and Poroshell S-C columns, shown in Figure, Figure, and Figure. The total analysis time was reduced from utes to only utes, while still meeting the requirements of the method. Of the three phases, the Poroshell EC-C column provided the best peak shapes and resolutions between additional impurities that eluted around utes p-aophenol. acetaophen. chloroacetanilide - mg/ml acetaophen 7 Figure. System suitability and test solution for USP acetaophen analysis using gilent Poroshell EC-C. Standards, corresponding to ppm (), test solution () p-aophenol. acetaophen. chloroacetanilide - mg/ml acetaophen 7 Figure. System suitability and test solution for USP acetaophen analysis using gilent Poroshell EC-C. Standards, corresponding to ppm (), test solution ().

5 - 7. p-aophenol. acetaophen. chloroacetanilide - mg/ml acetaophen 7 Figure. System suitability and test solution for USP acetaophen analysis using gilent Poroshell S-C. Standards, corresponding to ppm (), test solution (). In addition to these Poroshell phases, the original method was also transferred to other phases, including Poroshell onus-rp, a polar embedded ae column that gave unique selectivity, and Poroshell Phenyl-Hexyl, a phenyl-hexyl bonded column that has improved selectivity for aromatic compounds. Results are shown in Figure and Figure 7. onus-rp provided good resolution for all the impurities, while the Phenyl-Hexyl column showed several coeluted peaks. Therefore, the onus-rp column could be an alternative to a C phase due to its unique selectivity p-aophenol. acetaophen. chloroacetanilide - mg/ml acetaophen 7 9 Figure. System suitability and test solution for USP acetaophen analysis using gilent Poroshell onus-rp. Standards, corresponding to ppm (), test solution ().

6 p-aophenol. acetaophen. chloroacetanilide - mg/ml acetaophen 7 9 Figure 7. System suitability and test solution for USP acetaophen analysis using gilent Poroshell Phenyl-Hexyl. Standards, corresponding to ppm (), test solution (). ccording to the EP method for related-substance analysis, the resolution between p-aophenol and acetaophen, and S/N ratio for the peak p-chloroacetanilide are required for system suitability. Table lists the resolution and S/N with the new gradient method we developed, which all meet the EP method requirements. Table. Chromatographic system requirements and measured values for related compounds of acetaophen System requirements* gilent ZORX XD ( µm) gilent ZORX Plus C ( µm) gilent Poroshell EC-C gilent Poroshell EC-C gilent Poroshell S-C gilent Poroshell onus-rp gilent Poroshell Phenyl-Hexyl Resolution: imum. between the peaks due to impurity K (p-aophenol) and to acetaophen S/N ratio: imum for the peak due to impurity J (p-chloroacetanilide) *ccording to EP. Paracetamol

7 Conclusions HPLC methods can easily detere p-aophenol and p-chloroacetanilide in acetaophen, replacing current spectrophotometer and TLC methods. oth traditional -µm columns and gilent Poroshell columns can be used for the analysis of related compounds. The gilent ZORX Eclipse XD C phase is good for the separation of additional impurities. gilent Poroshell EC-C provides the best peak shapes and separation for this analysis, while gilent Poroshell onus-rp provides unique selectivity for these impurities. References. non. cetaophen. USP-NF. United States Pharmacopeia, Rockville, MD, US ().. non. USP Seeks Submission of Proposals for Monograph Modernization. United States Pharmacopeia, Rockville, MD, US (). non. Paracetamol. EP.. European Directorate for the Quality of Medicines & Healthcare, Council of Europe, Strasbourg, France (). For More Information These data represent typical results. For more information on our products and services, visit our Web site at 7

8 gilent shall not be liable for errors contained herein or for incidental or consequential damages in connection with the furnishing, performance, or use of this material. Information, descriptions, and specifications in this publication are subject to change without notice. gilent Technologies, Inc., Printed in the US November 7, 99-79EN