New method for determination of total sulfur using high...

New method for determination of total sulfur using high temperature combustion

Tyson RowlandElementar Americas Product Manager

Fertilizer Methods Forum February 2016

A member of elementargroup

Current method

AOAC Method 980.02

• Gravimetric technique using barium to precipitate sulfate and carbon disulfide to solubilize the elemental S

• Drawbacks: this can be labor intensive and require the handling of hazardous materials


Proposal – Make a method for HTC

High temperature combustion

• Fast – single element analysis under 5 minutes

• Less chemicals and in most cases not hazardous materials

• Improve safety

• Multi-element analysis!


Basic operating principle


CH3(CH2)xCH3+ O2

+ contaminants

CO2 + H2O + NOx +SO2

Schematic 1: Infrared Detection


Advantage: Sensitive (as low as a under 10 mg/kg)

Disadvantage: Matrix dependent

Schematic 2: Thermal Conductivity Detection


Advantage: Multi-element analysis for simultaneous N analysis (run in conjunction with AOAC 993.13)

Disadvantage: Sensitivity (as low at 100 mg/kg, 0.01%), time (CNS)

Sample data


H2O

N2

CO2

SO2

• Powerful, clear peak focusing and separation

• Area underneath peak corresponds to element content

Single-lab validation study


Point of Study“Combustion analyzers without absorption/desorption chromatography were investigated by

the Office of the Indiana State Chemist (OISC) as an alternative to the gravimetric method. Matrix and concentration sensitivities posed several analytical challenges, especially when S determination for a wide range of fertilizer products or an unknown source was required. Burn rates, scrubber types, and the need for accelerants was a function of the fertilizer type. As a result, different scan shapes and areas were generated for different products, and the most accurate data were obtained when sample and calibration sources matched. For example, a pure ammonium sulfate [(NH4)2SO4] fertilizer source has a quick burn that requires no accelerant, whereas a blended fertilizer product containing potassium-magnesium sulfate (K2MgO8S2) and potassium chloride (KCl) is a slow burn that may require an accelerant and a halogen scrubber. Another requirement was the separation of samples into low and high S concentrations because low concentration required a longer cell length that could be overwhelmed by high concentration samples resulting in carryover for the subsequent samples. As a result, samples were presorted into categories based upon S source, S concentration, and matrix to best match the calibration material and concentration range. If the S source was unknown, the sample was pretested and the scan compared to scans from various fertilizer sources to determine the best calibration material and concentration. For a company or laboratory that knows the source and history of the product, presorting of samples presents no problem but can be a challenge for a laboratory testing largely unknown samples.

The objective of this work was to investigate an automated, matrix-independent method using less hazardous reagents than the current regulatory procedure that allows equally simple. determination in single species and complex blended fertilizer products.”


SLV Overview


Instrument: vario MACRO cube


Sample preparation (solids)

sample formertin boats and tin foil cups


Sample preparation (liquids)

capsule press



Sample preparation (liquids)


Sample preparation (crucibles)


Sample preparation (auto-loader)


Recent Data – Liquid Fertilizers

Name Area [N] Area [S] % N % S Name Area [N] Area [S] % N % S

Sample 1 35289 25063 11.882 26.811 Sample 3 99 10504 0.044 11.158

Sample 1 36909 26239 11.897 26.853 Sample 3 108 10533 0.046 11.172

Sample 1 34296 24640 11.836 27.023 Sample 3 121 10541 0.051 11.127

Sample 1 40842 29128 11.915 26.95 Sample 3 111 10546 0.047 11.086

Sample 1 36939 26530 11.784 26.869 Sample 3 111 10585 0.047 11.194

Sample 1 37605 26904 11.889 26.999 Sample 3 102 10561 0.044 11.111

Avg. 11.867 26.918 Avg. 0.047 11.141

Dev. 0.049 0.086 Dev. 0.003 0.040

Sample 2 117 18286 0.046 18.001 Sample 4 69 9047 0.035 10.048

Sample 2 119 17423 0.049 18.044 Sample 4 75 9570 0.035 9.938

Sample 2 127 18340 0.049 17.918 Sample 4 77 9909 0.034 9.829

Sample 2 132 19171 0.048 18.023 Sample 4 88 10921 0.035 10.156

Sample 2 121 17215 0.05 17.925 Sample 4 90 12868 0.03 9.939

Sample 2 157 18498 0.057 17.971 Sample 4 74 9482 0.035 9.96

Avg. 0.050 17.980 Avg. 0.034 9.978

Dev. 0.004 0.052 Dev. 0.002 0.112



Sample C% N% S% Comb. S% TKI

Sample 1 0.10 11.87 26.92 26.36

Sample 2 0.07 0.05 17.98 17.00

Sample 3 0.07 0.034 11.14 10.65

Sample 4 0.07 0.034 9.98 9.33



C

N

S


Method Status


Method OrganizationMaterial Expected S (%) No. of Labsa(b) Mean (%) Recoveryc (%) RSDr (%) RSDR (%)

HorRat

2011‐05 1.56 x (y) 0.01 95.0 1.0 1.5 0.52011‐08 6.392011‐06 11.952011‐01 13.222011‐07 7.76(NH4)SO4 24S 12‐508 90Cysteine 26.72Sulpomag 12‐1773 22(NH4)2SO3 12‐591 26K2SO4 KY12289 18a(b) a = number of labs retained after eliminating outliers, (b) = number of labs removed as outliersc c = when applicable

1. Principle2. Apparatus and Materials

a) Apparatus A: By TCDb) Apparatus B: By IR

3. Reagents4. Calibration Curve and Daily Factor5. Preparation of Test Samples (Analytical Samples)6. Determination7. Calculation8. Appendix

Next: Multi-lab validation study

• Currently we have enough labs who have offered to participate in upcoming ILS.


Teresa GrantNorth Carolina Dept. of Agriculture & CoFood and Drug Protection Division

Paulo PagliariAsst ProfessorSoil Water ClimateUniversity of Minnesota/SWROC

Keith WegnerColorado Dept of Agriculture***collaborator and stakeholderContact about Leco analyzer

Larry CihacekSoil ScienceNorth Dakota State University

Jason KongOhio Dept. of Agriculture***stakeholder only

Job FugiceIFDC

Jian ZhangNevada Dept of Agriculture

Frank SikoraUniversity of Kentucky

Calum McCuskerElementar Americas

Bill HallMosaic Fertilizer LLC

Brenda KeaveyWest Virginia Department of AgricultureRegulatory and Environmental Affairs Division***needs to borrow analyzer***collaborator and stakeholder

Jack SchmanskyScotts Company****possible sponsor***collaborator and stakeholder

Sabine KrauseElementar Analysensysteme

Craig SpearsInspectorate3904 Corporex Park Dr.Tampa, FL 33619

Thank you!

Dr. Nancy ThiexAOAC International

Bill HallMosiac

Dr. Michael Hojjatie

Tessenderlo Kerely


New method for determination of total sulfur using high...

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