Hello
I work in an environmental lab we are in the process of developing a method using HPLC as the primary instrument to quantitate our compounds.
Can anyone recommend a book which describes how to accurately make up standard solutions with concentrations in ppm (ug/ml) units? How many ug equal 1 mg? How many nanograms in a microgram? The metric conversion charts I see do not cover these units.

ex:
How many grams of Bromacil(MW=261.1 "is this info even required to do this?") do I weigh out to make 100mls of a 1000ppm soln?

1000ug/ml x 100ml=100000ugx1mg/1000ug=100mg=.1g
I came up with .1g to weigh out.

milli = 10^-3
micro = 10^-6
nano = 10^-9
pico = 10^-12
femto = 10^-15

"ppm" can be either w/w (i.e., micrograms of analyte per gram of matrix) or w/v (i.e, micrograms of analyte per mL of solution); for most lab purposes, the latter is understood.
If it helps:
* 1 ppt (parts per thousand) is the same as 10^-3 grams of analyte per mL.
* 1 ppm (parts per million) is 10^-6 grams per mL.
* 1 ppb (parts per million) is 10^-9 grams per mL.
* 1 ppt (parts per billion [in the US, anyway!]) is 10^-12 grams per mL.

This is where scientific notation comes in *real* handy:

100 mL of 1000 ppm solution requires:

(10^2mL)x(10^3ppm)x(10^-6 g/mL/ppm)= 10^-1g = 0.1g

You might try to find a copy of "The Chemical Technicians Ready Reference Handbook". If you can't find it in the usual places (e.g., Amazon, etc.), check out:
http://www.technologysource.net/chemical/chemtechready.htm

Bromacil is one of our favorite compounds!! If you need analytical methodology, contact me. Sounds like we can get you going on the right track, whatever you are trying to analyze.

Tom,
In your Tues., Aug. 31, answer to Robert about standard concentrations, your message reads:
1 ppt (parts per thousand)...
1 ppm (parts per million)...
1 ppb (parts per million)...
1 ppt (parts per billion)...
Have I missed something here? I hope Robert isn't as confused as I am.

What you need is high school chemistry or any basic science textbook to refresh your memory.

Now that you've all had a good chuckle at my expense, what I need is to quit answering messages after midnight!

Duh!

What I *meant* to say was:

1 ppt (parts per thousand) . . .
1 ppm (parts per million) . . .
1 ppb (parts per billion) . . .
1 ppt (parts per trillion) . . .

and, yes, ppt is ambiguous (hopefully clear from context).

-- Tom (red-in-the-face) Jupille / LC Resources Inc.

The reference of “… refresh memory. “ , was addressed to Robert.

However, Tom, the correct abbreviation for parts per thousand is ppth, at least according to the EPA. This information can be found at, http://www.epa.gov/OCEPAterms/aajq.html

Your student

I stand corrected. (and many thanks for the URL).

-- tom jupille / LC Resources