Ultra Small-Mass Graphitization by Sealed Tube Zinc Reduction Method for AMS 14C Measurements

Radiocarbon ◽  
2013 ◽  
Vol 55 (2) ◽  
pp. 608-616 ◽  
Author(s):  
Xiaomei Xu ◽  
Pan Gao ◽  
Eric G Salamanca
Keyword(s):  
Reduction Method ◽  
Isotopic Fractionation ◽  
Small Mass ◽  
Previous Method ◽  
University Of California ◽  
Fe Powder ◽  
Accuracy And Precision ◽  
On Line ◽  
Zinc Reduction ◽  
Graphitization Temperature

A modified sealed tube Zn reduction method based on Khosh et al. (2010) has been developed to graphitize ultra small-mass samples ranging from 4–15 μg carbon (C) for accelerator mass spectrometry (AMS) radiocarbon measurements. In this method, the reagent TiH2 is removed from the previous method while the amounts of Zn and Fe powder remain the same. The volume of the sealed reactor is further reduced by ∼40% to ∼0.75 cm3 and the graphitization temperature is lowered to 450 °C. Graphite targets produced by this method generally yield 12C+1 currents of about 0.5 μA per 1 μg C, similar to the small mass (15–100 μg C) sealed tube Zn reduction method previously reported by Khosh et al. (2010) when measured on the same AMS system at KCCAMS, University of California, Irvine. Change of Fe powder to Sigma-Aldrich (400-mesh) has yielded further improved backgrounds over Fe powder of Alfa Aesar (325-mesh). Modern C background from combustion and graphitization is estimated to be 0.2–0.8 μg C, and dead-C background to be 0.1–0.4 μg C. The accuracy and precision of ultra small-mass samples prepared by this method are size and 14C content dependent, but is usually ±4–5% for the smallest sample size of ∼4–5 μg C with modern 14C content. AMS on-line δ13C measurement that allows for correction of both graphitization and machine-induced isotopic fractionation is the key for applying the sealed tube Zn reduction method to ultra small-mass sample graphitization.

Optimization of the Amount of Zinc in the Graphitization Reaction for Radiocarbon AMS Measurements at LAC-UFF

Radiocarbon ◽  
2016 ◽  
Vol 59 (3) ◽  
pp. 885-891 ◽  
Author(s):  
Kita D Macario ◽  
Fabiana M Oliveira ◽  
Vinicius N Moreira ◽  
Eduardo Q Alves ◽  
Carla Carvalho ◽  
...  
Keyword(s):  
Isotope Ratio ◽  
Isotope Fractionation ◽  
Reduction Method ◽  
Isotopic Fractionation ◽  
Isotope Ratio Mass Spectrometry ◽  
Methodological Research ◽  
Lower Variation ◽  
Zinc Reduction ◽  
Precision And Accuracy ◽  
Graphitization Temperature

AbstractThe Radiocarbon Laboratory of the Universidade Federal Fluminense, in Brazil, has been successfully applying the zinc reduction method for graphitization of carbon samples since the development of its early protocols in 2009. Successive methodological research aiming to improve and, ultimately, optimize the precision and accuracy of our results indicates that graphitization temperatures as low as 460°C promote erratic 13C isotopic fractionation, but an approximately constant fractionation of about –5‰ is achieved at 520°C. In this work, we present isotope ratio mass spectrometry (IRMS) δ13C results for 14C reference materials graphitized at 550°C with variable amounts of zinc. Based on the results obtained from the addition of 20, 35, and 50 mg of zinc, we conclude that a slightly lower variation in 13C isotope fractionation during graphitization is obtained with less zinc. Moreover, the average isotopic fractionation is not altered by increasing the graphitization temperature from 520°C to 550°C.

