Pyrolysis, Thermal Desorption & Evolved Gas Analysis - Frontier Laboratories
Frequently Asked Question (FAQ)
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What material are the Eco-Cups LF and SF made of? Is there any interaction between the Eco-Cup material and pyrolyzates?
The Eco-Cups are mode of stainless steel and the surface is coated by a thin quartz film. Therefore, there is very little interaction with pyrolyzates. However, repeated heating of the cups using torch flame can damage the surface and expose the stainless steel surface. It is recommended that the cup be tested, in advance, using a standard sample, especially in an analysis of vulnerable compounds such as brominated flame retardants.
What is the max use temperature of sample cups?
Are quartz pyrolysis tubes deactivated?
The surface of the quartz tubes is an inactive siloxane (SiO2) structure, therefore; no additional deactivation treatments are necessary.
Do all the Frontier pyrolyzer models share the same consumable parts?
The 2020 and 3030 series pyrolyzers have several parts that are the same. These include the Eco-Cup, Eco-Stick, Graphite Vespel ferrule, and the ITF (interface) union. Parts not shared include the pyrolysis tube and associated O-ring(s). All consumable parts are listed in the operation manual of your pyrolyzer. The manuals are available on the Frontier website.
What is the difference between the EGA capillary tube used for evolved gas analysis and a simple deactivated tube?
The chemistry of the inner surfaces of both tubes is the same. The EGA capillary tube used for evolved gas analysis （P/N：UADTM-2.5N） is designed specifically for evolved gas analysis (0.15 mm id, 2.5 m length, with cage) and is included with the Multi-Shot Pyrolyzer and the Selective Sampler accessory. A general purpose deactivated tube (P/N：UADTM-5N) 5m X 0.15 mm id is available. It does not include a cage.
When do I use an Eco-Cup LF and when should I use an Eco-Cup SF?
Eco-Cup LF and Eco-Cup SF have the same inner diameter (3.6 mm) and the same surface deactivation, but they different in height: 8 mm and 5 mm, respectively. Because the Eco-Cup SF is smaller, better reproducibility is generally obtained. Eco-Cup LF is used in normal analysis, in particular, when analyzing a large amount of sample (several mg to several tens of mg). Also, whenever an Auto-Shot Sampler is used, it is essential that an Eco-Cup LF be used. See this page for details.
When do I use an Eco-Stick SF and when should I use an Eco-Stick DF?
The Eco-Stick SF is used when making “manual” – one sample at a time – pyrolysis experiments such as single-shot, EGA, and heart-cut EGA analysis. Eco-Stick DF is used in Double-Shot analysis. Note: when an Auto-Shot Sampler is used, an Eco-Stick is not used.
I just have purchased Eco-Cups; do I need to clean them before using for the first time?
Normally, there is no need to clean new Eco-Cups before using them. Eco-Cups are cleaned prior to shipping. However, if they are exposed to laboratory air for an extended period of time, or when performing trace analysis, ghost peaks originating from atmospheric contamination may be observed. To avoid these historic peaks, clean the Eco-Cups using volatile solvents such as acetone or dichloromethane before use. Also, care must be exercised in handling the (1) sample cup holders, (2) tweezers used in sampling, and (3) Eco-Pickup in order to prevent contaminations.
I understand that Eco-Cups are considered a disposable item, but is there a way to clean them so that they can be re-used?
Depending on the types of samples and analyses you are running, Eco-Cups can be reused, if they are properly cleaned. When reusing the cups, analysts must be able to judge whether it is acceptable or not for their analytical purposes.
Examples of various cleaning methods which have been employed at various laboratories are listed below:
Clean Eco-Cups with a solvent which dissolves (or swells) analytes
Dry the cups.
Heat the cups using butane torch flame to red hot for a few seconds. Excessive heat will destroy the inertness of the cups). When a large number of cups need to be cleaned, heat them in a muffle furnace at 600ºC for one hour, rinse with a volatile solvent and dry them prior to use. Store them in a desiccator. It is a good practice to use one cup as a check sample. The pyrogram should be the same as that obtained when the same cup was previously cleaned and re-used.
Residues such as inorganics and carbons remain in the cups depending on samples. If this is the case, remove them with a cotton swab then clean with a solvent such as acetone.
Tests conducted by Frontier Lab with polyethylene and polystyrene showed that five times repeated use did not cause adverse effects on the pyrograms when the cup is cleaned as described above.
Can Eco-Cups be reused in the analysis of brominated flame retardants (PBDE)?
When analyzing compounds susceptible to thermal decomposition such as brominated flame retardants and compounds which are very polar such as acids and bases, sample cups should NOT be cleaned and re-used. DecaBDE in particular may decompose (debrominate) during thermal desorption if the surface of the sample cup has any chemical activity. Frontier Labs has demonstrated that the DecaBDE response decreases over 30%, when an Eco-Cup is used 10 times.
Does heating an Eco-Cup by a torch generate active points? Or, are they generated under normal analytical conditions (e.g., 600ºC)?
As a general rule, active points are generated by sample residues in the cup and carbon material formed during the pyrolysis step or as the cup is “cleaned” using a propane or butane torch. Normal pyrolysis temperatures (e.g., <800ºC will not damage the sample cups. When analyzing compounds susceptible to decomposition such as brominated flame retardants, do mot heat the sample cup until it ‘glows’ red. Flame cleaning is a process that requires 2-3 seconds at the most. Excessive or prolonged exposure to a flame will damage the quartz surface.
What kinds of samples tends to be decomposed if active spots exist in Eco-Cup, pyrolysis tube, or GC injector insert? How about compounds with a large molecular weight, halogenated compounds or phthalates?
It is difficult to generalize the tendency of decomposition, however, compounds with a large molecular weight tend to thermally decompose due to the fact that the elution temperature is high in thermal desorption. Normal phthalates are not harmed by using the Eco-Cups.