Accuracy & Precision.

Accuracy and precision, what’s the difference? Accuracy and precision are not the same although the terms are both a measure of the reliability of an analytical result. The difference between the two terms is clearly illustrated in the example of a shooters target. Remember a measurement can be precise without being accurate and vice versa. | read more.

Sampling.

An environmental sampling guide is provided for information to assist you in pre field sample collection and preservation. The sampling guide provided is to be used only as a guideline by samplers already familiar with sampling protocols.

Field-blanks are encouraged to monitor the effectiveness of all sample preparers and handlers.

Measurement Uncertainty.

The new accreditation standard ISO/IEC 17025: 1999 requires laboratories to estimate the uncertainty of measurement. The word uncertainty does not inspire confidence, but from an analytical laboratory perspective, uncertainty defines the range of the values that could reasonably be attributed to an analytical result. When laboratories report uncertainty it gives a quantitative indication of the quality of the analytical results. The complexity involved in estimation of uncertainty of measurement in the case of testing varies considerably from one test field to another and also within one field itself. This technical paper outlines the processes involved in measurement uncertainty estimation. | read more.

Implementation of ISO/IEC 17025.

The general requirements for the competence of testing and calibration laboratories is now described by in ISO/IEC 17025: 1999 General requirements for the competence of testing and calibration laboratories. These requirements are designed to apply to all types of testing and calibration. The International Laboratory Accreditation Cooperation (ILAC), of which the National Association of Testing Authorities (NATA) is a full member, has proposed that all laboratories accredited by its members show compliance with ISO/IEC 17025 by 31 December 2002. After that date, NATA accredited laboratories that have not yet demonstrated compliance with the new Standard will not be considered part of the existing multilateral recognition agreements. Therefore the implementation of ISO/IEC 17025: 1999 is pivotal for continued accreditation. | read more.

Internal Audits.

Internal audits are an organisations own process for monitoring the correct implementation of its management system. Internal audits serve three basic purposes:

• To provide assurance to management that the system is operating as intended;
• To investigate the cause of noted problems, determine how the system allowed such problems to occur, and implement corrective action to prevent recurrence;
• To identify opportunities to improve the system or the manner in which it is implemented.

Essentially, internal audits give an organisation assurance regarding the effective operation of its management system and identify opportunities for continuous improvement. This technical paper examines the different types of audit used by auditors and details the processes involved in conducting an internal audit. | read more.

Accreditation of ICP-MS Techniques.

Although ICP-MS techniques has “been around” laboratories for more than a decade, it appears that some laboratories still have difficulties addressing the accreditation requirements of bodies like the National Association of Testing Authorities (NATA). This technical paper “NATA requirements for accreditation of ICP-MS techniques” examines the technical elements that are examined during laboratory assessments when ICP-MS techniques are part of the scope of the accreditation. | read more.

Quality Assurance.

A “Simple Guide to Quality Assurance” examines the quality assurance elements that must be addressed by laboratories and their customers when samples are submitted for analysis. The quality assurance processes begin at the sampling design stage.

The paper looks in detail at method validation & verification as well as QC samples and standards that should be included with sample batches during the analytical process.
| read more.

Buying an Instrument.

Purchasing a new instrument or changing suppliers involves a mixture of reason and emotion, of analysis and salesmanship, of confidence and fear. It’s rather like buying a new house or car. There is no perfect choice, and even one that seems ideal before the purchase will turn out to have severe flaws - or the perfect instrument may have abysmal service.

The “Challenge of Buying an Instrument” gives guidance to laboratories on:

• How a lab can select an instrument in a way that will minimise the chance for errors?
• How laboratories really buy instruments?
• What roles tangible and intangible factors actually play in the purchase process?
• How to gather adequate information about suppliers?

| read more.

Assay Results.

The integrity of a resource database is pivotal to a company’s success in securing debt or equity finance for a new mining project. The quality of data and thus the validity of the database can only be guaranteed when appropriate sampling and assaying protocols have been implemented. No amount of mathematical sophistry can replace them. “Unrealistic Expectations of Assay Results” examines the key sampling, analytical and quality assurance factors impacting on project success and how a project manager should set about establishing an analytical protocol in liaison with a commercial laboratory. What can really be expected from assay data? Laboratories are not perfect, mistakes can happen we are all human, even geologists make mistakes. It is the duty of both the chemist and geologist to minimise mistakes, and ensure that assay data is fit for purpose. An analytical performance specification should be clearly defined in contract documents ensuring laboratories deliver technically sound and legally defensible assay results. It is irresponsible to assay samples using a “cheap and nasty” geochemical technique if the project involves resource estimation. | read more.

Reference Materials.

The “Use of Reference Materials in the Laboratory” examines in detail the use of reference

materials in the laboratory. It is generally accepted that references materials serve five main purposes in a laboratory:

• Method development & validation.
• Verification of instrument, laboratory and chemist.
• To calibrate measurement systems.
• Instrument calibration.
• Internal quality control.
• Uncertainty estimation.