Non-destructive neutron-activation analysis for determining the chlorine content of paper-pulp

Non-destructive neutron-activation analysis is used for determining chlorine in paper-pulp. Numerical data have been obtained for bleached and unbleached paper-pulps of different types and origins. The sensitivity of this method is 100 ppm for an irradiation time of 30 min and a neutron flux of 6 x 10(10) neutrons.cm(-2).sec(-1) and 10 ppm for an irradiation time of 1 min and a neutron flux of 2 x 10(12) neutrons.cm(-2).sec(-1). In both cases the amount of chlorine that can be determined depends on the presence of the interfering elements manganese and sodium in the paper-pulp. The time required for a complete analysis, after irradiation, is 5 min.     

Use of NAA in marine environment and in archaeology in Greece

Neutron activation analysis (NAA) is a very sensitive and accurate multielement analytical method that is widely applied to the investigation of environmental and archaeological problems. The first part of this paper is a review of pollution studies of toxic trace elements in sediments, seawater and marine organisms of Saronikos Gulf, Greece by NAA. The second part of this paper is a review of provenance studies based on minor and trace element research in ancient ceramics, obsidian, flint, limestone, marble and lead by Instrumental NAA, performed at the NCSR Demokritos.     

Extraction studies of antimony bromide into benzene

Antimony(III) can be extracted rapidly and quantitatively into benzene from a 10 M H₂SO₄–0.03 M HBr system. The extracted antimony bromide has an antimony to bromine ratio of 1:3. Under the above optimum conditions for extraction of antimony, the behaviour of 35 other elements was studied; As³⁺, Ge⁴⁺, Se⁴⁺, and Sn²⁺ were extracted almost quantitatively, and the percentage extraction of Hg²⁺, Bi³⁺, and Te⁴⁺ was 74.1%, 10% and 5.5% respectively. The extraction of the elements into benzene from a 5 M H₂SO₄–0.01 M KI system was also investigated, A comparison of the two systems is given.     

Neutron activation and statistical analysis of pottery from Thera,Greece

Neutron activation analysis, in combination with multivariate analysis of the generated data, was used for the chemical characterization of prehistoric pottery from the Greek islands of Thera, Melos (islands with similar geology) and Crete. The statistical procedure which proved that Theran pottery could be distinguishable from Melian, is described. This discrimination, attained for the first time, was mainly based on the concentrations of the trace elements Sm, Yb, Lu and Cr. Also, Cretan imports to both Thera and Melos were clearly separable from local wares.     

Precise mass measurement of a double-stranded 500 base-pair (309 kDa) polymerase chain reaction product by negative ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry

Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICRMS) has been used to determine the mass of a double-stranded 500 base-pair (bp) polymerase chain reaction (PCR) product with an average theoretical mass of the blunt-ended (i.e. unadenylated) species of 308 859.35 Da. The PCR product was generated from the linearized bacteriophage Lambda genome which is a double-stranded template. Utilization of ethanol precipitation in tandem with a rapid microdialysis step to purify and desalt the PCR product was crucial to obtain a precise mass measurement. The PCR product (0.8 pmol/μL) was electrosprayed from a solution containing 75% acetonitrile, 25 mM piperidine, and 25 mM imidazole and was infused at a rate of 200 nL/min. The average molecular mass and the corresponding precision were determined using the charge-states ranging from 172 to 235 net negative charges. The experimental mass and corresponding precision (reported as the 95% confidence interval of the mean) was 309 406 +/- 27 Da (87 ppm). The mass accuracy was compromised due to the fact that the PCR generates multiple products when using Taq polymerase due to the non-template directed 3'-adenylation. This results in a mixture of three PCR products with nearly identical mass (i.e. blunt-ended, mono-adenylated and di-adenylated) with unknown relative abundances that were not resolved in the spectrum. Thus, the experimental mass will be a weighted average of the three species which, under our experimental conditions, reflects a nearly equal concentration of the mono- and di-adenylated species. This report demonstrates that precise mass measurements of PCR products up to 309 kDa (500 bp) can be routinely obtained by ESI-FTICR requiring low femtomole amounts. Copyright 1999 John Wiley & Sons, Ltd.     

