More and more companies are using TOC analysis for cleaning validation, as it outperforms other methodsFaster, simpler, and more economicalThe TOC method can achieve a higher sample analysis volume and reduce the execution time of cleaning validation procedures.Even for compounds generally considered insoluble in water and common macromolecular proteins in the biotechnology industry, the same appliesIn addition, the FDA has already implemented the TOC method¹Established as a standard procedure for detecting residual pollutants.

In cleaning validation surveys, it is often necessary to establish acceptance criteria based on more than one target residue or compound. The limitation of HPLC is that in one experiment,Can only detect one type of residueTherefore, in cleaning validation, multiple compounds require multiple analytical experiments to be completed. In these experiments, many unforeseen pollutants and cleaning agents may be overlooked, resulting in many unknown peaks appearing in the chromatography. Due to TOC being a non specific method, more than one target compound can be detected.

Due to the lengthy setup and analysis process, it often takes one or two days to verify that the equipment meets the cleaning standards when using HPLC, resulting in production downtime.Unknown peaks and high maintenance costs in HPLC are the reasons for the shutdownIn addition, HPLC is the most cited analytical method in the warning letters issued by the FDA after inspecting pharmaceutical facilities. The issues mentioned in recent warning letters include: the HPLC method can lead to insufficient detection, inability to determine unknown peaks, inability to calibrate the instrument before use, low linearity of detection, insufficient instrument accuracy, inability to bring the instrument to a suitable state before analysis, and so on.²

The insufficient training and certification level of operators operating HPLC instruments in the laboratory has also received high attentionA recent warning letter stated: "The HPLC testing process is not comprehensive because the running time and retention time of the samples have not been determined in the experimental methods you provided. Our investigator found that the employees in your laboratory habitually stop the operation of the chromatography after the elution of the active peak, resulting in the inability to detect peaks eluted after the active peak. ”³

Strengthening supervision in this area indicates that the FDA is aware of the shortcomings of HPLCThese understandings are FDA “Guide to Inspections of Pharmaceutical Quality Control Laboratories”（《FDA This has been further reflected in the Guidelines for Laboratory Review of Drug Quality Control. Sometimes company employees do not receive sufficient training or have enough time to clarify situations that require further investigation and explanation. Therefore, when they encounter peaks in chromatography that cannot be explained, they ignore them instead of further confirming them⁴

As is well known, there are many uncertainties in using HPLC analysis for cleaning validation. Unknown peaks, also known as' false peaks', are one of the uncertain factors,Can lead to lengthy troubleshooting difficulties and failure of verification operationsIn the past, factors such as injection, pollutants, bubbles, dirt inside the column, worn protective columns, and trace amounts of pollutants and cleaning agents in the sample were all factors that led to the need to replace HPLC components. For example, worn polymer joints or pipes, contaminated protective columns can affect peak shape and require replacement. According to the changes in peak shape, the protective column needs to be replaced weekly or even daily, which greatly increases unplanned maintenance costs.

The "downtime calculation" shown in Table 1 compares the costs associated with downtime caused by analytical methods commonly used for clean validation in the pharmaceutical industry. The "downtime calculation" shows that the pharmaceutical company uses HPLC and TOC to produce a "popular" formulation for 315 production days (24 hours per working day, 7 days per week).⁵Using 750 resources for drug product production, the annual gross profit of the product is $2500000000. Using TOC for cleaning validation, the cost incurred by pharmaceutical companies due to production shutdownsCan reduce by 97%.

For the use of non specific methods, some people believe that if there are insoluble organic matter, the recovery rate of cleaning validation using TOC is poor, and the recovery percentage cannot exceed 50%. Table 2 compares the recovery percentages of three "insoluble organic compounds" analyzed by cotton swab method using HPLC and TOC.

TOC recovery concentration in 20ml of water is 4 μ g/cm²Or one millionth of the sample, with a reaction efficiency of over 50.⁶

After more than 20 years of exploration into clean validation work in the United States and Europe, currently over half of pharmaceutical companies use the Total Organic Carbon (TOC) method for clean validation. In order to better assist pharmaceutical companies in adopting simple and convenient TOC methods and developing SOP for clean validation,Sievers^®The analyzer has specially developed a 'Cleaning Verification Support Package'Support you to quickly use the TOC method and establish an SOP for cleaning validation.

Sievers^®M9 TOC analyzerProvides accuracy, reliability, sensitivity, and can simultaneously detect conductivity while detecting TOC, especially suitable for clean validation applications.

1. FDA website:

   fda.gov/cder/guidance/cGMPs/equipment.htm#TOC.

2. The Gold Sheet. "FDC report, March 2005.

3. FDA website:

   accessdata.fda.gov/scripts/wlcfm/indexdate.cfm。

4. FDA指导文档 : Guide to Inspections of Pharmaceutical Quality Control Laboratories。

5. Assuming that routine maintenance of production equipment causes a shutdown, relevant calculations can be obtained by contacting Sievers analyzer.

6. Andrew W. Walsh provided content for this article.