// Actual Code
DataColumn col = dt.Columns[0]; // Call this the one you have

DataTable tbl = col.Table;

var first = tbl.AsEnumerable()
               .Select(cols => cols.Field<DateTime>(col.ColumnName))
               .OrderBy(p => p.Ticks)
               .FirstOrDefault();

var last = tbl.AsEnumerable()
              .Select(cols => cols.Field<DateTime>(col.ColumnName))
              .OrderByDescending(p => p.Ticks)
              .FirstOrDefault();



https://stackoverflow.com/questions/8299139/how-to-find-the-max-in-a-datacolumn-of-datetime