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Célia Martinez

A new generation of ATP tests is out!

ATP test - drinking water

ATP-metry

The 4th generation of ATP tests is now available!

 

ATP testing is a very easy-to-use field method, used since the 80s. It gives an estimation of the water microbiological quality. ATPmetry measures the total flora contained in a water sample in less than 2 minutes. First qualitative, then quantitative, this technique never stopped evolving to become one of the most reliable, reproducible and relevant tests for monitoring of water circuits.

1st generation

1st generation ATP test, or qualitative ATP test, exists since the 80s. Very easy-to-use, this method generally uses a pen-sized sample collection device composed of a swab or comb for sampling, and reagents in the upper part. The bioluminescence measurement only takes a few seconds using a luminometer. The result is given in RLU (Relative Light Unit).

2nd generation

2nd generation ATP test includes the measurement calibration using an external standard. The result is then quantitative, in picogram of ATP. A filtration step is often added to concentrate the sample. Consequently, the sensitivity is increased, the sampling is more representative while free ATP is eliminated. However, these 2nd generation ATP kits generally require a dilution step which significantly decrease the sensitivity.

3rd generation
Kit test ATP pour eau potable - ATPmétrie GL Biocontrol

3rd generation ATP test uses an internal standard. In this way, all the environmental constraints acting on the enzyme are taken into account for each sample (temperature, pH, salt concentration, inhibitors…). This evolution makes quantitative ATPmetry more reliable and sensitive. Indeed, the dilution step is suppressed. Furthermore, the use dropper bottles makes these kits more user friendly.

4th generation

The main remaining default of ATP test was the storage of reagents at 4°C. This 4th generation of ATP test involves freeze-dried reagents. Now, the kit can be stored at room temperature and stay stable for months. All of this preserving the qualities of the 3rd generation of ATP test!

GL Biocontrol offers two ATP test kits of the latest generation for water analysis.
Choose your own application!

How to reduce non-quality costs in the electroplating industry?

HOW TO REDUCE NON-QUALITY COSTS IN THE ELECTROPLATING INDUSTRY?

Microorganism development in rinsing baths in the electroplating industry can cause visual defects on the treated items. This kind of contamination can lead to substantial non-quality costs and production shutdowns.

To this day, few water system operators implemented monitoring procedures of the microbial development. Preventive measures are done “blind” at a frequency arbitrarily defined and without concrete follow-up. To address this contamination issue, GL BIOCONTROL developed a three-step systematic approach. It has been tested in several watchmaking factories, and companies specialized in surface treatments. Feedback on an innovative process.

Microbial contamination remains poorly known by operators

When a new production unit is installed, the water system is generally properly thought: the water pipes are new and clean with smooth surfaces, and maintenance procedures are well defined. All the ingredients required to ensure a high-quality production.

However, over time, we often observe drifts in the system. Several problems can appear:

  • Modifications of the water system leading to dead legs.
  • Selection of a few bacteria due to repeated treatment. Indeed, common prevention mainly relies on biocides such as isothiazolone, only biocide compatible with the surface treatment processes. Over time, this treatment can lead to the selection of a resistant flora.
  • A cleaning and disinfection strategy not adapted to the water system. A too short contact time and/or a weak biocide concentration lead to ineffective biocide treatments.
  • Appearance of corroded spots or scaled areas in the pipes and baths. This induces microorganism adhesion and biofilm formation.
  • A high turbidity, often due to a closed loop water recycling system, that limits UV efficiency.

All these parameters lead to microbiological development in the water system and in the rinsing baths.

This microbial contamination has a negative impact on the quality of the treated items. Besides, the facility’s manager suffers a dual financial penalty: costs related to production defects (batch recalls…) and costs induced by production shutdowns to clean and disinfect the unit. Without mentioning the negative effect on the brand image…

The need of the electroplating sector is dual: ensuring the good microbiological quality of the treatment baths while limiting the maintenance costs.

A three-step approach

At GL Biocontrol, we developed a systematic approach in order to secure the manufacturing process. This solution, organised in three stages, answers to the industrial needs and optimises the corrective actions.

Identify…

The first step aims to map the water circuits in order to identify in real-time the areas under control and the critical areas. This thorough inspection highlights the circuit’s components producing biomass. To be as responsive as possible, we use a measuring tool that gives you the result directly on the field: quantitative ATPmetry. The delay, inherent to the cultural methods, is thus avoided. The production water system, the treatment baths as well as the surfaces must be analysed.

