Sample Gathering for Oil Concentration Measurement

General guidelines one should follow to improve measurement 

The person taking the sample must he well trained and experienced and be able to recognize a spoiled or unrepresentative sample. Samples must be correctly labeled immediately after being taken and any abnormal circumstances must be noted on the sample. If any doubt exists, the sample should be discarded and a new one taken in a fresh container. 

The sampling frequency depends on the practicality of sampling at each site or may also be specified by the authorities having jurisdiction. A manned installation would require a higher-analysis frequency than an unmanned site, which may be less accessible. For example, in the United States, the EPA states, The sample type shall be a 24-h composite consisting of the arithmetic average of results of 4 grab samples taken over a 24-h period. If only one sample is taken for any one month, it must meet both the daily and monthly limits. Samples shall be collected prior to the addition of any seawater to the produced water waste stream.  

---