Method to transform text into a XML Doc (escape characters)

We have string variable that may contain a XML definition, string which may have also some special characters (like '&'). There is any method that allow us to transform that string into a correct XML Doc, i.e. replacing all special characters into escape characters (e.g. '&' into '& amp ;')

All the process is execute inside Siebel. The values that may contain special character like & are usually obtained from fields stored in Siebel DB, which need to be converted into XML escape characters before processing the XML doc by the EAI XML Converter.

I did checked the bookshelf XML Reference: Siebel Enterprise Application Integration > Overview > Special Characters in XML Documents