Pharma · ICH Q3C / Q3D
ICH Q3C / Q3D impurity limit calculator
Turn ICH permitted-daily-exposure (PDE) values into concrete ppm acceptance limits — for residual solvents (Q3C) and elemental impurities (Q3D) — by daily dose and route, and check a measured result pass or fail. Free, cited, runs in your browser.
Compiled by Hemant RawatLast reviewed July 2026How we verify
Residual solvent
ICH Option 1 assumes 10 g/day; enter your actual dose for Option 2.
Elemental impurity
Acceptance limit
⚠ Reference/education only — not for regulatory submission without independent verification against the current ICH guideline and your own analysis. See how we verify.
The two calculations
Q3C residual solvents. The Option 1 concentration limit is ppm = 1000 × PDE (mg/day) ÷ dose (g/day). Option 1 assumes a 10 g/day daily dose (that's how the published limits are derived); Option 2 uses your actual dose, so a smaller dose allows a higher ppm. Class 1 solvents (benzene, carbon tetrachloride…) should be avoided; Class 2 are PDE-limited; Class 3 default to 5000 ppm.
Q3D elemental impurities. The limit is simply ppm = PDE (µg/day) ÷ dose (g/day), using the PDE for your route of administration — oral, parenteral, or inhalation (parenteral and inhalation limits are usually much lower than oral).
Same audience as the solvent tools
This is part of the lab hub: if you're selecting or evaluating solvents, see the solvent miscibility chart and per-solvent UV cutoff / polarity references.
Q3C residual-solvent reference
Class 1 (avoid) and Class 2 (PDE-limited) concentration limits. Class 3 default to 5000 ppm.
| Solvent | Class | PDE (mg/day) | Limit (ppm) |
|---|---|---|---|
| 1,1-Dichloroethene | 1 | — | 8 |
| 1,1,1-Trichloroethane | 1 | — | 1500 |
| 1,2-Dichloroethane | 1 | — | 5 |
| Benzene | 1 | — | 2 |
| Carbon tetrachloride | 1 | — | 4 |
| 1,1,2-Trichloroethene | 2 | 0.8 | 80 |
| 1,2-Dichloroethene | 2 | 18.7 | 1870 |
| 1,2-Dimethoxyethane | 2 | 1 | 100 |
| 1,4-Dioxane | 2 | 3.8 | 380 |
| 2-Ethoxyethanol | 2 | 1.6 | 160 |
| 2-Methoxyethanol | 2 | 0.5 | 50 |
| Acetonitrile | 2 | 4.1 | 410 |
| Chlorobenzene | 2 | 3.6 | 360 |
| Chloroform | 2 | 0.6 | 60 |
| Cumene | 2 | 0.7 | 70 |
| Cyclohexane | 2 | 38.8 | 3880 |
| Cyclopentyl methyl ether | 2 | 15 | 1500 |
| Dichloromethane | 2 | 6 | 600 |
| Ethyleneglycol | 2 | 6.2 | 620 |
| Formamide | 2 | 2.2 | 220 |
| Hexane | 2 | 2.9 | 290 |
| Methanol | 2 | 30 | 3000 |
| Methylbutylketone | 2 | 0.5 | 50 |
| Methylcyclohexane | 2 | 11.8 | 1180 |
| Methylisobutylketone | 2 | 45 | 4500 |
| N-Methylpyrrolidone | 2 | 5.3 | 530 |
| N,N-Dimethylacetamide | 2 | 10.9 | 1090 |
| N,N-Dimethylformamide | 2 | 8.8 | 880 |
| Nitromethane | 2 | 0.5 | 50 |
| Pyridine | 2 | 2 | 200 |
| Sulfolane | 2 | 1.6 | 160 |
| Tetrahydrofuran | 2 | 7.2 | 720 |
| Tetralin | 2 | 1 | 100 |
| Toluene | 2 | 8.9 | 890 |
| Xylene | 2 | 21.7 | 2170 |
Full Class 2 & Class 3 lists load in the calculator. Values cited to ICH Q3C(R9) / USP <467>. Download CSV.
Q3D elemental-impurity PDEs (µg/day)
| Element | Class | Oral | Parenteral | Inhalation |
|---|---|---|---|---|
| Arsenic (As) | 1 | 15 | 15 | 2 |
| Cadmium (Cd) | 1 | 5 | 2 | 3 |
| Lead (Pb) | 1 | 5 | 5 | 5 |
| Mercury (Hg) | 1 | 30 | 3 | 1 |
| Cobalt (Co) | 2A | 50 | 5 | 3 |
| Nickel (Ni) | 2A | 200 | 20 | 6 |
| Vanadium (V) | 2A | 100 | 10 | 1 |
| Gold (Au) | 2B | 300 | 300 | 3 |
| Iridium (Ir) | 2B | 100 | 10 | 1 |
| Osmium (Os) | 2B | 100 | 10 | 1 |
| Palladium (Pd) | 2B | 100 | 10 | 1 |
| Platinum (Pt) | 2B | 100 | 10 | 1 |
| Rhodium (Rh) | 2B | 100 | 10 | 1 |
| Ruthenium (Ru) | 2B | 100 | 10 | 1 |
| Selenium (Se) | 2B | 150 | 80 | 130 |
| Silver (Ag) | 2B | 150 | 15 | 7 |
| Thallium (Tl) | 2B | 8 | 8 | 8 |
| Antimony (Sb) | 3 | 1200 | 90 | 20 |
| Barium (Ba) | 3 | 1400 | 700 | 300 |
| Chromium (Cr) | 3 | 11000 | 1100 | 3 |
| Copper (Cu) | 3 | 3000 | 300 | 30 |
| Lithium (Li) | 3 | 550 | 250 | 25 |
| Molybdenum (Mo) | 3 | 3000 | 1500 | 10 |
| Tin (Sn) | 3 | 6000 | 600 | 60 |
Cited to ICH Q3D(R2) / USP <232>. Download CSV.