Recently developed direct LSC method for the biogenic fraction determination in biodiesel samples was evaluated. Intercomparison samples had the unknown composition of biomaterials/fossil fuels and a ...broad range of quench levels. Reliable results were obtained with the direct two-step LSC method for the samples with a quench level of roughly 50 channels above the SQP(E) limit of the method’s applicability. The Internal Standard method for the detection efficiency determination provided better accuracy, additionally lowering the SQP(E) limit of the method’s applicability. The adapted two-step method’s calibration via Internal Standard technique was tested on samples with sunflower seed biocomponent.
Carbonization, i.e., turning organic sample to carbon, was validated for the benzene synthesis for the radiocarbon liquid scintillation measurement. Tests of sample preparation by combustion, ...carbonization followed by combustion and carbonization followed by a direct reaction with lithium were performed. Wood and charcoal samples were good for carbonization followed by direct reaction with lithium, while collagen obtained from bones had to be combusted. Direct reaction of carbonized sample with lithium required three times less amount of lithium than the combusted sample.
•Carbonization was tested for radiocarbon measurement.•Wood and charcoal samples are good for carbonization and direct reaction with lithium.•Sample preparation is less expensive.•Collagen can be carbonized, but it had to be combusted.
Isotopes of hydrogen (
3
H,
2
H) and oxygen (
18
O) are perfect candidates for groundwater tracers. A survey of isotopic composition of 34 groundwater samples and one Lake from Vojvodina region ...(Serbia) is presented here. Tritium activity concentration and stable isotope composition (δ
2
H, δ
18
O), as well as deuterium excess, were determined. The groundwater samples lie on the groundwater regression line. Minor deviations and a few lower deuterium excess values indicate waters recharged in a different climate regime and subjected to evaporation, respectively. According to the obtained results, most of the analyzed groundwater can be characterized as modern waters, recharged mostly from precipitation.
Determination of fraction of biogenic component in liquid fuels by a direct radiocarbon measurement in liquid scintillation counter (direct-LSC method) has been validated by participation in the ...international intercomparison exercise. All the results for samples with the standard quench parameter SQP(E) value above ≈ 650 were accepted. Highly quenched sample of used edible oil was diluted with the
14
C-free petroleum ether to optimize the region of applicability. It was established that quantitative results were obtained for SQP(E) values above 700, while in the SQP(E) region between 700 and 600 only the qualitative results of
f
bio
can be taken.
Radiocarbon activity (a
14
C) and
13
C composition (δ
13
C) were measured in hygrophyte and mesophyte (land) mosses collected in the natural habitat of the Plitvice Lakes and along the Zrmanja and ...Krupa Rivers (typical continental and Mediterranean climates, respectively), Croatia. a
14
C and δ
13
C values of mosses, of atmospheric CO
2
and dissolved inorganic carbon (DIC) were compared with contemporary data and with data from 30 years ago at the Plitvice Lakes when
14
C activity of atmospheric CO
2
was ∼30% higher. A positive correlation between a
14
C
moss
and δ
13
C
moss
was observed for all data reflecting the change of carbon isotopic composition in DIC along the water flows and in atmospheric CO
2
regardless of the climatic regions and historic period. Fraction of the atmospheric carbon in moss
and carbon fractionation factor from aquatic CO
2
(DIC) to moss tissue
were calculated for each individual moss. Three species of mosses had ω
atm.C
∼ 0 % implying that they turn to anabiosis during dry periods. The relation
differentiates true aquatic and amphiphyte mosses. The first had a statistically significant negative correlation between
and
. The amphiphyte mosses had lower
with higher water flow rates.
A new line for preparation of the graphite samples for 14C dating by Accelerator Mass Spectrometry (AMS) in the Zagreb Radiocarbon Laboratory has been validated by preparing graphite from various ...materials distributed within the Fifth International Radiocarbon Intercomparison (VIRI) study. 14C activity of prepared graphite was measured at the SUERC AMS facility. The results are statistically evaluated by means of the z-score and u-score values. The mean z-score value of 28 prepared VIRI samples is (0.06±0.23) showing excellent agreement with the consensus VIRI values. Only one sample resulted in the u-score value above the limit of acceptability (defined for the confidence interval of 99%) and this was probably caused by a random contamination of the graphitization rig. After the rig had been moved to the new adapted and isolated room, all u-score values laid within the acceptable limits. Our LSC results of VIRI intercomparison samples are also presented and they are all accepted according to the u-score values.
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