Untitled

read serial numbers with regex and place them as individual elements of a List<string>
string[] mySerialNumbers = searchString.Split(new char[]{' '});

List<string> mySerialNumbers = new List<string>(searchString.Split(new char[]{' '});

foreach(Match match in Regex.Matches("1108656 1108657 1108658 1108659", "[0-9]{5,8}"))
{
    // Do something with match.Value here like : int.Parse(match.Value)
}

string[] SerialNum = Regex.Split("yourStringVar", " ")