Mapping detects the critical areas of the circuit. Since then, the operator can implement the correctives actions to improve the microbiological quality of the process.

…Assess…

Next, these corrective actions must be monitored over time and assessed. For example, the various stages a treatment procedure (cleaning and disinfection) are assessed and optimised in real-time. The goal of this second step is to adjust the treatment to the ecosystem encountered to ensure an optimal efficacy. In this way, we durably limit microbial growth and biofilm formation.

…Monitor

Finally, the third and last step aims to monitor over time the evolution of the production unit microbiological quality. Using ATP tests, one can self-monitor its water circuits, the electroplating and rinsing baths. Service technicians can perform themselves the sampling and analysis on a regular basis. Implementing a biomonitoring will allow you to control in real-time the microbiological activity of the circuits. In this way, it is possible to react immediately in case of a significant increase of the microorganism level. The operator starts the earlier corrective actions to limit non-conformity on the treated parts. Besides, using an indicator of biocontamination will allow you to trigger the cleaning and disinfection procedures only when needed.

Personalized support and follow-up

GL Biocontrol offers a complete provision of expertise of the water systems and treatment baths. We also supply you with all the reagents, consumables and measurement device required for monitoring the microbial quality.
Furthermore, the offer comprises a personalized support covered by our experts to ensure that it is properly implemented: handling of the ATP tests, definition of the surveillance limits, determination of the corrective actions, etc…

To sum up…

The DIADEM approach has many advantages for production units in the sector of surface treatments. Optimisation of the microbial quality of the water and baths, as well as the implementation of a self-monitoring by ATPmetry will allow you to:

  • Reduce production costs (avoid production shutdown, limit volumes of treatment products used, reduce the C.I.P procedures)
  • Reduce non-quality costs due to visual defects on the treated items.  

For more information :

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Research project: development of a detection kit for somatic coliphages

By Estelle Alaume

In Europe, water intended for human consumption is highly regulated by the Drinking Water Directive. Water intended for human consumption includes distribution systems, drinking water in bottles or containers and water used in the food-processing industry. Recently, the revision of the Drinking Water Directive (n°98/83/CE) adds new parameters to the list of criteria determining water safety, such as control of somatic coliphages. These viruses are used as indicator organisms for faecal contamination. Its control represents an important step towards a high quality of drinking water.

Somatic coliphages, new faecal contamination indicatorContinue Reading

ATP tests: comparison of ATPmetry kits

Test ATP, analyse microbiologique des bactéries

Quantitative ATP tests vs qualitative ATP tests


 

You need to monitor the microbial quality of your water? You need an ultra-fast, easy-to use, sensitive, reliable and accurate method…

ATPmetry is a technique that measures ATP quantity. It is known to evaluate instantaneously and efficiently the quantity of microorganisms of a water sample.

However, ATP tests performances vary strongly depending on the kit.

This study compares different commercial ATP tests for the monitoring of bacteria in water. ATPmetry is a very fast analysis method that is used on the field. Results are obtained in less than 2 minutes, thus allowing early-responsiveness.  The DENDRIDIAG® kit, 2nd generation ATPmetry, includes sample concentration and internal calibration. It is compared to several first-generation ATP kits:

    • AquaSnap® (Hygiena)
    • Clean-TraceTM(3M)
    • AccuPoint® (Neogen)
    • LIGHTNING MVP ICON® (Biocontrol Systems)
Test ATP - comparaison de kits d'ATPmétrie

All the kits include the sampling system, the reagents and the matching luminometer. The different ATP monitoring tests are assessed based on several criteria:

    • Linearity: gives the measuring interval for each kit.
    • Repeatability: gives the measurement precision by replicate measurements on the same sample by a same operator.
    • Sensitivity: research of contamination traces in sterile water
    • Robustness: influence of the environment on the measure

What is the measuring interval of my kit?

Analysis of the linearity gives the measuring interval. A solution of ATP is diluted in sterile water. Each solution is tested 3 times with each method. This study does not take into account the lysis efficiency of the kit.

“The straighter the line, the better it is.”

Good performances
DENDRIDIAG, Clean-Trace and AccuPoint: ATP monitoring tests show great linearity from 0 to 4.00 LOG of picogram of ATP per ml.

