Examining the Role of TOC Analyzers in the Pharmaceutical Laboratory

Transcription

1 Shim adzu Scientific Instrum ents, 7102 Riverwood Drive, Columbia, MD Tel: / ; Fax: ; Examining the Role of TOC Analyzers in the Pharmaceutical Laboratory Total Organic Carbon (TOC) analyzers are utilized across a wide range of industries for such measures as process and water quality control, experimental research, and EPA compliance. Within the pharmaceutical industry, they serve vital roles in the manufacturing process. From inspections of the water used in drug manufacture (ultrapure water) to evaluation of cleaning effectiveness (cleaning validation), TOC analyzers are essential instruments in the pharmaceutical laboratory to ensure compliance with applicable regulations. Ensuring Compliance Compliance with regulations must be maintained throughout the different processes, which can be grouped under three general categories: 1) Preparation (includes processing and innovation) 2) Production 3) Waste Discharge Throughout such processes, it is required to use pharmaceutical quality water, monitor the pharmaceutical water used, and achieve the required cleaning level to avoid any crosscontamination. For these steps, the FDA does not recommend any one specific analytical technique. In fact, the FDA states that any Specific or Non-Specific analytical technique can be used, as long as the technique provides results that prove its ability to detect any contaminants that would affect the quality of the water used 1. Several specific and non-specific analytical techniques can be utilized to monitor the pharmaceutical water used and achieve the required cleaning validation. A Specific technique is defined as one that identifies the concentration of a specific chemical within the analyzed sample. A Non-Specific technique identifies the presence of all the chemicals in the analyzed sample, i.e. a cumulative representation of the effect of all the chemicals present within the sample.

2 During the cleaning processes, pharmaceutical water and different cleaning agents are used. Different analytical methods can be used to identify these agents, drug residue, and excipients. The method used depends on whether a specific chemical within the residue must be monitored, or a cumulative study of all of the chemicals within the residue must be determined. The following table presents some of the available specific and non-specific techniques that can be used. Analytical Method TOC Specific Method Advantages Disadvantages NO Broad spectrum analysis with low level detection, and requires minimal sample preparation. Quantitative analytical method Non-Specific Method HPLC YES Highly specific with moderate to high sensitivity, quantitative method Requires long analysis time and is very expensive tool TLC YES Highly specific with moderate to high sensitivity, and fairly expensive Visual endpoint not quantitative and require long time sample preparation CONDUCTIVITY (Not TOC Method) NO Rapid and inexpensive analysis Non-specific with limited sensitivity SPECTROPHOTOMETRIC YES/NO Moderate to high specificity, high sensitivity, and used as screening method Not quantitative TOC Analysis as a Non-Specific Analytical Technique TOC analysis is a Non-Specific analytical method. TOC is not only used in the cleaning validation process, but also for the monitoring of the pharmaceutical water used within the cleaning process and for the preparation of drugs. TOC can measure the active compounds, excipients, cleaning agents, and water system organics within the sample. As a result, TOC is a Non-Specific tool that provides an accurate result representing all of the chemicals under study within the sample, in a few minutes. The following table compares the detection capability of TOC to other techniques. Analytical Method Detection Capability Drug Residue Excipient Cleaning Agent HPLC YES YES TLC YES YES TOC YES YES YES Spectrophotometric YES/NO YES/NO Conductivity (Not TOC Method) Several pharmaceutical waters exist, including Purified Water (PW) and Water for Injection (WFI). PW is used for the cleaning process as well as in the preparation of drugs that do not enter into the blood stream 2. As a result, PW must be maintained under certain chemical purity levels, but need YES

3 not be biologically ultra-pure. The TOC acceptable level for PW should be less than or equal to 500 ppb. WFI, on the other hand, is used in the production of intravenous drugs, i.e. drugs that enter the blood stream, and in the cleaning validation process of specific systems 2. WFI must be maintained under the same chemical and biological purity levels of the PW. In addition, WFI must undergo other tests to determine bacteria count and endotoxin content, to achieve a more stringent biological purity level. WFI s TOC level must be maintained at 500 ppb or less. TOC analysis for either the cleaning validation processes or monitoring of pharmaceutical water can be measured using different organic carbon analyzers. The analyzer identifies the carbon levels present in the sample by oxidizing the carbon present to carbon dioxide, and consecutively detecting the carbon dioxide produced 3. Results for TOC can be either reported as TOC or NPOC (non-purgeable organic carbon) 3,4. TOC within a sample consists of purgeable organic carbon (POC), volatile carbon, and NPOC (hard to volatilize carbon). According to the USP, the amount of POC in pharmaceutical water is negligible and can be discounted 4 ; therefore, TOC can be reported as NPOC and vice versa. Several oxidation and detection methods can be used in conjunction with each other to accomplish the carbon analysis. Use of any of the combined oxidation/detection methods depends on the preference of the user, required detection levels, oxidation and detection method, matrix of the sample, characteristics of the sample, and/or sample type (solid or liquid). The table below indicates the different oxidation and detection methods ( denotes possible and available combinations) Detection Method Oxidation Method Detection Method NDIR CONDUCTOMETRIC TOC INSTRUMENTS Non-Dispersive Infrared Memebrane Direct COMBUSTION Catalytic / High Temperature WET CHEMICAL Persulfate UV/Persulfate Heated Persulfate Heated UV/Persulfate Heated UV UV TITANIUM Photocatalytic Oxidation

