By Yazeed on Sunday, July 4, 1999 - 02:35 am:
Hi, I'm looking for methods to quantify active ingrediants in Oilfield chemicals (Water and hydrocarbon based corrosion inhibitors, Demulsifiers, Scale inhibitors and biocides). HPLC, FTIR, GC/MS and GC/NPD are available for use.
By Anonymous on Tuesday, July 6, 1999 - 01:25 pm:
For water, run a Karl Fischer titration. For hydrocarbon based corrosion inhibitors and biocides use gradient HPLC. You will need to run gradient since the additives will most likely vary considerably in hydrophobicity. I would start with an end capped C-18 4.6 mm x 25 cm, 1 mL/min. 10 % to 100 % ACN 0.01% phosphoric acid over 30 min.. UV detection will detect many additives and biocides. For additives that are not UV active, you may want to consider evaporative light scattering detection. Also, many corrosion inhibitors, demulsifiers, etc. are crude mixtures and not well defined single compounds. A number of corrosion inhibitors are metal salts, so you will want to take this into consideration.
FTIR would of little use to quantify additives at low weight percent levels. CG may show some, but not all additives. You may be quite limited here. GC would be very useful in looking at the base oil. i.e., composition.
In any case, you will need authentic reference standards to compare to.