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LOD/LOQ for ICP measurements in water samples with different nebulizers
Jana Durkovicova, operator of ICP and head of CFL NFC Zvolen, Slovakia
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• Central Forest Laboratory was moved to the reconstructed laboratory of Forestproject at the Sokolská Street 2 at the beginning of 2010.
• Laboratory was updated purchasing new lab furniture, new modern analytical apparatus and appropriate equipment.
• One of the most important machine was AES ICP spectrometer VARIAN 725 ES with radial plasma and Wgroove nebulizer in Sturman Master spray chamber
• The first samples validated by AES ICP were water samples.• The topic of my presentation is „ Comparison LOD and LOQ in waters
measured by ICP AES VARIAN 725 with using various types of nebulizers
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Determination LOD, LOQ for water samples
• LOD - limit of detection - the lowest signal that can be measured by given technique
• LOQ - limit of quantification - the lowest possible concentration, which can provide results by given technique with some uncertainty
• The principle of our determination LOD/LOQ is the measurement ofdeionised water at least 10 times for each elements
• The results are expressed in mg / l
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Determination LOD, LOQ for water samples
• Calculate standard deviation
• LOD - 3 times the standard deviation
• LOQ -10 times the standard deviation
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Chemicals
• Deionised water with EC = 1, uScm-1
• standard solutions S1, S2, S3 S4 with different concentrations of elements
The device
• Atomic emission spectrometer with inductively coupled plasma VARIAN 725 EC • Wgroove nebulizer with Sturman Mastrers spraychamber• MEINHARDT nebulizer with Sturman Mastrers spraychamber• USN 5000 AT CETAC
0,0050,020,0050,020,0050,030,070,0050,10,005mg/lSt 1
0,050,20,050,20,050,30,70,0510,05mg/lSt 2
0,520,520,5370,5100,5mg/lSt 3
520520510705505mg/lSt 4
CuTPTZnTNaTMnTMgTKTFeTCaTAlT
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Determination LOD, LOQ for water samples
Conditions
• Performance of plasma = 1,15 kW
• Cool flow = 15 l/min
• Plasma flow = 7 l/mn
• Sample flow = 0,75 l/mi
• Integration time for Ca, Mg, Na= 1 s
• Integration time for Al, Cu, Fe, K, Mn, P, Zn= 4 s
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0,00110,02560,00250,00330,00120,00170,01880,00300,01620,002619.4.2011USN CETACLOQ
0,00030,00770,00080,00100,00040,00050,00560,00090,00490,000819.4.2011USN CETACLOD
0,000110,002560,000250,000330,000120,000170,001880,000300,001620,0002619.4.2011USN CETACDeviation.
-0,0006-0,0098-0,0011-0,0128-0,00130,0164-0,01720,00090,0582-0,002919.4.2011USN CETACAverage
324,754213,618213,857589,592257,610279,533766,491238,204422,673396,152nm
CuTPT ZnTNaTMnTMgTKTFeTCaTAlT
0,00910,01930,00380,00060,15560,01680,00060,02997.1.2011W GrooveLOQ
0,00270,00580,00110,00020,04670,00500,00020,00907.1.2011W GrooveLOD
0,0010,00190,00040,000060,0160,0020,00010,00307.1.2011W GrooveDeviation.
no signal-0,010-0,0081-0,00072-0,01070-0,021-0,014-0,03900,00207.1.2011W GrooveAverage
324,754213,618213,857589,592257,610279,533766,491238,204396,847396,152nm
CuP ZnTNaTMnTMgTKTFeTCaTAlT
0,69420,01410,06380,00550,00130,49800,02670,04050,067518.2.2011MeinhardtLOQ
0,20820,00420,01910,00160,00040,14940,00800,01220,020218.2.2011MeinhardtLOD
0,06940,0010,00640,0010,000130,04980,00270,00410,006718.2.2011MeinhardtDeviation.
