The following code can be used to concatenate the items with , and enclosing each item with single quotes
List<string> histList = new List<string>
{"one","two","three"};
string EmpArrayCsv = histList.Aggregate ("",(string agg, string it) =>
agg +=string.Format("{0} '{1}'", agg == "" ? "" : ",", it ));
Console.WriteLine (EmpArrayCsv);
string EmpArrayCsv2 = "";
foreach(string item in histList)
EmpArrayCsv2 += string.Format("{0} '{1}'", EmpArrayCsv2 == "" ? "" : ",", item );
Console.WriteLine (EmpArrayCsv2);