Question

CLIVILY DZ VEEN Tasks: prepare stock substrate in appropriate buffer o 10 mL 10 mM L-DOPA in 100 mM phosphate buffer, pH 6.0
I’m trying to figure out how much of each i need to use to prepare the stock buffer

Answer 1

Preparation of 100 mL PBS (pH 6)

To prepare 100 mL of 100 mM PBS (pH 6), 100 mL solution of KH₂PO₄ (Monopotassium phosphate

) should be mixed with 11.2 mL of 100 mM NaOH.

Preparation of 100 mL of 100 mM Monopotassium phosphate

Molar mass of Monopotassium phosphate = 136.086 g/mol

Mass required to prepare 100 mL 100 mM KH₂PO₄ solution = 0.1 M x 0.1 L x 136.086 g/mol = 1.36 g

Preparation of 100 mL of 100 mM Sodium hydroxide

Molar mass of sodium hydroxide = 40 g/mol

Mass required to prepare 100 mL 100 mM NaOH solution = 0.1 M x 0.1 L x 40 g/mol = 0.4 g

Prepare 100 mM 100 mL solutions of and NaOH separately. Mix 11.2 mL of NaOH with 100 mL KH₂PO₄ solution. This solution will be your 100 mM PBS (pH 6).

Preparation of 10 mL of 10 mM L-DOPA in 100 mM phosphate buffer (pH 6)

Molar mass of L-DOPA = 197.1879 g/mol

Mass of L-DOPA required to prepare 10 mL of 10 mM L-DOPA = 0.01 M x 0.01 L x 197.1879 g/mol = 0.0197 g

Take 10 mL of the 100 mM PBS(pH 6) and dissolve 0.0197 g of L-DOPA to prepare 10 mL of 10 mM L-DOPA in 100 mM phosphate buffer (pH 6)

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