【PY】While other companies can pyrolyze samples at the same temperature as the Frontier pyrolyzer, why don’t they guarantee the reproducibility of pyrograms?
We think that other companies do not guarantee the reproducibility in the specifications in the manual mode, because their reproducibilities of pyrograms are generally 20-30 %, and its reliability is too poor to put it in the specifications.
Frontier Lab has developed a high precision temperature controller, with extensive optimization of relevant parts used, we thus are able to guarantee the reproducibility be less than 2 % relative standard deviation by peek area ratios for trimer of polystyrene pyrolyzed at 550 °C and internal standard (methyl stearate).
【PY】How do we know the pyrolyzer that we are currently using is working properly?
The pyrogram of polystyrene is used to monitor system performance. A polystyrene standard (P/N: PY1-4908) is included with each pyrolyzer. The standard includes 5 % methyl stearate (5 %). Analyze the standard and compare the pyrogram to the one shown in Chapter 8, Fig. 8.2 (Guarantee of basic performance) of the operation manual.
【PY】What is the rate of pyrolysis? How does it compare with Currie Point Pyrolyzers? How would the influences reflect in the final results?
The time it takes to heat the sample to 600 ⁰C in N2 using a vertical furnace is less than 100 msec, as reported by Dr. Tsuge, Emeritus Professor of Nagoya University. Theoretically, the time will be reduced by one seventh in a helium atmosphere, and is, therefore, comparable to the rate achieved when using a Currie point foil. The actual rate of pyrolysis, the reproducibility and stability of the furnace temperature and the physicality (e.g. weight, density, distribution of the sample in the furnace, etc.) determine the reproducibility of the pyrogram. These factors also play a role in what pyrolzates are formed as well as their relative intensities.
In the case of Currie point devices, the temperature of the ferromagnetic foil increases instantly; however, the contact between the sample and sample holder is different in each run, which reduces the reproducibility of the pyrograms. In the case of pyrolyzers using a filament, the sample position in the quartz sample tube (id. 2 mm or less, length 30 mm) relative to the filament coils differs in each run, resulting in poor reproducibility.
【PY】What is the precision of the temperature control?
The furnace temperature is within +/- 0.1 °C of the set point for Frontier’s Multi-Shot Pyrolyzer.
【PY】Does any adsorption occur in the pyrolyzer?
The pyrolysis tube is quartz, and the inner surface of the interface needle, which is located between the GC injection port and the pyrolyzer furnace, is deactivated with our Ultra ALLOY® technology, thus adsorption inside the pyrolyzer should be negligible. All pyrolyzers must meet stringent inertness specifications. Inertness of the entire GC system (i.e., from the pyrolyzer liner to the outlet of the separation column). The operator must also consider the possibility of system contamination when using the pyrolyzer. For example, if too much sample is placed in the sample cup the pyrolysis tube could be contaminated. Frontier recommends that a system check sample be analyzed daily. Over time the series of pyrograms will enable the operator to quickly ascertain system performance and determine when routine maintenance is necessary.
【PY】What is the purpose of the cooling gas used with the pyrolyzer? Is it required?
Cooling gas is required when using a Frontier multi-mode (a.k.a. Double Shot) pyrolyzer. The gas reduces the time required to cool the furnace temperature down to the initial temperature when using methods that require the temperature of the furnace to be cycled. On the other hand, a Single-Shot Pyrolyzer is used at a constant temperature and cooling gas is not required.
【PY】How much cooling gas is needed for the Multi-Shot Pyrolyzer? What grade of gas do you recommend? What is the actual cooling time?
The consumption of cooling gas is 7 L/min at an inlet supply pressure of 500 kPa. Compressed air with a mist-trap or industry grade compressed air or N2 can be used.
The EGA/PY-3030D pyrolyzer takes about 5 minutes to cool from 600 to 100 °C.
The PY-2020iD pyrolyzer takes about 20 minutes to cycle from 600 to 100 °C.
【PY】What is the difference in the final results between evolved gas analysis using the Pyrolyzer and a head-space sampler?
Because the pyrolyzer is designed to minimize cold spots in its flow path from the furnace to the GC injection port, a wide range of compounds from low boiling to high boiling compounds up to C40 compounds can be analyzed. The amount of sample required is several tens of milligrams; therefore, chemical species at as low as several ppb can be analyzed.
Although, head space samplers can handle several hundreds mg of samples, the thermal desorption of target compounds hidden inside the sample matrix is difficult. Because headspace sampling is normally limited to 200 °C and the fact that most have a relatively long flow path from the sample heater to GC injection port, compounds analyzed by headspace sampler is generally limited to relatively low boiling compounds, up to C20.
【PY】There are three types of pyrolyzers: furnace, filament and Curie point. What are the differences?
The basic difference is how the sample is heated
Furnace type: the sample is placed in a small, inert sample cup and dropped into a preheated furnace. The sample is instantly heated to the set-point temperature of the furnace
Filament type: the sample is held in a quartz tube (i.d. 2 mm) that is placed in a filament coil(i.d. 3 mm). The filament is rapidly heated and the sample is heated by radiant heat from the filament. The “set point’ pyrolysis temperature, however, is often different from the actual sample temperature
Curie point type: the sample is wrapped in a ferromagnetic sample holder (pyrofoil). The foil is heated by electromagnetic induction. The sample is heated by thermal radiation. The temperature attained depends on the composition of the ferromagnetic foil
【PY】How does dead volume (un-swept areas of the sample flow path.) influence the data?
The flow path from the quartz pyrolysis tube to the GC injection port is designed so that dead volumes are minimized. During “final checkout”, we confirm that there is no peak broadening due to the presence of dead volume. A simple way to check for “dead” volume is to change the flow through the system while holding the column flow constant. The peak width at half height should be independent of the inlet flow, assuming the column flow is held constant. Contamination will have the appearance of ‘dead’ volume and it is much more likely to occur than the the sudden appearance of ‘dead’ volume.