VOCs — Analytical quick reference screening · speciation · compliance
| Technique | Best for | Typical range | Notes |
|---|---|---|---|
| PID (photo-ionization detector) | Fast TVOC screening, leak checks | ppb–ppm | Non-specific; response factor per compound; humidity effects. |
| FID (flame ionization) | Total hydrocarbons / TVOC | ppb–% | Excellent sensitivity; not species-specific; needs fuel/air and flame safety. |
| FTIR | Multi-component, real-time speciation | ppm → low ppb (path-length dependent) | Simultaneous gases; needs library and matrix compensation (H₂O/CO₂). |
| NDIR | Target single species (high ppm) | 10s ppm → % | Robust; limited to species with strong IR bands and minimal overlap. |
| GC-FID | Routine speciation / compliance | ppb–ppm | Good quantitation; needs sampling (canister, Sorbent TD) and cycle time. |
| GC-MS | Definitive identification (unknowns) | sub-ppb–ppm | Highest specificity; longer analysis time; lab/online possible. |
| PTR-MS | Real-time mass-selective VOCs | ppt–ppb | Very fast; soft ionization; isobaric overlaps require care. |
| Sulfur-specific (SCD/FPD) | Reduced S-VOCs (DMS, mercaptans) | ppt–ppm | High selectivity for S; ideal for odorants and refinery gases. |
| Dust/PM + TD-GC | Condensable VOC aerosols | ng–µg on filter | Collect on filter → thermal desorb and analyze; capture semi-volatiles. |
*Choose method(s) by target compounds, expected range, time resolution, and matrix (humidity/CO₂/other gases).