Here are the general usage methods of TOC (Total Organic Carbon) cleaning verification swabs:

I. Preparation

1. Select the Appropriate Swab
   Choose the suitable TOC cleaning verification swab according to the material, shape, and size of the surface to be tested. For example, if detecting the inside of a pipeline, a long and slender swab may be required; for large – area flat surfaces, a swab with a larger area will be more efficient. Also, ensure that the swab is sterile and its material will not interfere with the test results.
2. Check Supporting Tools and Reagents
   Confirm that the tools complementary with the swab, such as sampling tubes and preservation solutions, are complete. The preservation solution is generally used to maintain the stability of the sample collected by the swab, preventing the decomposition or contamination of organic carbon components. Check the expiration date and quality of the preservation solution to ensure it can meet the test requirements.
3. Clean the Surface to be Tested (Optional)
   In some cases, if there are obvious large – scale dirt or impurities on the surface to be tested, preliminary cleaning may be needed. However, pay attention to the cleaning method and the choice of cleaning agent to avoid introducing new organic carbon pollutants. For example, a carbon – free – residue cleaning cloth and a verified cleaning agent can be used for simple wiping, but do not over – clean to avoid affecting the detection of target residues.

II. Sample Collection

1. Open the Packaging
   Carefully open the packaging of the TOC cleaning verification swab in a clean environment. Avoid touching the head of the swab to prevent contaminants such as grease and dust from the hands from contaminating the swab and affecting the test results.
2. Wiping Operation
   Hold the handle of the swab and closely contact the head of the swab with the surface to be tested. Adopt an appropriate wiping method according to the test standard or operating procedure. Common wiping methods include linear wiping, circular wiping, or S – shaped wiping. For example, for a small – area flat surface, circular wiping can be used. Rotate the swab 3 – 5 circles around the center of the swab head; for a long and narrow surface, such as the edge of a pipeline, linear wiping can be used, wiping from one end to the other end and repeating 2 – 3 times.
   During the wiping process, apply appropriate pressure to ensure that the swab can effectively adsorb the residues on the surface. However, do not apply excessive pressure to avoid damaging the swab or causing the swab fibers to fall off and mix into the sample.
3. Cover the Test Area
   Ensure that the swab can cover the entire area to be tested. For larger surfaces, multiple swabs can be used or the swab can be used to wipe in sections. For example, when detecting the inner surface of a large reaction kettle, the inner surface can be divided into several areas, and each area can be wiped with a separate swab to ensure full coverage without omission.

III. Sample Preservation

1. Put into the Preservation Tube
   After wiping, immediately place the swab into the matching preservation tube. Break off the handle of the swab or insert it into the card slot or other fixed position of the preservation tube to ensure that the head of the swab is completely immersed in the preservation solution. The amount of the preservation solution should be sufficient, generally covering the head of the swab to ensure that the sample collected on the swab can fully contact the preservation solution.
2. Mark Information
   Clearly mark relevant information on the preservation tube, such as sample number, collection date, collection location, and the name of the equipment or area being tested. Accurate marking information is very important for subsequent testing and result analysis to avoid sample confusion.

IV. Transportation and Testing

1. Transportation Conditions
   Place the preservation tube containing the swab in a suitable transportation container and send it to the laboratory according to the specified transportation conditions. Generally, a low – temperature and light – avoiding environment is required to prevent changes in the organic carbon components in the sample. For example, an insulated box with ice packs can be used for transportation to ensure that the temperature is maintained within an appropriate range.
2. Laboratory Testing
   After receiving the sample, the laboratory conducts tests according to the established TOC testing method. Usually, the swab is first taken out from the preservation solution, and the organic carbon components in the sample are extracted into the test solution through an appropriate extraction method. Then, professional equipment such as a TOC analyzer is used for quantitative testing. Based on the test results, it is determined whether the cleanliness of the surface to be tested meets the requirements.