ASTM D7575 Total Oil and Grease in Water Tutorial: Sample Preparation and Homogenization скачать в хорошем качестве

ASTM D7575 Total Oil and Grease in Water Tutorial: Sample Preparation and Homogenization

Hi. Today you are going to learn how to properly prepare and homogenize the sample that you have collected to analyze total oil and grease in water. Homogenization is arguably the most important and crucial part of this process to gain an accurate analysis of total oil and grease. We all know that oil does not like to evenly disperse in water, and therefore it is extremely important since we are only processing 10mL out of the 1L sample through the OSS extractor, that those 10mL are a very representative sample of the entire bottle. Let’s get to it! Collect 1 liter of sample in a clean glass container with a Teflon lined lid, leaving headspace. Acidify to a pH of 2 with hydrochloric acid. Next, prepare a hot sonic bath for homogenization. First, set the water temperature to 40 degrees Celsius, and the total sonication time to 20 minutes. More time may be required for extremely greasy samples. Once the water is at 40 degrees Celsius, SHAKE the sample VIGOROUSLY for 30 seconds! Then, place the sample in the sonic bath and hit start. Every five minutes, return to the sample and shake for 10 seconds, rotating the bottle in the bath. Continue for 20 minutes or more, until the sample is visually homogeneous.