1) HOW DO I SOLVE PROBLEMS WITH SAMPLE VOLUME USING A NO-PURGE SAMPLER? HOW DO I GET MORE VOLUME FROM MY NO-PURGE SAMPLER?
By definition, no-purge sampling devices are restricted to collecting the volume of fluid contained within the well screen. For example, a 2-inch well with a 10-foot long saturated screen has an absolute maximum of 6.4 liters (1.6 gallons) of water available for no-purge sampling.
In response to the sample volume issue, GeoInsight has developed a sampler which will collect the most water available from a 2-inch (schedule 40) well. This new device, developed in the summer of 2009, the HydraSleeve Super/SkinnySleeve (SS), has almost doubled the amount of water that could be collected out of a 2-inch well as compared with earlier designs of the HydraSleeve. Prior to the development of the HydraSleeve SS, only about 45% of the available water could be captured from the well screen. Using the HydraSleeve SS, up to 80% of the available water in the well screen can be collected as sample. This is very important for 2-inch wells with a short screened interval or a short water column within the screen.
Due to continued requests for even more than 2 liters of sample volume we have developed an even larger SuperSleeve. We call it the TurboSleeve. It will collect 4 liters of sample volume from a 10-foot screen. Please read the white paper and field instructions for more information on the TurboSleeve. There are limitations to the use of the TurboSleeve. Please call 800-996-2225 if you are interested in this size HydraSleeve.
Another option for ensuring that you have sufficient water for all of your analytical needs is to check with your laboratory to see if they really need as much sample volume as they request. Most laboratories ask for 2 to 4 times as much sample as they need, so they can actually work with much less than they initially asked for. The table below illustrates just how skewed the lab-requested volume vs. the accepted minimum volume can be:
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Minimum Sample Volumes for Common Environmental Analytical Methods |
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| Parameter | Asked for | Accepted Minimum Volume for one Analysis |
| Alkalinity | 200 (mls) | 10 (mls) |
| Hex Chromium | 300 | 5 |
| Perchlorate | 50 | 25 |
| Total Hardness | 100 | 10 |
| VOC's | 140 | 20 |
| BNAs | 1000 | 250 |
| Pesticides | 1000 | 100 |
| PCBs | 1000 | 100 |
| Total | 3790 | 510 |
For your convenience we are providing a minimum sample volume requirement spreadsheet for you to use as a guideline to negotiate sample volumes with your lab. To download the Excel spreadsheet, please click here.
This spreadsheet was developed by Columbia Analytical Services Inc in conjunction with the ITRC. They are a full-service analytical laboratory testing network, with locations across the United States. They were part of the original ITRC Passive Sampling Team that organized a panel of well known laboratories to agree on the absolute minimum volumes that were necessary for a wide variety of analytical methods in response to the sample volume limitations of the passive sampling devices.