Chromatography Theory Chapter 4, Part 2 – Integration Timed Events

Chromatography Theory - Timed events in Chromperfect chromatography software

This chapter (Part 2 of 3) explains how chromatography timed events or integration timed events in Chromperfect (demo shown in Version 8) can improve peak detection and baseline placement in difficult chromatograms. Timed events live in the method file, so they can be reused across runs—unlike manual baseline edits.

When to use timed eventsUse them for noisy baselines, baseline upsets, big peak-width changes, negative peaks, or poor resolution. Keep them minimal; overuse creates instability across runs. Exact placement matters—especially for events that depend on whether they occur inside a peak.

Event classes (what they affect and why they matter)

1. Class 1 — Chromatogram trace• R1C/R1O … R8C/R8O: Close/open Tigre relays (acquisition only).• CLAMP+/-: “Clamp” the trace to prevent negative excursions from pulling baselines down.• FLIP+/-: Reflect negative peaks to positive for integration when they sit next to positive peaks.Notes: CLAMP/FLIP modify the trace used by integration; placement sets the reference level. FLIP dominates over CLAMP if regions overlap.

   
   

2. Class 2 — Peak detection parameters• PW+/-: Double/halve Peak Width to track broader or narrower later-eluting peaks.• TH+/-: Step threshold up/down to match changing noise.• MUT: Measure noise for one peak-width and auto-set threshold.Notes: Use PW when width changes by ~2×; TH when noise changes are predictable; MUT when they’re not (but keep MUT on real baseline).

   
   

3. Class 3 — Modify peak detection• INT+/-: Turn integration on/off (skip solvent or junk regions).• SBN: “Set Baseline Now” to end current peak/cluster immediately.• HORZ+/-: Force horizontal baselines at a sampled level (stabilizes baselines on low drift).• NEG+/-: Detect negative peaks using a horizontal reference, without flipping the trace.• SPLIT: Divide a shoulder into separate peaks (placement is critical; use sparingly).• SUM+/-: Treat multiple unresolved peaks as one (generally avoid—prefer multi-peak windows/reporting).

   
   

4. Class 4 — Clusters & baselines• SBNV: “Set Baseline at Next Valley” to break clusters cleanly (placement less critical than SBN).• SBAV+/-: Disable/enable clustering → valley-to-valley baselines in region (each peak its own cluster).• COM+/-: Force common baselines to include complex, unresolved groups (fills “no man’s land” under the trace).

   
   

5. Class 5 — Peak skimming• SKIMA+/-: Enable/disable automatic tangent skimming (parent/rider behavior).• SKIM: Force skimming in the current/next cluster (choose parent by placement).Notes: Works only on multi-peak clusters; negative-peak skimming is unsupported.

   
   

6. Class 6 — Amount calculations• ARJ+/-: Double/halve Area Reject Threshold during the run to exclude tiny junk peaks from totals.

   
   

7. Class 7 — Plots & reports• RET+/-: Show/hide retention-time labels on plots.• SEL= / SEL1…SEL9: Control automatic peak selection index for reporting/formatting.

   
   

Best-practice checklist

• Start with correct Peak Width and Threshold; add as few events as needed.

• Place MUT/HORZ/NEG on true baseline (not inside peaks).

• Prefer SBNV over SBN to break clusters (less placement-sensitive).

• Avoid overlapping HORZ+ and NEG+ unless co-extensive.

• Avoid SUM+; use calibration multi-peak/nested windows or formatted reports instead.

• If negative peaks lie near positives, try FLIP+ (trace inversion) or NEG+ (algorithmic) depending on context.