Chromatography Forum

We recently coupled a PerkinElmer 350 ATD to an Agilent 6890 with 5973 MSD. We had horrible contamination issues, greater than 10,000,000 abundance for two analytes, dodecane phosphoric acid and butyphos. We demonstrated that the contamination was not coming from the GC, the column, the gas liners or filter. PerkinElmer took initiative and replaced our 350 ATD this week. Unfortunately, we are back to where we started with these two gigantic contamination peaks.

Anyone else seen these peaks before? Are they coming from the o-rings inside the ATD?

Any feedback would be greatly appreciated.

Thanks,
Aaron

Just as a followup... The PerkinElmer technician thought the problem wasn't coming from the ATD-350. I suspected the o-rings, so I chopped up one of the o-rings used (perfluoroelastomer) and packed them into a Varian injector liner. I placed the liner into the Varian 1079 PTV, ramped it from 50 to 250C, and also ramped the column oven. All the contamination we've observed on the Agilent was detected by the Varian 2000. Mostly organophosphates, butyphos and decane phosphoric acid, in addition to the usual phthalate contaminants.

So what would be a good type of o-ring to use in the thermal desorber? Something capable of high temperatures (250C) with minimal bleed?

-Aaron

Hi there. It is normal to have contamination peaks when you changed the O-rings and ferrules as well as the filters in the ATD system. However, the significant peaks that you've mentioned; will gradually be removed once the O-rings, ferrules and filters have been conditioned ie to run a few blank runs and monitor if the peaks get lowered each time.

I guess if the replacement parts from Perkin Elmer doesnt help in removing the contaminating peaks; there wont be any other better replacement parts than the manufacturer, right?

Anyway, do keep us update and we'll see what we can do to help you out. I have encountered this before and all I have to do is to replace the parts and conditioned the system. XD