Chemical Pretreatment

Chemical Pretreatment

ABA (acid-base-acid) method
Soxhlet extraction
Cellulose extraction
Collagen extraction
Acid treatment
Dissolved Inorganic Carbon (DIC) of Groundwater

ABA (acid-base-acid) method

the standard ABA protocol is used on most organic materials, such as macrofossile, peat, seed, twig and charcoal. Samples are treated with a sequence of 1N HCl, distilled water, 1M NaOH, distilled water, and then 1N HCl. Samples are treated with a sequence of acid to eliminate carbonates, base (alkali) to remove secondary organic acids and then acid to neutralize the solution before drying. After each pretreatment samples are washed with distilled water to neutral pH (4-5). Finally samples are dried. The samples are then ready for combustion.

Soxhlet extraction

protocol may be used where preservatives, contamination by synthetic resins and other chemical contaminants are present. This protocol was adopted for textiles, canvas and art samples (after Hajdas et al. 2004). In this case, the samples are extracted in a sequence of solvents: hexane, ethanol, and methanol, followed by a distilled water wash. The samples are dried before the combustion.

BABAB method

- modified ABA procedure for cellulose extraction was adapted from ETH Zürich laboratory after Nemec et al. 2010. The BABAB procedure uses an alkaline step at the beginning of the process to remove alcohols, phenols, and compounds with carboxyl groups. At the end of the pretreatment there is an additional alkaline bleaching step. The extracted material is washed to a weakly acidic pH at the end of the process and carefully dried. Cellulose extraction is recommended for wood samples, where alpha-cellulose is the most stable constituent and is the most suitable for a 14C age determination. 

Collagen extraction

A continuous-flow automate ABA cleaning system was developed for the preparation of bone samples. Reagents are selectively pumped to the reaction cells containing small-grained bone samples, with a sequence of acid-base, interspersed with flushing with distilled water. System is controlled by a computer program and a special electronic driver device. Cleaned sample is than heated in aqueous solution. Dissolved collagen/gelatine is filtered and freeze-dried. 

Acid treatment

for snails, shells and other carbonaceous depositions. A vacuum-tight two-finger glass flask with a valve is used for this preparation. The sample is placed into one of the fingers, with acid in the other, than after evacuating the flask, the acid can be poured onto the sample in the other finger. The produced CO2 is than purified in the on-line purification system). 

Dissolved Inorganic Carbon (DIC) of Groundwater

Our septa sealed vacuum cell based DI14C preparation method allows analyses of groundwater down to the 10 ml sample sizes with excellent blank level (around 0.2 pMC). In case of lower DIC content we apply a bigger volume system, where up to 500 ml sample sizes are pretreated in one reaction step. Those allow the analyses of very low carbon content samples (0.001-0.01 mg C/cm3 water). more information here

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