It is that time of year again when laboratories are fulfilling accreditation requirements for the methods that they offer. One of the requirements that must be met for each method is called proficiency testing (PT). If you are not familiar with proficiency testing, it is a sample purchased from an approved vendor to evaluate the ability of a lab to meet the acceptance criteria of the method. If the labs’ results are out of the PT samples acceptance criteria, they can redo the testing.
IR technology is a rapid and convenient tool for both qualitative and quantitative analysis that has been around for over a century. Traditional IR spectroscopy relies on vibration energies from the molecular bindings, where IR emission is absorbed by the bond when it has the same frequency as the specific vibration or movement as the bond.
Have you ever put your water sample onto your Biotage® Horizon 3100 extractor and all your prewet/conditioning steps worked great and then suddenly, the water inlet valve opens, and nothing happens! This can be terrifying because a lot is riding on those samples! If you notice this right when it happens, a simple wiggle of the sample bottle should introduce air into the bottle releasing the water, in turn loading your sample. However, you do not want this happening all the time, especially when you leave your extractor for a while, come back, and see that your sample never loaded!
Anyone familiar with EPH methods such as those developed by the Massachusetts or New Jersey Department of Environmental Protection is familiar with the long and grueling process of fractionation. For those unfamiliar, an EPH or Extractable Petroleum Hydrocarbon is an extraction that essentially occurs in two distinct parts: the initial extraction & concentration and the fractionation of that initial extract into the aromatic and aliphatic fractions and then concentration again. EPH is a method that replaces the TPH (Total Petroleum Hydrocarbons) or 8015 methods and allows for the calculation of specified carbon ranges giving you a more accurate assessment of potential health risks.
Do you ever tire of using sodium sulfate to dry your extracts? I know I do. That is why, whenever I get the chance to avoid using it, I do. The worst experience when using sodium sulfate is when you do not use enough of it, and the sodium sulfate reaches its maximum capacity leading to water breakthrough into your ‘what was supposed to be a dried extract.’ Then, you must dry the extract again with more sodium sulfate. When you are a high throughput lab, redoing steps is not ideal. Unfortunately, EPA Methods 525.2 and 525.3 require sodium sulfate drying as the drying technique, to name a couple, but not all EPA methods require sodium sulfate for drying. That is why when there is an alternative technique available and you are permitted to use it, why not use it?!
Believe it or not, we’re all familiar with emulsions. Have you ever added food oil to a pot of water while cooking? That’s an emulsion. Do you put dressing on your salad? It should be called salad emulsion – although, that may not have the same edible appeal. Do you drink milk? Emulsion. What about milk? Butter? Eggs? All emulsions.
If we’re referring to emulsions in the laboratory, the examples are different, but the chemistry involved is very similar – as are the mechanisms for breaking them. Continue reading Tackling Emulsions Just Got Easier