A Minivial for Small-Sample ¹⁴C Dating

Abstract

ABSTRACT. We have designed a 0.3-m1 Teflon minivial for 14C dating of small samples in a liquid scintillation counter. We use a special adapter of standard vial size to optimize the position of the vial with respect to the phototubes and to intercept the light path between them, thus reducing optical cross-talk. Better performance can be achieved by using customized vials than by diluting small samples for counting in large vials. We have achieved counting efficiencies up to 80% in 0.3-ml vials typically with 0.05 cpm background.

Small Sample Dating in China

“…The value of the modern standard obtained as a mean of the two vials is 2.9853 cpm, and background is 0.07 cpm, giving an FM of 11.28. With this value, the theoretical age limit for the vials is 43,270 BP, using the equations listed by Gupta and Polach (1985), and by Kaihola, Kojola and Heinonen (1992). These values were obtained with a counting efficiency of 88%.This theoretical age limit compares favorably with that obtained by Polach et al (1988).…”

“…Sample benzene was added to the 0.3-ml Teflon vials together with butyl PBD scintillant at a relative concentration of 15 g liter'1(0.0045 g). It was found that the 0.3-ml vial as supplied (Kaihola, Kojola and Heinonen 1992) tended to lose up to 1 mg benzene by evaporation over a period of 7-8 days. The use of 2 Tuffbond silicone/Teflon seals instead of 1 caused benzene loss to be as low as 0.3 mg per week.…”

“…The use of 2 Tuffbond silicone/Teflon seals instead of 1 caused benzene loss to be as low as 0.3 mg per week. The vials were positioned for maximum quantum yield (Kaihola, Kojola and Heinonen 1992) by lining up a mark on each vial with a mark on the Quantulus sample lift mechanism. The value of the modern standard obtained as a mean of the two vials is 2.9853 cpm, and background is 0.07 cpm, giving an FM of 11.28.…”

Surface and Underground Ultra Low-Level Liquid Scintillation Spectrometry

“…background (Kaihola et al 1992). When a large 9-mL teflon vial is used for variable volumes, background dependence is again linear, but additional contribution remains due to the unfilled empty volume, which is a source of air scintillations (Kaihola 1996).…”

“…Quantulus™ (PerkinElmer, Inc.) is an ultra low-level liquid scintillation spectrometer used in numerous radiocarbon laboratories for radiometric 14 C age determinations. Sample sizes down to a few hundred mg of carbon have been measured with various sample holder configurations (Haas 1979;Kalin and Long 1989;Hogg 1992;Kaihola et al 1992;Buzinny and Skripkin 1995) which give lower backgrounds than larger vials.…”