LabMatters

Lab Matters is a series of technical articles from Environmental Express that are intended to aid in the comprehension of the common analyses in the environmental laboratory. They will all have the same basic format that you see here; an introduction section that will give some basics about the parameter and test method, and approved method listing for a listing of analytical methods to choose from, a method summary that gives a brief outline of what the method does, and a section with important things to know. Finally, each Lab Matters guide will contain a simplified step by step method on how to perform the analysis. This will help you get the sequence of your analysis right as well as give guidance on products you can use to simplify the process.

Click here to download the full Lab Matters Introduction



Understanding Sample Collection
Thursday, 05 December 2013 15:49

Introduction – Everyone that has worked in an environmental lab has seen it; the bacteria sample that is collected in a general use plastic container, the trace metals or anions sample that comes in a Gatorade bottle (with the label removed of course), or the soil sample that arrives in an ordinary zip seal bag. We all smirk when we see these come across our lab benches, but do we really stop to think what kind of effect that could have on the results of the test? The collection method for our samples is just as important as the method used for the analysis. Everything from the type of container, to what should or should not be added, to how to store it plays a vital role in assuring that what you analyze will give an accurate measure of what is in the sample.

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Understanding Semi Volatile Extractions
Monday, 26 August 2013 09:16

Introduction – Organic compounds have become an ever growing presence in our society. Many products use some form of organic compound in their formulation and the release of these compounds in the air is an area of concern for health officials. A subset of organic chemicals known as semi volatile organic compounds (SVOCs) is also a growing concern in water and soil pollution. These semi volatile compounds are composed of pesticides, herbicides, and a laundry list of compounds guaranteed to give even the most seasoned chemist trouble pronouncing them.

Approved Methods – This LabMatters will focus solely on the preparatory extraction methods for SVOCs. There are quite a few that have been approved for use. The Clean Water Act (CWA) methods are generally for liquid samples and have an extraction procedure written into the method. The SW-846 methods are for general waste analysis, both liquid and solid, and have extraction methods written separately from the analytical methods. Because of the large number of methods available you should consult 40 CFR Part 136 and SW-846 (3000 Series) for the list of methods numbers.

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Understanding Biochemical Oxygen Demand (BOD)
Friday, 03 May 2013 11:23

Introduction - BOD, like COD, is not one definable particle. You cannot count BOD molecules. BOD is the amount of oxygen consumed by decomposition of the sample during the incubation period. The intent is to measure what affect the sample will have on oxygen available to living organisms in the waters into which the waste is discharged. If the BOD of a waste is high enough, the microbial population will quickly deoxygenate the water and render it unsuitable for other forms of marine life. This can cause dead zones in a river or other body of water. There is an additional subset of BOD that is required in certain areas. This is referred to as carbonaceous BOD or CBOD. This measures along the same basic principle as BOD, except that an inhibitor is added to exclude the oxygen consumption by nitrogen fixing bacteria. Sometimes BOD will be referred to as BOD5 or five day BOD.

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Understanding Total Dissolved Solids (TDS)
Tuesday, 30 April 2013 15:31

Introduction –

Water has the ability to dissolve a large variety of materials.

Approved Methods – –

There are three different approved methods; all of which follow a similar analysis procedure. The notable differences are slight variations in requirements for the supplies used.

• SM2540 C – 1997 • ASTM D5907-03 • USGS I-1750-85
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Understanding Coliform
Friday, 25 January 2013 08:39
Introduction – The presence of certain bacteria are often a good indicator of water quality. Members of the coliform group serve as an indicator of pollutant vectors in the water system, specifically gaps in sanitary treatments. Coliform bacteria are quite common in the environment and most of them, by themselves, are not threats to the public health. The EPA recently revised the total coliform rule to eliminate public notification requirements based only on the presence of total coliforms. It is the detection of coliform bacteria associated with fecal material that is a true cause for concern.

Approved Methods – There are two different approved methodologies to test for bacteria. These are most probable number (MPN) and membrane filtration (MF). The MPN procedure can be further broken down into traditional multiple tube methods, which generally rely on physical indicators of gas production and chemical indicators of acid production by the growing bacteria and multiple well methods, which are also referred to as defined enzyme substrate tests. The approved methods are broken down as follows:

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