Portable analysers

At present, the air/fuel ratio of each burner in a multiple burner installation in the steel industry will be manually adjusted about every 3 to 9 months by a fuel technician using portable analysers to measure the carbon monoxide and oxygen concentrations in the waste gases of each burner. 

Portable analysers are available which measure the concentration of oxygen in the air by the depolarisation produced at a sensitive electrode mounted in the instrument (Figure 18.5). Several different devices are available which vary in sensitivity, reliability and ease of maintenance but they must all be checked and carefully calibrated to the manufacturer s... 

Near-infrared instruments of the UV-VIS-NIR type have become commercially available about 1955 with applications for agricultural commodities. Instruments designed specifically for measuring NIR energy reflected from solids have been commercially available as from 1971 [214] the development of these devices was pioneered by Norris [215]. The first successful uses of modem MRS were in the 1100-2500 nm region. NIR instrumentation is now extremely varied from UV-VIS-NIR to FTIR instm-ments, NIR reflectance instruments, PAS technology, on-line and portable analysers. 

Portable x-ray energy dispersive sulphur in oil analyser ASE-1 with measurement range 0.015 - 5% and a detection limit near 0.001%. SPARK-1-2M, BRA-17-02 and ASE-1 have been certified as measuring... 

Analyses of gases and vapours tend to utilize the teehniques deseribed on page 308. Many of these methods were traditionally limited to laboratory analyses but some portable instruments are now available for, e.g., gas ehromatography (Table 10.16) and non-dispersive infra-red speetrometry (Table 10.17). 

The portable vibration analyzer incorporates a microprocessor that allows it to mathematically convert the electrical signal to acceleration per unit time, perform a TFT, and store the data. It can be programmed to generate alarms and displays of the data. The data stored by the analyzer can be downloaded to a personal or a more powerful computer to perform more sophisticated analyses, data storage and retrieval, and report generation. 

The basis of this technique is absorption of ir radiation by molecules over a wide spectrum of wavelengths to give a characteristic fingerprint spectrum providing both qualitative and quantitative data on the substance. This versatile technique owes its success in occupational hygiene to the development of a portable spectrometer. Table 9.8 lists some compounds detectable by one type of portable ir analyser. 

One of the limitations of the portable field survey instruments in the measurement of americium is that their quantitative accuracy depends on how well the lateral and vertical distribution of americium in the soil compares with the calibration parameters used. These methods can provide a rapid assessment of americium levels on or below surfaces in a particular environment however, laboratory-based analyses of samples procured from these environmental surfaces must be performed in order to ensure accurate quantification of americium (and other radionuclides). This is due, in part, to the strong self absorption of the 59.5 keV gamma-ray by environmental media, such as soil. Consequently, the uncertainty in the depth distribution of americium and the density of the environmental media may contribute to a >30% error in the field survey measurements. Currently, refinements in calibration strategies are being developed to improve both the precision and accuracy (10%) of gamma-ray spectroscopy measurements of americium within contaminated soils (Fong and Alvarez 1997). 

Applications GC-IMS is applied only in a few laboratories. Most applications have been directed toward environmental analyses. GC-IMS is used in niche areas, such as high-speed air-quality monitoring (on board space stations) and detecting chemical warfare agents. Snyder et al. [319] have described a hyphenated field-portable hand-held GC-IMS device, which was applied to the separation of phosphate (TMP, TEP)/phosphonate (DMMP, DEMP, DIMP, DEEP) mixtures. A mixture of four phosphonate analytes can be successfully resolved with a small GC-IMS device in under 8 s. 

In analyses where molecular masses are being matched, more accurate mass measurements provide more reliable matches and identifications.26,65,66 In a reference laboratory the mass accuracy to several decimal points, provided by a Fourier transform ion cyclotron resonance mass analyzer, may be desirable. In field or portable systems there is usually a trade-off in mass accuracy for size and ruggedness. Reliable identifications can be made with moderate mass accuracy, even 1 Da, if a large enough suite of molecular ions is recorded and used to search the database. If both positive ion and negative ion spectra are... 

The relative simplicity of the sensor setup allows them to be implemented into portable automated devices or bed-side analyzers (Fig. 4.2), which are easily installed at patient beds, eliminating the time-consuming laboratory analyses. On the other hand, modem high throughput clinical analyzers may process more than 1000 samples per hour and simultaneously determine dozens of analytes, using a handful of analytical methods. Blood electrolyte analysis, however, remains one of the most important in... 

Dissolved oxygen Winkler reagents Addition of reagent immediately after sampling. Fixed sample should be kept in the dark and analysed as soon as possible. Where measurements are needed on liquids containing high levels of easily oxidisable organic matter, a portable meter should be used, otherwise the copper sul-fate/sulfamic acid mix should be used. DoE recommendation. 

The unique appearance of an infrared spectrum has resulted in the extensive use of infrared spectrometry to characterize such materials as natural products, polymers, detergents, lubricants, fats and resins. It is of particular value to the petroleum and polymer industries, to drug manufacturers and to producers of organic chemicals. Quantitative applications include the quality control of additives in fuel and lubricant blends and to assess the extent of chemical changes in various products due to ageing and use. Non-dispersive infrared analysers are used to monitor gas streams in industrial processes and atmospheric pollution. The instruments are generally portable and robust, consisting only of a radiation source, reference and sample cells and a detector filled with the gas which is to be monitored. 

Mass spectrometers have been used at some level in all of these types of investigations because of their unsurpassed sensitivity and specificity, their multicomponent analytical capability and, in some cases, their ability to provide precise and accurate isotope ratios. Traditional methods of analysis typically involve the collection of water and sediment samples, or biological specimens, during field expeditions and cmises on research vessels (R/Vs), and subsequent delivery of samples to a shore-based laboratory for mass spectrometric analyses. The recent development of field-portable mass spectrometers, however, has greatly facilitated prompt shipboard analyses. Further adaptation of portable mass spectrometer technology has also led to construction of submersible instruments that can be deployed at depth for in situ measurements. 

Fiorini, C. and Longoni, A. (1998). Application of a new noncryogenic X-ray detector in portable instruments for archaeometric analyses. Review of Scientific Instruments 69 1523-1528. 

Material balance analysis proves to be a critical diagnostic tool for the development of portable DMFC systems. In this analysis methanol balance on the anode side along with the methanol crossover rate typically measured by an infrared CO2 sensor is conducted. In addition, water balance on both anode and cathode sides is performed in which the cathode water amount is carefully collected by a moisture trap and measured. From such analyses Muller et al. " revealed that the water balance on the DMFC anode is highly negative, thus calling for membrane development with low water crossover in addition to low methanol crossover. 

Vibrational spectroscopy, in the form of mid-IR, NIR and Raman spectroscopy has been featured extensively in industrial analyses, both quality control (QC), process monitoring applications and held-portable applications [1-6]. The latter has been aided by the need for advanced instrumentation for homeland security and related HazMat applications. Next to chromatography, it is the most widely purchased classihcation of instrumentation for these measurements and analyses. Spectroscopic methods in general are favored because they are relatively straightforward to apply and to implement, are rapid in terms of providing results, and are often more economical in terms of service, support and maintenance. Furthermore, a single spectrometer or spectral analyzer, in a near-line application, may serve many functions, whereas chromatographs (gas and liquid) tend to be dedicated to only a few methods at best. 

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