Sample Preparation for GC Analysis
Proper sample preparation is essential for reliable results on the Shimadzu GC-2025 or any GC system. The goal is to produce a clean, appropriately concentrated solution suitable for injection.
Common Techniques
| Method | Purpose | Notes |
|---|---|---|
| Dissolution | Dissolve sample in appropriate solvent | Solvent must be GC-compatible and volatile |
| Distillation | Separate compounds by boiling point | Pre-concentration of volatile fractions |
| Liquid-Liquid Extraction | Isolate target compounds between immiscible solvents | Choose solvent polarity to match analyte |
| SPE (Solid Phase Extraction) | Selective extraction and cleanup | ⚠️ Never let cartridge dry after conditioning |
| QuEChERS | Quick extraction for complex matrices | Common for drugs, pesticides in food/biological samples |
📋 From course materials
Injection Mode Considerations
Your sample concentration determines which injection mode to use on the GC — see Split_vs_Splitless_Injection for detailed guidance:
| Concentration | Mode | Typical Volume |
|---|---|---|
| High (> 0.1%) | Split | 0.1–1 µL |
| Trace (< 0.01%) | Splitless | Up to ~3 µL |
📋 From course materials
Manual Injection Technique
When using a manual syringe (no auto-sampler):
- Use a 10 µL syringe
- Wash 3–5× with solvent, then 3–5× with sample solution
- Aspirate the required volume; pump to remove air bubbles
- Wipe the needle clean
- Pull plunger slightly to create an air gap (prevents dripping)
- Insert syringe into injection port until touching the guide
- Push plunger and press START simultaneously
- Remove syringe promptly
⚠️ Safety: Wear goggles. Never touch the hot injection port.
📋 From course materials
See Also
- Split_vs_Splitless_Injection — Choosing injection mode based on concentration
- Run One Sample — Running the prepared sample
- Quantification_Methods — Preparing standards for calibration
- Method_Development — Setting injection parameters in GCsolution