If you are performing oil & grease analyses according to EPA Method 1664, you are familiar with the requirement to dry your extract prior to evaporation. There are those who might perform this step for reasons such as “this is the way we’ve always performed our extractions” or “the government-regulated method told me so” or “we have a giant container of sodium sulfate in the lab, so we might as well use it”; however, there is sound logic in removing water from your organic solvent prior to evaporating it.
As today is World Water Monitoring Day, I assume you are wearing your “I Water” t-shirt – or perhaps you are secretly wearing it to work, under your formal business attire? If so, you are probably in good company.
On the eve of World Water Monitoring Day, we thought we would post last Tuesday’s response a day earlier! Celebrations for tomorrow’s epic event might otherwise interfere.
Just a reminder of last week’s post:
According to EPA Method 1664 A/B, n-hexane is used as an extraction solvent and must have a minimum purity level of…
EPA Method 1664 B outlines the use of n-hexane as an extraction solvent and Section 1.7.2 specifies a minimum purity level of 85% (Method 1664 A has the same requirement).
Believe it or not, hexane solutions typically contain a mixture of 5 structural isomers (i.e. same molecular formula, different arrangement of atoms). N-hexane is the longest (least branched) of the 5 isomers, which gives it the highest boiling point and lowest vapor pressure. Therefore, specifying a minimum purity level of 85% means you’re dictating that at least 85% of the solution must contain the x-hexane isomer.
Join us next week to Expand Your Horizon!
PFAS chemicals can be found in every aspect of our life from nonstick pans and cleaning products to firefighting foam. This group of chemicals has caused concern nationwide as it has been found in drinking water and has shown to have negative effects on our health. Starting in the 1980s, chemicals in the PFAS family, PFOS and PFOA, were linked to a number of health concerns, from cancer to hormonal disruption. (See our earlier blog for terms and definitions). These chemicals are extremely difficult to get rid of because they do not break down in the environment and they build up in the body.
Happy Tuesday! This week’s question will focus on the EPA method for performing n-hexane extractions, otherwise known as “oil and grease” extractions. If you are ready to Expand Your Horizon, read on.
Today’s question: According to EPA Method 1664 A/B, n-hexane is used as an extraction solvent and must have a minimum purity level of…
(e) None of the above
Hazard a guess in the comments below! (need a hint? The answer isn’t “none of the above”)
Stay tuned next Tuesday….
1,4 dioxane – sometimes referred to as just dioxane – has gotten a lot of press since the U.S. EPA added it to the third Unregulated Contaminant Monitoring Rule (UCMR 3). It is a relatively common solvent in analytical laboratories; however, it also finds use as a stabilizer for manufacturing items such as shampoo, cosmetics and food additives. After the EPA deemed this compound “likely to be carcinogenic to humans” and found it in a number of groundwater sources across the U.S., 1,4 dioxane was added to the UCMR 3 list and is now a regulated, routinely monitored contaminant.
Just to recap last week’s Tuesday Trivia post: Due to rising levels of ______ (fill in the blank) ________, some species of fish are slowly losing their ability to smell.
Answer: Carbon dioxide (CO2)
As the levels of carbon dioxide rise in a body of water, carbon dioxide converts to carbonic acid which increases the acidity of the water. It turns out, acidic conditions reduce the sensitivity of the olfactory sensors in a fish (i.e. the nerves responsible for being able to smell).
As we’ve demonstrated with posts and trivia questions in the past, protecting, testing and treating our fresh water sources is important to the health of everyone. Read through this helpful infographic for a quick review of the potential contaminants that could find their way into our water sources.
Join us next week to Expand Your Horizon!