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DMA_Protocol.md

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DMA Operating Protocol

For a typical daily sample run

Cleaning Procedure

To clean used quartz boats:

  1. Gently scrape ash out of quartz boats with spatula and/or kimwipes.

  2. Rinse quartz boats in acetone. Perform this step in the fume hood to prevent inhalation of harmful acetone vapors.

  3. Rinse quartz boats in deionized water and place on rack to air dry.

  4. Place quartz boats in DMA turntable.

  5. Open new “sample” file under the “measurements” tab.

  6. Enter 1.0 gram weight for each empty quartz boat to clean.

  7. Under the “Methods” tab, select “cleaning procedure”.

  8. Under the “Calibration” tab select current calibration file.

  9. Return to sample and save sample file as “trash.”

  10. Start DMA and the cleaning procedure begins.

  11. Once the procedure is complete, determine if any sample boats had high levels of Hg residue (>0.005 mg/kg.) These boats may need to be burned again.

Starting Up the DMA

To prepare the DMA for sample runs each morning, it is necessary to remove residual Hg within the machine and check the accuracy of the calibration curve.

  1. Turn DMA-80 machine on using power button

  2. Open oxygen tank and adjust pressure to just below 60 PSI

  3. Login on the terminal by selecting “administrator” and entering the password “123456”

  4. Wait for the machine to warm up (about 15 minutes) and when it is ready the start button will become functional

  5. Under the “Measurements” tab, select the “sample” tab and select the blank sheet to start a new file. Save file as “trash”

  6. Run two “ghost samples” i.e. no boats in positions 1 and 2 on the turntable to vaporize any mercury that may remain in the system. Select “clean procedure” in the “Methods” tab.

  7. Under the “Measurements” tab, select the “sample” tab and select the blank sheet to start a new file. Select the add line button for each sample. Save file as trash.

  8. Run two samples of powdered standards dorm and dolt to determine machine is still accurately calibrated. Select “organic fish” in the methods tab and current calibration curve in the calibration tab. Dorm and dolt mg/kg of Hg should fall within the given ranges.

Running Samples

When running bird samples in the machine, each run must be accompanied by blanks and standard reference materials to make sure the machine is performing the analysis accurately.

  1. Under the “Measurements” tab, select “Sample,” and select the new file button to create a new sample file. Select the add line button for each sample.

  2. Under the “Methods” tab, select organic fish method

  3. Under the “Calibration” tab, select desired calibration curve file

  4. Return to “Measurements” tab and save sample file with desired file name (e.g. mm_dd_yyyy_feathers_LG)

  5. Place a clean and empty sample boat in turntable position 1 as a blank. Enter 1.0 gram for the weight.

  6. Weigh around 0.025 grams of dorm, dolt, and tort standards and place boats in turntable positions 2, 3, and 4. Enter actual weight and sample names in sample sheet.

  7. Weigh albumen, blood, or feather samples one at a time using analytical scale and place boats in the correct turntable positions. Record data from samples on data sheet.

  8. Enter sample ID and weight in grams in the sample table.

  9. Save sample file again. After all samples have been measured and placed in the turntable, hit the green start button to begin the analysis.

  10. Once the run begins, make sure the method and calibration selected are still selected (*sometimes the machine switches the calibration file on its own, we don’t want that to happen)

  11. Once sample run is complete, save the measurement file, and record the mercury concentration mg/kg on the datasheet.

  12. Place datasheet in binder