Hello there, I am working on investigation of pharmaceuticals and other micro-pollutants in urban water by using HPLC-DAD with SPE sample preparation >>>>the problem is its very low limit of detection and I'm not sure my detector could achieve that , another problem is that my SPE technology couldn't accept more than 30 or 100 ml of sample and this quiet small regarding to environmental samples (1 liter to reach appreciable concentration) could some expert help
note:* L-L solvent extraction is not applicable as most of the drugs are water soluble
* evaporation of aqueous sample will affect the drugs stability
WWhen you need low LOD/LOQ do not use SPE. Go to direct detection. Try HPLC-CAD and you wil be able to handdle la wide range of organic/aqueous mixtures.The detectors evolved a lot, they are at the third generation of CAD detectors.
actually this diode array detector is all what I have, and I have already tried with standard solutions but still the detection limits far, that why I'm asking about SPE
The LOQ/LOD depends on the chemical structure of analytes that You want to assay. Assay of substances in waste water is mostly done by LC-MS because it has the sensitivity and by doing MRM conformation with 99% that is Your compounds.
The question is why Your SPE method couldn't accept more than 30 or 100 ml of sample. Did you spike a 1l of wastewater with Your compounds and the recovery was low? Or did you SPE cartridge after 100 ml of wastewater was clogged? If clogged that water needs to be first filtered, may be removed from any proteins?
You can alwasy buy a cartigde with more of the sorbent mass in order to increase capacity
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