I would make fields 2 character wider, append text including quotes and remove the double quotes in the post-processing.

append from input.txt delimited with "" with character tab
* Remove double quotes 
...

>Then this is apparently the problem. When looking at the input data via the Hex Editor, where there are empty fields, they are represented by TAB character only, no double quote pairs. Have you ever come across data in this type of format?
>
>Thanks for your insight, Sergey.