Lassaigne's test used in qualitative analysis to detect :

In Amines, the nitrogen atom bonds with alkyl or aryl groups replacing hydrogen, whereas in amides, the nitrogen atom bonds directly with the carbonyl group (-CO-).

Kjeldahl's method is not applicable to compounds containing nitrogen in nitro and azo groups and nitrogen present in the ring.

$C{H}_{3}C{H}_{2}N{O}_2\stackrel{573K}{\to }C{H}_2=C{H}_2+HN{O}_2$

Correct order of basic strength in aqueous medium is

${\left(C{H}_3\right)}_{2}NH>C{H}_{3}N{H}_2>{\left(C{H}_3\right)}_{3}N>N{H}_3$

Kindly consider the following figure