The common reagent tests are thus
for general alkaloid identification:
Marquis - 100 mL of concentrated (95–98%) sulfuric acid to 5 mL of 40% formaldehyde
Mecke - 100 mL of concentrated (95–98%) sulfuric acid to 1 g of selenious acid
Mandelin - 100 mL of concentrated (95–98%) sulfuric acid to 1 g of ammonium vanadate
other general purpose reagents
Froehde - 100 mL of hot, concentrated (95–98%) sulfuric acid to 0.5 g of e.g. sodium molybdate
Liebermann - 100 mL of concentrated sulfuric to 10 g of potassium nitrite
Duquenois–Levine - 100 mL ethanol, 2 g vanillin, 2.5 mL acetaldehyde (+ hydrochloric acid and chloroform)
Zwikker - Part A is 0.5 g of copper (II) sulfate in 100 ml of distilled water. Part B consists of 5% pyridine (v/v) in chloroform.
Ehrlich and Modified Ehrlich - "improved hallucinogen reagent" uses 5 g DMAB in 100 mls concentrated phosphoric acid (specific gravity 1.75) and 100 mls of methanol.
differentiating primary/secondary amines:
Simons - sodium nitroprusside, sodium carbonate and acetaldehyde
Robadope - sodium nitroprusside, sodium carbonate and acetone
If you add TLC some combination of these stains is enough to identify most classes of alkaloids.
