How to Synthesize Metaphosphoric Acid?

Here is a variety of information about this: http://www.google.com/search?sourceid=ie7&q=metaphosphoric+acid&rls=com.microsoft:en-us:IE-SearchBox&ie=UTF-8&oe=UTF-8&rlz=1I7ACEW_enUS408US408

For the small amount you need, you might be able to find a chemical or scientific supplier that can furnish it, without needing to devise your own dehydrating process. However, there may be restrictions on shipping this material across legal boundaries. (It probably classifies as a mildly hazardous material.)

THANK YOU FOR OPINION, But I need to synthesize a small quantity in order to know the methodology and then synthesize the metaphosphoric acid in the order of 4 to 5 Kg.

antonio conde