Average performances
MVP ICON and AquaSnap are saturated above 3.00 LOG of ATP. Furthermore, the curve starts to bend after 2.00 log of ATP. The measuring interval is limited. In other words, above 100-1000 pg/ml, those kits will not display accurate results.

Does the result change if the analysis is done several times by the same operator?

The measure of dispersion helps us study the repeatability of each kit. In other words, we observe the variability of the result when the measurement is done by a same operator on the same sample.

“For repeatable measurements, variations must be as low as possible.”

The dispersion is measured through the coefficient of variation (CV) which should be the lowest possible.

Good performances
DENDRIDIAG®: CV = 8%

Average performances
Clean-Trace: CV = 33%
MVP ICON: CV = 16%

Weak performances 
AquaSnap
: CV = 90%
Accupoint: CV = 70%

First generation ATPmetry kits analyse water from 100 µl samples. The sampling volume can vary from 80 to 160 µl depending on the operator. Furthermore, with such a small volume, it is difficult to get a representative sample of the monitored water. Consequently, result variations are very high for a same sample.

The key value of DENDRIDIAG® kit is the filtration step. 10 ml to 1 liter of water sample are concentrated in 100 µl making the analysis representative. In this way, variations due to the heterogeneity of the water are strongly limited.

Sensitivity – Research of contamination traces

The main goal is to compare the sensitivity of the different ATP monitoring tests. To do this, we are looking for the smallest volume of water which can be detected in 1 liter of sterile water.

Which volume of waste water can I detect in 1 liter of sterile water?

Good performances
DENDRIDIAG: detection of 10 µl of waste water in 1 liter of sterile water.

Average performances
AquaSnap and Clean-Trace: detection of 1 ml of waste water in 1 liter of sterile water.

Weak performances
AccuPoint: detection of 10 ml of waste water in 1 liter of sterile water.
MVP ICON: detection of 100 ml of waste water in 1 liter of sterile water.

 

Search for contamination traces requires high sensitivity. DENDRIDIAG® kit has a major advantage: sample filtration before analysis. Indeed, the procedure includes concentration of bacteria on a membrane. Filtration helps reach higher level of sensitivity without extending the handling time. Thereby, you can gain on the sensitivity threshold by a factor of 100 compared to first generation kit.

Are my results affected by environmental factors (temperature, pH…)?

Environmental factors are different for each water sample. Hot domestic water’s temperature is obviously very different from drinking water’s temperature for example. It also differs whether it is summer or winter. Same is true for the pH, salt content, etc…

In this study, we chose to play on the temperature and pH of a surface water. It is analysed 3 times with each ATP tests and measurement variations are assessed. Robustness evaluates the capacity of a method to maintain its performances when parameters are modified.

“For reliable results, variations must be as low as possible.”

Tested parameters: 22°C – pH8; 60°C – pH8; 4°C – pH8; 22°C – pH4; 22°C – pH10

Variations are measured by the coefficient of variation which must be the smallest possible.

Good performances
DENDRIDIAG: CV = 6%
Average performances
AquaSnap:
CV = 58%
Clean-Trace: CV = 64%
Weak performances 
MVP ICON:
CV = 109%
Accupoint: CV = 133%

Regarding robustness, DENDRIDIAG® ATP tests is largely more efficient than other kits thanks to internal calibration. This standardisation takes into account the environmental factors. Indeed, all ATPmetry kits use an enzyme: the luciferase. It is sensitive to the environment (temperature, pH, inhibitors, activators…). For instance, if the sampled water is very cold, the enzyme will have a reduced activity. Therefore, the result obtained will be lower than reality. It then leads to high rate of false negatives.

Addition of a known quantity of ATP in each sample helps you avoid this effect and makes the analysis much more reliable.

CONCLUSION

Comparaison ATPmetry kits

Second generation DENDRIDIAG® kit clearly differentiates itself from first generation ATPmetry kits. It has 2 major advantages:

  • Filtration: it concentrates microorganisms of the sample to reach very low level of sensitivity. In this way, it is possible to monitor the microbial quality of drinking water and ultra-pure water. Up to 10 µl of waste water can be detected in 1 liter of sterile water.
  • Internal calibration: after each measurement, the operator adds a known quantity of ATP to standardized the measure. Consequently, environmental factors are considered. This internal calibration prevents high rate of false negatives. Besides, it makes it possible to compare results over time and space and for different luminometers.
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