Analytical Methods

Standard and Reference has a long-term and ongoing commitment to research and development, which leads to unique and quantifiable steps in method development.
The following methods reflect our commitment to classical methods over less accurate instrumental methods at high concentrations.

The techniques developed at Standard and Reference, are complimented by those developed and refined at other laboratories within the Inspectorate group.

Silver - Concentrates

Samples are assayed by fire assaying with a gravimetric finish.
If the sample contains Gold, the Silver is dissolved, the Gold quantified and subtracted from the total.
The extra steps taken on concentrates samples are:

Silver corrections - if the sample is parted, the resultant Gold is dissolved and any retained silver quantified to add to the silver result.

Slag and cupel corrections - for samples with relatively high silver content (>1000g/T) the assay slag and cupel is refired, and the recovered silver is added to the initial result.

Cupel recoveries - Silver retained in the cupel is recovered, quantified, and added to the main portion of Silver.
For high Silver levels this is done in addition to the slag and primary cupel recoveries i.e the process involves recovery of Silver from two cupels.

Gold – Concentrates

Samples are assayed by fire assaying with a gravimetric finish.
Extra corrections to improve precision and accuracy include:

Slag and cupel corrections – the assay slag and cupel are refired, and the Gold content quantified by AAS to correct the Gold result

Silver corrections – the solid gold retrieved from the initial fire assay process is dissolved and any contained silver is quantified by AAS to remove any errors from the Gold result

These corrections are carried out on all Gold party assays.

Gold – Lower Levels

Samples are assayed by fire assaying.
For Gold levels greater than 2g/T the resultant prill is parted and the Gold quantified gravimetrically to 0.1micrograms.
For levels less than 2g/T the entire resultant prill is dissolved and the gold quantified by AAS.

Copper - Concentrates

Short Iodide Titration
The sample is digested and titrated with sodium thiosulfate.

Electro-Gravimetric
The sample is digested and the Copper plated out onto platinum electrodes.
The resultant Copper is quantified gravimetrically.

Copper – Lower Levels

AAS Analysis
The sample is digested and quantified by AAS.This method can be combined with other AAS-readable elements.

Lead

The sample is digested and the lead precipitated, removed from impurities and redissolved before titrating
with Ethylene Diamine Tetraacetic Acid (EDTA).

Zinc

The sample is digested and the impurities removed before titrating the zinc with EDTA.
The separated impurities are redissolved and the zinc content quantified by AAS to improve the accuracy.
The entire process takes at least 3 days.

Nickel

The sample is digested and the nickel is precipitated with Dimethyl Glyoxime (DMG).
The precipitate is filtered and quantified gravimetrically. As an extra step, the precipitate can be redissolved
and precipitated to remove any possible copper precipitate that could cause an erroneously high result.

Other Elements

When extra elements are required, other suitable methods are available.
These other methods include:

· Platinum / Palladium – via fire assay, graphite furnace (ETA)

· Sulphur – gravimetric precipitation analysis

· Aluminium – sodium hydroxide fusion

· Chloride – potentiometric or ion selective electrode

· Fluoride – ion selective electrode

· Mercury – hydride generation

· Magnesium – gravimetric or titration

· Iron – dichromate titration

Other Metals – various digests and dilutions to suit your requirements.

In addition to the specialised assays listed here, we also offer mainstream geochemical analytical methods.

Please contact us to discuss your specific needs.

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