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| Do I need to cool my samples? |
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| Samples collected from a waste stream nearly always need some form of preservation in order to be used in further testing. Preservation, simply stated, means keeping a parameter in a sample from degrading or changing unfavorably from the state it was in when drawn. |
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| Some preservation techniques involve addition of chemicals, but the most universal form is cooling. If a sample must be held until finished, such as in a 24 hour composite, most common procedures indicate a temperature of 4 degrees C (39.2 degrees F) must be maintained in order for that sample to be usable. Freezing should not occur as this can damage or influence the water sample. |
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| Quickly collecting a grab sample and transferring to a refrigerator or cooler is common. Automatic samplers with built in compartments for ice are also common. For short-term storage, coolers packed with ice are generally acceptable. Keep in mind temperature will fluctuate, and will not be as constant as a refrigerator. Also, as the ice melts, possible cross contamination can occur if bottles are not sealed tightly and left to sit in ice water. It is never recommended to use dry ice as complications with off gassing and freezing may occur. |
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| Sampling with an automatic sampler that has an EPA recommended temperature setting of 4 degrees C would be the best option for proper temperature. |
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| Some applications do not allow for a large refrigerated sampler, such as sampling inside manholes. |
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| Contact USABLUEBOOK to discuss which procedure will work best in your application. |
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