First, loosen the black protective sleeve below, and then loosen the stainless steel metal cover. Note: The stainless steel metal cover will sometimes be loosened and stuck in the black protective sleeve. At this time, please turn the black protective sleeve tightly and then loosen it. The stainless steel metal cover will be stuck on the outer teeth again. Remove it and leave. Push the push rod to the lower end.
At this time, the black round rod is bald. Take it out for use. After locking the outer thread of the upper head, the push rod is carefully pulled back to the upper end, and then the stainless steel metal cover and black that has just been removed. The protective sleeves are carefully tightened in sequence to complete the device. Carefully try to push the push rod to the middle end of the card and get stuck.
At this time, it has been bald from the protection needle. You can adjust the black protection sleeve up and down and check the upper scale to estimate the length of the protection needle plus the extension. To meet the needs of the experiment.
Note: After installation, do not push the push rod to the bottom end at this time, it will damage the spring. To insert the septum stopper of the sample bottle (bag) for sampling or insert the syringe, when the septum stopper is thermally desorbed, first insert the protective needle into the septum stopper, and then push the push rod to the middle end to jam. Retract the protective needle first, and then remove the protective needle.
Composition of Extraction Thimble
It consists of a handle and an extraction head, a chromatographic syringe. The extraction head is a fused silica fiber coated with different chromatographic stationary phases or adsorbents, connected with stainless steel wire, and a thin stainless steel needle tube (to protect the quartz fiber from being broken and entering), the fiber head can be retracted in the needle tube, and the handle is used to install the extraction head, which can be used permanently.
Steps of Extraction Thimble
Sample extraction: Pass the SPME needle through the septum of the sample bottle and insert it into the bottle. Push the handlebar to extend the fiber head out of the needle tube. The fiber head can be immersed in the aqueous solution (immersion method) or placed in the upper space of the sample (headspace method). The extraction thimble extraction time is about 2-30 minutes. Retract the fiber tip, and then pull the needle tube out of the vial.
Principle of Extraction Thimble
Solid phase extraction uses a quartz fiber coated with a specific coating, such as polydimethylsiloxane, to absorb volatile compounds in the headspace of plants or insects. Different coatings can be selected according to the nature of the volatiles to be extracted.
During the extraction process, the quartz fiber is pushed out of the protective needle sleeve by the handle, and it is in the volatile matter. The volatile matter is adsorbed on the fiber coating, and then the quartz fiber is directly injected into the inlet of the gas chromatograph to absorb the volatilized surface layer. Substances are quickly desorbed under instantaneous high-temperature conditions and enter the chromatographic column for separation.
It can continuously sample living organisms in natural or semi-natural conditions. It is the most accurate method for analyzing and identifying a small number of volatile compounds. The biggest advantage of this method is that only a small amount of sample material is needed, and no intermediate steps of purification are required, so there is no solvent interference.
At the same time, this method can basically reflect the types and concentrations of semiochemicals used by insects in the field foraging. The disadvantage is that the amount of information collected is small and can only be used for chemical analysis, not enough for biological determination.