title: Techniques for quantitative organic analysis in microdroplets.
abstract: Techniques are described for the chemical analysis of urea by means of X-ray microanalysis. A selective labelling reagent, thioxanthen-9-ol, is used to precipitate urea together with a sulfur label. Reagents are added to and removed from microdroplets of 50 picoliter volume by means of oil-water partition. The sensitivity of the method is less than 1 picomole. The possibility of extension of these techniques to other analyses is discussed.
mesh_terms: D055598:Chemical Phenomena; D002621:Chemistry; D003460:Crystallization; D004577:Electron Probe Microanalysis / Q000379:methods*; D008832:Microchemistry / Q000379:methods; D009821:Oils; D014508:Urea / Q000032:analysis*; D014966:Xanthenes
chemical_list: D009821:Oils; D014966:Xanthenes; D014508:Urea