4 Applications Following are examples illustrating the use of TOC analyzers in the pharmaceutical lab. Cleaning Validation Quality control and product safety are paramount in the manufacture of pharmaceutical products. The effective removal of residues in pharmaceutical production lines is a crucial prerequisite for production. A properly cleaned system prevents contamination and, consequently, the adulteration of the produced drug. This is especially important in the production of active agents in batch processes, as the system is used for different products and contamination of the next product must be prevented. Cleaning validation confirms the effectiveness of a cleaning procedure and assures that no residues remain. To verify standards are met, pharmaceutical companies often use HPLC systems. However, when sample preparation requires the use of solvent extraction or enrichment, HPLC can become complicated and time consuming. In contrast, measurement with a TOC analyzer does not require sample preparation. Therefore, the quantity of drug residues can be quickly and easily detected. For cleaning validation using a TOC analyzer, the following 3 methods are available. (1) Rinse sampling TOC measurement method (2) Swab sampling aqueous extraction TOC measurement method (3) Swab sampling direct combustion carbon measurement method For the purpose of this article, the swab sampling direct combustion carbon measurement method will be examined. The Swab Sampling Direct Combustion method consists of wiping a fixed area of the equipment surface with the swab material, and the residues adhering to the material are physically collected and analyzed using a direct combustion carbon measurement system. The swab material with adhering residue is merely placed in the sample boat, and the carbon content is measured directly by the TOC analyzer in combination with a solid sample combustion unit. Quick, accurate measurement can be conducted even when there are insoluble compounds, bakedon residues or encrustations that cannot be easily removed via a rinsing solution. No special pretreatment procedures are required to extract residues from the swab. In order to evaluate this method, residue measurement samples were created by applying various types of pharmaceutical products and their constituents to stainless steel pots. The aqueous and non-aqueous substances that were used are listed in the table below.

5 Substance Name Solubility in Water Solvent used Solution Preparation Tranexamic acid Soluble Water Anhydrous caffeine Soluble Water Isopropylantipyrine Insoluble Ethanol Nifedipine Insoluble Acetone Gentashin ointment Insoluble Ethanol Rinderon ointment Insoluble Acetone The aqueous and non-aqueous substances were dissolved in water and ethanol or acetone, respectively, and the solution concentrations were adjusted to 2000 mgc/l (= carbon concentration of 2000 mg/l). Each residue substance measurement sample consisted of a 5 cm 2 area on the surface of a pot to which a volume of 100 µl of each solution was applied and dried. Thus, the amount of carbon in the sample at each application site was 200 µg. Among these, Gentashin ointment (aminoglycoside antibiotic) and Rinderon ointment (corticosteroid) were prepared based on determination of their carbon concentrations using the TOC analyzer equipped with a solid sampling module. To evaluate the rate of recovery of the different types of substances using the swab sampling direct combustion method, we used the quartz glass filter paper swab material to wipe the sample off the sample adhering to the stainless steel pot, placed the swab in the sample boat, and conducted TC measurement. Some of the measurement data, representing each of the sample types: 1) water soluble (Tranexamic Acid (top left)), 2) water insoluble (Isopropylantipyrine (top right)), and 3) water insoluble ointments (Gentashin Ointment (bottom left)), are shown in following figure. Measurement Conditions Analyzer: Total Organic Analyzer TOC-LCPH + Solid Sample Combustion Unit (IC circuit bypass using system with cell switching valve set) (Shimadzu, Columbia, MD) Cell length: Short cell SSM carrier gas: 400 ml/min oxygen gas Measurement item: TC Calibration curve: 1-point calibration curve using 1% C glucose aqueous solution Swab material: Advantec quartz glass paper QR-100 (diameter 45 mm) heat-treated at 600 C for 15 minutes

