The Total Organic Carbon (TOC) test can be used as a process control to monitor the performance of water purification and distribution systems. Rinses or extracts from medical devices and swabs are analyzed for TOC to determine cleaning material residuals.
TOC testing is required to meet USP standards of Purified Water, Pure Stream and Water for Injection, as well as EP standards for Purified Water in Bulk. Nelson Laboratories uses state-of-the-art equipment that achieves very low detection limits.
- USP 643
- EP 2.2.44
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|TOC101||Total Organic Carbon (TOC), O.I., liquid only||Add|
|TOC105||Total Organic Carbon (TOC), O.I, device extraction, each||Add|
|TOC205||Total Organic Carbon (TOC), Percent Carbon, in triplicate||Add|
|TOC701||Total Organic Carbon (TOC): Dilution or Prep Fee||Add|
TOC101 - Total Organic Carbon (TOC), O.I., liquid only
TOC105 - Total Organic Carbon (TOC), O.I, device extraction, each
TOC205 - Total Organic Carbon (TOC), Percent Carbon, in triplicate
TOC701 - Total Organic Carbon (TOC): Dilution or Prep Fee
TOC205: Sample taken from TOC test
Study OutlineThe Total Organic Carbon (TOC) test is performed by the wet oxidation method on an OI Analytical Total Organic Carbon Analyzer. The sample is injected into the instrument where it is acidified and purged of inorganic carbon. Sodium persulfate is added and this oxidant quickly reacts with organic carbon in the sample at 100°C to form carbon dioxide. The carbon dioxide from the oxidized organic carbon is purged from the solution and detected by a non-dispersive infrared (NDIR) detector that has been calibrated to directly display the mass of carbon dioxide detected. This mass is proportional to the mass of TOC in the sample.
For medical devices, TOC analysis is a relatively straightforward and inexpensive method for validating a cleaning process and for performing routine monitoring of residual levels once the validation is complete. Samples are extracted in a known amount of purified water, and the extract is analyzed on the instrument.
In order for TOC to be a suitable analysis technique, first it must be established that a substantial amount of organic carbon is contained in the target compound(s). The carbon present must also be oxidizable under the TOC test conditions, and adequate water solubility of the target compound(s) must be demonstrated. Even some essentially insoluble organic residues may be removed by water extraction and analyzed by TOC.
A TOC analysis is quantitative but not qualitative. In other words, TOC does not identify or distinguish among different compounds containing oxidizable carbon. Therefore, a manufacturer should limit the amount of background carbon (i.e., carbon from sources other than the target compounds) as much as possible. Any established limits for the target compounds must be corrected for background carbon.
When possible, it is recommended that the extraction efficiency be determined. There are two techniques which can be used:
Spike recovery technique: This uses positive controls which contain a known level of contamination. The positive controls are created at Nelson Laboratories using clean devices which are spiked with a known amount of the target residue(s). The sponsor must provide us with samples of the target residue(s). Spike recovery positive controls only need to be extracted once. Dilutions may be required to ensure that the amount of carbon in the extract may be accurately quantified.
Exhaustive extraction technique: This uses positive controls which contain an unknown level of contamination. The positive controls are normally created by exposing devices to the regular manufacturing processes but then not subjecting them to the cleaning process being validated. These are “real-life” positive controls. Exhaustive extraction positive controls should be extracted until no significant increase in the cumulative residue level is detected upon re-extraction, or until the amount extracted is less than 10% of what was detected in the first extraction. Dilutions may be required to ensure that the amount of carbon in the extract may be accurately quantified.
Liquids: 40 ml placed in a VOA bottle with a Teflon® septa. Fill the vials completely leaving no headspace. After sampling, the bottles should be wrapped in bubble wrap or placed in a container with packing peanuts and shipped overnight, preferably refrigerated. Two replicates are recommended.
Devices: It is the responsibility of the sponsor to determine the number of devices needed to establish known reproducibility. It is recommended that test devices be taken in random groupings from different lots, if available. Devices may be pooled or tested individually; pooled devices should be of the same type and size.
Nelson Laboratories offers VOA bottles with a Teflon® septa for purchase plus shipping charges.