Have a variable in first column of a datatable, would like to extract the value that is next to this variable in the third column

So far I have this:

Purch_org is the name of the column, purch_org is the string that I look for and get the value from the third column that is in the same row with the purch_org variable.

GetValue(As string) = Pmapping.Select(“Purch_org = '” + purch_org +"’").FirstOrDefault.item(2)

But it’s not working. Any ideas?