TC_EA

__**TC/EA**__: Company: Thermo. Link to [|website]. Please note, the brochure is available from the company's website in .pdf format.

The TC/EA is designed for high temperature breakdown of compounds in a carbon tube under a reducing conditions, releasing hydrogen as H2 and oxygen as CO. They gases are seperated by an integrated GC column, and then run through a ConfloIII mass spectometer interface. Solids are packed in silver capsules and dropped into the furnace using an autosampler, e.g. Costech ZeroBlank (see below). Liquid samples can either be sealed (cold-weld) into silver tubing/smooth wall capsules or injected directly using a CTC Pal autosampler. For direct injections, a modified glassy C tube is needed. Oxygen on phosphates (as silver phosphate) or sulfates (as barite) are routinely done. Please note--never run phosphates after sulfates, reactor needs to be cleaned and repacked (sulfates after phosphates are ok). Nitrates can be run too, though reading both the N2 peak and the CO peak is difficult--and it may be better to dilute the N2 peak coming off the TC/EA and only study the 18O. The N2 can be analyzed via combustion on an EA.
 * Overview**:


 * Read more about it:**

18O on silver phosphate:
 * Analyses:**

18O on barite:

18O on nitrates:

18O and 13C on carbonates:

18O on silicates via in situ flourination:

HD and 18O on hydrous minerals:

HD and 18O on water (total HD and 18O):

HD and 18O on organic compounds:

Costech ZeroBlank autosampler (solids):
 * Devices:**

Note: Information is from the Costech Analytical website.

The “Zero Blank” autosampler developed by Costech uses a “sealed carousel” design which has several advantages over an “open carousel” autosampler. All samples are purged simultaneously with helium in an enclosed chamber. This eliminates any nitrogen background (from atmosphere) which is introduced in the open carousel sampler when it moves to drop the sample into the reactor. The microstepper motor which drives the autosampler can switch from a 50 position carousel to a 32 position carousel for large or bulky samples.

The sampler consists of two parts; the sampler carousel and the control module. It can be connected to any CE Instruments (formerly Carlo Erba) elemental analyzer using 18 or 20 mm OD combustion reactors. The connection to the analyzer is simple, place the carousel on the combustion reactor and connect the helium carrier gas using the standard 2mm tubing. The purge line can be turned off (except for use with the optional isolation valve) as the carrier gas will now act as the purge for the carousel. A cable connects the carousel to the control module, and an additional wire is connected to the electrovalves (for the standard pneumatic autosampler) which will control the start and stop of the “Zero Blank” sampler. Set the sample start normally, and the sample stop for 1-2 seconds later. This generates a signal which will turn the carousel and drop the sample.

The front controls are; power (on and off), a manual advance button, and a switch to select the 50 or 32 position carousels. On the back is a “jog” switch which is used to initially align the carousel, and that alignment will hold as long as power is maintained. Optional Isolation Valve An optional valve to minimize system changes is available. It replaces the standard drop tube and is the same length. The carrier gas connection is below the valve and a separate purge connection is provided above the valve. When opening the carousel to add samples it is only necessary to turn the valve, isolating the entire carousel section. The carrier gas will continue to flow through the rest of the analytical circuit. After adding samples to the carousel, close the lid, turn on the purge flow and let the carousel purge for 2-5 minutes. Close the purge vent, turn off the purge flow, and open the isolation valve.

CTC Pal autosampler (liquid injections):

http://www.scisw.com/products/literature/cds/5989-4292EN.pdf

Traps

GC column

Conflo III mass spectrometer interface

http://www.instr.science.ru.nl/irms/conflo_3.pdf


 * Tips and Tricks:**


 * Troubleshooting:**

Furnace not heating: 1. Check carrier gas pressure. If pressure falls below the set point (5 or 10 psi), the heater is shut down. 2. Double check the set point and the ramp rate. Please note, if it is set to "0", but reads room temperature, e.g. "20", the heater will not kick on when you raise the temperature until the temperature is supposed to be greater than room temperature. Also, you will notice it overshoots in the low temperature range so you can even see the temperature drop at times. 3. Solid state relay shot. The wires from the temperature controller are on one side, the wires to the furnace on the other--and it's attached to a heat sink. You can replace this with a corresponding one from any electronics dealer, e.g. DigiKey in the US--just make sure the power is off when you do this. 4. Thermocouple shot. If it's broken, you'll see a "1999" error code on the controller. They can also get poisoned and give invalid readings, though that is not likely here. The furnace is an "S" type, Pt10%Rh-Pt, and the GC oven is a "K" type. (Thermo element available for furnace, part # 1 12 14 70--but double check that). 5. Furnance blown/connection(s) blown. You may see marks on the alumina tube when you take it out corresponding to the break in the furnace. With the power off, you can check for continuity of the furnace at the terminal block that sits on top of the furnace housing (remove top panel off TC/EA). Please note, it's easier to test it at the terminal block, or the metal connectors, and not the heating element directly, which develops an insulating coating that has to be scrapped away. The aluminum tubes from carrying the current from the terminal block to the heating element holder can also corrode/crack.

Furnace not holding temperature: 1. From the manual (not a direct quote, but check it out yourself on page 11-4), you may have to increase the voltage that supplies the furnace at the transformer. Basically, with the power off, move the jumper down one position. Again, follow the instructions in the manual. Please note, I've only done this twice, once for TC/EA and once for the GC/TC--and the furnace blew shortly afterwards on both occasions. That does not mean it will happen for you. 2. Double check the temperature controls--make sure the high temperature cut off is higher than your set point. **Do not exceed the default cutoff setting**, and if your are running above 1460 or so, be careful. Also, if you use a fast ramp rate, the controller will not hold the temperature as steady as if you used as slow ramp rate.

Repairs: 1. Solid state relay or jumbotron controller--you should be able to find a retailer for those. 2. Thermocouple--Thermo sells one or you can try to build your own 3. Furnace. Thermo sells a replacement unit for exchange (cash back). If you try to replace the heating element yourself, make sure it is lined up properly and that you have good contact between the holder and the element.