There is no information about the risk to Argentinean livestock of poisoning by exposure to
L. as a result of ingestion of its two most toxic alkaloids,
-coniceine and coniine. To measure their concentrations in this weed an aqueous sulfuric acid extract of
foliage alkaloids was adjusted to pH 9 and extracted exhaustively with chloroform. The partly evaporated chloroform extract was used for TLC detection and quantification of
-coniceine and coniine by using
spray reagent to detect the alkaloids and visual comparison of the intensity of the color of the sample spots with that of the spots of the corresponding standards. Regression equations for recoveries (
) after different standard additions (
= −0.761 + 1.051
< 0.0001) for coniine and
= −0.193 + 0.863
< 0.0001) for
-coniceine. Average recoveries were 92.0 ± 3.5% and 82.6 ± 3.9% for coniine and
-coniceine, respectively. By
-tests on addition and recovery values it was shown that for both equations
= 0 and
= 1 (
> 0.05), which implies recovery is 100%. Detection limits were 1.7 and 0.7 μg per spot for coniine and
-coniceine, respectively; the respective quantification limits were 0.8 and 0.6 μg mL
. The method is suitable for simple, precise, and accurate TLC analysis of these alkaloids.
The IAEA conducted the IAEA-CU-2006-06 Proficiency Test (PT) on “The determination of major, minor and trace elements in ancient
Chinese ceramic” in 2006. The results of this PT showed that of the 21 analytes reported by our laboratory 9 failed the precision
criteria. Therefore the results reported by our laboratory along with the results of other laboratories which carried out
analysis using neutron activation analysis (NAA) were studied. It was found that the major factor contributing towards data
falling in the “Warning” category, failing the precision criteria was the high uncertainties cited in the certificates of
the reference materials (RMs) used for quantification of data. In this regard, it is recommended that synthetic standards
should be prepared and used on a routine basis especially for the measurement of the elements K, Eu, Lu, Ta, Tb and Yb.
While silver can be efficiently collected from biological materials into lead beads by conventional fire assay, reagent blanks make this method unsuitable for determining the metal at concentrations less than 1 ppm. A radiochemical neutron activation analysis method is described which avoids this problem and can give reliable results down to 1 ng g–1. The method has been tested using various reference materials /RM/, and it is concluded that NIES Mussel and Pepperbush are the best characterised RMs for determining traces of silver.
Variations in sample properties and sample geometry, such as filling height, sample density and chemical composition, were
found to have a much more significant influence on the full peak counting efficiency in gamma ray spectrometric analyses,
than variations in sample holder properties, such as wall and bottom thickness. This means that in attempting to guarantee
a consistent high quality of gamma ray spectrometric analyses one should focus on sample preparation. Sample holders do not
have to meet very high specifications.
Repeated irradiation enhances the precision and sensitivity of INAA based on short-live radionuclides, but entail systematic losses due to dead time. The relative standard deviation in the net peak area decreases with the square root of the number of cycles while the systematic bias increases with it. The limits of decision, detection and determination decrease in a somewhat more complicated way with the number of cycles. The derived formulation is applied to the determination of selenium in hair by the 161.9 keV photopeak of77mSe,T1/2=17.8 s.