13-QAQC and Sample Security

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Considerations on QA&QC and Sample Security

Armando Simn and Greg Gosson

AMEC Americas Limited

Sampling 2008, 27-29 May 2008, Perth, Western Australia


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Presentation Outline

QA/QC and Sample Security

Sampling 2008, 27-29 May 2008, Perth, WA 2

Objective assessment of precision

Why blind insertion of control samples?

QC versus Sample Security

Recommendations


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Introduccin

"Bre-X Minerals eolo ist

The BreThe Bre--X AffairX Affair


Michael de Guzman, centre,conducts a survey with hiscolleagues at the Busang-2 fieldin Indonesia in this March 1997

picture. (Associated Press/Gatra

Magazine)


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Introduccin


!

" #


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Quality in NI 43-101

All written information of scientific or technical naturerelated to mining projects should:

Introduccin


Specifyif a Qualified Person verified the data on which

this information is based, including sampling, assayingand tests

Describethe quality assurance program and the qualitycontrol measures

Describethe nature and limitations of such verification

Explainany deficiencies detected during the verification


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Quality in JORC

A Competent Person report should:

Introduccin


Describethe nature, quality and appropriateselection of sampling and analytical procedures

Describethe quality control procedures, includingthe insertion of standards, blanks, duplicates and

external checks

Assessthe accuracy and precision levels attained

during the project


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However, quality of geological data is a matter

of concern not only for companies working under

Introduccin


- , or o er w e y recogn ze co es:

Hundreds (or thousands?) of private exploration

companies, mines and laboratories are involved

in exploration and mining all over the world.


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Consequence of Lack of QC Protocols

(or Poor QC Protocols)

Entire drilling campaign data may have to be partially or

Quality Control


totally excluded from the resource estimation databases

The estimated resources may be down-graded

If QC data were not timely processed, then only aforensic analysis can be done.


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Quality Control

Hence, we need comprehensive

geological QC programs!!!


,

appropriate measurements (if necessary)

Assessing precision (sampling, sub-sampling,analytical)

Assessing accuracy

Assessing contamination during preparationand assaying


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Assessment of Precision (1)

ISO 3534-1 defines precision as "the closeness of agreement

Quality Control


conditions.

Repeatabilityconditions are fulfilled when re-sampling occurs inthesamesampling intervals, with thesamesampling procedure,

when samples are processed with thesameequipment and thesame preparation procedure, and are assayed with the samemeasuring instrument, under thesamemeasurement conditions,and are repeated over ashort period of time.


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Assessment of Precision (2)

Therefore, an objective assessment of precision on repeatabilityconditions requires thatthe original and the duplicate samples be

Quality Control


.

However, at least for preparation and pulp duplicates this isseldom accomplished:

Duplicates are usually inserted in another batch, sometimesmonths (or years) later, or

Duplicates are submitted to another laboratory, alleguedly toassess precision.


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Is Independent QC Actually Needed? (1)

Internationally certified and competently managed laboratorieshave their own internal QC rotocols and the assa certificates

Quality Control


commonly include the results of at least some of the internallaboratory QC. However,most laboratories will only reveal thosechecks that pass their internal controls, but not the failures.

Problems with sampling, preparation and assaying areseldomtheresult of dishonest attempts to hide or falsify certain facts, butratherunintentional errors or biasintroduced by improper samplecollection, preparation and assaying.


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However, from time to time we witness some deceptive practicesat the laboratory, like:

Quality Control


Altering the sample order:

Preparing all the ordinary samples first, and leaving theblanks to be processed at the end, after cleaning theequipment

Correcting the values of the whole batch to compensate for thedeviations from the CRM certified value.


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Quality Control


n or una e y, regar ess o e goo n en ons o a ora orymanagement, the incidence of poor sample preparation practicesand unreported blank, duplicate and CRM failures ishigher thanexpected or desired.

Sole reliance on the internal laboratory QC is anunacceptably poor practice.


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Do We Need Blind Insertions? The identity and characteristics of the control samples must remain

unknown to the controlled entity. Otherwise, the objectivity is lost,

Blind Insertions


e con ro may no onger e va , an can consequen y e ca einto question.

The purpose of the blind insertion of control samples is to preventthe laboratory from identifying the control samples, or at the very

least, their nature and sought values, so that an objective andindependent assessment of precision, accuracy and contaminationcan be conducted.


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Are Blind Insertions Possible?

Blind insertion of field duplicates and coarse blanks can be easilyconducted at site, during the sampling process.

