Saving Chromatography Data – RAW vs. Bound Files
- Chromperfect
- Sep 24
- 2 min read
When working with chromatography data in Chromperfect, new users often wonder why their changes don’t appear to be saved when they reopen a chromatogram. The answer lies in the difference between RAW files and BND (bound) files. Understanding this distinction is critical for ensuring the integrity and reproducibility of your chromatography results.
Why Are My Changes Not Being Saved?
When you edit a chromatogram and save it, you might be surprised to find that your changes are not visible when reopening the same file. This happens because RAW files store only the original detector data points and rely on separate external files (method and calibration) for processing instructions. If those external files have changed, the chromatogram may look different when reprocessed later.
RAW vs. Bound Files
RAW Files (.raw)Contain only the collected detector response data and reference external method and calibration files.Advantages: preserve original untouched data.Disadvantages: results may change if external method/calibration files are updated.
Bound Files (.bnd)Contain the chromatogram data plus the exact method, calibration, integration, and reporting instructions used at the time of analysis.Advantages: complete archive of the processed run, independent of external file changes.Disadvantages: cannot be edited directly (a new bound file must be created for modifications).
Why We Recommend Using Bound Files
Chromperfect pioneered the concept of bound files to provide a reliable archive of chromatography data.
Bound files ensure that results remain consistent over time, even if methods or calibrations are updated.
Regulatory audits require original data integrity, and the separation of RAW vs. BND files ensures compliance.
For everyday work, Chromperfect strongly recommends using bound files for analysis, reporting, and archiving.
When Should You Still Use RAW Files?
There are some advanced scenarios where working directly with RAW files is necessary, such as:
Reprocessing with new calibration data.
Extracting methods or parameters for advanced workflows.
However, these cases are exceptions. For routine use, bound files should always be your default.
Final Comments on Bound Files
Bound files cannot be edited directly. Instead, you can:
Generate a new bound file when making changes.
Save bound files under different names if multiple versions are needed.
Use batch processing to update and regenerate bound files.
This ensures a consistent, traceable history of your chromatography data. RAW vs. Bound Files
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