Recently, some customers reflected some problems e.g. data errors with residual solvent testing of packaging materials. In order to solve this problem, we have specially interviewed Mr. Li, the senior tester of Labthink Packaging Safety Testing Center to figure out the root causes of the error in residual solvent testing.
"The residual solvent tests require very careful operation. Even a slight error may cause the contamination of the sample and affect the test results. In addition, the test speed is another factor that may also influence the test, I believe, it is beyond the imagination of many users", said by Mr. Li.
According to his actual experience, Mr. Li gave the following 5 advices on the residual solvent test, which may help minimize the test data errors.
1. The sample shall be stored separately in clean bags. Unclean bags may cause contamination to the sample and lead to inaccurate test results.
2. The tester shall not use strong-smell cosmetics, skin cream or perfume because the volatile ingredients may enter the head-space bottle which holds the sample and cause inaccurate test results.
3. It is required to prepare sample cutter and vessel used only for residual solvent tests to avoid cross-contamination.
4. When the tester cuts the sample or loads the sample into the headspace bottle, it is recommended to wear disposable rubber gloves to avoid contamination caused by hand touch. If it is handled by bare hands, the hands must be washed repeatedly with a large amount of flowing water. Do not use detergents such as soap and liquid soap.
5. Samples dropped during sampling and loading process must be discarded to avoid contamination.
In addition, the residual gas of the sample is volatile, which may be another indefinite factor affecting the test accuracy. “There was a test case of solvent residue. The test samples were a batch of samples from the production line. The test results on the first day were larger than the next day, and the next day was larger than the third day. This is the "result error" caused by the continuous volatilization of the gas", Mr. Li said.