11 replies to this topic

[Mad researcher]

How do you convert 0.1 or 0.4 uM (micro molar) to uL (micro liter)

[bob1]

You don't - the units are not compatible uM is a measure of concentration, ul is a measure of volume...  If you want to know uM/ul or mg/ul or something similar that is a different story.

[Mad researcher]

yes, i wanted to know uM/uL

[Trof]

I use simple uM (micromolar) -> pmol/uL.
0.4 uM -> 0.4 pmol/uL, thats 0.0004 uM/uL

But for such calculations you only need to know that uM means uM/L. From that you only need to calculate the thousands.

[mdfenko]

Trof, on 26 September 2012 - 06:07 AM, said:

But for such calculations you only need to know that uM means uM/L.

not to be a stickler (okay, maybe it is to be a stickler), uM means um/L (micromolar means micromoles per liter).

Edited by mdfenko, 27 September 2012 - 11:26 AM.

[Trof]

Yeah right, umol/l actually. I still don't get why you need to write liters in big letters in english

[bob1]

Trof, on 27 September 2012 - 01:15 PM, said:

I still don't get why you need to write liters in big letters in english

You don't - Americans use "L", other english speaking countries (UK, Australia, NZ, probably Canada too) use "l" as far as I can tell.  Technically capitals should only be used for units that are derived from someone's name, e.g. Volt from Alessandro Volta.

[mdfenko]

bob1, on 27 September 2012 - 02:11 PM, said:

Trof, on 27 September 2012 - 01:15 PM, said:

I still don't get why you need to write liters in big letters in english

You don't - Americans use "L", other english speaking countries (UK, Australia, NZ, probably Canada too) use "l" as far as I can tell.  Technically capitals should only be used for units that are derived from someone's name, e.g. Volt from Alessandro Volta.

i'm not sure but it may have come from typewriter days. most typewriters did not have a "1" key. lower case L was used when the number 1 was to be typed ("l"). i would think that it may have been confusing to type "ll" for "1 liter".

[Trof]

It may seem as a good reason, but.. those days are long gone and.. the rest of the world didn't use typewriters?

[El Crazy Xabi]

mdfenko, on 27 September 2012 - 11:24 AM, said:

Trof, on 26 September 2012 - 06:07 AM, said:

But for such calculations you only need to know that uM means uM/L.

not to be a stickler (okay, maybe it is to be a stickler), uM means um/L (micromolar means micromoles per liter).

umol/L, um would be micrometer

bob1, on 27 September 2012 - 02:11 PM, said:

Trof, on 27 September 2012 - 01:15 PM, said:

I still don't get why you need to write liters in big letters in english

You don't - Americans use "L", other english speaking countries (UK, Australia, NZ, probably Canada too) use "l" as far as I can tell.  Technically capitals should only be used for units that are derived from someone's name, e.g. Volt from Alessandro Volta.

That rule is for SI units. Litre is accepted but is not SI.


From the SI web:
http://www.bipm.org/...er4/table6.html
(l and L appear as abbreviations)

Quote

(f) The litre, and the symbol lower-case l, were adopted by the CIPM in 1879 (PV, 1879, 41). The alternative symbol, capital L, was adopted by the 16th CGPM (1979, Resolution 6) in order to avoid the risk of confusion between the letter l (el) and the numeral 1 (one).

In the 16th CGPM (1979):http://www.bipm.org/en/CGPM/db/16/6/

Quote

Symbols for the litre* (5) (7)

The 16th Conférence Générale des Poids et Mesures (CGPM),
recognizing the general principles adopted for writing the unit symbols in Resolution 7 of the 9th CGPM (1948),
considering that the symbol l for the unit litre was adopted by the Comité International des Poids et Mesures (CIPM) in 1879 and confirmed in the same Resolution of 1948,
considering also that, in order to avoid the risk of confusion between the letter l and the number 1, several countries have adopted the symbol L instead of l for the unit litre,
considering that the name litre, although not included in the Système International d'Unités, must be admitted for general use with the System,
decides, as an exception, to adopt the two symbols l and L as symbols to be used for the unit litre,
considering further that in the future only one of these two symbols should be retained,
invites the CIPM to follow the development of the use of these two symbols and to give the 18th CGPM its opinion as to the possibility of suppressing one of them.

And a note at the end states that

Quote

The CIPM, in 1990, considered that it was still too early to choose a single symbol for the litre.

[mdfenko]

trof and el crazy xabi, although the intent of my post was to point out that the m should not be capitalized, you are correct that it should be umol, not um.

it's nice to find out that i was part right about why L is used (so that l and 1 aren't confused) since it was a guess on my part (sounded good, though, and is true about older typewriters). i normally use l but used L in my earlier post to be consistent with the earlier posts.

[Trof]

It's about time people all over the world just burried typewriters. What evil comes from them.. capital L, qwertz keyboard in my country.. I'm sure there are more..