Common Laboratory Solutions and Methods

Ethidium bromide solutions for gel staining

Stock solution is 10 mg/mL and is made with deionized water.  Store the stock solution at 4°C.

Add 4 µL of the stock solution to 100 mL of dissolved agarose.


DNA Sample Loading Buffer

There are several solutions that can be used.

1) 0.25 (w/v) % bromophenol blue; 0.25% (w/v) xylene cyanol; 30% glycerol.

Make a 10 mL solution and store at either 4°C or -20°C.

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This is a common solution used in molecular biology and is the abbreviation for a 10 mM Tris, 1 mM EDTA solution.  The pH of the solution is usually 8.0.


0.5 M EDTA

Add 186.1 g of disodium EDTA (always double check molecular weight and calculations) to 800 mL of dH2O.  Adjust the pH to 8.0 with NaOH (ca. 20 g of NaOH pellets).  Adjust volume to 1 L.  Dispense into aliquots and autoclave.



Isopropylthio-ß-D-galactoside (m.w. = 238.3).  Make a solution of IPTG by dissolving 2 g of IPTG in 8 mL of dH2O.  Adjust volume to 10 mL and sterilize by filtration through a 0.22 µ disposable filter.  Dispense the solution in 1 mL aliquots and store them at -20° C.

D.L. Robertson
Revised: March 10, 2009 .