Chromatography Forum

I'm a newbie so, to those experts... Please be patient...

Trying to develop procedure for HS-GC standardization but have come upon some difficulty with concentration in analysis. It's basically a spiked sample to see if detection is accurate. We currently use a external five level calibration from 0.0100 to 0.5000%. Here's a snap shot of preparation:

Reference Sample 1
5g of Styrene in 100ml Methylene Chloride = 5% Styrene in Sol.

Add 3ul of 5% sol. to 500mg of dry powder in 20ml vial.



Formula used:

5/100 Methylene Chloride x 1ml/1000ul x 1000mg/1g x 3ul = 0.15 mg of Styrene

0.15mg/500 of powder x 10E+6 = 0.0300% of Styrene in powder

GC detected amount = 0.1716% ?

My method of discussing parameters is somewhat different from yours, but they confirm yours.

You make a solution consisting of 5 grams of styrene in 100 mL of DCM, that is 5000mg per 100mL or

50mg per mL styrene in DCM ============ this equals 50 micrograms per microliter

You add 3 microliters of DCM solution to 500 mg of dry sample.

that is, 150 micrograms of styrene in 3 microliters of DCM.

150 micrograms per 500 mg of sample is 150 micrograms per 500,000 micrograms of sample

this equals 300 ppm of styrene added to sample on wt/wt basis.

Now the question before us is: How did you calculate the 0.1716% you say is in the sample?

best wishes,

Rod