How to Read a Trace Analysis Data Packet

Trace analysis data packets, which are part of our expanded data packs for Restek’s single and multicomponent PFAS reference standards, include detailed information to help you understand the composition of your standards. This article explains how to read your packet, using our br-PFHxS standard (cat.# 30803) as an example.

Restek’s trace analysis data packets include data from two methods, each for a different purpose. The first section of the data pack uses LC-MS/MS for trace analysis of samples. The second section, which is explained later in this article, uses NMR to identify individual isomers.

LC-MS/MS Trace Analysis of Samples

Analytical Method Summary Table

The first table (figure 1) within the trace analysis data packet includes a summary of the analytical method used for trace analysis of samples.

Figure 1: LC MS/MS Data

Method detection limit (MDL) is determined in each analytical batch to ensure there is no background contamination within the instrument. This is used to determine the final LOQ.

The Summary of Results for each analyte is measured >LOQ in % wt.

MRM Transitions Table

The second table (figure 2) contains an analyte list and transitions measured by the trace analysis.

Figure 2: MRM Transitions

Quantification is based on response from transition corresponding to Parent 1 > Daughter 1. Secondary transition is used for qualitative identification.

Trace Analysis Summary

The third table (figure 3) is summary of the trace analysis. We have color coded the columns to help explain the table. The columns will be uncolored in your data packet.

Figure 3: Trace Analysis Summary

Reporting Limit (red column): Typically, 0.05% for sulfonates, 0.10% carboxylic acids, and 0.125% for sulfonamides.

LOQ (blue column): Limit of Quantitation (LOQ) of the instrument. Value is equal to the lowest calibrator or the batch specific MDL, whichever is greater.

Measured Conc (green column): Measured concentration on instrument. <LOQ means the peak was detected but below the analyte’s LOQ. Not Detected (N.D.) analyte was below the detection limit of the instrument.

Dilution factor (orange column): The dilution factor each analyte was quantified from. Target analyte typically had to be diluted to ensure the measured concentration was within the linear range of the analyte.

% Composition (purple column): Results in % wt for each target analyte. Values are calculated from Measured Concentration * Dilution Factor. Final values are normalized to 100%. Reporting limits are applied after normalization.

Overlay MRM Chromatogram

The next data (figure 4) is an overlay MRM chromatogram of the trace analysis. The full scan data can be found in the CofA. The data is typically from the most concentrated value measured.

Figure 4: Overlay MRM Chromatogram

NMR Analysis to Identify Individual Isomers

NMR Table

Figure 5: NMR Table

The fourth table (figure 5) includes NMR data, which lists sample preparation information and summary of results.

In the Summary of Results, the number denotes distance from end-functional group. m stands for “methyl” and dm for “dimethyl,” indicating the isomer contains either a single-branching CF3 group or two CF3 groups respectively.

Figure 6: Example Numbering Convention for PFAS Isomers

Figure 7: Example Isomer Naming Convention

NMR Data

The final data (figure 8) included in the trace analysis data packet is additional NMR data.

Figure 8: NMR Data-Annotated

Figure annotations:

1. Acquisition parameters for NMR data.
2. Hexafluorobenzene (HFB) added as an internal standard to determine relative chemical shifts.

Full Support for Your Restek PFAS Standards

For more information about our expanded data packs and PFAS reference standards, review our full reference standard FAQ. Additionally, if you have questions about your specific standard, contact our Technical Service team.