2. HISTORY OF SHEFFIELD ASSAY OFFICE
Assay of an item involves testing and assessing the precious metal
content.
1772 Act of Parliament assigned 30 men the job to assay and hallmark
silver at the office – they were appointed the title of Guardians.
At the beginning, business was only local and precious items were ‘over
the counter’ for assay service.
3. TODAY…
Sheffield Assay Office is divided into hallmarking department and
Analytical Laboratory department.
The Analytical division has offered precious metal hallmarking and
analysis for over 245 years.
The cutting edge technology is very different from Sheffield assay
office’s origins in hallmarking.
A wider variety of businesses and industries are customers of the
analytical department; the assay office was originally for the
jewellery trade.
One of the first laboratories in the UK to become UKAS accredited
to ISO 17025 standard.
4. ANALYTICAL
SERVICES
LABORATORY
This department offers a range of
services which includes:
Metal and alloys analysis
Minerals, environmental and
healthcare
Precious Metals analysis
3D printing powders
Jewellery testing
Nickel testing
Mercury screening
5. MY EXPERIENCE
Originally placed in the precious metal analysis.
Fully trained in this service and spent the
majority of the placement in this role.
Day to day, samples would arrive and be directed
to the appropriate service. Some samples would
require multiple services.
The laboratory has analytical testing methods
(ATM’s) that are specifically followed for each
method/service.
For me, the method I focused on in precious
metal analysis involved qualitative determination
of elements in samples using XRF, prepping the
sample, dissolving and batching up ready for
ICP-OES analysis for quantitative results.
6. THE SCIENCE
For precious metal analysis, the method performed was
an aqua regia.
If a customer is interested in gold, palladium, platinum
(or less frequently rhodium, nickel and iridium), the
sample will be sent to precious metal analysis.
XRF is used for a quantitative result of elements in the
sample – these percentages are used for a rough idea of
what treatment the sample requires.
For a typical sample, sample prep involved pressing and
rolling. A specific amount is then weighed into the
correct apparatus.
An aqua regia is then performed, following the ATM,
using the correct amount of acid.
7. BROADENING MY KNOWLEDGE
Other methods I was trained on were metallic and powder nitro-
sulphuric silver, potentiometric silver titrations, and powder acid
dissolutions.
Being trained on multiple areas made the experience more engaging
as if a sample required different methods, it was interesting to follow
it all the way through the process.
All samples are analysed by senior analysts using ICP-OES/ICP-MS. I
asked for a talk through and demonstration of the process of the
sample process using this instrumentation.
I also had a demonstration in the furnace room of using the furnace
for pot smelts.
8. SKILLS AND
ATTRIBUTES
Confidence – shadowed by UKAS auditor
Communication – making sure samples are directed to the correct place
Teamwork – helping others if they’re busy vice versa in order to reach
the sample deadline
Creativity – if unfamiliar samples needed the method tweaking.
Problem solving – fluctuating results meant repeat samples to identify
the cause.
Time management – meeting sample turnaround times whilst
maintaining accuracy and precision
