| 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. |
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| Calcium chloride: | Exists as dihydrate (CaCl2.2h20). Total MW= (40.1 + 35.5 + 35.5+ (2×2) + (2×16)= 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 solutions | D10: 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: 7400 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. |
| Normality | Normality 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 |
