Title

Developing and Validating a Standard Operating Procedure for Quantitative Analysis using Central Washington University's X-ray Diffractometer

Document Type

Poster

Event Website

https://source2022.sched.com/

Start Date

16-5-2022

End Date

16-5-2022

Keywords

X-ray Diffraction, Mineralogy, Quantitative Analysis

Abstract

X-ray diffraction (XRD) is widely applied in a variety of disciplines to identify the different materials present in a powdered sample. Recent software advances allow the use of XRD data analysis to quantify the amount of each material in a sample, but the quality of the result depends on the sample preparation and data collection procedure. I am developing standard operating procedures for sample preparation, data collection, and analysis to achieve optimized results for quantitative XRD analysis of geological samples at CWU. First, I determined that the grinding time necessary to powder 10 g of different mineral samples, at a frequency of 30 Hz, varies considerably depending on mineral type. Biotite and muscovite took the shortest time (35 minutes), while the plagioclase minerals took the longest (at least 70 minutes). Next, I tested the effect of measurement time on data quality, and found that the smaller XRD peaks become more pronounced with increasing measurement time, especially with a duration of 1 hour or more. I performed preliminary quantitative analysis on the mineral samples. Sample purity ranged from 75-99%; I selected samples with more than 90% purity to be used in further tests. Future work will involve using synthetic rock mixtures to determine the accuracy, precision, and detection limits of the XRD’s software by comparing my XRD quantitative analysis results to the known composition of the mixtures. I will then determine the measurement duration necessary to collect publishable results for quantitative analysis, and write standard operating procedures for other users.

Faculty Mentor(s)

Angela Halfpenny, Chris Mattinson

Department/Program

Geological Sciences

Additional Mentoring Department

Geological Sciences

Additional Mentoring Department

William O. Douglas Honors College (DHC)

Additional Mentoring Department

Funding from Central OUR Grants

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May 16th, 12:00 AM May 16th, 12:00 AM

Developing and Validating a Standard Operating Procedure for Quantitative Analysis using Central Washington University's X-ray Diffractometer

X-ray diffraction (XRD) is widely applied in a variety of disciplines to identify the different materials present in a powdered sample. Recent software advances allow the use of XRD data analysis to quantify the amount of each material in a sample, but the quality of the result depends on the sample preparation and data collection procedure. I am developing standard operating procedures for sample preparation, data collection, and analysis to achieve optimized results for quantitative XRD analysis of geological samples at CWU. First, I determined that the grinding time necessary to powder 10 g of different mineral samples, at a frequency of 30 Hz, varies considerably depending on mineral type. Biotite and muscovite took the shortest time (35 minutes), while the plagioclase minerals took the longest (at least 70 minutes). Next, I tested the effect of measurement time on data quality, and found that the smaller XRD peaks become more pronounced with increasing measurement time, especially with a duration of 1 hour or more. I performed preliminary quantitative analysis on the mineral samples. Sample purity ranged from 75-99%; I selected samples with more than 90% purity to be used in further tests. Future work will involve using synthetic rock mixtures to determine the accuracy, precision, and detection limits of the XRD’s software by comparing my XRD quantitative analysis results to the known composition of the mixtures. I will then determine the measurement duration necessary to collect publishable results for quantitative analysis, and write standard operating procedures for other users.

https://digitalcommons.cwu.edu/source/2022/COTS/69