microwave calibration brenda r. cleveland plant/waste/solution/media section ncda&cs agronomic...

Microwave CalibrationMicrowave Calibration

Brenda R. ClevelandBrenda R. Cleveland

Plant/Waste/Solution/Media Plant/Waste/Solution/Media SectionSection

NCDA&CS Agronomic DivisionNCDA&CS Agronomic Division

June 21, 2011June 21, 2011 NCDA&CS Agronomic DivisionNCDA&CS Agronomic Division

Presentation TodayPresentation TodayMicrowave CalibrationMicrowave Calibration

ProcedureProcedure But first . . .But first . . .


PWSM SectionPWSM Section

Legislature enacted the service in Legislature enacted the service in 19741974

Analyze about 30,000 up to 35,000 Analyze about 30,000 up to 35,000 samples annuallysamples annually 18,000 waste18,000 waste 9-10,000 plant (this year >11,300)9-10,000 plant (this year >11,300) 2-3,000 solution and2-3,000 solution and 2-300 media2-300 media



Analyses (N, P, K, Ca, Mg, S, Fe, Mn, Zn, Analyses (N, P, K, Ca, Mg, S, Fe, Mn, Zn, Cu, B, Na)Cu, B, Na)

FeesFees Routine $5Routine $5 Research $12Research $12 Out-of-State (2005) $25Out-of-State (2005) $25

Plus fees for additional testsPlus 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)



Six full-time laboratory staff plus 2-3 Six full-time laboratory staff plus 2-3 additional staff during busy seasonadditional staff during busy season Chemistry Lab Supervisor (Mark Chemistry Lab Supervisor (Mark

Buchanan)Buchanan) Chemist I (Jan Queen)Chemist I (Jan Queen) 3 Chemistry Technician III (Ying Kritalugs, 3 Chemistry Technician III (Ying Kritalugs,

Donta Baker and Kyle Crump)Donta Baker and Kyle Crump) 3 Research Technicians (Karla Barefoot, 3 Research Technicians (Karla Barefoot,

Ma Kpa, Brenda Woodall)Ma Kpa, Brenda Woodall)



One Agronomist (Dr. Michelle One Agronomist (Dr. Michelle McGinnis)McGinnis)

One Processing Assistant (Darlene One Processing Assistant (Darlene Carpenter)Carpenter)

One Section Chief (Brenda Cleveland)One Section Chief (Brenda Cleveland)


Microwave Procedure for ICP Microwave Procedure for ICP AnalysisAnalysis

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 waste0.5 g plant/solid waste or 5 ml liquid waste

Space samples evenly in microwaveSpace samples evenly in microwave Digest for 30 minutes at 210 wattsDigest for 30 minutes at 210 watts Flush sides of the flasks with hydrogen Flush sides of the flasks with hydrogen

peroxideperoxide Digest for 4 minutes more at 390 wattsDigest for 4 minutes more at 390 watts

Actual time varies depending upon the # of samplesActual time varies depending upon the # of samples


Quality ControlQuality Control

To verify that the samplesTo verify that the samples

have been cooked athave been cooked at

the correct power?the correct power?

(210 then 390 watts)(210 then 390 watts) calibratecalibrate adjustadjust

NIST sampleNIST sample


CalibrateCalibrate

Calibration is the process of Calibration is the process of adjustingadjusting the output or indication the output or indication on a measure-ment instrument to on a measure-ment instrument to agree with value of the applied agree with value of the applied standard, within a specified accuracystandard, within a specified accuracy

Assures that microwave power is Assures that microwave power is accurate and samples are digested accurate and samples are digested according to the SOP according to the SOP


CalibrationCalibration

Monthly calibration of all microwaves Monthly calibration of all microwaves Followed by analysis of a NIST Followed by analysis of a NIST

sample to verify that our procedure sample to verify that our procedure from start to finish from start to finish


Calibration - PreliminaryCalibration - Preliminary

Microwave is Microwave is warmed warmed Remove turntableRemove turntable Cook 1000 ml of Cook 1000 ml of

water in a beaker at water in a beaker at full power (100%) full power (100%) for 5 minutes for 5 minutes

Use room Use room temperature DI temperature DI waterwater


Calibration - SecondCalibration - Second

Watts determined Watts determined at four locationsat four locations front rightfront right front leftfront left back right andback right and back leftback left


Determine Power for 210 Determine Power for 210 WattsWatts

1.1. Measure Measure initial tempinitial temp of 1000 ml DI waterof 1000 ml DI water

2.2. Place beaker in the Place beaker in the front left section of front left section of cavitycavity

3.3. Cook 2 minutes at Cook 2 minutes at 210 watts210 watts

36% power36% power4.4. Remove and stir then Remove and stir then

measure measure final tempfinal temp5.5. Repeat steps 1-4:Repeat steps 1-4:

front right, left rear front right, left rear and right rearand right rear


Watts CalculationWatts Calculation

Calculate the watts Calculate the watts for each of these for each of these locations and runslocations and runs

T [final]-T [initial] * 35T [final]-T [initial] * 35 Calculate the average Calculate the average

If the average does If the average does ≠≠ 210 watts OR 210 watts OR

If the watts of any of If the watts of any of the locations is very the locations is very different from the different from the others others

Repeat the stepsRepeat the steps


Determine Power for 390 Determine Power for 390 WattsWatts

1.1. Same stepsSame steps 49% power49% power

2.2. And calculationsAnd calculations


Quality ControlQuality Control

To verify that the samplesTo verify that the samples

have been cooked athave been cooked at

the correct power?the correct power?

(210 then 390 watts)(210 then 390 watts) calibratecalibrate adjustadjust

NIST sampleNIST sample


That’s ItThat’s It

Any QuestionsAny Questions ThanksThanks

microwave calibration brenda r. cleveland plant/waste/solution/media section ncda&cs agronomic...

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