-0,18110,0020,0081-0,001-0,000010,04470,00400,00001-0,008518.2.2011MeinhardtAverage
mg/lmg/lmg/lmg/lmg/lmg/lmg/lmg/lmg/lmg/l
324,754213,618213,857589,592257,610279,533766,491238,204422,673396,152nm
CuP ZnTNaTMnTMgTKTFeTCaTAlTdate
Tab1Results of different nebuliser LOD a LOQ
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0,00030,00770,00080,00100,00040,00050,00560,00090,00490,000819.4.2013USN CETAC
0,00270,00580,00110,00020,04670,00500,00020,00907.1.2011W Groove
0,20820,00420,01910,00160,00040,14940,00800,01220,020218.2.2011Meinhardt
CuTPTZnTNaTMnTMgTKTFeTCaTAlT
Comparision LOD of various nebulizers
0,0000
0,0500
0,1000
0,1500
0,2000
0,2500
AlT CaT FeT KT MgT MnT NaT ZnT PT CuT
mg/l
Meinhardt 18.2.2011W Groove 7.1.2011USN CETAC 19.4.2013
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0,00110,02560,00250,00330,00120,00170,01880,00300,01620,002619.4.2014USN CETAC
0,00910,01930,00380,00060,15560,01680,00060,02997.1.2011W Groove
0,69420,01410,06380,00550,00130,49800,02670,04050,067518.2.2011Meinhardt
CuTPTZnTNaTMnTMgTKTFeTCaTAlTdátumLOQ
Comparision LOQ of various nebulizers
0,0000
0,1000
0,2000
0,3000
0,4000
0,5000
0,6000
0,7000
AlT CaT FeT KT MgT MnT NaT ZnT PT CuT
mg/l
Meinhardt 18.2.2011W Groove 7.1.2011USN CETAC 19.4.2014
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102,0093,25100,10109,8398,4098,39100,6182,7094,65106,70RecoveryUSN
2,7731,8964,0972,3503,7373,2102,5601,1972,4650,398CVUSN
0,00140,00350,00210,00520,00180,00950,01800,00050,02330,0002DeviationUSN
0,05100,18650,05010,21970,04920,29520,70430,04140,94650,0534AverageUSN
94,7059,2891,3381,0297,2594,1076,4259,1593,3293,20RecoveryWgroove
0,71415,7142,2771,4861,5410,9411,5448,6191,2923,183CVWgroove
0,00030,01860,00100,00240,00070,00270,00830,00250,01210,0015DeviationWgroove
0,04740,11860,04570,16200,04860,28230,53500,02960,93320,0466AverageWgroove
0,050,20,050,20,050,30,70,0510,05mg/l
CuP ZnTNaTMnTMgTKTFeTCaTAlTSt 2
90108,599281,2510094,5121,5117100,584,00RecoveryUSN
3,1431,9557,1423,6462,8284,2080,4163,6260,70421,162CVUSN
0,000140,000420,000350,002050,000140,001190,000350,000210,000710,00089DeviationUSN
0,00450,02170,004950,056250,0050,028350,085050,005850,10050,0042AverageUSN
110,67-62,0699,56107,38118,37142,17-98,13-347,62103,63103,33RecoveryWgroove
4,998-144,4218,96718,36512,9481,691-9,201-3,3163,53515,627CVWgroove
0,00030,01790,00040,00390,00080,00070,00630,00060,00370,0008DeviationWgroove
0,0055-0,01240,00500,02150,00590,0426-0,0687-0,01740,10360,0052AverageWgroove
0,0050,020,0050,020,0050,030,070,0050,10,005mg/l
CuP ZnTNaTMnTMgTKTFeTCaTAlTSt 1
Coeficient of variance as an expresion of precision for measuring of elements was determinatedfrom several measurements of Standard solutions S1-HS.
Tab 2.
