Data_Analysis

Data Analysis — GCsolution

This page covers what happens after the GC run completes: opening your chromatogram, understanding the data window, adjusting peak integration, and how peak identification works. For calibration curve review, see Calibration_Review. For applying a different method to old data, see Data_Reprocessing.

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Accessing the Postrun Application

To review a chromatogram after acquisition, you must use the GC Postrun Analysis application, which is dedicated to offline data processing and reporting.

How to open it:

• Click the GC Postrun icon on the GCsolution Launcher, OR
• Click the GC Postrun Analysis icon on the software’s [Operation] tab

📋 From manual

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Opening and Reviewing a Chromatogram

Loading Your Data

Several ways to open a completed run in the Data Analysis window:

Method	Steps
From Data Explorer	Double-click the data file (.gcd) in the [VERIFY: Data Explorer] pane, or drag and drop it into the Data Analysis window
From the menu	Select [Window] → [Show Window] → [Data Analysis]
From Real Time Analysis	Select Browse Last Data (Line #) from the [Data Analysis] menu — automatically opens Postrun and loads the most recent data file

📋 From manual

The Data Analysis Window

Once a file is loaded, the window displays three primary views:

[VERIFY: Chromatogram] View — visually displays the chromatogram and sample information. Shows two graphs: the upper graph is the full original chromatogram (entire run), and the lower graph is the expanded chromatogram (magnified section). X-axis = time (minutes), Y-axis = intensity (voltage).

[VERIFY: Table] View — provides the calculated data from your run:

• [Peak Table] tab: lists each detected peak with Peak Number, Retention Time, Area, and Height
• [Compound], [Group], and [Calibration Curve] tabs for quantitative results

[VERIFY: Method] View — located in the lower right, displays the data processing parameters used. Includes tabs for Integration, Quantitative, Compound, Group, and Performance parameters.

📋 From manual

Zooming and Navigation

Drag your mouse over a specific section of the full chromatogram (upper graph) to zoom the expanded chromatogram (lower graph) to that region.

📋 From manual

Saving

Once satisfied with your review and any modifications: File → Save Data File.

📋 From manual

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Peak Integration

How It Works

GCsolution detects and integrates peaks using three core mechanisms:

• Peak Detection: the software uses the Slope of the chromatogram (tangent angle) to detect when a peak starts and ends
• Width filtering: the Width parameter ensures only valid peaks are detected by comparing them to the expected half-height width, allowing the software to ignore high-frequency noise
• Baseline and unresolved peaks: if peaks overlap, the Drift parameter calculates the baseline. Depending on peak shapes and valley depth, the software resolves overlaps either by dropping a vertical line to the baseline or by processing one as a “tailing” or “leading” peak

📋 From manual

Adjusting Integration Parameters

If the default parameters do not properly integrate your peaks:

1. Open your data file in the Data Analysis window
2. In the [VERIFY: Method] view (bottom right), click the [Edit] button to enter Edit Mode
3. Click the Integration tab
4. Modify parameters as needed (see table below)
5. Click the [View] button to exit Edit Mode — the software automatically re-analyzes and updates the chromatogram and peak table

Parameter	What It Controls	How to Set It
Width	Half-height width of narrowest peak of interest (seconds). Peaks narrower than half this value are ignored.	Measure from your chromatogram
Slope	Detection sensitivity (µV/min). Lower = more sensitive to broader peaks.	Use the Slope Test button to auto-measure baseline noise and suggest a value
Drift	Baseline evaluation. 0 = automatic baseline. A specific value forces a baseline slope (useful for temperature-programmed runs with significant drift).	Set to 0 initially, adjust if baseline is problematic
Min. Area/Height	Threshold (counts). Any peak smaller than this is excluded from detection and quantification.	Set based on your noise level

📋 From manual

Manually Adding or Removing Peaks

For fixing specific peaks without changing overall method parameters. These manual changes are saved as a time program in the data file without permanently altering your core method file.

1. Click the [Manual Peak Integration] icon on the Assistant Bar to display the manual integration toolbar

To add a peak:

1. Click the Insert Peak button (or Insert Peak (Auto Correct))
2. Click once on the chromatogram at the desired peak start point
3. Click again at the desired end point

To remove a peak:

1. Click the Reject Peak button
2. Click directly on the apex of the peak to delete

To remove multiple peaks at once:

1. Click the Reject Peaks button
2. Click to specify the starting time of the section
3. Click again to specify the ending time

Dedicated buttons like Reject TL.Peak are also available for removing tailing or leading peaks specifically.

📋 From manual

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Peak Identification

How It Works

GCsolution identifies peaks by matching their measured retention time to a standard retention time defined for each compound in the method’s Compound Table. Because retention times can fluctuate slightly between runs, the software uses a time allowance (“window”) around each expected retention time.

📋 From manual

Time Allowance Methods

Method	How It Works	Best For
Window	Time allowance is a percentage (%) of the retention time, applied uniformly to all peaks. Window grows wider for later-eluting peaks. Formula: (Standard RT × Window%) / 100 + 0.02 min	Isothermal GC analyses
Band	Time allowance is a fixed time value (minutes) set individually for each peak	Temperature-programmed GC analyses

📋 From manual

Identification Method

The software can anchor these windows using two logic paths:

Absolute Rt — searches for the peak strictly based on the absolute time in the Compound Table and the defined Window/Band.

Relative Rt — first identifies a reliable “Reference” peak using the absolute method, then dynamically shifts all other search windows based on how much the reference peak shifted. Compensates for retention time drift.

📋 From manual

When Multiple Peaks Fall in One Window (Peak Select)

Setting	Behavior
Closest Peak	Selects the peak with retention time nearest to the standard RT
Largest Peak	Selects the peak with the largest area or height. (Internal Standards and Reference peaks always default to this, regardless of setting.)
All Peaks	Identifies all peaks within the window as that compound; concentrations are summed

📋 From manual

Overlapping Windows

When two compounds have retention times close enough that their windows overlap:

• Window method: peak is assigned to the compound with the closest standard retention time
• Band method: peak is assigned to the compound with the lowest ID number in the Compound Table

📋 From manual

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See Also

• Single_Run_Analysis — Running a sample
• Batch_Processing — Running automated sequences
• Calibration_Review — Evaluating calibration curves and requantifying
• Reporting — Generating and printing reports
• Data_Reprocessing — Applying a new method to old data
• Method_Development — Setting up method parameters before acquisition