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Laboratory services
generally fall into 2 main groups—that is party or control assays and
umpire or referee assays. Ledoux’s reputation as an umpire laboratory is
well known to the industries that we have serviced for so many years. For
umpire assays, our methods are more rigorous, generally involving different
methods with different chemists responsible and certainly more portions. As
splitting limits have gotten so narrow over the years, umpiring between them is
becoming increasingly more difficult because of analytical differences. You can
very easily see that only certain laboratories with the proper resources will
be able to provide what is expected. As you would expect, the majority of our
referee assays are in the precious metal elements.
Ledoux and Company
routinely use Fire Assay, Clasical Wet
Chemistry and Instrumental Analysis as appropriate to
provide a representative assays for major and minor constituents in your
material.
Methods employed for assay purposes are dependant on the type of
material and the size of a particular lot. Please contact Dr. M.S. Basi: (mbasi@ledoux.com) if you need to discuss any
aspects of assays recommended for your material prior to submitting samples.
The merits and applicability of some of the techniques used everyday at Ledoux
and Co are summarized in the following sections.
Fire Assay
Ledoux and Company
provides comprehensive fire assay facilities for the determination of precious
metals in a variety of materials. The method is capable of extracting milligram
or even microgram amounts of gold, silver and other precious metals from even
the most complex matrices. The technique is rigorously tested and proven to be
accurate and reliable. It is accepted as the method of choice for commercial
assays. Applications include :
• Gold and silver assays for
commercial trade.
• Precious metal determination in scrap and sweeps
from the jewelry industry.
• Evaluation of ores and concentrates.
The laboratory is well equipped with two fusion
furnaces, and two cupellation furnaces for lead fire assay work as well as 2
cupellation furnaces for gold and silver assay
Two additional fusion
furnaces are available for Nickel sulfide and Copper sulfide collections.
Fire Assay personnel at Ledoux and Co are well trained professionals with many
years of experience.
The Company has offered this type of expertise to the
industry throughout the last century.
Wet Chemistry
Our wet
chemistry section is made up of a base metal department, a reforming catalyst
section, an automotive catalyst department and a Precious Metal department.
For precious metals in the trace to few percent range, our analysts
will perform separations, then the solutions go to our ICP department for
measurement.
The company has 3 ICP Emission Spec units and one ICP Mass
Spec unit.
For the higher grades, after separation, generally gravimetric
methods are preferred for the precious metals, and titrimetric methods for the
base metals.
Instrumental
Analysis Instrumental techniques are used
where appropriate for quantification. In this way results can be provided to
the client at an affordable price in a less time that will normally be required
by classical assays. Even in this case initial sample preparation and
separation of the elements of interest is very often necessary to achieve the
quality that the industry has become accustomed from a major independent Lab
like Ledoux and Company.
- Reforming Catalysts
- Autocatalysts
- Mineral and Geological
Materials.
Trace element and trace impurity analysis
Trace element and trace impurity analysis includes all
naturally occurring elements in diverse matrices. Major constituents in a
variety of materials can also be determined. Various instrumental techniques
are employed. However X-ray Fluorescence, plasma emission spectrometry and
atomic absorption have become especially popular over the years. Some of these
techniques and their capabilities have been described below:
Applications:
- Solutions:
Direct
solution analysis is carried out in some cases. Very often some type of
pretreatment is necessary. It may include sample dilution, matrix matching,
internal reference addition etc.
- Metals:
Dissolution
in appropriate acid is the minimum requirement. Trace constituents may need a
chemical separation and pre-concentration for accurate
determination.
- Powders:
Catalysts,
precious metal containing materials, minerals and geological materials require
complex sample handling before presentation for plasma emission analysis. Wet
chemical or fire assay separations are very often needed to produce an accurate
analysis.
Type of materials submitted for
assay include:
- Bullion, metal and dore.
- Scrap and sweeps from the jewelry
industry.
- Ores and concentrates.
- Catalysts.
We also have the capability to test for
halides with our Ion Chromatography equipment. We can also test for carbon
and/or sulfur with our Carbon Sulfur Analyzer. Ledoux & Company also has an
X-ray Fluorescence Unit capable of fast, non-destructive qualitative to
semi-quantitative analysis. This helps to assign samples by identifying the
matrix and relative concentration of the elements present. Accurate
quantitative analysis can be accomplished if proper reference standards are
available.
Ledoux & Company is an ISO
9001-2000 registered company since 2003.
Having now been through three
semi-annual audits, we are keenly aware of what is expected as it pertains to
documentation and quality programs from a laboratory providing services on an
international basis.
Whether or not being ISO certified is important to you
specifically, we cannot know, except to state that such certification implies
that we have methods and operational procedures that are written, and followed,
and that when change is necessary or errors/complaints occur, as they always
do, that such is documented and remedied if necessary.
Through Ledoux's industry alliances, we have
additional sampling capabilities on a national level via locations from New
York to California. At the international level, Ledoux has representation in
Belgium, Canada, France, Germany, Japan, Russia, Spain, Sweden, and the United
Kingdom. |
