Breadcrumbs

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
(ideal weight)

Radiometric dating+
(minimum weight)

AMS dating
(minimum weight)

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
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