ECD - negative output

[lusi]

Hello,
Could someone tell me what would cause an ECD's output negative?
Thanks

[Koichi]

"The Troubleshooting and Maintenance Guide for Gas Chromatographers" Dean Rood
page 163, 8.5.8.4 Negative Peaks with an ECD
ISBN978-3527313730

Please refer to this book.
Search in Google books, you can read this book.

In this book,
"In most cases, negative peaks are a sign of a highly contaminated detector or a detector that needs reconditioning."

[fsistere]

hidrocarbons can cause negative peaks too

[lusi]

Thanks so much for all your help.