Rapid determination of copper in plants by neutron activation analysis

A rapid and simple neutron-activation analysis method has been developed for the determination of copper in plant leaves. Irradiated samples are dissolved in a mixture of fuming nitric acid, 70% perchloric acid and concentrated sulphuric acid in the presence of copper carrier solution. The copper in the resulting solution is extracted as copper cupferronate into chloroform and back-extracted into concentrated ammonia solution. The copper is precipitated as sulphide with 3% aqueous thioacetanude solution and the precipitate is dissolved in nitric acid. The induced activity of copper-64 in the resulting solution is counted with a 400-channel analyser. The photopeak of the annihilation energy of copper-64 at 0.51 MeV is compared with that of a copper standard processed in the same manner. After counting, the chemical yield of the separated copper is found by re-irradiating aliquots of the copper nitrate solution and comparing the induced activity of coppcr-66 at 1.04 MeV with that of another standard processed in a similar manner. The time required to complete the analysis, including the second irradiation and all radioactivity measurements, is about 25 min. The accuracy of the method was checked by analysing a biological standard of known copper content. The proposed method was successfully applied to the determination of copper in the leaves of 10 different plants (copper content 4-30 ppm).     

Simultaneous determination of mercury and selenium in biological materials by radiochemical neutron activation analysis

A simple and sensitive radiochemical neutron activation analysis (RNAA) method has been developed for the simultaneous determination of mercury and selenium in biological materials. The radiochemical procedure is based upon the digestion of irradiated samples with sulphuric and nitric acids followed by subsequent extractions of mercury and selenium into toluene, first of mercury from 7.5 M H₂SO₄-0.01M HBr media and after of selenium from 7M H₂SO₄-1 M HBr media. After washing of the organic phases with similar media, the mercury bromide was back-extracted into 0.034M EDTA in 5% aqueous ammonia and the selenium bromide into 0.14M H₂O₂ in aqueous solution. The¹⁹⁷Hg and the⁷⁵Se were counted on a Ge(Li) detector. The precision and accuracy of the method was checked by analysing NBS Standard Reference Materials: orchard leaves and bovine liver.     

Investigation of the quantitative properties of the quadrupole orthogonal acceleration time-of-flight mass spectrometer with electrospray ionisation using 3,4-methylenedioxymethamphetamine

This paper describes the investigation of the potential of a quadrupole orthogonal acceleration time-of-flight mass spectrometer (Q-TOF) equipped with an atmospheric pressure ionisation interface for quantitative measurements of small molecules separated by reversed phase liquid chromatography. To this end, the detection limits and linear dynamic range in particular were studied in an LC/MS/MS experiment using 3,4-methylenedioxymethamphetamine standards and 3,4-methylenedioxyethylamphetamine for internal standardisation. In a second phase, the experiment was repeated with real biological extracts (whole blood, serum, and vitreous humour). A calibration for 3,4-methylenedioxymethamphetamine and its metabolite 3,4-methylenedioxyamphetamine was prepared in each of these matrices again using 3,4-methylenedioxyethylamphetamine as internal standard. The resulting quantitative data were compared with those obtained by liquid chromatography with fluorescence detection for the same extracts. The Q-TOF results revealed excellent sensitivity and a linear dynamic range of nearly four decades (2-10 000 pg on-column, r(2) = 0.9998, 1/x weighting). Furthermore, all the calibration curves prepared in biological material were superimposable, LC/MS/MS and LC-fluorescence, and the quantitative results for actual samples compared very favourably. It was concluded that the Q-TOF achieves a linear dynamic range for quantitative LC/MS/MS work exceeding that of fluorescence detection and at much better absolute sensitivity. Copyright 1999 John Wiley & Sons, Ltd.