Convert utf-8 XML document to utf-16 for inserting into SQL

[PLEAMEWEP]

I have an XML document that has been created using utf-8 encoding. I want to store that document in a sql 2008 xml column but I understand I need to convert it to utf-16 in order to do that.I've tried using XDocument to do this but I'm not getting a valid XML result after the conversion. Here is what I've tried to do the conversion on (Utf8StringWriter is a small class that inherits from StringWriter and overloads Encoding):\[code\]XDocument xDoc = XDocument.Parse(utf8Xml);StringWriter writer = new StringWriter();XmlWriter xml = XmlWriter.Create(writer, new XmlWriterSettings() { Encoding = writer.Encoding, Indent = true });xDoc.WriteTo(xml);string utf16Xml = writer.ToString();\[/code\]The data in the utf16Xml is invalid and when trying to insert into the database I get the error:\[code\]{"XML parsing: line 1, character 38, unable to switch the encoding"}\[/code\]However the initial utf8Xml data is definitely valid and contains all the info I need.UPDATE:The initial XML is obtained by using XMLSerializer (with an Utf8StringWriter class) to create the xml string from an existing object model (engine). The code for this is:\[code\]public static void Serialise<T>(T engine, ref StringWriter writer){ XmlWriter xml = XmlWriter.Create(writer, new XmlWriterSettings() { Encoding = writer.Encoding }); XmlSerializer xs = new XmlSerializer(engine.GetType()); xs.Serialize(xml, engine);}\[/code\]I have to leave this like this as that code is out of my control to change.Before I even send the utf16Xml string to the failing database call I can view it via the Visual Studio debugger and I notice that the entire string is not present and instead I get a string literal was not closed error on the XML viewer.