Amount versus Concentration?

[EmpowersBane]

Whats the difference?

If I set my Sample Value Type to Concentration in my processing method, and I enter the concentration value in the component editor, any concentrations in my samples are calculated from the calibration curve. I don't really understand the concept of "Concentration = Amount/Injection Volume", depending on if you picked amount or concentration. Can anyone give me a clear example to demonstrate what this means as our amounts in my job are reported in Empower as "mcg/mL".

[DR]

Search here or in Empower's help files to be certain but I'm pretty sure that all going w/ conc. does is allow Empower to ignore the dilution column in a given SSM. You can process one each way to be certain as well.

[James_Ball]

From the looks of that equation it is allowing you to enter weight on column (amount) then it will calculate concentration in injected sample from the injection volume. This could be handy for those people who like to calibrate by injecting different volumes of the same concentration standard, personally I do not trust that type of calibration though.

[DR]

From the looks of that equation it is allowing you to enter weight on column (amount) then it will calculate concentration in injected sample from the injection volume. This could be handy for those people who like to calibrate by injecting different volumes of the same concentration standard, personally I do not trust that type of calibration though.

Good point - this approach always struck me as an excellent way to propagate an error and deny one the chance to evaluate their own pipetting skills.

[EmpowersBane]

Its strange because our samples in work are part of a medical device so the total amount per dose for our active comes to 150mg. When we run samples we have the component editor set to "mcg/ML" as the units yet our processing method is set to "Amount" under the component tab.

When our sample sets are processed, the "Amount" is 148 (typical) mcg/mL when surely 148mg is the amount. Mcg/Ml is the concentration units. Even after searching Empower Help its still confusing!

[DR]

Standard units are strictly optional - they're whatever one sets them to in the amount table <Mcg/mL, <mg/mL, <µg/mL, <fortnights/furlong - whatever (I think the "<" is a delimeter - does not show up in reports, but is required for entry).

[EmpowersBane]

Standard units are strictly optional - they're whatever one sets them to in the amount table <Mcg/mL, <mg/mL, <µg/mL, <fortnights/furlong - whatever (I think the "<" is a delimeter - does not show up in reports, but is required for entry).

Ah, I didn't know that. Thanks very much and interesting you say that because I always noticed the component editor would not accept any entry unless the < was in the cell but as you say, I could follow the < with "I hate Mondays" for all the difference it makes.
The only reason we put in mcg/mL is because we enter the concentration of the standard in the cells, not the weight of standard.

[Peter Apps]

Standard units are strictly optional - they're whatever one sets them to in the amount table <Mcg/mL, <mg/mL, <µg/mL, <fortnights/furlong - whatever (I think the "<" is a delimeter - does not show up in reports, but is required for entry).

Ah, I didn't know that. Thanks very much and interesting you say that because I always noticed the component editor would not accept any entry unless the < was in the cell but as you say, I could follow the < with "I hate Mondays" for all the difference it makes.
The only reason we put in mcg/mL is because we enter the concentration of the standard in the cells, not the weight of standard.

What on Earth is "mcg" and abbreviation for ?

Peter

[EmpowersBane]

mcg = micrograms. mcg/mL is a measure of concentration ie micrograms per Ml.

[Peter Apps]

That is bizarre.

If they want to avoid the µ sign it would make more sense to use mmg - millimilligrams. mcg is millicentigrams, which is 10 micrograms. No wonder people get confused.

Peter

[DR]

PS - For those not in the know on escape codes,
if you want to use µ anywhere that accepts ascii escape codes, it's alt-0181 (hold down alt key, type 0181 on keypad, release alt). Other useful ones are alt-0176 °
alt-0178 ²
and alt-0177 ±

[EmpowersBane]

DR, thanks for that, I will try that.

[James_Ball]

That is bizarre.

If they want to avoid the µ sign it would make more sense to use mmg - millimilligrams. mcg is millicentigrams, which is 10 micrograms. No wonder people get confused.

Peter

It is mostly a pharma spelling of the unit. Look on any vitamin bottle and you will see mcg for micrograms. EPA would use ug = micrograms(if you can get the mu to appear) I tried it and it wouldn't print it here for some reason.

[Peter Apps]

That is bizarre.

If they want to avoid the µ sign it would make more sense to use mmg - millimilligrams. mcg is millicentigrams, which is 10 micrograms. No wonder people get confused.

Peter

It is mostly a pharma spelling of the unit. Look on any vitamin bottle and you will see mcg for micrograms. EPA would use ug = micrograms(if you can get the mu to appear) I tried it and it wouldn't print it here for some reason.

I cheated and copied the mu from an MSWord document - bit too much of a faff most of the time, but in this case I thought that it was worth it.

cL is a centilitre - one hundredth of the litre = 10 ml, and cg is a centigram - one hundredth of a gram = 10 mg.

It's a modern miracle that we are not all dead of drug overdoses.

Peter