In chromatographic analysis, increasing work efficiency (ie, the number of samples that can be analyzed per unit time 20ml CTC headspace vials) is a goal that people have been pursuing. From packed columns to capillary tubes, from manual injection to automated injection, everything from routine chromatography to fast chromatography increases productivity. From the current instrument, the analysis time of the gas chromatograph GC itself has been quite short. In contrast, sample processing is often time consuming, and headspace chromatography is often a simple and effective method. The so-called headspace gas chromatograph analysis is to take the gas phase of the sample matrix (liquid and solid, by heating pressure balance) for chromatographic analysis, with good repeatability and accuracy, while reducing the interference level of the injection technology. .
Headspace Gas Chromatograph (GC) two major considerations:
1. Septum: It mainly plays the role of sealing injection and cleaning the injection needle. Generally, the septum can reach the life of more than one hundred injections. Different materials have different life spans. If the inlet pressure is found to be degraded, check whether the septum is severely worn, the sealability is deteriorated, and if necessary, replace it. Separator debris can cause the background to rise, and it can contaminate the liner, block the column, and should be replaced frequently, without having to wait for non-replaceme20ml CTC headspace vialsnt.
2. Lining: The liner mainly functions as a sample vaporization chamber in the gas chromatograph GC. The sample is vaporized in the liner and brought into the gas phase. 20ml CTC headspace vials There are deactivated and non-deactivated fractions, and there are also split/splitless , no split, split, direct injection, direct connection, focus, PTV and other points. Irregular replacement or improper use can result in poor peak shape, solute discrimination, poor reproducibility, sample decomposition, and ghost peaks. The maintenance of the liner is mainly cleaning, silanization and rational use of glass wool.
1) General cleaning headspace sampler is mainly rinsed or ultrasonically cleaned with pure water, methanol or absolute ethanol. The pollution can be wiped gently with a cotton swab. The force is not excessive, avoiding damage to the inner surface to produce active spots, and then placing it in the oven 70. After drying, dry and cool sealed and stored.
2) Silanization is one of the more effective ways to eliminate the surface activity of the carrier. It can eliminate the silanol groups on the surface of the carrier, weaken the hydrogen bond generating force, and make the surface inert. The general method is to soak or reflux with a toluene solution of 5~8% silylating reagent for more than 1 hour, then wash it with neutral methanol to neutrality and dry for use.
3) Use of the injector glass wool. In most practical applications of gas chromatographs, a certain amount of glass wool can usually be filled in the liner to increase the vaporization efficiency of the sample.20ml CTC headspace vials At the same time, it can also prevent the separator from clogging the column, but if the glass wool Without deactivation or more breakpoints, the active point will increase and it will be counterproductive. Glass wool is not recommended for the following applications: phenols, organic acids, pesticides, amines, drugs of abuse, reactive polar compounds, heat labile compounds, etc.
4) Metal gasket (split / splitless plate): sealing and current limiting, etc., pure copper, stainless steel, gold plating and other materials, with gold-plated. Regular or on-demand inspection, if it is contaminated, it can be removed by ultrasonic cleaning with pure water or organic solvent. Wipe with a cotton swab to show that it is not possible to scratch the upper surface with hard objects.
5) Gas Chromatograph Column Seal: Seal the column to the liner. Generally, it is pure graphite, Teflon, metal, and proportionally added Vespel or 100% Vespel. Pure graphite materials are generally used at one time. If the sealing effect is ok, it can be used multiple times. Other materials can be used multiple times, and the seal is not leaking.20ml CTC headspace vials
This is the end of the introduction of Headspace Gas Chromatograph (GC) two major considerations: septum and liner. I hope it can help you.