6 Since the carbon content in each of the residue measurement samples is 200 µg, the TC value would be 200 µg if all of the sample were wiped off. For the blank, measurement was conducted in the same way by wiping the stainless pot, which had no sample applied. The measured blank value was subtracted from each TC value, and then compared to the theoretical value of 200 µg to determine the rate of recovery. The results are shown below. A high recovery rate of about 100% was obtained for all the substances, regardless of whether they were water-soluble or waterinsoluble. Substance Name TOC Value [µc] Recovery Rate, [TC Value Blank / Theoretical Value] Blank Tranexamic acid % Anhydrous caffeine % Isopropylantipyrine % Nifedipine % Gentashin ointment % Rinderon ointment % When using the Rinse Sampling TOC Measurement and the Swab Sampling Water Extraction TOC Measurement methods, substances that do not easily dissolve in water were found to include those that had both high and low recovery rates 5. It is thought that this may be due to differences in the strength with which the substances adhere to the stainless steel pot. Accordingly, it is probable that residue evaluation using these methods would be difficult for substances with low recovery rates. In contrast, high recovery rates were obtained for all the substances when using the Swab Sampling Direct Combustion method, regardless of whether the substances were water-soluble or water-insoluble, thereby permitting residue evaluation. Therefore, this method is considered to be the most effective measurement method for conducting cleaning validation, especially when multiple compounds are being manufactured in the same vat. Measuring Samples Per USP <643> The United States Pharmacopoeia has established guidelines for determining system suitability and established the acceptance of Water For Injection (WFI) purposes and Purified Water (PW) (USP Method <643>). Shimadzu s TOC-LC*H analyzer is perfectly adapted to meet the requirements of USP Method <643>. The TOC-LC*H analyzer utilizes 680 C heat and platinum catalyst to provide a lower maintenance instrument with a detection limit of mg per liter. USP <643> In the system suitability test, the response from a solution of sucrose, a relatively easily oxidized compound, is compared to the response from 1,4 benzoquinone, a more difficult compound to oxidize. The response of the reagent water is subtracted from each response to yield a corrected response.

7 The requirement for passing the system suitability test is to obtain results for the control standard (1,4 BQ) minus the reagent water that are within +/- 15% of the sucrose standard minus the reagent water as shown in equation 1. %R = [(rss-rw) / (rs-rw)] * 100 (equation 1) Table 1 - Key to equation 1 Rss 1,4-Benzoquinone (area counts) rs Sucrose (area counts) rw Reagent Water (area counts) %R Percent Recovery (%) Samples are acceptable for Purified Water (PW) or Water For Injection (WFI) if equation 2 is satisfied. (Sample Area Counts) (rs-rw) (equation 2) Procedure First 25.0 mg of glucose was accurately weighed out and brought to 100 ml with purified water; this yields a 100 mg per liter carbon solution. 0.5 ml of this solution was then diluted to 100 ml yielding a 0.5 mg per liter carbon solution. This was used as the high standard for calibration. Standard Analysis Prepared System Suitability Standards were purchased from Shimadzu. The standards were analyzed on the Shimadzu TOC-LC*H. The instrument parameters are shown in Table 2. Table 2 - Parameters Analysis NPOC Injection Volume 816 μl Sparge Time 1.50 minutes Sparge gas flow 150 ml / min. Acid added 3.0% Injections 3 Max injections 5 Carrier gas flow 150 ml / min. Standard Results Table 3 - Results Standard Mean Area Counts rw 8.51 rs rss 43.63

8 System Suitability %R = [(rss-rw) / (rs-rw)] * 100 (equation 1) %R = [( ) / ( )] * 100 = % (equation 3) According to the requirements outlined by USP, the Shimadzu TOC-LC*H is suitable for the analysis of Purified Water and Water For Injection. 1,4-Benzoquinone is more difficult to oxidize than sucrose, therefore it is used as a system suitability solution. As shown in table 3 the area counts are very similar, and the recovery was 100.4%, validating the instrument s ability to accurately measure TOC in the ranges of mg per liter TOC. Conclusion As shown, TOC analyzers play a valuable role in the pharmaceutical laboratory, in both the drug development and manufacturing processes. When the right equipment is used, the TOC analyzer enables a laboratory to be safer, cleaner, and more productive. References 1. Weitzel, S. Critical Process Cleaning and Cleaning Validation, CFPA USP 29, <1231> USP/NF The Official Compendia of Standards. U.S. Pharmacopeia. Webcom Limited: Toronto, Canada. 3. TOC-V CPH/CPN & TOC-Control V Software User Manual. Shimadzu Corporation: Process & Environmental Instrumentation Division. Japan, Kyoto, USP 29 <643>. USP/NF The Official Compendia of Standards. U.S. Pharmacopeia. Webcom Limited: Toronto, Canada. 5. Shimadzu Application Note, Cleaning Validation by TOC Analyzer, No. O41, SHIMADZU Corporation SHIMADZU SCIENTIFIC INSTRUMENTS 7102 Riverwood Drive, Columbia, MD 21046, USA Phone: / , Fax: URL: 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