Small-mass graphite preparation for AMS 14C measurements performed at GIGCAS, China

Radiocarbon ◽  
2017 ◽  
Vol 59 (3) ◽  
pp. 705-711
Author(s):  
P Ding ◽  
C D Shen ◽  
W X Yi ◽  
N Wang ◽  
X F Ding
Keyword(s):  
Mass Spectrometry ◽  
Reduction Method ◽  
Small Mass ◽  
University Of California ◽  
Standard Samples ◽  
Carbon Contamination ◽  
Size Dependent ◽  
Chinese Academy Of Sciences ◽  
The University ◽  
Academy Of Sciences

AbstractThe sealed tube Zn reduction method has been applied for small-mass samples ranging from 15 to 100 μg carbon preparation for accelerator mass spectrometry (AMS) radiocarbon (14C) measurements at the AMS-14C Preparation Lab in Guangzhou Institute of Geochemistry, Chinese Academy of Sciences (GIGCAS). The volume of the sealed reactor tube is reduced to ~0.75 cm3 in order to increase the yield of graphite. Graphite targets are measured at the Keck Carbon Cycle AMS Facility at the University of California, Irvine (KCCAMS). The targets generate a maximum 12C+1 current of about 0.5 μA per 1 μg C. The modern-carbon background is estimated to be 0.25–0.60 μg C, and dead-carbon background to be ~0.3–0.9 μg C. Both modern-carbon background and dead-carbon background are size dependent, so the results can be corrected. The precision of the small-mass modern carbon standard samples is±15–25‰ for the size of ~15–20 μg C,±5–10‰ for ~20–50 μg C, and±3–10‰ for 50–100 μg C. Further reduction of dead-carbon and modern-carbon contamination is needed in preparation of small-mass samples at GIGCAS.

Collaborative Study of Simultaneous Carbon, Hydrogen, Nitrogen Determination by Two Automatic Analyzers

1971 ◽  
Vol 54 (4) ◽  
pp. 808-818
Author(s):  
Laverne H Scroggins
Keyword(s):  
Collaborative Study ◽  
Critical Factor ◽  
Detector Response ◽  
Temperature Differential ◽  
Combustion Time ◽  
Accuracy And Precision ◽  
Electronic Integrator ◽  
On Line ◽  
Electronic Integration ◽  
The One

Abstract A collaborative study was conducted, using 2 types of automatic carbon-hydrogen-nitrogen analyzers. Thirty collaborators performed duplicate analyses on 6 samples with the duplicates being run on different days. Two collaborators sent a set of results for both types of apparatus. The samples studied were sulfadiazine, sulfanilamide, benzyl isothiourea hydrochloride, nicotinic acid, stearic acid, and ethyl laurate. A critical factor was the choice of parameters or parameter combinations such as the catalyst used, combustion time, combustion temperature, reduction temperature, temperature differential between main and sub-ovens of the gas chromatographic column and detector unit, and use of on-line computer or electronic integrator. Evaluation of the data and overall consideration indicate that satisfactory results for carbon, hydrogen, and nitrogen may be obtained with either instrument. It is further indicated that certain conclusions will make possible an improvement in the results obtained by these apparatus. High combination temperature, low temperature differential between ovens, and the use of electronic integration of the detector response seem to be required for good accuracy and precision with the one apparatus. High temperature, longer combustion time, additional catalyst, and electronic integration led to better results with the other. It is, therefore, recommended that, before adoption as official first action, a second collaborative study be made, using the parameters indicated by this study.

scholarly journals Zinc Reduction as an Alternative Method for AMS Radiocarbon Dating: Process Optimization at Circe

Radiocarbon ◽  
2008 ◽  
Vol 50 (1) ◽  
pp. 139-149 ◽  
Author(s):  
F Marzaioli ◽  
G Borriello ◽  
I Passariello ◽  
C Lubritto ◽  
N De Cesare ◽  
...  
Keyword(s):  
Radiocarbon Dating ◽  
Reduction Method ◽  
Hydrogen Reduction ◽  
State Of The Art ◽  
Graphite Target ◽  
Ams Radiocarbon Dating ◽  
Alternative Method ◽  
Comparable Performance ◽  
Zinc Reduction ◽  
Target Production

The pretreatment of samples for radiocarbon measurements, transforming a variety of materials into graphite solid targets, represents a critical point in the accelerator mass spectrometry (AMS) procedure. We describe the new, state-of-the-art CIRCE AMS preparation laboratory, particularly the setup and optimization of an alternative method, the zinc reduction method, for graphite target production, compared to the more common hydrogen reduction method. Measured 14C values on standard and blank samples reduced via zinc reaction revealed mean background levels, accuracy, and sensitivity comparable to those obtained by our conventional hydrogen reaction lines. Zinc line reduction at the CIRCE laboratory represents an effective and powerful alternative to the conventional hydrogen reduction, ensuring higher sample throughput with lower costs at a comparable performance level.

