The best method for chromosamal preparation is the by following method

TC flasks and was added with 2.5 mg/ml colchicine at 50-60% confluency.

The colchicine treatment was observed in the form of rounding

of cells after incubation at 37 °C in atmosphere for 80-90 min.

The cells were harvested by Trypsin-EDTA protocol. The rounded cells were

treated with hypotonic (0.075 M KCI) for 8 min at 37 °C in 5% CO2 and then were fixed

in chilled acetic:methanol (1:3) and washed thrice in the fixative. Air/flame

drying chromosomal slides were prepared and stained in 2% Giemsa (pH

6.8) for 30 min

Thank you very much Neelam Gupta