Blank Spike
A laboratory control sample free of the target analytes or interference, is fortified with a known concentration of all or selected target analytes. The blank spike is processed through the entire analytical method including any extraction, digestion or any other preparation procedure. Results are expressed as a percentage recovery.
Frequency and Purpose
Optional control measure. Ideally 1 per batch run
Monitors analyte recovery and potential loss during the preparation procedures (extraction efficiency). It also serves to validate the calibration of the instrumentation technique.
Application and Regulatory Criteria
Used for most analytical parameters.
Acceptable recovery ranges:
| EC, Salinity | 90% - 110% water; 80% - 120% soil |
| Metals and Inorganics | 80% - 120%; HWS B 70% - 130% |
| FOC, Methyl Mercury | 70% - 130% (all matrices) |
| VOCs, THMs, BTEX except gases and ketones | 60% - 130% (water and soil) |
| PHCs | 60% - 140% (water and soil) |
| CPs, PFOS, PAHs, PCBs, Volatile Gases & Ketones | 50% - 140% (water and soil) 30% - 130% for difficult compounds |
| Dioxins & Furans | 70% - 140% (water and soil) |
| 1,4-Dioxane | 70% - 130% waters; 60% - 140% soils |
Recommended Actions
Bureau Veritas Laboratories recommends using the acceptable recovery ranges listed above (adopted from CCME Analytical protocols). Re-extract/re-analyse all associated samples, if possible. If not, report the data flagged for all failing analytes, Re-analysis is performed if the laboratory control sample (LCS) in a single analyte test or >10% of the analytes in a multi-element scan are outside the control limits by >10% absolute.