GC vs. LC: Key Differences, Pros & Which to Choose
GC is gas chromatography: sample vaporized and pushed by an inert gas through a column. LC is liquid chromatography: sample dissolved in liquid and pumped through a packed column. Both separate compounds, but the moving phase is gas for GC and solvent for LC.
Students and analysts mix them up because both end in “-chromatography,” both spit out peak graphs, and sales reps toss around acronyms like candy. Picture a forensic lab tech deciding if a mystery powder needs a helium blast or a solvent bath—the wrong choice wastes a day and a thousand dollars.
Key Differences
GC excels at small, volatile molecules (think pesticides in tap water). LC handles larger, heat-sensitive ones (think insulin purity). GC runs 150–300 °C; LC stays room-temperature. GC columns last longer but hate water; LC columns tolerate salts and gradients.
Which One Should You Choose?
If your sample can boil without decomposing, GC is cheaper and faster. If it’s thermally fragile or water-loving, pick LC. Budget labs often start with GC; biopharma and food-safety labs rarely skip LC.
Can GC analyze proteins?
No—proteins decompose at the high temperatures required for GC.
Is LC more expensive to maintain?
Generally yes; solvents, pumps, and columns add recurring costs.
Can one lab own both?
Absolutely; many pharma labs run GC for residual solvents and LC for active ingredients.