Short Answer: Yes, the volume of liquid you filter can significantly impact the accuracy and reliability of your ATP testing results.
Why Does Filtered Volume Matter?
1. Small Volumes May Reduce Sensitivity
Filtering insufficient volumes (under-filtering) can fail to capture a representative microbial load, especially in samples with low microbial concentrations. Biocide-treated fluids may have exceptionally low microbial loads. A smaller sample size reduces assay sensitivity, potentially leading to misleading results. If 5mL clogs the filter, use the Viscous Fluids procedure.
2. Excessive Volumes Can Skew Results
Water from environmental sources (ponds, rivers, dugouts, etc.) typically contain higher microbial loads than treated fluids (municipal water, biocide-treated fluids). While filtering larger volumes can improve the accuracy of microbial load averages, excessive volumes may dilute ATP concentrations or overwhelm the filter. This can result in ATP loss and interfere with light output measurements during testing.
3. Consistency Is Key
The most important factor in filtering is consistency. To ensure reliable and comparable results across tests, maintain a standard filtered volume for all samples. For liquid samples, the recommended range is 10–60 mL. This volume strikes a balance between capturing an accurate microbial load and maintaining assay sensitivity.
Best Practices for Accurate Filtering
- Follow Recommended Volumes: Filter 10–60 mL for liquid samples to achieve reliable results.
- Be Consistent: Use the same filtered volume across comparable samples to minimize variability and ensure data integrity.
- Monitor Low Microbial Load Samples: For samples with low microbial activity, ensure you maximize the volume filtered to improve sensitivity and detection accuracy.
Why Is Accurate Filtering Important in ATP Testing?
ATP testing measures the living microbial content in your sample by detecting ATP, a molecule found in all active cells, including bacteria, fungi, and other microbes. By filtering a representative volume, you ensure that ATP results reflect the true microbial load, enabling:
- Baseline Establishment: Accurate measurement of ATP allows you to establish reliable treatment baselines.
- Treatment Validation: Drops in ATP concentrations can confirm the effectiveness of biocide treatments and microbial control programs.
- Routine Monitoring: Consistent filtering practices support reliable, long-term microbial management.
LuminUltra®’s LifeCheckTM ATP test kits combine speed, versatility, and accuracy, making ATP monitoring an essential tool for microbial enumeration and control strategies.
Need Help or Want to Learn More?
Our team of experts is here to assist you with your microbiological monitoring needs. Whether you have questions, need technical support, or want to learn more about LifeCheckTM ATP testing, contact LuminUltra® Support to get started.