Question of the Day: Water Sampling

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Taxonomy

• Industrial Water Treatment
• Industrial Water Treatment
• Chemical Analysis
• Analytical Chemistry
• Testing
• Laboratory Testing

8 Answers

1. Sampling is the heart of the analysis.  The main objective is to collect the representative sample. One can have grab sample if there is no variation. Other wise continuous or intermittent sampling can be done to have fair representation. Please inform whether the sample is to be drawn from close conduit pipe of from the open channel.

2. - Follow proper safety precautions

   - Prevent samples contamination

   - Maintain proper sample custody

   - Preserve samples properly

   - Use proper container

   - Observe DOT or IATA regulations when shipping samples

   - Take notes

   - Take time to; establish samples required based on type of study to be performed, select sampling ports, establish quality control, define if grab or composite samples are required, define sampling length and frequency.

   - Take time to understand the system to sample; continuous, batch, peak load, etc.

   - Clean and calibrate sampling equipment

3. If you are analyzing water for trace metals, please make sure the sample bottles are plastic based (Teflon or polypropylene) and add as much pure concentrated nitric acid (metal free) so as to reduce the sample to pH < 2. Please refer to Standard Methods for the Examination of Water and Wastewater for more details on sample bottle preparation, the procedure during collection, and preservation until analysis.  Agreed, the objective of sampling and constituents in water to be analyzed would further narrow down specific steps. Agee with suggestions already provided by colleagues in the group. 

4. Sample extraction method is important.  You must adhere to strict protocols to be certain the sample is representative of the stream being sampled.  ASTM has several publications regarding proper techniques.

5. Contamination is the biggest problem when performing sampling. Avoid foreign contact (i.e hand contact) with samples when taking sample at sampling points. Try to avoid aerating the sample (i.e., don't allow water to "bubble" into the container.

    

   
   

    

6. Use either the same bottles daily for the same samples, or use new ones constantly, which is a real pain.  Also make sure that samples which are air sensitive are filled and sealed solidly full, or better, fill them underwater.

   1 Comment

   1. dear james as you have mentioned that the samples sensitive to the air, which kind of samples are sensitive to air??? if possible can you make anyone of the examples.

7. 1st need to specify the objective of sampling. Then study the system to find the related area of system considering objective specified for study. The sampling  point to be selected based probability to authenticated the information for the study or finding to conclude.

    

8. Essentially try to measure the minimum pH parameters at the site, preferably store them in glass containers, keep them well refrigerated and sealed