Step 1
Molecule & study Choose the analyte and the study it must serve. Everything downstream — ions, column, extraction, risks and the report — is derived from the structure plus these settings.
Analyse molecule → Worked examples Search PubChem Paste SMILES
Amlodipine Lipophilic primary amine, Cl isotope pattern — classic ESI+ / MCX or LLE case Metformin Very polar strong base — elutes in the void on C18; HILIC / WCX case Diclofenac Lipophilic carboxylic acid with two Cl — ESI−, acidic LLE / MAX case Testosterone Neutral steroid — weak ESI, APCI or NH4+ adduct case; endogenous Losartan Tetrazole acid + imidazole; active acid metabolite EXP3174 Ibuprofen Lipophilic acid, poor fragmentation in ESI− (loss of CO2) Midazolam Weak base (imidazole), CYP3A probe; 1′-hydroxy metabolite Clopidogrel Methyl ester prodrug — esterase hydrolysis in blood; low pg/mL levels Omeprazole Acid-labile sulfoxide benzimidazole — keep samples neutral/basic Paracetamol (acetaminophen) Small polar phenol; glucuronide/sulfate in-source risk Morphine Polar ampholyte; M3G/M6G glucuronides fragment to morphine in-source Warfarin Vinylogous acid, racemic — enantioselective assay often required Atorvastatin Hydroxy-acid ⇄ lactone interconversion; ortho/para-OH metabolites Tamoxifen Very lipophilic tertiary amine — carryover and adsorption case
Known values (override estimates)
Leave blank to use structure-based estimates. Literature or measured values always give a better prediction.
logP (neutral form)
pKa values