The Sheffield Assay Office has been in operation for over 250 years. The 1772 Act of Parliament required 30 local men to serve as ‘Guardians of the Standard of Wrought Plate in the Town of Sheffield,’ tasking them with supervising the analysis and hallmarking of silver.
The Office welcomed its first customer on the 11th of September 1772, with the first items hallmarked on the 20th of that month. Since that time, the Office has developed a range of specialized analytical services for the analysis of precious and other metals.
Boasting over two centuries of experience, The Sheffield Assay continues to prioritize independence and integrity in its work, while its reputation for innovation sees a wide range of businesses and other organizations using the Office’s services to ensure consumer protection and product quality.
Almost any element from the periodic table can be analyzed in virtually any matrix, including medical devices, automotive and aerospace components, gold bars, jewelry, and toys.
Technical Considerations
The Sheffield Assay Office’s analytical services division is staffed by around 20 highly qualified laboratory workers and equipped with cutting-edge technology.
Because its customers tend to have such diverse analytical requirements, the Office leverages a range of analytical technologies in its lab. These include ICP/OES, ICP/MS, a type of fine “assay” performed with gravimetry, a significant number of titrations, and a range of further analysis types.
The LECO ONH836 and CS744 analyzers form a core part of the Office’s analysis of gases in solid samples, with these instruments being used to determine the amounts of oxygen, nitrogen, hydrogen, carbon, and sulfur content in several matrices.
These analyzers are also used for testing different metals, including steels, titanium, and other powders used in 3D printing components for medical and aerospace applications. The precise and accurate determination of gas content is especially important for jewelry, because these delicate and often expensive items have very narrow tolerances in terms of acceptable quality.
LECO ONH 836 & CS744 at Sheffield Assay Office Lab. Image Credit: LECO Corporation
Sample Considerations
The Sheffield Assay Office analyzes between 2000 and 2500 samples a month, or 500 and 600 samples a week. Analyses are all performed in duplicate, meaning that the Office processes around 60,000 samples every year.
Gas content in samples can vary greatly. Oxygen content ranges from approximately 10 ppm to more than 5% in most samples, while nitrogen content tends to be no more than 1%.
The widespread development of new batteries has also led to an increase in testing requests for lithium- and silicon-based batteries, with a need to determine carbon and oxygen levels at around 20%.
Samples tend to be tested as received, and no specialized preparation is required unless the customer asks for special treatment. For example, some customers require that the sample surface be cleaned via etching prior to testing.
Data Considerations
Data integrity and efficiency are also vital to the work of the Sheffield Assay Office.
Accurate, error-free data must be transferred to an electronic LIMS system, with the system required to integrate data from several instruments, including ICP/OES and CSONH systems. The LECO CORNERSTONE® software is key to ensuring the smooth integration and processing of this data.
Summary
The Sheffield Assay Office has opted to work with LECO instruments due to its practicality. The option to perform simultaneous multi-element analysis for oxygen, nitrogen, and hydrogen is central to the Office’s ability to process so many samples every month.
The Office also benefits from LECO’s aftersales service and support, maintaining service contracts with LECO on all its instruments.
Acknowledgments
Produced from materials originally authored by Dr. Belen Morales from LECO.
This information has been sourced, reviewed and adapted from materials provided by LECO Corporation.
For more information on this source, please visit LECO Corporation.