“Why do I keep seeing background contamination from phthalate and adipate when I do extractions for semi-volatiles?”
This is one of the most common questions I’ve been asked when I’m traveling in the field. It’s an issue I’ve come across in my own lab on occasion and if you can’t find the source of your contamination, it can turn routine application work into a troubleshooting nightmare. Given how often I’ve seen these compounds cause contamination issues, I thought I’d review some of the most common sources for these. Continue reading 5 Sources of Phthalate and Adipate Contamination You Probably Didn’t Know About
“Pesticides” is one of those terms that invokes a wide range of emotions in people. Some people smile when they think of the insecticides that keep their award-winning flower garden looking beautiful all season. Some people feel grateful for the algaecides in their fish tank that let their kids’ pet fish (who’ve probably been given cute names like “Nemo” and “Frankie Fish”) swim around freely, without having to navigate around huge algae blooms. Then there are other people who hear the word “pesticides” and think of dangerous chemicals that are sprayed onto our crops, eventually ending up in our food and water supply. In this post, I’m going to walk through the good, the bad and the ugly when it comes to pesticides, but that term actually includes a huge number of compounds, so I’m going to narrow my focus to just organochlorine pesticides for the purposes of this post.
Continue reading Organochlorine Pesticides: The Good, the Bad and the Ugly
In the first part of this 2-part blog series, I highlighted the improvements made by the EPA regarding the preparation and preservation of samples. In this post, I will focus more on the changes the EPA has made to Method 525 which affect the analysis of the prepared samples.
Continue reading Improvements in Processing Drinking Water Samples by Method 525, Part 2: Extraction Procedure
Since its release in 1995, EPA method 525.2 has been one of the most widely used methods for quantifying semi-volatile compounds in drinking water. Chances are, if you work for or own a drinking water lab, you probably analyze for compounds in this method – at the very least, you’re probably at least familiar with the method. This is a widely accepted method for quantifying semi-volatile organic compounds; however, there are some glaring issues with the method that the EPA has recognized and addressed. These changes have been collected and implemented in a new revision – Method 525.3 – which was published in 2012. Method 525.2 is still more frequently used by laboratories processing drinking water samples; however, I would argue that Method 525.3 is more scientifically sound. In this 2-part blog series, I will address multiple aspects of Method 525.2 that have been modified to improve the collection, preservation, and processing of drinking water samples. In this first part, I will focus on the improvements that have been made with respect to the sample preservation process.
Continue reading Improvements in Processing Drinking Water Samples by Method 525, Part 1 Sample Preservation
Phenolic compounds can be some of the most challenging compounds to extract from the compound lists in EPA Method 8270 and EPA Method 625.1. The recovery of these compounds suffer tremendously compared to some of the other target analytes on the list. So what exactly are phenols and why are they challenging to extract and quantitate?
Continue reading Why are Phenols so Challenging to Extract from Water?
In the world of solid phase extraction (SPE), the list of media that is available seems to be ever-growing. From polymeric stationary phases, to silica-based media, and even molecularly imprinted polymers specifically designed for target analytes. The possibilities seem endless. Luckily for us, most EPA methods specify which media type is required for analysis, but what about methods that don’t specify?
For the methods which don’t specify the media you must use, how do you select your media type?
Continue reading Which Media Type is Right for my Environmental Application?
In a never-ending list of chemical pollutants, a compound that is gaining a lot of attention is 1,4-dioxane. In fact, New Jersey just became the first state to set regulations on the quantity of 1,4-dioxane that can be present in drinking water.
1,4-dioxane, commonly called dioxane (the other two isomers – 1,2-dioxane and 1,3-dioxane are rarely ever seen), is an ether with the molecular formula of C4H8O2. Dioxane was previously used as a polar aprotic solvent. For those who remember their organic chemistry from college, SN2 reactions involve the use of polar aprotic solvents. Since its original use in laboratories, dioxane has been determined to be carcinogenic and, unlike many organic pollutants, it is completely soluble in water. Dioxane’s use as a solvent for industrial purposes has been mostly replaced with tetrahydrofuran, which has a higher boiling point and a lower toxicity. However, the story does not end there!
Continue reading 1,4 Dioxane Contamination and Updated Regulations – Are You Being Impacted?
Have you ever opened a jar of olives and noticed the shimmering liquid floating on the surface? Believe it or not, that liquid is actually residual oil that is given off by the olives themselves. Since the oil is less dense than the aqueous solution that the olives are stored in (olive brine), it floats to the top of the jar. This may not seem like a big concern to the typical olive consumer, however, olive manufacturers believe that too much oil in a jar is something that negatively affects the final product. For this reason, olive companies are putting effort and resource into finding a way to quantify the amount of oil in their final product.
Continue reading Reducing the Headache of Challenging Emulsions
Bisphenol A (BPA) is one of the most widely produced chemicals in the world – approximately 4 million metric tons annually. In recent years, BPA has received a lot of negative attention. In fact, I can’t remember the last time I saw a plastic item in the store that didn’t have a “BPA free” marking on it. These labels are for good reason, though, as BPA has been found to produce negative hormonal effects within the body. BPA is a chemical that mimics estrogen and disrupts the endocrine system, which can lead to developmental disorders, thyroid issues, diabetes and even reproductive organ cancers. BPA is so prevalent because it has many uses in polymer chemistry. First and foremost, BPA is used as a monomer in the production of polycarbonate, a very hard thermoplastic which has countless applications, including: water bottles, baby bottles, CDs, DVDs, eyeglass lenses and many more.
Continue reading Simplified BPA Analysis
For thousands of years, tea has been one of the most popular drinks around the world. Not only is tea delicious, it is also full of health benefits. Tea is an abundant source of antioxidants called polyphenols. One of these polyphenolic compounds, catechins, are found mostly in green tea. Catechins have been studied thoroughly and have been found to reduce free radical stress, they have also been found to be anti-inflammatory as well as potentially therapeutic for cancer cells.
Continue reading Extraction of Polyphenols in Tea with Lemon Juice