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This is especially common for measurement of compounds in biological fluids; for instance, the healthy level of potassium in the blood of a human is defined between 3.5 and 5.0 mEq/L. A certain amount of univalent ions provides the same amount of equivalents while the same amount of divalent ions provides twice the amount of equivalents.
The osmol gap is typically calculated with the following formula (all values in mmol/L): = = ([+] + [] + []) In non-SI laboratory units: Calculated osmolality = 2 x [Na mmol/L] + [glucose mg/dL] / 18 + [BUN mg/dL] / 2.8 + [ethanol/3.7] [3] (note: the values 18 and 2.8 convert mg/dL into mmol/L; the molecular weight of ethanol is 46, but empiric data shows that it does not act as an ideal ...
Calculated osmolarity = 2 Na + Glucose + Urea (all in mmol/L) As Na+ is the major extracellular cation, the sum of osmolarity of all other anions can be assumed to be equal to natremia, hence [Na+]x2 ≈ [Na+] + [anions] To calculate plasma osmolality use the following equation (typical in the US): = 2[Na +
The peroxide value is defined as the amount of peroxide oxygen per 1 kilogram of fat or oil. Traditionally this was expressed in units of milliequivalents, although in SI units the appropriate option would be in millimoles per kilogram (N.B. 1 milliequivalents = 0.5 millimole; because 1 mEq of O 2 =1 mmol/2 of O 2 =0.5 mmol of O 2, where 2 is valence).
It is computed with a formula that uses the results of several individual lab tests, each of which measures the concentration of a specific anion or cation. The concentrations are expressed in units of milliequivalents / liter (mEq/L) or in millimoles/litre (mmol/L).
Environmental laboratories typically report concentrations for anion and cation parameters using units of mass/volume, usually mg/L. In order to convert the mass concentration to an equivalent concentration the following mathematical relationship is used: (mass concentration) * (ionic charge) / (molecular weight) = (equivalent concentration)
The different definitions came from the practice of quoting gravimetric results as mass fractions of the analyte, often expressed as a percentage. A related term was the equivalence factor, one gram divided by equivalent weight, which was the numerical factor by which the mass of precipitate had to be multiplied to obtain the mass of analyte.
However, there is another cluster containing many metabolic substances like cholesterol and glucose at the limit with the blue part (g/L or mmol/L). [ citation needed ] The unit conversions of substance concentrations from the molar to the mass concentration scale above are made as follows: