Protocols and Safet Guidelines
SAMPLE PREPARATION FOR DOSE ESTIMATION
This section provides guidelines for sample preparation and the safety procedures required in the laboratory.
OSL dating is most commonly applied to quartz and feldspar grains from sand (63–250 µm) or fine silt (4–11 µm) fractions. Tables 1 and 2 below outline the preparation steps for concentrating quartz and feldspar grains in these size ranges. An illustrated guide of sample preparation for the sand fraction is also available (português/english)
Table 1. Steps for sample preparation of quartz or feldspar in fine to very fine sand fraction.
1
Opening of samples under subdued orange/red light. Discard portions that were exposed to the light during field sampling.
2
Wet sieving of 180 – 250 µm (or 63 – 125 µm or 125-180 µm) fraction
3
38% H2O2 treatment
4
10% HCl treatment
5
Drying for ~24h
6
Mineral separation with LMT liquid (click here to see mineral separation protocol)
7
40% HF (quartz) or 10% HF (feldspar) treatment
8
10% HCl treatment
9
Dry sieving of 180 – 250 µm (or 63 – 125 µm or 125-180 µm) fraction
Table 2. Steps for sample preparation of polymineral silt fraction.
1
Opening of samples under subdued orange/red light. Discard portions that were exposed to the light during field sampling.
2
Wet sieving of < 63 µm fraction
3
Settling for separation of 4 – 11 µm fraction (click here to see the settling protocol
4
38% H2O2 treatment
5
10% HCl treatment
6
Storage of the silt fraction in acetone solution
As part of the preparation process, hydrofluoric acid (HF) is required to obtain pure quartz or feldspar concentrates. Since HF is highly toxic and corrosive, this SOP (português/english) provides guidelines for its safe handling in the laboratory.
SAMPLE PREPARATION FOR DOSE RATE ESTIMATION
To determine luminescence ages, the dose rate of ionizing radiation absorbed by a sample must be calculated. For that, sample preparation is also required. You can find instructions on sample preparation for dose rate calculations here: português/english.
USE OF IONIZING RADIATION AT LEGAL
The laboratory has four sealed radioactive sources installed in the equipment — three used in the Automated TL/OSL readers DA-20 and DA-22, and one used in the Lexsyg Smart Luminescence Measuring System. This SOP (português/english) provides guidelines for user safety in the laboratory.