Germanium detection limits

The sensitivity of this system is 430 pg/0.0044 absolute. The standard deviation of the baseline noise is about 0.0007 absolute, resulting in a noise-limited detection limit of 140 pg of germanium at the 95% confidence level. 

The introduction of high-resolution, high-efficiency /-ray detectors composed of lithium-drifted germanium crystals has revolutionised /-measurement techniques. Thus, /-spectrometry allows the rapid measurement of relatively low-activity samples without complex analytical preparations. A technique described by Michel et al. [25] uses Ge(Li) /-ray detectors for the simultaneous measurements of 228radium and 226radium in natural waters. This method simplifies the analytical procedures and reduces the labour while improving the precision, accuracy, and detection limits. 

The results are shown in Tables I, II, and III. The major elements in coal and in the derived products are, in order of decreasing abundance in the materials studied, silicon, aluminum, calcium, iron, and magnesium. With the minor and trace elements, the detection limits vary with the ash content of each type of material about 1-5 ppm for the coals and residues and 1-3 ppb for the oils. The elements thallium, bismuth, germanium, and gallium were sought but not detected. 

The germanium films deposited between 190 and 300 °C were characterized for their structural properties by XRD. All films show amorphous scattering pattern with a detection limit of 1 vol % of crystalline component. 

Human activities often mobilize and redistribute natural compounds in the environment to an extent that they can cause adverse effects. Much attention has been paid to the determination of trace of pollutant elements on account of their significant effect on the environment. The potential of USAL has been put into use in environmental element analysis. Thus, the US leaching of cadmium from coals and pyrolysed oil shale prior to ETAAS [56] resulted in a twofold increase in precision, better detection limits and decreased background absorbance in relation to total digestion. Cadmium has also been successfully leached with US assistance from ash samples with subsequent flow-injection coid-vapour atomic absorption spectrometry [57]. Additional examples include the leaching of germanium from soiis with an uitrasonic probe in 10 min [58] or that of lead from coal in 60 s [59]. 

Divalent germanium has been used as a reducing agent for the determination of mercury in soils and sediments (Zelyukova et al., 1987). In alkaline solution, also organic mercury compounds were reduced. The detection limit can be estimated at about... 

The detection limits were 0.05 mBq/I and 0.02 mBq/1 for dissolved and particulate Cs, respectively. The activity of Be was determined by gamma-ray spectrometry simultaneously with Cs. The activity of unsupported °Pb was then determined from the difference between the total activity of °Pb and the activity of Ra, as deduced from the measurement of Pb. The samples were sealed in a gas-tight plastic vessel with an o-ring, and allowed to stand for at least 2 weeks before the measurement to attain radioequilibrium between Ra and " Pb via gaseous Rn. The total activity of °Pb in the sample was determined by gamma-ray spectrometry using a hyper-pure germanium detector with a beryllium window, which was calibrated with certified U and Th ore standards (Yanase and Sekine, 1995). Hereafter, unsupported Pb will be written simply as Pb in this chapter, unless specified. The detection limits were approximately 0.1 and 0.01 Bq/g for total Pb and Be, respectively. 

EDLs are very intense, stable emission sources. They provide better detection limits than HCLs for those elements that are intensity-limited either because they are volatile or because their primary resonance lines are in the low-UV region. Some elements like As, Se, and Cd suffer from both problems. For these types of elements, the use of an EDL can result in a limit of detection that is two to three times lower than that obtained with an HCL. EDLs are available for many elements, including antimony, arsenic, bismuth, cadmium, germanium, lead, mercury, phosphorus, selenium, thallium, tin, and zinc. Older EDLs required a separate power supply to operate the lamp. Modern systems are self-contained. EDL lamps cost slightly more than the comparable HCL. 

The photometric determination of germanium with phenylfluoron was and still is a procedure for the analysis of this element in inorganic and organic samples. The detection limit can be improved when the formed germanium complex is transferred into benzyl alcohol by extraction before measuring. The detection limit is then at about 0.01 p,g Ge/mL [4]. 

The determination of germanium by means of atomic absorption spectrophotometry at the end of the 1960s was replaced by the introduction of the hydride technique with sodium tetrahydroborate as means of reduction. The detection limit is indicated with 2 x lOr g and 0.01 xg Ge/liter [44]. 

The combination of extraction-spectrophotometry and atomic absorption spectrometry after extraction of germanium tetrachloride with CCI4 brings about new advantages. A detection limit of 5 ng Ge/mL with a standard deviation of 6% was obtained [45]. 

The adsorptive stripping voltammetric technique led to further improvements of the detection limit of germanium in biological material. By using pyrogallol, the detection limit is 0.1 ng/mL with a standard deviation of 13% [47]. 

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