Carboxyl groups have an electronegative oxygen atom double bonded to a carbon atom. This carbon-oxygen bond is very polar and the fact that its a double bond increases the polarity of the bond.
PEA agar, also referred to as Phenylethyl Alcohol Agar is a medium  used by microbiologists to grow microorganisms. The ingredient that  supplies nitrogen is casein. Making the world better, one answer at a time.
Agrotain Plus is a stabilizing agent which keeps nitrogen in the ammonium form for a longer period of time and reduces volatilization, denitrification, and leaching losses. Instinctâ¢ is a nitrogen stabilizer that contains the active ingredient nitripyrin, the same active ingredient as N-Serve. Instinct is a nitrogen stabilizer for liquid UAN solutions and works to ensure that nitrogen is stabilized in the ammonium form, which is less susceptible to losses from leaching and denitrification.