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Microwave Calibration Brenda R. Cleveland Plant/Waste/Solution/Media Section NCDA&CS Agronomic Division

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June 21, 2011NCDA&CS Agronomic Division Presentation Today Microwave Calibration Procedure Procedure But first... But first...

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June 21, 2011NCDA&CS Agronomic Division PWSM Section Legislature enacted the service in 1974 Legislature enacted the service in 1974 Analyze about 30,000 up to 35,000 samples annually Analyze about 30,000 up to 35,000 samples annually 18,000 waste 18,000 waste 9-10,000 plant (this year >11,300) 9-10,000 plant (this year >11,300) 2-3,000 solution and 2-3,000 solution and media media

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June 21, 2011NCDA&CS Agronomic Division PWSM Section Analyses (N, P, K, Ca, Mg, S, Fe, Mn, Zn, Cu, B, Na) Analyses (N, P, K, Ca, Mg, S, Fe, Mn, Zn, Cu, B, Na) Fees Fees Routine $5 Routine $5 Research $12 Research $12 Out-of-State (2005) $25 Out-of-State (2005) $25 Plus fees for additional tests Plus fees for additional tests NO3-N/NH4-N, heavy metals, CCE ($10 each) NO3-N/NH4-N, heavy metals, CCE ($10 each) Petiole NO3-N, Mo, Cl ($2 each) Petiole NO3-N, Mo, Cl ($2 each)

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June 21, 2011NCDA&CS Agronomic Division PWSM Section Six full-time laboratory staff plus 2-3 additional staff during busy season Six full-time laboratory staff plus 2-3 additional staff during busy season Chemistry Lab Supervisor (Mark Buchanan) Chemistry Lab Supervisor (Mark Buchanan) Chemist I (Jan Queen) Chemist I (Jan Queen) 3 Chemistry Technician III (Ying Kritalugs, Donta Baker and Kyle Crump) 3 Chemistry Technician III (Ying Kritalugs, Donta Baker and Kyle Crump) 3 Research Technicians (Karla Barefoot, Ma Kpa, Brenda Woodall) 3 Research Technicians (Karla Barefoot, Ma Kpa, Brenda Woodall)

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June 21, 2011NCDA&CS Agronomic Division PWSM Section One Agronomist (Dr. Michelle McGinnis) One Agronomist (Dr. Michelle McGinnis) One Processing Assistant (Darlene Carpenter) One Processing Assistant (Darlene Carpenter) One Section Chief (Brenda Cleveland) One Section Chief (Brenda Cleveland)

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June 21, 2011NCDA&CS Agronomic Division Microwave Procedure for ICP Analysis Add 10 ml of nitric acid to each sample; Add 10 ml of nitric acid to each sample; 0.5 g plant/solid waste or 5 ml liquid waste 0.5 g plant/solid waste or 5 ml liquid waste Space samples evenly in microwave Space samples evenly in microwave Digest for 30 minutes at 210 watts Digest for 30 minutes at 210 watts Flush sides of the flasks with hydrogen peroxide Flush sides of the flasks with hydrogen peroxide Digest for 4 minutes more at 390 watts Digest for 4 minutes more at 390 watts Actual time varies depending upon the # of samples

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June 21, 2011NCDA&CS Agronomic Division Quality Control To verify that the samples To verify that the samples have been cooked at have been cooked at the correct power? the correct power? (210 then 390 watts) (210 then 390 watts) calibrate calibrate adjust adjust NIST sample NIST sample

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June 21, 2011NCDA&CS Agronomic Division Calibrate Calibration is the process of adjusting the output or indication on a measure- ment instrument to agree with value of the applied standard, within a specified accuracy Calibration is the process of adjusting the output or indication on a measure- ment instrument to agree with value of the applied standard, within a specified accuracy Assures that microwave power is accurate and samples are digested according to the SOP Assures that microwave power is accurate and samples are digested according to the SOP

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June 21, 2011NCDA&CS Agronomic Division Calibration Monthly calibration of all microwaves Monthly calibration of all microwaves Followed by analysis of a NIST sample to verify that our procedure from start to finish Followed by analysis of a NIST sample to verify that our procedure from start to finish

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June 21, 2011NCDA&CS Agronomic Division Calibration - Preliminary Microwave is warmed Microwave is warmed Remove turntable Cook 1000 ml of water in a beaker at full power (100%) for 5 minutes Use room temperature DI water

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June 21, 2011NCDA&CS Agronomic Division Calibration - Second Watts determined at four locations Watts determined at four locations front right front left back right and back left

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June 21, 2011NCDA&CS Agronomic Division Determine Power for 210 Watts 1. Measure initial temp of 1000 ml DI water 2. Place beaker in the front left section of cavity 3. Cook 2 minutes at 210 watts 36% power 4. Remove and stir then measure final temp 5. Repeat steps 1-4: front right, left rear and right rear

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June 21, 2011NCDA&CS Agronomic Division Watts Calculation Calculate the watts for each of these locations and runs Calculate the watts for each of these locations and runs T [final]-T [initial] * 35 T [final]-T [initial] * 35 Calculate the average Calculate the average If the average does ≠ 210 watts OR If the average does ≠ 210 watts OR If the watts of any of the locations is very different from the others If the watts of any of the locations is very different from the others Repeat the steps Repeat the steps

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June 21, 2011NCDA&CS Agronomic Division Determine Power for 390 Watts 1. Same steps 49% power 2. And calculations

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June 21, 2011NCDA&CS Agronomic Division Quality Control To verify that the samples To verify that the samples have been cooked at have been cooked at the correct power? the correct power? (210 then 390 watts) (210 then 390 watts) calibrate calibrate adjust adjust NIST sample NIST sample

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June 21, 2011NCDA&CS Agronomic Division That’s It Any Questions Any Questions Thanks Thanks

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