Sample Type and Size Requirements
A wide range of sample types can be submitted for dating. We can advise on the suitability of different materials and the most effective pretreatments. Table 1 shows the ideal weights necessary to achieve the level of precision (standard error) listed in Table 2.
Table 1: Sample size requirements (Dry weights*).
Material | Radiometric dating | Radiometric dating+ | AMS dating |
| Wood | 10-20 g | 2.0 g | 100 mg |
| Charcoal | 8-12 g | 1.0 g | 100 mg |
| Carbonates | 35 g | 5.0 g | 60 mg |
| Peat^ | 10-100 g | 5-10 g | 1 g |
| Bone^ | 100-200 g | 50 g | 1-5 g |
| Lake Sediment^ | 30-100 g | 10-20 g | 1 g |
| Water (DIC) | - | - | 100ml |
| Methane | - | - | ~ 20mls of >15% methane |
* Recommended weights given are for clean, dry material.
^ Ranges reflect varying carbon content (weights approximate).
+ Sample standard errors will increase as radiometric samples size decreases (see Table 2).
Table 2: Approximate size of standard error (±1 sigma) for radiocarbon samples.
|
Magnitude of standard error for standard radiometric samples
|
||||
|
Sample age (yrs)
|
Precision for full-sized (~ideal weight) sample
|
Precision for 50% ideal weight sample
|
Precision for 20% ideal weight sample
|
Magnitude of standard error for AMS samples
|
|
500
|
35
|
60
|
100
|
25
|
|
1000
|
35
|
60
|
100
|
25
|
|
5000
|
40
|
65
|
110
|
25
|
|
10,000
|
55
|
65
|
170
|
45
|
|
20,000
|
120
|
200
|
350
|
100
|
|
30,000
|
200
|
570
|
850
|
300
|
|
40,000
|
900
|
2500
|
5000
|
2000
|
|
50,000
|
2700
|
-
|
-
|
- |