From: Williams, Andrew <Williams.A@skalar.com>
Sent: Thursday, September 3, 2020 17:33
To: Dani Shahar‏ <dani@bioanalytics.co.il>
Cc: 'Tomer Douek'‏ <tomer@bioanalytics.co.il>; Afd. Sales Support‏ <salessupport@skalar.com>
Subject: RE: TOC for aquoues samples

 

Hi Tomer and Dani  ,

 

You have two main techniques for TOC measurement: catalytic combustion and wet-chemical oxidation.

 

• In catalytic combustion, carbon compounds are converted to CO2 using high temperatures and a catalyst, with subsequent detection of the resulting CO2 using an NDIR detector. You can also measure TN simultaneously with combustion.
• Wet-chemical oxidation uses a combination of UV irradiation and persulfate oxidation.
• Wet chemical oxidation detects less particles. To measure samples containing particles, catalytic combustion with its higher oxidation potential has to be used. Again, you can also measure TN simultaneously with combustion.

 

These days I only encounter wet cehmistry in pharma labs as you can go much lower due to higher injection volumes and the really clean samples (no particles). For our environmental applications, no other choice than combustion. This is why Skalar discontinued its version of this technology some years ago.

 

To consider:

 

• For saline/salty samples, you can take the ceramic combustion tube (I sahred this info with you for the ‘brines customer’ a while ago – please refer to that.

 

• You might consider the CO2 scrubber for lower level analysis if the lab environment is very bad, Haifa chemicals have them, for exemple. Option 5 of the attached standard quote.

 

• We specidfy a MDL of 50 ppb, plenty for environmental applications. Others can go lower, but this is absolutely not necessary and very difficult indeed to achieve. If you’re analysing wastewater on a sewage works, why would you build a clean room to measure 10,000 times above the levels you need a clean room for….

 

 

Enough for a start?

 

Best regards

 

Andrew Williams

Area Manager

 

Skalar Analytical BV

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