Blind Insertions


Blind insertion of other control samples (same-batch preparationand pulp duplicates, CRMs, pulp blanks) would require insertion intothe batches during or after sample preparation, and prior toassaying.

Unless sample preparation and assaying take place at differentlaboratories or facilities,this operation would be impossible withoutthe participation of non-laboratory personnel.


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Then, What About Sample Security?

Under these conditions, samples would have to be temporarilyreturned to the custody of anon-laboratory personin charge of theinsertions, even if this occurswithinthe laboratory premises.

Sample Security


Is this an acceptable practice? Does it represent a breach in theChain of Custody principle? If so,what do we give up?

Proper assessment of precision, accuracy and contamination? Sample security and the Chain of Custody principle?

Are those two alternatives compatible?


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Being in Custody

A sample is considered to be in custody if it meets at least one of

Sample Security


t e o ow ng con t ons:

The sample is insomeones physical possession or view;

The sample issecured to prevent tampering; or

The sample is secured in an area restricted to authorizedpersonnel.

(WSDE, 2007)


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Chain of Custody

Chain of Custody is defined as "an unbroken trail of accountability

Sample Security


a ensures e p ys ca secur y o samp es, a a, an recor s

(EPA, 1998).This definition has to do withsecure traceability.

According to this definition, respecting the chain of custody impliesthat it should be known and documented who has custody of asampleat any particular moment. As long as this principle is followed,

the chain of custody concept is respected.


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Currently accepted situations when neither the company

nor the laboratory are in permanent custody of the samples:

Samples are taken on site, andsubmitted for preparation and assaying to

Sample Security


, ,

buffalo, truck, bus, train, plane, mail or courier), using company personnel orcontractors (individuals, same laboratory, another laboratory or othercontractors).

Samples are prepared on site by company personnel or by a specialcontractor or by laboratory personnel, and are submitted for assaying toanother location(city, country or continent) by various means (horse, waterbuffalo, truck, bus, train, plane, mail or courier), using contractors (individuals,

same laboratory, another laboratory or other contractors).


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Currently accepted situations when neither the company

nor the laboratory are in permanent custody of the samples:

Samples are prepared by a laboratory facility in one location andsubmitted

Sample Security


or assay ng o ano er ac yo e same a ora ory n e same oca on or

in another location (city, country or continent) by various means (truck, bus,train, plane, mail or courier) using laboratory personnel or various contractors

(individuals, laboratory, other contractors).

Samples are prepared by a laboratory facility in one location andsubmittedfor assaying to another facilityof another laboratory in the same location or inanother location (city, country or continent) by various means (truck, bus,

train, plane, mail or courier) using laboratory personnel or various contractors.


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Therefore, in spite of the fact that potential

Sample Security


amper ng poss es ex s , suc s ua ons

(and others) are customarily accepted because

changes of custody are well documented with

Chain of Custody forms.


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Conditions for Blind Insertions

The QP is entitled to follow or to accept practices based on

Quality Control versus Sample Security


criteria that aregenerally accepted by the industry, or thatcan reasonably bejustified on scientific or technical grounds.

The QC process should be sufficientlytransparentto preventany suspicion of improper behaviour or actions; an essentialrequirement is that the events should be adequately

documented.


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When AMEC is retained by an exploration or mining companyfor the independent, ongoing review of a quality controlprogram:

Atrained AMEC employeeis in charge of the blind insertion

of control sam les at the laborator remises with

AMECs Blind Insertion Practice


authorization of company and laboratory management; Control samples are repackaged in pouches identical to

those used for unknown samples, supplied by the laboratoryon the spot, and chain of custody forms are filled by theAMEC and the laboratory representativesat the time when

sample custody changes. AMEC does not recommend nor accept that samples be

retrieved from the laboratory premisesbefore assaying for the

insertion of blind control samples or for any other purpose.


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Using one laboratory (or branch) for preparation and insertion of thecontrol samples, and another laboratory (or branch) for assaying.This procedure can be considered as best practice.

Using trained personnel independent of the exploration or mining

Recommended Blind Insertion Procedures


company, w t no veste nterest n t e pro ect, to o t e ninsertionswithin the laboratory premises. This process should bewell documented with chain of custody forms. This procedure can beconsidered as best practice.

Using a trained person from the company to do the blind insertionswithin the laboratory premises. The process should be welldocumented with chain of custody forms. This procedure can beconsidered as acceptable.


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Final Recommendations

Implement from Day 1 a comprehensiveQA/QC


.

Use same-batchduplicates.

Use blindinsertions.

Keep proper records of changes of custody.

13-QAQC and Sample Security

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