An integral multilayer analytical element for the analysis of an ammonia-forming substrate comprising:(I) a light-transmissive, liquid-impermeable support:(II) an ammonia indicator layer containing a reagent capable of undergoing a detectable change by gaseous ammonia;(III) a liquid barrier layer which allows gaseous ammonia passing therethrough;(IV) an ammonia-forming substrate reaction layer containing a reagent capable of reacting with an ammonia-forming substrate to form gaseous ammonia;(V) an intrinsic ammonia trapping layer containing a reagent which acts on intrinsic ammonia to convert it into a form which can not reach said reaction layer; and(IV) a porous spreading layer, in a laminate form.