Assume you have the following stock solutions: 1 M Tris-HCl (pH 8.0) 0.5 M EDTA

Question

Assume you have the following stock solutions: 1 M Tris-HCl (pH 8.0) 0.5 M EDTA (pH 8.0) 5 M NaCl 20% sodium dodecyl sulphate Perform the calculations to make 20 mL of lysis buffer, which has the following composition: a. 100 mM Tris-HCI (pH8.0) 1% sodium dodecyl sulfate 50 mM NaCl 100 mM EDTA b. Perform the calculations to make 25 mL of TE buffer, which has the following composition: 10 mM Tris-HCI (pH8.0) 1 mM EDTA . Explain in detail how to prepare 25 ml CTAB Buffer (10% CTAB [hexadecyltrimethylammonium bromide], 0.7 M NaCI).

Explanation / Answer

Answer

A. For 20ml lysis buffer

100mM Tris Hcl
1M X x = 0.1M X 20ml
     x = (0.1M X 20ml) / 1M
     x = 2ml

1% sodium dodecyl sulphate

20% X x = 1% X 20ml
      x = (1% X 20ml) / 20%
        = 1ml

50mM Nacl

5M X x = 0.05M X 20ml
     x = (0.05M X 20ml) / 5
       = 0.2ml

100mM EDTA

0.5M X x = 0.1M X 20ml
       x = 4ml

B. 25mL TE buffer

10mM Tris-Hcl
1M X x = 0.01M X 25ml
     x = 0.25ml or 250ul

1mM EDTA
0.5 X x = 0.001M X 25
      x = 0.05ml or 50ul

C. 0.025 L * 0.7 M NaCl / L * 58.5 g NaCl /mole = 1.02 g NaCl. Measure 1.02 g NaCl and add water to 25 mL.

25 * 0.1 = 2.5g and measure 2.5 g CTAB and dissolve in 25 ml.

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