This sample is treated in the same manner as the field samples. The concentration of the low standard is added to the concentration of the field sample and compared to the spiked solution. A second water sample is taken in another sample bottle at one of the test sites. It is treated as a field sample and used for comparison. 4. a field blank.
Distilled water is poured into another sample bottle at one of the test sites.
It is analyzed along with the other samples and used for comparison. It is used primarily as a random check on the cleanliness of the sample bottles. All forms of phosphorus are converted to orthophosphates by hot acid digestion using standard Hach methodology. Each 25ml sample is treated with an oxidant and 2ml of 5N sulfuric acid. The samples are boiled on a hot plate for 30 minuets and allowed to cool to room temperature.