AOAC RI ERP EBOOK FOR FERTILIZERS

AOAC RESEARCH INSTITUTE AOAC OFFICIAL METHODS OF ANALYSIS (OMA)

OMAMAN-28/AOAC 2006.03 Study Director: Sharon Webb, University of Kentucky, Division of Regulatory Services, 103 Regulatory Services Bldg, Lexington , Kentucky 40546-0275 17 materials have been utilized for the validation, including two samples for the determination of accuracy; in addition, data demonstrating calibration and linearity, accuracy, precision, comparability, working range, LOD/LOQ estimation, and ruggedness tests are present. In general, the document method performance is compliant with Standard Method Performance Requirements (SMPR) criteria. Method is well written and data presented supports most conclusions. Lot's of good work done in the study and background research. well thought out and much needed.

ER 9

ER 10 None Pros/Strengths of the Manuscript: ER 1

QC and analytical methodology is fine

ER 2

The purpose of the study is easy to understand and the data represents marked improvement over AOAC 2006.03 for Group B metals. The ruggedness testing section is excellent and well- done.

ER 3 ER 4 ER 5 ER 6 ER 7 ER 8

Will expedite lab analyses and have cost savings

Well written and validated

The manuscript references many different methods, used Magruder samples for consistency.

fast analysis

Clear explanation of the results

The paper considers the following aspects with high attention: 1) Choice of samples for validation. 15 of the 30 original collaborative study materials from 2006.03 have been used for method validation. In addition, NIST SRM 695 and Magruder 2009- 06 have been incorporated as validation materials 2) Description of needed equipments and reagents 3) Description of operative procedures, from the description of the principle of the proposed method and instrumentation to calculations and quality control tests 4) Validation study: Calibration and Linearity; Trueness or Accuracy; Precision; Comparability; Working range; LOD and LOQ estimation; Ruggedness tests. In detail, Authors claim (preliminary study results – Appendix - comparison of the new method with AOAC 965.09, AOAC 2006.03, hot block-acid digestion and microwave acid digestion) that the simultaneous digestion with two acids and the subsequent ICP-OES analysis allow a notable recovery for both metal Groups. There are not significant differences between AOAC 965.09 and the proposed method with relation to Ca, Cu, Mn and Zn (P = 0.05), while differences are significant for Mg (P level of 0.05). The same situation is observed when comparing the proposed extension and AOAC 2006.03. For this reason, it may be assumed that Mg should be recovered with addition of HCl. The same situation is observed with iron; in addition: a) Should Fe be derived from organic materials, AOAC 965.09 Part C method would not be applicable b) Should Fe be in the range: 10-50 %, the mixed digestion method should demonstrate slightly

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