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106,64101,3899,93106,48100,49107,30110,1999,48105,92105,54RecoveryUSN
4,7216,0865,1653,7525,9254,2544,3466,2273,1514,904CVUSN
0,25171,23390,25810,79900,29770,45653,35170,30971,66880,2588DeviationUSN
5,33220,2764,996521,2955,024510,7377,134,97452,965,277AverageUSN
100,4899,85100,7798,3390,8299,5296,17104,9789,0897,03RecoveryWgroove
0,1860,5500,3061,6983,0120,7590,3931,1420,6760,546CVWgroove
0,00940,10980,01540,33390,13680,07550,26470,05990,30090,0265DeviationWgroove
5,0219,975,0419,674,549,9567,325,2544,544,85AverageWgroove
520520510705505mg/l
CuP ZnTNaTMnTMgTKTFeTCaTAlTHS
100,40100,0898,6298,70100,42100,84100,8198,5098,70101,07RecoveryUSN
1,4091,1660,2296,8781,0986,3221,4431,0057,0211,357CVUSN
0,00710,02330,00110,13580,00550,19120,10180,00490,69300,0069DeviationUSN
0,5022,00150,49311,9740,50213,02516677,0570,49259,870,50535AverageUSN
98,33107,4298,76102,7297,4497,93102,73103,7397,9896,95RecoveryWgroove
0,0871,3361,0302,0420,5400,3750,4760,4870,7140,498CVWgroove
0,00040,02870,00510,04190,00260,01100,03420,00250,07000,0024DeviationWgroove
0,49172,14830,49382,05440,48722,93797,19130,51879,79850,4848AverageWgroove
0,520,520,5370,5100,5mg/l
CuP ZnTNaTMnTMgTKTFeTCaTAlTSt 3
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4,7216,0865,1653,7525,9254,2544,3466,2273,1514,904CVUSN
0,1860,5500,3061,6983,0120,7590,3931,1420,6760,546CVWgroove
520520510705505mg/lHS
1,4091,1660,2296,8781,0986,3221,4431,0057,0211,357CVUSN
0,0871,3361,0302,0420,5400,3750,4760,4870,7140,498CVWgroove
0,520,520,5370,5100,5mg/lSt 3
2,7731,8964,0972,3503,7373,2102,5601,1972,4650,398CVUSN
0,71415,7142,2771,4861,5410,9411,5448,6191,2923,183CVWgroove
0,050,20,050,20,050,30,70,0510,05mg/lSt 2
3,1431,9557,1423,6462,8284,2080,4163,6260,70421,162CVUSN
4,998-144,4218,96718,36512,9481,691-9,201-3,3163,53515,627CVWgroove
0,0050,020,0050,020,0050,030,070,0050,10,005mg/lSt 1
CuP ZnTNaTMnTMgTKTFeTCaTAlTSt 1
CV nebulizers - comparision
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Interpretation of results
• We compared Coefficient of variance (CV) for USN and Wgroove nebulizer.
• USN nebulizer has lower CV values for low concentration as we can see on the results of standard solution S1 and S2.
• This nebuliser was more stabile for low concentration .
• Wgroove nebulizer has better CV values for higher concentration in S3
and S4 solutions • Dispersion of measurements for every elements was lower with using
Wgroove nebulizer than USN one for high conentration.
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Conclusion
• USN CETAC nebulizer provides the better results for lower concentration of elements than Wgroove or Meinhardt nebulizers. Loading the sample to the plasma by this system is more suitable mainlyfor Al, Fe, K, P
• The results of USN nebulizer according to CV values areacceptable only for lower concentration (S1, S2) but not for higher concentration (S3,S4). W groove nebulizer is more suitable for higher concentration. The dispersions of measured values is lower in comparison of USN nebulizer
• The establishment of the efficient and homogeneous fog created through US transduser is very important thing for the achievement of reliable and precious results.
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• Thank for your attention
• Please, send me your questions on the e-mail [email protected] and I will answer you in written form .
