AOAC ERP Fertilizers - December 2017

AOAC RESEARCH INSTITUTE AOAC OFFICIAL METHODS OF ANALYSIS (OMA) OMAMAN-24: DETERMINATION OF TOTAL SULFUR IN FERTILIZERS BY HIGH TEMPERATURE COMBUSTION

BACKGROUND In September 2015, the AOAC Expert Review Panel for Fertilizer Methods, Total Sulfur met to review the manuscript entitled, Determination of Total Sulfur in Fertilizers by High Temperature Combustion as submitted by Elementar Americas. The ERP passed the following motions: 1. Motion by Phillips; Second by Wegner, to move OMAMAN‐24 to AOAC First Action Official Methods status. Passed unanimously. 2. Motion by Phillips; Second by Wegner, to edit the method prior to First Action publication to accommodate sample preparation, instrument conditions, safety, and to allow for other instrument manufacturers. Passed unanimously. In February 2016, the method authors of Elementar Americas submitted their final revised manuscript with the incorporated ERP pre-publication requirements to AOAC. AOAC forwarded the manuscript and AOAC forwarded the revised manuscript to the ERP for review to determine that the ERP pre-publication criteria were met. In March 2016, the following comments resulted from this electronic review by the ERP: 1. Table 1 is out-of-place. The First Action method recommendation is based upon the SLV study and as such there is no collaborative/interlaboratory data available yet. This would be appropriate at the next stage after the collaborative study has been completed, but should be deleted at this point. That said, based upon my next comment, a modified version of Table 1 would be appropriate if previous Elementar data from the SLV study could be compared with new Apparatus B/Figure 2 instrument data from another source(s). 2. The ERP expressed concerns that the method was primarily tailored to one manufacturer. Apparatus B and Figure 2 does adequately address the fact that another common approach/technology exists, but there are also concerns expressed regarding its performance. If data could be generated from one competent lab that uses the Apparatus B/Figure 2, then this comparative data would go a long way to satisfy anyone’s concern about the method being developed for only one instrument manufacturer. 3. This may be beyond the scope of simply determining whether the authors addressed the concerns raised by the ERP, but extra work will be required to place the document in First Action format. For example, sections B and C will require the manufacturer, model or part number, and corporate headquarters and the word “or equivalent.” Also, more information on Preparation of Test Samples (i.e. Prepare an analytical sample of sufficiently small particle size to ensure sufficient representation… is too vague; how to prepare the sample and particle size range is recommended). Reconciling the difference between %S in the sample and mg S in the sample to weigh may need to be added to the calculations and/or in a Table. In May - August 2016: Held teleconferences with ERP chair and the specific ERP member(s) with the above comments to work out details of what would be needed. Additionally, the ERP chair corresponded with the method authors

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