- Course Introduction
- 01: Evidence & DNA
- 02: Forensic Biology
- 03: DNA Extraction & Quantitation
- 04: DNA Amplification
- 05: Amplified DNA Product Separation
- 06: STR Data Analysis & Interpretation
- Data Troubleshooting
- Data Interpretation & Allele Calls
President's DNA Initiative
-
Advancing Justice Through DNA Technology
-
Advancing Justice Through DNA Technology
DNA Analyst Training
Spikes
Home > STR Data Analysis & Interpretation > Data Troubleshooting > Spurious Peaks > Spikes
Spikes are narrow peaks usually attributed to fluctuation in voltage or the presence of minute air bubbles in the capillary. Spikes can also be caused by crystals in the polymer and/or fluorescent material in the polymer or formamide. Spikes, unlike other artifacts, are generally seen in the same position in all colors. However, it is possible to detect spikes in a single color.
Analysts should view both the raw and analyzed data for each sample. The raw data produces a non-filtered view of the sample run, while analyzed data can obscure detection of a spike. Frequently, spikes are more readily detected in raw data versus analyzed data. The analyzed data provides an exact data point and base pair size for each peak. Spikes that are not obscured in the analyzed data can be assigned an exact data point for each color displayed.
The occurrence of spikes can be minimized by following the instrument manufacturer’s procedures for reagent and sample handling. If spikes persist, analysts may need to contact the manufacturer. Frequent electronic spiking can occur due to poorly functioning instruments.
