+255 760 759 472
info@orelysis.com
Contact Us

The 3 Duplicate types every Geochemist must understand: Precision #One.

Orelysis Geosciences

·

·

Duplicate analysis is the primary method for quantifying precision in geochemical programs. Precision, however, is not a single value. It comprises multiple components, each attributable to a distinct stage of the sampling and analytical sequence. Selecting the appropriate duplicate type is therefore essential for making technically sound, data-driven decisions.

Field Duplicate / Twin Sample
Independently collected from the same sampling interval or location.

Variance captured: Total variance, encompassing geological heterogeneity, sampling error, sample preparation error, and analytical error.

Key metric: Half Absolute Relative Difference (HARD%). Elevated variance at this stage typically indicates geological variability, deficiencies in sampling methodology, or both.

Preparation Duplicate / Coarse or Pulp Split
A subsample obtained from the same crushed or pulverised material before withdrawal of the final analytical aliquot.

Variance captured: Sample preparation error and analytical error only. Geological and sampling variance are excluded.

Application: Comparison with field duplicate results isolates and quantifies the combined geological and sampling error component.

Analytical Duplicate / Laboratory Pulp Replicate
A second subsample was weighed from the same pulp and subjected to independent digestion and measurement.

Variance captured: Analytical precision attributable to the instrument and method only.

Identifying which variance component is dominant is critical for targeted quality improvement. When field duplicate variance is high but analytical duplicate variance is low, imprecision originates in field sampling and sample preparation rather than in laboratory analysis.

Orelysis Geosciences

Leave a Reply

Your email address will not be published. Required fields are marked *