Correct about percentage not being grams per milliter, and yes, that is
a concentration.. But, that's not solution percentage. For example,
weight-to-volume (w/v) percentage is defined as grams of solute per 100
milliliters of total solution. Hence "per cent." That's what I stated
in my submission on alcoholic beverage labeling (see your quote of it
below). Solution percentages are also concentrations, but expressed to
as percentage instead of per-unit concentration.
In laboratory medicine, results used to be stated as "milligram percent"
( mg% or mg/100 mL), but the percent aspect was removed when the
expression was changed to milligrams per deciliter (mg/dL).
Bill Hooper wrote:
On 2008 Jan 26 , at 11:04 AM, Paul Trusten wrote:
Also, since percentages by weight or volume are defined
in metric units (g/100 mL or mL/100 mL),
Percentages must be found from a ratio of two similar quantities. You
can find the number of grams per milllilitre if you want to, but it's
not a percentage and can't be expressed as a percentage. It could be
called a concentration, perhaps.
One can express percentage by mass as "grams per gram" or percentage
by volume as "millilitres per millilitre"*, but not in the form of
grams per millilitre.
Regards,
Bill Hooper
Fernandina Beach, Florida, USA
*I think of this calculation as, first, finding the ratio of the two
things (in this case volume of alcohol divided by volume of beverage)
and then, separately, expressing the first result as a percent by
dividing by 100. Certainly it is OK to combine the steps into one as
Paul does in referring to "mL/100mL".
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SImplification Begins With SI.
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--
Paul Trusten, R.Ph.
Acting Secretary
The Pharmacy Alliance
Midland TX 79707-2872 USA
+1(432)528-7724
mailto:[EMAIL PROTECTED]
http://health.groups.yahoo.com/group/ThePharmacyAlliance
