Precautions for solid phase extraction technology (part 3)
Use only once
The solid phase extraction column is preferably used only once. Because in a strict sense, the adsorption of many substances is irreversible, can not be eluted, which affecting the next adsorption. Although some people have done repeated experiments in order to save a money, in general it is very uneconomical behaviors as it greatly increased the unreliability and uncertainty of the results.
Therefore it is recommended to use it only once. If you want to save money, you can start with stacking joints and extension tubes by reducing the amount of filler and using small volume tubes.
Use a solid phase extractor with caution
All suppliers promote the solid phase extractor with the solid phase extraction column. The price for the simplest solid phase extractor are several hundreds dollars, and might be several times for the leading brands. The air extractor will make it more. However, it is difficult to obtain good results even with a speed switch. The main problem is that enlarge the non-parallelism of the small column.
Recommendation: use a solid phase extractor only when It is not suitable for the gravity method.
As for the automatic solid phase extractor, there is no ideal machine for food testing on the market. The main problem is that it cannot solve the problem of inconsistent liquid level drop in a small column, and the price is very expensive. It is impossible to simultaneously detect multiple batches of small columns with liquid level measurement, and there is a risk of cross contamination.
The current automatic solid phase extractor is basically a gravity-traffic route, but it avoids the problem of sealing.