XPath to collect data

I'm developing a bot to capture certain site information, but when I try to collect the information related to the description of the collected item, it does not go through while making the other collections.

It saves the different information, but adds the same description for all items.

Here is the snippet of code:

var target = trs[tr_num].SelectNodes("//button[@class='btn btn-default']")
    [0].Attributes["data-target"].Value.CopyAfter("#").Trim();

string xpathCompara = ("//section[@id='about']/div[@id='" + target + "']");