EPA Methods and the Use of Drying Techniques

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?!

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Improvements in Processing Drinking Water Samples by Method 525, Part 1 Sample Preservation

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.

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