Search Results

You are looking at 1 - 5 of 5 items for

  • Author or Editor: D. Hoede x
  • Refine by Access: All Content x
Clear All Modify Search

Abstract  

A fast routine method for the determination of tin in rocks is discussed. The method is based on coprecipitation of tetravalent tin with ferric hydroxide, followed by a short irradiation in a high thermal neutron flux, extraction in toluene from 1∶1 sulphuric acid which is 5N in potassium iodide, and counting of123mSn (T=40 m) or125mSn (T=9.7 m) with a well-type NaI detector. In the present work125mSn was used. The lower limit of determination is governed by the blank of the reagents. For a sample of at least one gram it is ≌ 0.2 μg Sn·g−1.

Restricted access

Abstract  

The success of a systematic application in INAA using γ-lines of ≥50 keV depends on the accuracy and precision and thus on the reproducibility of the measuring conditions. This text describes a procedure based on a 30 mm2 planar ultrapure Ge detector with a multichannel analyzer.

Restricted access

Abstract  

The application of selective evaporation in an air-flow to the determination of arsenic and bromine in neutron-activated freeze-dried biological material is reported. Bromine is evaporated as Br2 during oxidative mineralisation. After addition of 48% HBr, arsenic is removed as AsBr3. The evaporated elements are collected in 7M NaOH;82Br (T=35.3 h) and76As (T=26.4 h) are used for quantitative assay. The chemical yield is (98±2)% for arsenic, irrespective of the amount of arsenic carrier. For bromine it varies from (70±10)% for carrier-free evaporation to (98±2)% if sufficient carrier is added. This addition is not permitted if arsenic has to be determined. The limits of determination are 5 ng·g−1 and 2 ng·g−1 respectively. The precision is ≤10% for both elements. The procedure is performed in a standardised apparatus. It was applied to the analysis of standard kale, orchard leaves and animal blood. Bromine was determined instrumentally for purpose of comparison.

Restricted access

Abstract  

Procedures for the determination of bromine by the reactions81Br(n, γ)82Br (T=35.4 h) and79Br(n, γ)80mBr (T=4.4 h). In the case of82Br a flat coaxial Ge(Li) crystal is used to measure the 619 keV photopeak. For80mBr a planar Ge(Li) detector is applied to measure the 39 keV γ-ray. The agreement between the data obtained with both techniques for some Standard Reference Materials is satisfactory.

Restricted access

Abstract  

This text describes the instrumental determination of some elements in silicate samples of ≃1 g by photon activation. The following elements can be determined: In acidic rocks: Mg, Ca, Ti, Mn, Sr, Zr and Nb, in ultramafic rocks: Mg, Cr, Ni, and Mn. The relative standard deviation is a few percent.

Restricted access