Thread Content
Although the sample bottle is small, there is a lot of knowledge involved. When selecting the appropriate sample bottle for an application, three decisions need to be made: the gasket, the lid, and the sample bottle itself. Guide to spacer selection: PTFE is recommended for single-sampling applications ； Excellent solvent resistance and chemical compatibility ； It will not re-seal after being punctured ； Long-term sample storage is not recommended. PTFE/silicone is recommended for multiple injections and sample storage ； Excellent resealing properties ； It possesses PTFE chemical resistance before penetration, and the gasket will have silicone chemical compatibility after penetration ； The operating temperature range is from -40°C to 200°C. Pre-cut PTFE/silicone provides good ventilation to prevent a vacuum from forming inside the sample bottle, thereby ensuring excellent sampling reproducibility ； Eliminate clogging of the needle at the bottom end after sampling ； Good resealing capability ； Recommended for multiple injections ； The operating temperature range is from -40°C to 200°C. Seamless PE has the same advantages as PTFE. Guide to sample bottle caps: Sample bottles come in three types of caps: clip-on caps, bayonet caps, and screw-on caps. Each sealing method has its own advantages. Clamp cover: The clamp cover presses the gasket between the rim of the glass sample bottle and the folded aluminum lid. The sealing effect is excellent, effectively preventing the sample from evaporating. When the injection needle of the automatic sampler pierces the sample, the position of the spacer remains unchanged. Sealing the sample bottle with the jaw cover requires the use of a capper. For a few samples, a manual capper is the best choice. For a large number of samples, an automatic capper can be used. Bayonet cover: The bayonet cover is an extension of the jaw cover sealing method. The plastic cap fitted over the rim of the sample bottle creates a seal by pressing a gasket between the glass and the extended plastic cap. The tension in the plastic lid arises from its attempt to return to its original size. This tension creates a seal between the glass, the bottle cap, and the gasket. The plastic bayonet lid can be closed without any tools. The sealing effect of the bayonet cover is inferior to that of the other two sealing methods. If the fit of the bottle cap is too tight, it will be difficult to close, and the cap may break. If it is too loose, the sealing effect will be poor, and the gasket may move out of place. Screw-on cap: The screw-on cap is universal. Tightening the bottle cap applies mechanical force, pressing on the gasket between the glass bottle rim and the aluminum cap. During the piercing sampling process, the screw-on cap provides excellent sealing performance by mechanically pressing against the gasket. No tools are required for assembly. The PTFE/silicone gasket of the screw-on cap is fixed to the polypropylene cap using a solvent-free bonding process. This bonding technique is designed to ensure that the spacer remains with the bottle cap throughout transportation and when the cap is attached to the sample bottle. This adhesion helps prevent the gasket from coming loose or shifting during use, but the primary sealing mechanism remains the mechanical force applied when the cap is tightened onto the sample bottle. The mechanism of tightening the bottle cap is to create a seal and keep the gasket in place during the insertion of the sampling needle. There is no need to tighten the bottle cap too much, as this can affect the seal and cause the gasket to fall off or shift. If the bottle cap is tightened too much, the gasket will become cup-shaped or develop dents. The sample bottle is made of type I, 33-expansion borosilicate glass, which is currently the most chemically inert type of glass and is commonly used in analytical laboratories to obtain high-quality experimental results. Its coefficient of expansion is approximately 33x10^(-7) °C; it is primarily composed of siloxane, with trace amounts of boron and sodium also present. Type I, 51-expansion glass is more alkaline than 33-expansion glass and can be used for various laboratory applications. Its coefficient of expansion is approximately 51x 10^(-7) °C; it is mainly composed of silicon and oxygen, with trace amounts of boron as well. Deactivated glass (DV) – For analytes with strong polarity that can bind to the polar glass surfaces, a deactivated sample vial may be a good choice. The glass sample bottles were treated with glass-phase reactive silanes to create a hydrophobic glass surface. Deactivated sample bottles can be stored dried indefinitely. Polypropylene plastic: Polypropylene (PP) is a non-reactive plastic that can be used in applications where glass is not suitable. Polypropylene sample bottles maintain good sealing properties even when heated, thereby minimizing the risk of exposure to potential hazardous substances. The maximum operating temperature is 135 ℃.