Sample Collection

1
Sample Collection

• Most important step is the collection of sample
• Sample for analysis must be representative
• Coarser grain size requires larger initial sample

2
Sample Collection
3
Steps of Procedure

• Sample preparation
• Decomposition
• Separation from interferences
• Analysis

4
Types of Preparation

• Drying
• Pulverizing
• Sieving
• Cutting, grinding, ashing

5
Sample Decomposition

• Acid Attack
• hot concentrated acid mixtures
• HF digestions
• Fusion
• acid - potassium bisulfate
• alkaline - sodium carbonate, lithium tetraborate
• reductive - fire assay

6
Rock Samples
Split Trim 3cm size
Crush 0.5cm
Grind 60-200 mesh
Field Sample
Loss on Ignition
Strong Acid Attack
Fusion
XRF
AAS
Plasma Emission
INNA
Titration Spec.
Separation
7
Rock Analysis
8
Total Iron
Reporting Units ?FeO FeOT FeO ?Fe2O3 Fe2O3T
Fe2O3
9
Water Samples
ISE
Buffers
Filter
Acidify Preserve
Field Sample
Ion Exchange
Solvent Extraction
Evaporation
AAS
Plasma Emission
Color. Spec.
Ion Chrom.
10
Water Analysis
11
Classical Methods

• Titration (Fe2 Alkalinity)
• requires standardization
• Gravimetric (LOI)

12
FeO Titration
Dissolve rock in HF in the presence of excess
vanadate to prevent oxidation of Fe2 by
atmospheric oxygen
Add excess Fe2 to remove excess vanadate prior
to analysis then titrate with dichromate
13
Electromagnetic Radiation
-
Absorption
-

0
0

-
Emission
-
14
Atomic Absorption Spectrophotometer
mirrors
Monochrometer
Photo- detector
Lamp
Half mirror
Rotating mirror
burner
Power Supply
Amplifier and Readout
sample
15
X-ray Fluorescence Spectrometer
X-ray tube
Primary radiation
Analyzing crystal
Secondary radiation
sample
ratemeter
counter
Pulse height analyzer
amplifier
Data collection
16
ICP Spectrometer
detector
detector
Data Collection System
grating
torch
RF generator
Ar
sample
17
Calibration

• Instrumental methods require calibration
• requires known concentration in similar matrix
• linear or non-linear curve