Chromatography Forum

We are planning to use the NPD for analyze the Nitrozamine (in samples of agrochemicals products), in this way we want to know wich is the best NPD bead (Black, Withe or Blos bead?) to use in this analysis... we think that someone in this forum can help us, we will very gratefully with your responses.

Thanks in advance and Best Regards,

MIlton Barrios
A&C

Hi, I have done this analysis with an ECD but not with an NPD. The question is how much is your detection level in an NPD. With ECD we can get easily to 0.3 ppm and we get a good peak. I don't know if you can get the same level of detection with an NPD. I am interested in your question because we have an NPD and want to check what can we do with it.

Somebody knows about it?

Regards,

Adolfo

Mr. Barrios, Analisis,

Forgive my ignorance here, but,... a nitrosamine, correct? And a particular one or several of a class of nitrosamines? What is piquing my interest is the mention of the ECD as I am always interested in applications using ECD.

Best regards,

AICMM

Hi,

When using an ECD, the trick is to mantain the noise level of the detector low. You get this using pure gases. I have used with good results Nitrogen 99.9995% and allways have used filters to get ride of hidrocarbons, water, etc. There are specific traps for this. Today I am using Hidrogen 99.9995% as the carrier gas in the ECD and Nitrogen as Makeup gas. Naturally with filters. I got an ECD with a very high signal level and can not get it to normal levels. I supouse I got the problem because of dirty gases and now we are sending it to be cleaned.

When you get a low noise baseline you can get very good results.

Hope it helps.

In the other hand, I want to know what is the best bead to use in a Nitrogen Phosphorus Detector (NPD): the black bead, white bead or blos bead. This are the terms in Agilent. I have asked but got no response or I really doesn't understood them.

Regards,

Adolfo Alvarez

Analisis,

Talk to DET (det-gc dot com.) These are the guys that make the beads other than BLOS. I will say they do not have a very high opinion of BLOS bead (not their product) so take that with a grain of salt but they have tons of experience with NPD beads.

Best regards,

AICMM

Hello All,

Why not use a TEA ( Thermal Energy Analyzer )?

Check out our website, http://www.ellutia.com/800TEA , and see the newest version we have out.

Thanks!

http://www.chem.agilent.com/en-US/produ ... 66770.aspx

Not sure about your particular application, but in general this link should answer your question. I cant comment on DET's opinion, but I've only heard good things about the BLOS beads from Agilent's service engineers.

I've worked with the black and white bead. The black bead is optimized for phopshorous to reduce tailing and has reduced sensitivity for nitrogen. The white bead works well but takes about a day to stabilize and lasts perhaps a few months. Tuning off the voltage and hydrogen when not in use helps. Water is what kills the beads converting the metal to the volatile hydroxide.