[ALW]

We have an old Spectro Flame (EOP) ICP - AES. We recently replaced our torch because arcing was occurring within the (old) torch. Since the torch has been replaced, we've been unable to light the instrument.

The nebulizer pressure is good. There is flow through the torch - there does not appear to be any issues with connections. The nebulizer was cleaned at the same time the torch was replaced.  We've narrowed it down to a problem with the RF coil. Note, the cable connection between the ignition coal and the generator appears fine.

Has anyone else had this problem? Are there any tricks to cleaning the RF coil? We tried using an old toothbrush to remove dirt, but the instrument still failed to light.

Any insight is greatly appreciated! Thanks!

[kikistare]

We have a newer ICP and we were having the same problem. The copper coil became dirty and caused an arc inside the ICP. The service tech tried many different things but ended up having to replace the motherboard. Apparently the acred current grounded out on it. I hope yours didn't do the same thing.

We clean the coil and the torch by soaking them in 1% Nitric Acid and sonicating them. This doesn't always work but sometime it will prolong the life of the parts. We usually replace both the coil and torch as well as the cones once a month or once every other month.

[Lorax]

We had a Perkin Elmer Optima that did the same thing.  Cleaning the coil didn't do anything, so we ended up replacing it whenever the arcing started.  When that instrument died, we purchased a Thermo iCAP, and the coil is similar but coated in a clear, plastic material.  We have had the instrument for more than a year and a half, and are still on the original coil, and the original torch!

[ToxLabRat]

I mainly work with ICP-MS, but the RF system is the same, in the way that the plasma is generated.  So my Perkin Elmer Elan 6000 also uses a copper RF load coil to supply the RF power to generate the plasma.  Over time these RF coils become dirty, but the bigger problem to look for is pitting within the coil.  If you notice that your coil has a lot of pitting, then you most likely just need to order a new coil and replace it.  Replacement is not difficult, you just unscrew the coil from the stage and take it out and screw the new one in.  Then of course you will have to re-align the torch and the torch box.

Now, the easiest way to see if it is in fact an issue with your load coil, or the induction coil (which is on the other side of the torch box and probably cannot be seen by you, as it is in the area of the power source and the main electronics section, or even the RF generator itself, is to go ahead and start the plasma ignitions sequence like regular.  Wait until the sequence is finished, and then open the instrument and carefully check the load coil for current.  You do this by just touching it with your hand and checking to see if it is warm.  Again, be careful with this, because it does get very hot...so do it quickly.  If it is cold, then you are not getting current and that is what is causing your ignition issues (I am assuming that if you suspect you are having RF coil issues then you are not able to ignite your plasma).  If the coil is hot or warm, then the current is good, which would mean that the RF coil, induction coil and RF generator are working properly.  It is at this point I would check the ignition rod.  You may need to remove this rod and clean it with fine grain sand paper and then put it back in.  You may also need to check the torch alignment again, as if the torch is back to far from the cones, then you will have difficulties achieving plasma.  Then there is always the possibility of your ignition transformer going out (if this is the case you will need to order a new one, and you will need to have a service engineer do this replacement, bc it is dangerous if you do not know what you are doing....voltage is very high and current can still remain within the system even if the main breakers have been shut off).

Oh and of course check your argon flow rate, and all of the argon tubing to make sure that you do not have any leaks within the system, especially check the connections that lead into the back side of the RF load coil.  You may have a loose connection, a bad ferrel, etc.

Good Luck