The Motto 'Be Prepared' Isn't Just for Boy Scouts: The Importance of Practice in Field Testing

By Dan Kroll

One of the most important aspects of preparedness for a water contamination emergency is the development of adequate field analysis proficiency. Having a good understanding of the analytical procedures to be utilized before attempting them in the field is a prudent tactic. Many analytical procedures have subtle nuances and can be very technique dependent. It is important not only to recognize the intricacies of the procedure but also to have a good understanding of the underlying chemistry or biology involved. A thorough understanding of the science involved including where it can go wrong (interfering substances, environmental conditions such as temperature, light, etc. as well as issues such as sample selection) can help to alleviate problems. The ability to recognize potential problems in performing a method and being able to address them when they arise can vastly improve the accuracy of procedures performed in the field.

Beyond having an intellectual understanding of the procedure, the old adage of practice makes perfect is aptly applied in this situation. Dry runs of the testing procedure should be practiced in as close to field-like conditions as possible. Many unexpected variables can come into play in field conditions. Aspects such as manipulation of equipment and chemistries when wearing protective equipment can be problematic.

Many procedures also exhibit procedural sensitivity to individual operators technique. Practice of non-instrumental procedures that rely upon the matching of colors or the recognition of a colorimetric endpoint such as in a titration should be practiced with especial diligence. Many people have difficulty in recognizing specific color (e.g., red-green colorblindness) and even though manufacturers try to calibrate to an average ability to match and recognize colors, not all individual diversity can be taken into account. The only way to compensate for this is though actual practice utilizing standards of known concentration. This allows operators to refine their technique. It is also advisable to practice with matrix spikes on matrices that are likely to be encountered. A matrix spike is when a known amount of a substance to be analyzed for is injected into a real world sample and the method is evaluated for percent recovery. This not only helps with practicing technique but also can allow for recognition of potential problems and interferences before reaching the field.

Even highly trained and proficient operators can make mistakes when trying to operate equipment or perform procedures in emergency situations. This failure to accurately complete even well drilled tasks in stressful situations was amply demonstrated in the American Civil War. Weapons of that time period were predominately cap and ball muzzleloaders. The procedure for loading was to place the powder in the barrel of the gun, then a wad and finally the ball. After loading a firing cap was attached and the weapon was discharged and the procedure repeated. Many times after a heated battle, when the troops were undergoing weapon inspection, it would be found that the barrels of the guns were completely full of unfired rounds. In the heat of battle, the troops had forgotten to place the firing cap before pulling the trigger and hence kept reloading an already loaded gun. While most water testing situations are by no means as stressful as battle, field-testing in emergency situations can be quite tense and the less demanding the procedure is, the better. Always remember that while practice may not make you perfect it sure can help.

About the Author: Dan Kroll is chief scientist at Hach Company's Homeland Security Technologies division, in Loveland, CO. He has been the lead researcher on a variety of method development projects for the physical, chemical and microbiological quality of water and soils for which he holds several patents.

[WaterWorld Online, July 2010]

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