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Thiex N.,Thiex Laboratory Solutions LLC | Paoletti C.,European Food Safety Authority | Esbensen K.H.,Geological Survey of Denmark | Esbensen K.H.,University of Aalborg
Journal of AOAC International | Year: 2015

International acceptance of data is a much-desired wish in many sectors to ensure equal standards for valid information and data exchange, facilitate trade, support food safety regulation, and promote reliable communication among all parties involved. However, this cannot be accomplished without a harmonized approach to sampling and a joint approach to assess the practical sampling protocols used. Harmonization based on a nonrepresentative protocol, or on a restricted terminology tradition forced upon other sectors would negate any constructive outcome. An international discussion on a harmonized approach to sampling is severely hampered by a plethora of divergent sampling definitions and terms. Different meanings for the same term are frequently used by the different sectors, and even within one specific sector. In other cases, different terms are used for the same concept. Before efforts to harmonize can be attempted, it is essential that all stakeholders can at least communicate effectively in this context. Therefore, a clear understanding of the main vocabularies becomes an essential prerequisite. As a first step, commonalities and dichotomies in terminology are here brought to attention by providing a comparative summary of the terminology as defined by the Theory of Sampling (TOS) and those in current use by the International Organization for Standardization, the World Health Organization, the Food and Agriculture Organization Codex Alimentarius, and the U.S. Food and Drug Administration. Terms having contradictory meaning to the TOS are emphasized. To the degree possible, we present a successful resolution of some of the most important issues outlined, sufficient to support the objectives of the present Special Section.


Medina L.C.,University of Florida | Medina L.C.,Monsanto Corporation | Sartain J.B.,University of Florida | Obreza T.A.,University of Florida | And 2 more authors.
Journal of AOAC International | Year: 2014

Several technologies have been proposed to characterize the nutrient release patterns of slowrelease fertilizers (SRF) and controlled-release fertilizers (CRF) during the last few decades. These technologies have been developed mainly by manufacturers, and are product-specific, based on the regulation and analysis of each SRF and CRF product. Despite previous efforts to characterize SRF and CRF materials, no standardized, validated method exists to assess their nutrient release patterns. However, the increased production and distribution of these materials in specialty and nonspecialty markets requires an appropriate method to verify product claims and material performance. A soil incubation column leaching procedure was evaluated to determine its suitability as a standard method to estimate nitrogen (N) release patterns of SRFs and CRFs during 180 days. The influence of three soil/sand ratios, three incubation temperatures, and four soils on method behavior was assessed using five SRFs and three CRFs. In general, the highest soil/sand ratio increased the N release rate of all materials, but this effect was more marked for the SRFs. Temperature had the greatest influence on N release rates. For CRFs, the initial N release rates and the percentage N released/day increased as temperature increased. For SRFs, raising the temperature from 25 to 35°C increased initial N release rate and the total cumulative N released, and almost doubled the percentage released/day. The percentage N released/day from all products generally increased as the texture of the soil changed from sandy to loamy (Iowa>California>Pennsylvania>Florida). The soil incubation technique was demonstrated to be robust and reliable for characterizing N release patterns from SRFs and CRFs. The method was reproducible, and variations in soil/sand ratio, temperature, and soil had little effect on the results.


Medina L.C.,University of Florida | Medina L.C.,Monsanto Corporation | Sartain J.B.,University of Florida | Obreza T.A.,University of Florida | And 2 more authors.
Journal of AOAC International | Year: 2014

Several technologies have been proposed to characterize the nutrient release and availability patterns of enhanced-efficiency fertilizers (EEFs), especially slow-release fertilizers (SRFs) and controlled-release fertilizers (CRFs) during the last few decades. These technologies have been developed mainly by manufacturers and are productspecific based on the regulation and analysis of each EEF product. Despite previous efforts to characterize EEF materials, no validated method exists to assess their nutrient release patterns. However, the increased use of EEFs in specialty and nonspecialty markets requires an appropriate method to verify nutrient claims and material performance. A series of experiments were conducted to evaluate the effect of temperature, fertilizer test portion size, and extraction time on the performance of a 74 h accelerated laboratory extraction method to measure SRF and CRF nutrient release profiles. Temperature was the only factor that influenced nutrient release rate, with a highly marked effect for phosphorus and to a lesser extent for nitrogen (N) and potassium. Based on the results, the optimal extraction temperature set was: Extraction No. 1-2:00 h at 25°C; Extraction No. 2-2:00 h at 50°C; Extraction No. 3-20:00 h at 55°C; and Extraction No. 4-50:00 h at 60°C. Ruggedness of the method was tested by evaluating the effect of small changes in seven selected factors on method behavior using a fractional multifactorial design. Overall, the method showed ruggedness for measuring N release rates of coated CRFs.


Medina L.C.,University of Florida | Medina L.C.,Monsanto Corporation | Sartain J.,University of Florida | Obreza T.,University of Florida | And 2 more authors.
Journal of AOAC International | Year: 2014

Several technologies have been proposed to characterize the nutrient release patterns of enhanced-efficiency fertilizers (EEFs) during the last few decades. These technologies have been developed mainly by manufacturers and are productspecific based on the regulation and analysis of each EEF product. Despite previous efforts to characterize nutrient release of slow-release fertilizer (SRF) and controlled-release fertilizer (CRF) materials, no official method exists to assess their nutrient release patterns. However, the increased production and distribution of EEFs in specialty and nonspecialty markets requires an appropriate method to verify nutrient claims and material performance. Nonlinear regression was used to establish a correlation between the data generated from a 180-day soil incubation-column leaching procedure and 74 h accelerated lab extraction method, and to develop a model that can predict the 180-day nitrogen (N) release curve for a specific SRF and CRF product based on the data from the accelerated laboratory extraction method. Based on the R2 > 0.90 obtained for most materials, results indicated that the data generated from the 74 h accelerated lab extraction method could be used to predict N release from the selected materials during 180 days, including those fertilizers that require biological activity for N release.


A single-laboratory validation study was conducted for the simultaneous determination of arsenic, cadmium, calcium, cobalt, copper, chromium, iron, lead, magnesium, manganese, molybdenum, nickel, selenium, and zinc in all major types of commercial fertilizer products by microwave digestion and inductively coupled plasma-optical emission spectroscopy analysis. This validation study proposes an extension and modification of AOAC 2006.03. The extension is the inclusion of calcium, copper, iron, magnesium, manganese, and zinc, and the modification is incorporation of hydrochloric acid in the digestion system. This dual acid digestion utilizes both hydrochloric and nitric acids in a 3 to 9 mL volume ratio/100 mL. In addition to 15 of the 30 original validation materials used in the 2006.03 collaborative study, National Institute of Standards and Technology Standard Reference Material 695 and Magruder 2009-06 were incorporated as accuracy materials. The main benefits of this proposed method are a significant increase in laboratory efficiency when compared to the use of both AOAC Methods 965.09 and 2006.03 to achieve the same objective and an enhanced recovery of several metals.

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