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Sample Osmolarity calculations
In some cases the calculated osmolarity of a commercially available preparation is greater or less than what is printed on the vial. In those cases, the manufacturer's data is used in the Osmolarity Determination Program.
Calcium chloride: Exists as dihydrate (CaCl2.2h20).  Total MW= (40.1 + 35.5 + 35.5+ (2x2) + (2x16)= 146.1   --    Calculations: (1gram CaCl2/146.1) x 1000 x valence (2)= 13.68 meq (vial states: 13.6). Osmolarity: 1 gram/10ml or (100g/liter)/146.1 x 1000 = 684.46 mmol x  #species (3) = 2053 mOsm/L (vial states: 2040 mOsm/L)
Calcium gluconate:Osmolarity: 680 mOsm/L.    MW: 430.38    concentration: 1 gram= 4.65 meq 9.3mg of calcium/ml.   Calculation: 1 g/10ml or 100g/L --- (100/430.38) x 1000 x   # species (3 -- ca(gluc)2   = 697 mOsm/L (calculated)
Common IV solutionsD10: 505 mOsmol/L;   NS: 308 mOsmol/L;   LR: 273 mOsmol/L;    D5LR: 525 mOsmol/L;   D5.45: 406 mOsmol/L;    D5NS: 560 mOsmol/L;    0.45NS: 154 mOsmol/L
Dextrose (glucose)Exists as a monohydrate:  MW=180 + 18=198.    5% dext= 5g/100ml or 50g/1000ml. 50g/198=0.252 moles or  252 mmol x species (=1), therefore osmolarity=252 mOsm/L.   D70: 700g/1000ml 700/198 x 1000=3535 mOsm/L (3530 bag).
Magnesium sulfate:Exists as magnesium sulfate heptahydrate - MgSO4.7H2O   MW=246.47   Calculations: (1gram MgSO4/246.47) x 1000= 4.057 or ~ 4.06 mmol  x  valence (2) = 8.12 meq. Osmolarity: 0.5g/ml or 500g/liter, therefore (500/246.47)x 1000=2028 mmol  x  # species (2)= 4057 mOsm/liter
Potassium acetate:  CH3COOK    MW=98.1     Calculation: 2 meq/ml [((0.196 g/ml) x 1000)/98.1] x 1000= 2000 mMol x # of species (2) = 4000 mOsm/L.
Potassium chloride: 149 mg/ml. MW=(39.1 + 35.5 = 74.6).  149/74.6 = 2 mmol  x  valence (1) = 2 meq/ml.  Osmolarity: ((149g/L) / 74.6) x 1000 x   # species(2) = ~ 4000 mOsm/L
Potassium phosphate: Each ml contains 224mg of monobasic kphos (KH2PO4), and 236mg of dibasic kphos (K2HPO4). 93 mg phosphorus/ml = 3 mMol.  170.3 mg K+/ml = 4.4 meq. Osmolarity: 12,000 mOsm/L.
Sodium acetate:  CH3cooNa    MW=82.   Calculations:   2 meq/ml solution (164 mg/ml) (0.164g x 1000)/82 x 1000= 2000 mMol x 2 species= 4000 mOsm/L.
Sodium bicarbonate: (NaHCO3 - MW=84).  Calculations: 8.4% soln = 8.4 g/100 ml (8.4/84g) x 1000 = 100 mmol x valence (1) = 100 meq or 1 meq/ml. Osmolarity: (84g/84g) x 1000  x  # species (2) = 2000 mOsm/L.     7.5 % soln (~1790 mosm/L)
Sodium chloride:Osmolarity: 8000 mOsm/L.   MW: 58.5    Concentration: 23.4% solution. Calculations: 23.4g/100ml or 234 mg/ml. 234/58.5 = 4.0 x  valence(1) = 4 meq/ml. Osmolarity: 234g/Liter = 4 moles or 4000 mmol x species(2)= 8000 mOsm/liter
Sodium phosphate:Each ml contains 276mg of monobasic Naphos (NaH2PO4), and 142mg of dibasic naphos (Na2HPO4). 93 mg of phosphorus/ml = 3 mmol.  92 mg of sodium per ml/23 = 4 meq/ml.  Osmolarity: 7000 mOsm/L
TPN Solutions Aminosyn II 15% amino acid: 1300 mOsm/L; Travasol 10% amino acid: 998 mOsm/L;  Lipid 10%: 276 mOsm/Liter    20%: 258 mOsm/L.    Novamine 15%: 1388 mOsm/L;     HepatAmine 8% amino acid: 785 mOsmol/L.
NormalityNormality of solution= equivalents per liter or meq per ml. //  # of moles of solute x valence= normality. Therefore a 1 molar solution of HCl= 1 normality. or a 1 molar CaCl2 solution = 2N cacl2