GC-FID System (Headspace) — Standard Operating Procedure

1. Pre-Operation

• [ ] Verify gas supplies: H₂, air, He
• [ ] Check column connected and conditioned
• [ ] Verify FID ignition
• [ ] Run system suitability check

2. Sample Preparation

1. Weigh 50 – 100 mg peptide into headspace vial
2. Add 1 mL DMSO or water (matrix-matched)
3. Seal vial with crimp cap
4. Place in headspace autosampler

3. Method

Parameter	Setting
Incubation	80 °C, 30 min
Transfer Line	100 °C
Injection	1 mL, split 10:1
GC Program	40 °C (5 min) → 10 °C/min → 200 °C (5 min)

4. Data Processing

1. Identify peaks by retention time vs standards
2. Quantify using external calibration curve
3. Report results in ppm
4. Compare to ICH Q3C limits