No. SSI-GC- Gas Chromatography No. GC- Analysis of Residual Solvents in Pharmaceuticals (USP<>) with Shimadzu GC- Plus and HS- Headspace Sampler Introduction Organic solvents are routinely used in manufacturing pharmaceutical products, yet the presence of these compounds in the final products can be harmful to the consumers. Despite various techniques employed to remove these solvents, small quantities may still remain in the final products, and are commonly known as residual solvents (RS). These solvents are categorized into three classes based on their risks to human health. The United States Pharmacopeia (USP) has published test methods that utilize static headspace sampling and gas chromatography followed by flame ionization detection (GC/) to identify and control the level of RS class and (USP<>). This application note demonstrates the analyses of residual solvents as described in USP<> carried out with an HS- static headspace sampler and a Shimadzu GC- Plus Gas Chromatograph (Figure ). Instrumentation A Shimadzu GC- Plus equipped with an advanced flow controller (AFC), a split/splitless injector (SPL) and a Flame Ionization Detector () was used for this study. An HS- static headspace sampler with transfer line was used for sample preparation and introduction into the GC through the SPL. A Rxi-Sil MS column (Restek #, G equivalent, m x.mm x.µm) and a Stabilwax column (Restek #, G equivalent, m x.mm x.µm) were used for the USP<> Procedure A and Procedure B respectively. Standards and Sample Preparation Class, Class Mixture A and Class Mixture B residual solvent standards were purchased from Restek (Cat.# 9, and, respectively) and diluted with DMSO (Sigma D, GC grade) and deionized water to make the standard stock solutions following USP<> procedures. For analyses, standard solutions of Class, Class Mixture A and Class Mixture B were prepared in ml screw top headspace vials (Shimadzu, - 99-) as described in USP<>. Analytical Conditions GC- Plus SPL Temp = C Temp = C, H flow = ml/min, Air flow = ml/min, N Makeup flow =. ml/min. Carrier gas: Helium Flow control mode: constant linear velocity @.cm/s, split ratio =., purge flow =. ml/min Injection volume: ml headspace Oven Temp Program o Procedure A: C for min, ramp at C/min to C, hold min o Procedure B: C for min, ramp at C/min to C, hold min HS- Vial equilibration: min @ C Sample Pathway Temp = C Transfer Line Temp = C Vial Pressurization:. min @ kpa Loop Load Time =. min Injection time =. min Figure : GC- Plus and HS- static headspace sampler
No. SSI-GC- Results USP RS Class There are five solvents in USP RS Class Mixture. The USP<> monograph requires that the signal-tonoise ratio (S/N) of,,-trichloroethane is not less than and that the S/N of each peak is not less than for Procedure A. For Procedure B, which is used to confirm the results from Procedure A, the criteria is that the S/N of benzene is not less than and that the S/N of each peak is not less than. As shown in figures - and table, using HS- and GC- Plus, all peaks in Procedure A have a S/N above. And for Procedure B, the S/N was over 9 for benzene and over for all peaks. 9..... 9.. min Figure : Chromatogram of Class Standard Solution, Procedure A + S/N =. Peak No. Name S/N Procedure A Table : Signal-to-noise ratios of peaks in Class Standard Solution, Procedure A and B S/N Procedure B,-Dichloroethene..,,-Trichloroehane. 9. Carbon Tetrachloride. co-elute Benzene.9 9.,-Dichloroethane.. USP RS Class Due to the large number of solvents in Class, the standards are divided into three mixtures: A, B and C. Solvents in Class Mixture C are not readily detected by HS-GC therefore must be evaluated using other methods. The system suitability requirements for Class Mixture A are that the resolution between acetonitrile and methylene chloride (dichloromethane) is not less than. for Procedure A, and the resolution between acetonitrile and cis-,-dichloroethene not be less than. for Procedure B. As shown in Figure and below, using Shimadzu HS- with the GC- Plus, the resolution between acetonitrile and methylene chloride or cis-,-dichloroethene is >. for both procedures. No criteria have been stated for Class Mixture B. Separation of the compounds in Class Mixture B are shown in Figures and. 9 a..... min Figure : Chromatogram of Class Standard Solution, Procedure B (a: artifact)
No. SSI-GC-, 9........... min 9 Acetonitrile R =. Methylene chloride -........ min Figure : Chromatogram of Class Mixture A Standard Solution, Procedure A, 9....... 9. min Acetonitrile cis-,- Dichloro R =. ethene,-dioxane...... min Figure : Chromatogram of Class Mixture A Standard Solution, Procedure B
No. SSI-GC-........... min Figure : Chromatogram of Class Mixture B Standard Solution, Procedure A........... min Figure : Chromatogram of Class Mixture B Standard Solution, Procedure B Repeatability of Area and Retention Times Compound RT (min) RT % RSD Area % RSD,-Dichloroethene...,,-Trichloroehane... Benzene...,-Dichloroethane... Methanol.9.9. Acetonitrile.9.. Dichloromethane... trans-,-dichloroethene.9.9. cis-,-dichloroethene...9 Tetrahydrofuran.9..,-Dioxane...9 Toluene.9..9 Chlorobenzene...9 Ethylbenzene.9.. o-xylene... Hexane... Chloroform..9.,-Dimethoxyehane.9.9. Trichloroethylene.9.. Pyridine... -Hexanone.9.. Tetralin.9..9 Table : Four replicates of different solvents were assayed using Procedure A and the Relative Standard Deviation (% RSD, n=) for retention times and area are reported
No. SSI-GC- Calibration Curves Area Area,-Dichloroethene r =.999 Benzene r =.999 Conc. Percent standard concentration Conc. Percent standard concentration Figure : Four dilutions of,-dichloroethene and Benzene corresponding to % to % of the USP Standard Solution concentration were assayed using procedure A. The calibration curves and the correlation coefficient (r ) are shown Conclusions In this study, USP<> residual solvent analysis was carried out with a Shimadzu HS- static headspace sampler and a GC- Plus chromatograph. The results show that all system suitability criteria have been satisfied. In addition, good repeatability and linearity have been achieved. First Edition: July SHIMADZU Corporation www.shimadzu.com/an/ SHIMADZU SCIENTIFIC INSTRUMENTS Riverwood Drive, Columbia, MD, USA Phone: --/--, Fax: -- URL: www.ssi.shimadzu.com For Research Use Only. Not for use in diagnostic procedures. The contents of this publication are provided to you as is without warranty of any kind, and are subject to change without notice. Shimadzu does not assume any responsibility or liability for any damage, whether direct or indirect, relating to the use of this publication. Shimadzu Corporation,