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J AOAC Int

Title:		Comparison of environmental chemical results for split samples analyzed in different laboratories
Author(s):		Grant CL; Jenkins TF; Mudambi AR;
Address:		"University of New Hampshire, Chemistry Department, Durham 03824, USA"
Journal Title:		J AOAC Int
Year:		1997
Volume:		80
Issue:		5
Page Number:		1129 - 1138
DOI:
ISSN/ISBN:		1060-3271 (Print) 1060-3271 (Linking)
Abstract:		"Data comparisons were made for split or co-located samples analyzed in contract laboratories and quality assurance (QA) laboratories during environmental studies directed by the U.S. Army Corps of Engineers. Archived results were analyzed statistically as concentration ratios (contract laboratory/QA laboratory). Concentration ratios were found to be lognormally distributed, and this was the model used for comparisons. For metals in soils and volatile organic compounds (VOCs) in groundwater, 10.2% of metal ratios in soils and 5.6% of VOC ratios in groundwater exceeded limits of 0.40-2.50. Considering that both methods are multianalyte, we find that only 4.0% of the metal samples and 2.0% of the VOC samples had more than one outlier ratio per sample. More recent data produced very similar results. For VOCs, total petroleum hydrocarbons (TPHs), and explosives in soils, limits of 0.25-4.00 are suggested with the understanding that large improvements are badly needed. Even with these wide limits, approximately 42% of VOCs, 14% of TPHs, and 11% of explosives contract laboratory/QA laboratory ratios were outside these limits. Here, too, the most recent data yielded very comparable results. Sampling and preparation procedures for VOCs in soils requires immediate attention, but all methods can and should be capable of producing improved agreement between laboratories"
Keywords:		"*Clinical Laboratory Techniques Environmental Monitoring/*methods Fresh Water/*chemistry Logistic Models Metals/*analysis Organic Chemicals/analysis Quality Assurance, Health Care Soil Pollutants/*analysis Volatilization Water Pollutants, Chemical/*analys;"
Notes:		"MedlineGrant, C L Jenkins, T F Mudambi, A R eng Comparative Study Research Support, U.S. Gov't, Non-P.H.S. England 1997/11/05 J AOAC Int. 1997 Sep-Oct; 80(5):1129-38"