How does the ASTRA™ software calculate and report the mass of my sample? - WKB319056
ENVIRONMENT
- ASTRA™ software
ANSWER
The ASTRA™ software calculates sample mass using user-defined injection volume and concentration values. It reports both Injected Mass and Calculated Mass for each defined peak. Calculated Mass is derived from the sum of all slice-by-slice data. ASTRA then computes Mass Recovery (%) by comparing Calculated Mass to Injected Mass, and Mass Fraction (%) by comparing a peak’s Calculated Mass to the total Calculated Mass of all peaks. These values are viewable in EASI Graph or Reports and can be manually overridden if needed.
ADDITIONAL INFORMATION
This article summarizes how the ASTRA™ software calculates and reports sample mass values. For related discussions about utilizing the 100% mass recovery assumption to calculate online dn/dc values, see TN4001a. For information about calculating individual mass components of any two-part system, see TN4001a: Protein Conjugate analysis.
ASTRA delineates sample mass based on a variety of different inputs and is easily viewed in tabulated form from EASI Graph or Reports.
The Injected mass is based on the user-defined sample injection volume and concentration values. When viewing your data file, the Injected mass is also displayed in the Peaks Procedure for each defined peak. If desired, these values can be manually overridden.
As illustrated above, ASTRA also reports the total mass that is measured for each defined peak, which is displayed as the Calculated Mass. This is calculated based on the sum of all slice-by-slice data as depicted below.
From this information, ASTRA calculates and reports Mass recovery (%) and Mass fraction (%).
In summary, we can see that when reporting Mass Recovery, ASTRA compares the Calculated Mass for a particular peak relative to the Injected Mass; this differs from how ASTRA computes Mass Fraction. Here ASTRA compares the Calculated Mass for a particular peak to the Total Calculated Mass for all peaks defined in the experiment file.