3. Old stuff
          3.2. Old physio stuff (around 2005)
              3.2.3. Physiology
                  3.2.3.4. General physiology
                      3.2.3.4.6. Electrolytes
                          3.2.3.4.6.1. Distribution of ions
 3.2.3.4.6.1.1. Extracellular vs intracellular concentration 

Extracellular vs intracellular concentration

[Ref: HH26:p416]
Substance Extracellular Intracellular
E Na+ 140 mmol/L 10 mmol/L
I K+ 4 mmol/L 140 mmol/L
E Ca2+ (free) 2.5 mmol/L 0.1 micromol/L
I Mg2+ 1.5 mmol/L 30 mmol/L
E Cl- 100 mmol/L 4 mmol/L
E HCO3- 27 mmol/L 10 mmol/L
I PO4 2 mmol/L 60 mmol/L
E Glucose 5.5 mmol/L 0-1 mmol/L
I Protein 2g/dL 16g/dL

NB:

Intracellular pH = 6.8-7.1

Reference range for serum [Mg2+]
= 0.7 to 1.0 mmol/L
= 1.4 to 2.0 mmol/L
* [KB2:p17]