scholarly journals Determinations of Labile Nutrients (Methylcobalamin, 5-Methyltetrahydrofolate, and Trans Menaquinone-7) in Oil- and Beadlet-Filled, Gastric-Resistant Capsule

2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 1183-1183
Author(s):  
Hong You ◽  
Yuhao Yin ◽  
Kangzi Ren ◽  
Zhiyan Liu ◽  
Jeffrey Whaley ◽  
...  
Keyword(s):  
Dietary Supplements ◽  
Analytical Methods ◽  
The United States ◽  
Nutrient Delivery ◽  
Funding Sources ◽  
Rp Hplc ◽  
Accuracy And Precision ◽  
Relative Standard ◽  
On Line ◽  
Superficially Porous Particles

Abstract Objectives The dietary supplement industry has grown substantially, and advances in technology have played important roles in the development of new forms of dietary supplements and delivery systems. While it is recommended to use compendia methods for testing dietary supplements, the analytical methods in place are often developed for single ingredients or simple matrices and are not always fit to be used for solving modern matrix challenges. Oil- and beadlet-filled, gastric acid-resistant capsule (OBGRC) is designed to improve nutrient delivery and absorption. However, it is challenging to accurately analyze labile nutrients in OBGRCs because nutrients within different physical locations are difficult to separate, and lengthy sample preparations lead to nutrient degradation. We developed and validated analytical methods to determine methylcobalamin (MeB12), 5-methyltetrahydrofolate (5-MTHF), and trans menaquinone-7 (MK-7) in OBGRCs. Methods MeB12 and 5-MTHF were extracted by completely dissolving the OBGRC shells using aqueous buffers and then applying hexane-facilitated liquid-liquid extraction to remove the oil phase and determined by RP-HPLC using superficially porous particles columns. For MK-7 analysis, the whole OBGRC was cut to open and the oil phase was collected to dissolve in a mixture of dimethyl sulfoxide/tetrahydrofuran/ethanol before analyzed by RP-HPLC with fluorescence detection after on-line, post-column zinc reduction. The methods were subjected to single-laboratory validations according to the United States Pharmacopeia (USP) guidelines for linearity, suitability, detection limits, specificity, accuracy, and precision. Results The methods achieved chromatographic resolution of target analytes without the expensive requirement of ultra-high pressure liquid chromatography and/or mass spectrometry. The methods have wide analytical ranges (from at least 50% to 250% of the input concentrations), high precision (repeatability relative standard deviations ranging from 1.04% to 4.90%), and high accuracy (spike recovery rate ranging from 89.2% to 108%). Conclusions All three methods passed USP method validation criteria and have the potential to be widely adopted to analyze MeB12, 5-MTHF, and MK-7 in similar matrices for quality control purposes. Funding Sources The research funding was provided by Ritual and Eurofins.

Advances in Fish Tagging and Marking Technology

2012 ◽  
Keyword(s):  
Reduction Method ◽  
Radio Telemetry ◽  
Simple Approach ◽  
Location Error ◽  
Error Range ◽  
Accuracy And Precision ◽  
Wide Range ◽  
Receiving Antenna ◽  
Tracking Time ◽  
Efficiency Test

<i>Abstract</i>.—This study describes an improved method that decreases tracking time but increases accuracy and precision for the fine-scale location of radio tags by reducing the receiving antenna efficiency. Test tags (48–49 MHz) were hidden in a lowland river and independently located by boat tracking using both the antenna reduction method and standard triangulation techniques. The antenna reduction method was found to be faster and more accurate, locating transmitters to within 0.19 ± 0.13 m (mean ± SE) of their actual location (error range 0–1.50 m) compared to 19.53 ± 4.81 m (error range 0–70.00 m) using triangulation. This simple approach can be applied to a wide range of radio telemetry studies and avoids many of the major sources of location error associated with triangulation including minimising the distance between the transmitter and receiver and avoiding the potential need for mapping.

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