Hi may I know your GAE is 93 mg and 102 mg or 93 mg/L and 102 mg/L? Since your calibration is in mg/L so I assume it is 93 mg/L and 102 mg/L first.

Sample size used = 1 g

Extraction solvent = 10 ml

Concentration of GAE (mg/g) = (93 mg/L X 0.01 L)/ 1 g

                                                     = 0.93 mg/ g

Doing the same calculation, your GAE concentration in food is 0.93 mg/g and 1.02 mg/g.   

If the concentration is 93 mg and 102 mg as stated,

Concentration of GAE (mg/L) = (93 mg X 1000) / 0.1 mL

                                                     = 930000 mg/L   

Concentration of GAE (mg/g) = (930000 mg/L X 0.01 L)/ 1g

                                                     = 9300 mg/g

If the concentration is 93 mg and 102 mg in 100 uL, calculated concentration (mg/g) are 9300 mg/g and 10200 mg/g.   

Hi Ooi Yan Jie, 

Thanks for your response. Yes my calibration curve is mg/L so the results I mention are expressed as 93 and 102 mg/L. So I will go with the first calculation. Thank you. 

Dear Kim Blaides,

Conversion of mg/L to mg/g

In General

Mg/L= mg/{Lit X Density of solvent(in g//lit)}

=mg/g

regards,

Prem Baboo

https://www.researchgate.net/post/How_to_convert_mg_L_to_mg_kg?_tpcectx=profile_questions

https://www.researchgate.net/post/How_do_I_get_mg_g_concentration_value_from_mg_l_units?_tpcectx=profile_questions

Dear Prem Baboo, 

I believe she want to convert her aliquot concentration of GAE in methanol extract to concentration of GAE in her food sample. Which in this case Ms Kim should multiply the volume of her extraction solvent first, followed by dividing weight of sample taken. 

mg/g = mg/L * [volume (L) / weight (g)]

If her sample was a liquid sample and she's taking her sample by volume measurement, she can later change back the unit from mg/L to mg/g by dividing density of her liquid sample. 

mg/g = mg/L / [density (g/ml) * 1000]  

Please advice if I mentioned something wrong. Thanks. 

Regards

OOI