When we are out in the field, there are a lot of small tasks to keep track of. One commonly missed step is taking pictures of both the fully processed Quantab Strip and pH Strip. These images are critical to the quality control check and help us to ensure that the data is being collected properly and your supplies are functioning correctly! Here is a quick list of reminders to jog your memory the next time you are out collecting data at your site:
1) Make sure the Quantab Strip is fully processed!
When a Quantab strip is brand new, there is a horizontal orange cross bar at the top of the strip (left). This strip turns BLACK when it has completed the test (right). Please make sure that the bar is totally black before documenting your data.
As Quantab strips pass their expiration date, it may take a longer time for the indicator bar to turn black. Similarly, if strips get wet or the storage bag becomes humid, this may also cause the indicator bar to stop turning fully black. If you are finding that it is taking longer and longer for the strip to process, please let us know and we will replace your Quantab Chloride strips!
2) Read the Quantab Strip values Exactly as written!
When you are reading the Quantab strip numbers, double check that you are recording values exactly as they appear on the conversion table. If the peak falls on between two lines, then use the number of the line that was crossed, do not estimate a middle value. All values should be even - please do not guesstimate an odd number.
In the image above, the Quantab strip values are:
Left: 0.6 : The peak ends ON the 0.6 line
Middle: 1.4: The peak crosses 1.4 but does not quite reach 1.6. While it is tempting to estimate at 1.5, we must stick to the known numbers.
Right: 2.6: The peak crosses 2.6 and does not reach 2.8.
3) Take a picture of the fully processed strip and conversion table!
Once you have a strip that has turned black at the top and have recorded an accurate number on your data sheet, then it is time to take a picture of the chloride strip and the conversion table.
Make sure that the image is in focus - we need to be able to see the entire strip as well as the numbers on the conversion table!
DO NOT send us an image with a Quantab or pH strip floating in space! These images are not helpful for troubleshooting strange data entries.
Quantab Chloride Strip Example Images:
Left: This is what we want to see - the strip and conversion table are in focus, and indicator cross bar (by the green star) is completely black. The blue arrow shows the yellow peak, which represents a Quantab value of 3.0. The red box shows the lot number, and all are easy to read.
Middle: This is a good photo with the conversion chart. This strip was NOT run to completion -- the indicator cross bar (by the red X) is completely orange. The blue arrow shows the yellow peak at 2.6 Quantab units, but this value may be incorrect because the strip was not properly run.
Right: This image is not useable. There is no conversion chart and the strip is not run to completion. The orange X shows the indicator bar, which is not turned completely black. The blue arrow shows the peak at 2.6 Quantab units, but this value may be inaccurate because the strip was not properly run.
pH Strip Example Images:
Left: This is what we want to see - the strip and conversion table are in focus, and the conversion looks accurate.
Middle: The strip and conversion table are in focus, but the reading is inaccurate. This is a valuable picture to help us troubleshoot that the reported value was incorrect.
Right: This image is not useable. The strip is out of focus and there is no conversion table to check.
Thank you for your hard work collecting data at your site! It takes a lot of time and energy to collect the data, and we are working hard to make sure that every data point is helping us better understand the Darby and Cobbs Creek watersheds!
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