Sectors concentration, measurement

Shen C-C, Edwards RL, Cheng H, Dorale JA, Thomas RB, Moran SB, Weinstein S, Edmonds HN (2002) Uranium and thorium isotopic and concentration measurements by magnetic sector inductively coupled plasma mass spectrometry. Chem Geol 185 165-178 Shen GT, Dunbar RB (1995) Environmental controls on uranium in reef corals. Geochim Cosmochim Acta 59 2009-2024... 

Figure 9.48 Correlation of halogen concentration measured in sediments and rock samples by isotope dilution LA-ICP-MS using a high ablation system UNA-Spark n -Atomizer and double-focusing sector-field / -MS Element 2 with the indicative values 59 Samples SRM 2704 (Buffalo River Sediment), SRM 1646 (Estuarine Sediment), Granite GS-N, Bauxite BX-N and Disthene DT-N. (S. Boulyga and K. G. Heumann, Int. ). Mass Spectrom., 242, 291 (2005). Reproduced by permission of Elsevier.)...

In Stingeder s group the unique capabilities of sector field ICP-MS and LA-ICP-MS were employed to reconstruct details of a homicide by thallium poisoning, which took place about 40 years ago in Austria.29 Thallium was determined in several human bone samples after acid digestion in a microwave oven. The thallium concentration measured by ICP-MS and GF-AAS varied from 1.07-2.63 p,gg 1, which was up to 170 times higher compared to the concentration found in persons who died due of natural causes. LA-ICP-MS was employed to analyze a thumbnail from the poisoned person compared to a control person. Thallium peaks were detected in the nail of the victim at a distance of 2.5 mm from the younger edge of nail.29... 

In the period 1958 - 1962, benzo(a)pyrene has been measured i different sectors of Liege. The results show levels of 100 ng/ m during winter, both in residential districts and industrial areas in the rural regions near Liege the levels were eight times lower. The seasonal variation was evident low in summer (ten times less than in winter) and medium in autumn and in spring (a third of the concentrations measured in winter). 

Emissions of CO in the United States peaked in the late 1960s, but have decreased consistendy since that time as transportation sector emissions significandy decreased. Between 1968 and 1983, CO emissions from new passenger cars were reduced by 96% (see Exhaust CONTUOL, automotive). This has been partially offset by an increase in the number of vehicle-miles traveled annually. Even so, there has been a steady decline in the CO concentrations across the United States and the decline is expected to continue until the late 1990s without the implementation of any additional emissions-reduction measures. In 1989, there were still 41 U.S. urban areas that exceeded the CO NAAQS on one or mote days per year, but the number of exceedances declined by about 80% from 1980 to 1989. Over the same time period, nationwide CO emissions decreased 23%, and ambient concentrations declined by 25% (4). 

In principle GD-MS is very well suited for analysis of layers, also, and all concepts developed for SNMS (Sect. 3.3) can be used to calculate the concentration-depth profile from the measured intensity-time profile by use of relative or absolute sensitivity factors [3.199]. So far, however, acceptance of this technique is hesitant compared with GD-OES. The main factors limiting wider acceptance are the greater cost of the instrument and the fact that no commercial ion source has yet been optimized for this purpose. The literature therefore contains only preliminary results from analysis of layers obtained with either modified sources of the commercial instrument [3.200, 3.201] or with homebuilt sources coupled to quadrupole [3.199], sector field [3.202], or time-of-flight instruments [3.203]. To summarize, the future success of GD-MS in this field of application strongly depends on the availability of commercial sources with adequate depth resolution comparable with that of GD-OES. 

To assess changes in mercuiy concentrations in the environment, it is important to have a baseline from which to measure change. Due to the fact that mercuiy emissions have already been reduced from a number of sectors in the United States, and that further emission reductions are expected from power plants over the next few decades, it is critical that an assessment program be implemented soon. 

Quetel CR, Prohaska T, Hamester M, Kerl W, Taylor PDP (2000b) Examination of the performance exhibited by a single detector double focusing magnetic sector ICP-MS instrument for uranium isotope abundance ratio measurements over almost three orders of magnitude and down to pg g-1 concentration levels. J Anal At Spectrom 15 353-358... 

Stuer et al. [46] evaluated the presence of the 25 most used pharmaceuticals in the primary health sector in Denmark (e.g., paracetamol, acetyl salicylic acid, diazepam, and ibuprofen). They compared PECs with experimental determinations and they conclude that measured concentrations were in general within a factor of 2-5 of PECs. Carballa et al. [45] also determined PECs for pharmaceuticals (17), musk fragrances (2) and hormones (2) in sewage sludge matrix. For that purpose they used three different approaches (1) extrapolation of the per capita use in Europe to the number of Spanish inhabitants for musk fragrances (2) annual prescription items multiplied by the average daily dose for pharmaceuticals and (3) excretion rates of different groups of population for hormones. They indicated that these PECs fitted with the measured values for half of them (carbamazepine, diazepam, ibuprofen, naproxen, diclofenac, sulfamethoxazole, roxithromycin, erythromycin, and 17a-ethiny I e strad iol). 

It is known from laboratory tests that surface tension measurement can provide reliable information regarding existing detergent concentration. Work is being carried out in various institutes on such sensors for the commercial sector. However, for use in domestic washing machines, only sensors that are extremely inexpensive, maintenance-free and durable are suitable. How much of a breakthrough can be achieved here in the future remains to be seen. 

Even if quantitative results are more often expected for wastewater quality measurement, qualitative information is of great interest, as is the case for other applications of the analytical sciences (in the health sector, the use of test kits and biodiagnostic systems leads to quick and useful information, often far from a classical analytical result). In fact, quantitative analysis gives the concentration not only of one substance, but also of a group of comparable substances (surfactants, PAH,...), and even the value of a specific (TOC, TKN,...) or aggregate (BOD, COD, toxicity,...) parameter. In this context, total indices are often proposed as parameters complementary to classical analytical results [1]. 

In some manufacturing process analysis applications the analyte requires sample preparation (dilution, derivatization, etc.) to afford a suitable analytical method. Derivatization, emission enhancement, and other extrinsic fluorescent approaches described previously are examples of such methods. On-line methods, in particular those requiring chemical reaction, are often reserved for unique cases where other PAT techniques (e.g., UV-vis, NIR, etc.) are insufficient (e.g., very low concentrations) and real-time process control is imperative. That is, there are several complexities to address with these types of on-line solutions to realize a robust process analysis method such as post reaction cleanup, filtering of reaction byproducts, etc. Nevertheless, real-time sample preparation is achieved via an on-line sample conditioning system. These systems can also address harsh process stream conditions (flow, pressure, temperature, etc.) that are either not appropriate for the desired measurement accuracy or precision or the mechanical limitations of the inline insertion probe or flow cell. This section summarizes some of the common LIF monitoring applications across various sectors. 

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