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Dear Mr. Pappas,

Thank you for your answer. I just purchased this microwave and was worried that this was a problem specific related to this model.

Yours sincerely,


Eloísa S. de Paula
Laboratory of Contaminants and Residues in Food Ministry of Agriculture, Livestock and Supply
Campinas, São Paulo, Brazil
________________________________
De: PLASMACHEM-L: Analytical Chem.(ICP's, DCP's, MIP's). <[log in to unmask]> em nome de Pappas, Richard Steve (CDC/ONDIEH/NCEH) <[log in to unmask]>
Enviado: quinta-feira, 30 de março de 2017 12:34
Para: [log in to unmask]
Assunto: Re: Non-homogeneous heating using Maxi-44 rotor (Milestone)

Presada Eloísa,

This is not uncommon for rotors with > 40 positions. I have experienced this in the past even with rotors that had fewer positions. It takes more time for a large number of vessels to absorb sufficient energy to reach final digestion temperature, so one solution is to increase the ramp time to the final temperature. The solution in some cases was to add a small amount of hydrogen peroxide to the digestion vessels. I do not know the composition of the digestion vessels that you are using, the sample types, or the present acid mix and volume, so I cannot comment in more detail.

Isto não é incomum para rotores com> 40 posições. Eu experimentei isso no passado, mesmo com rotores que tinham menos posições. Demora mais tempo para digerir um grande número de amostras por a causa que leva mais tempo para mais amostras absorver energia suficiente para atingir a temperatura de digestão final. Por isso uma solução é aumentar o tempo de ramp para a temperatura final. A solução em alguns casos foi adicionar uma pequena quantidade de peróxido de hidrogênio aos vasos de digestão. Eu não sei a composição dos vasos de digestão que está usando, o tipo de amostras, ou a mistura e volume de ácido, então eu não posso comentar com mais detalhes.

R. Steven Pappas, Ph.D.
Team Lead, Tobacco Inorganics Group
Centers for Disease Control & Prevention
4770 Buford Highway, NE
M.S. F44, Building 110
Atlanta, GA 30341-3717, USA

-----Original Message-----
From: PLASMACHEM-L: Analytical Chem.(ICP's, DCP's, MIP's). [mailto:[log in to unmask]] On Behalf Of Eloisa de Paula
Sent: Thursday, March 30, 2017 11:09 AM
To: [log in to unmask]
Subject: Non-homogeneous heating using Maxi-44 rotor (Milestone)

Dear Sirs,

I observed non-homogeneous heating of the vessels from Maxi-44 rotor (Ethos up microwave - Milestone) when performing fresh liver digestion (200 mg), all the vessels from the outer layer of rotor did not reach the final temperature (200°C). Have any of you had a similar problem when using this rotor?

Thank you.

Eloísa S. de Paula
Laboratory of Contaminants and Residues in Food Ministry of Agriculture, Livestock and Supply Campinas, São Paulo, Brazil