In order to make report interpretation easier Chemex will adopt protocols for 'flagging' of data values of significant interest. It will help to ensure that any sample concentrations reported are viewed in the context of other variables within the analytical process. All flagging used will be defined in an adjacent section of the report. Flagging may conform to established conventions adopted by USEPA or other agencies.

Typical reported values that may be subject to flagging include the following:

- Sample concentrations less than the MDL
- Analytes also found in method blanks
- Sample concentrations less than those in method blank
- Concentration outside instrument calibration range
- QC parameters outside target performance limits
- QC values that should be cross-checked against limits quoted elsewhere in the report.

For example, the following standard qualifier flags may appear alongside VOCs/ SVOCs data in Chemex corporate and first class reports:

U: Compound analysed for but not detected above instrument detection limit.
B: The compound was also detected in the blank.
E: Compound exceeds instrument calibration range.
J: Indicates an estimated concentration.
N: Presumptive evidence of a compound
D: Diluted sample

In Metals data corporate and first class reports, U indicates that the element was not detected at a concentration greater than the scaled method detection limit.

Any applied qualifier flags are always explained on the 'SAMPLE DATA AND BLANK DATA' section covering page of the corporate and first class report.