Frequently asked questions about QuEChERS products in experiments(part 6)

Q. During the sample pulverization process, it is mentioned that dry ice can be added to prevent the loss of volatile pesticides. Will the dry ice sublimate into a gas, will it take away the components to be analyzed? Can it be changed into an ice bath?

A: First of all, dry ice biochemicals will not take away pesticides. If pesticides are so volatile, then we do not need to test these pesticides. Volatile pesticides say that his boiling point is relatively low, and dry ice sublimation should reduce the environment and sample temperature to protect such pesticides without volatilizing them. As for whether to use the ice water bath, it is ok. The purpose of adding dry ice is to reduce the temperature of the sample to protect the volatile pesticides. The ice water bath can also achieve this purpose. However, the ice water bath does not seem to operate very well, because it needs to be oscillated immediately after adding the salting out package (in case of local overheating, and the violent and legitimate is also beneficial to the heat dissipation). At this time, the heat release will be particularly high, and the temperature will rise very much. High, no device can oscillate while still allowing ice water bath. If there are no conditions, the sample can be refrigerated to ensure that the temperature of the sample before analysis is as low as possible.

Q. Hawach has a finished product of graphitized carbon black SPE column. After the column has been used for a long time, will it be blocked because of the adsorption of pigment? If it is blocked, can it be removed by removing the adsorbed pigment? Can only be replaced?

A: Graphitized carbon black column is a one-time use. After use, his adsorption is saturated. Once used again, there is no function of removing pigment.