Portable instrument

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). 

Portable instrument should be of explosion-proof design fixed point systems may rely on remote sensing heads... 

All bought-in items of plant, especially those supplied without adequate materials certification, should be subject to random inspection. Portable instruments are available for many types of non-destructive examination, chemical analysis and mechanical testing of fabricated items of plant. 

Solid-state photodetectors are semiconductors. Because of their small size and the fact that they do not need high voltage, they are suited for portable instruments. Several subtypes are in use ... 

Based on the photoresistivity levels of certain crystals like Se, Ge, Si, CdS, and PbS, photoconductors are constructed. Under light impact, they reduce their electrical resistance up to about 10" times. They are used in portable instruments like light exposure meters. 

The devices described are mostly used in portable instruments. For a deeper understanding, extended studies are recommended. After a general review of the most important parts of optical spectrometers, we proceed now to colorimetric particularities. 

Based on these capabilities, the RRS detection method has already found commercial application in the nutritional supplement industry (BioPhotonic Scanner , Pharmanex LLC, Provo, and Utah), which has placed thousands of portable instruments with their customers for rapid optical measurements of dermal carotenoid levels, and which has further developed the instrumentation for rugged field use (Bergeson et al. 2008). 

Ion-selective electrode research for biomedical analysis is no longer the relatively narrow, focused field of identifying and synthesizing ionophores for improved selectivity and the integration of ion-selective electrodes into clinical analyzers and portable instruments. These efforts have matured now to such an extent that they can teach valuable lessons to other chemical sensing fields that are just emerging technologies. 

There is a longstanding demand for a simple and portable instrument for the detection and measurement of oxygen dissolved in water. Suitable electrodes have been developed and more recently have been ingeniously used as the basis for a range of biochemical sensors. 

The detector in a spectrometer must produce a signal related to the intensity of the radiation falling on it. For instruments operating in the visible region a photovoltaic or barrier-layer cell is the simplest and cheapest available. Current produced when radiation falls on a layer of a semiconductor material, e.g. selenium, sandwiched between two metallic electrodes, is proportional to the power of the incident radiation and can be monitored by a galvanometer. Barrier layer cells are robust and are often used in portable instruments but they are not very sensitive and tend to be unstable during extended use. 

Although field portable instrumentation, which is battery operated and self-contained, has been developed in the past, there has been a resurgence of interest in field portable instruments, some of which are small enough to be handheld. 

Describe the basic characteristics that a held portable instrument must have to be useful in the held. 

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. 

Cross-reactive sensing arrays were developed to detect odors and vapors in an artificial nose manner. Solvatochromic dyes such as Nile Red are adsorbed on the surface or embedded into various polymeric or porous silica beads. The beads respond to analyte vapor by a change in fluorescence maxima or/and intensity due to changes of polarity inside the bead. A portable instrument and preliminary field test for the detection of petroleum products was recently described [106]. 

Optical fiber detectors (OFD) are devices that measure electromagnetic radiation transmitted through optical fibers to produce a quantitative signal in response to the chemical or biochemical recognition of a specific analyte. Ideally, an OFD should produce a specific and accurate measurement, continuously and reversibly, of the presence of a particular molecular species in a given sample medium. Additionally, OFD should pro vide maximum sensitivity and minimal interferences fromsuperfluous ions or molecules to obtain low detection limits. Other attractive features include the miniaturization of the fiber s tip to accommodate single-cell analysis and portable instrumentation to allow in situ analysis. 

The excitation pulse tram is used to trigger of the excitation. Mode-locked lasers and cavity-dumped lasers are versatile excitation sources however, they are not ideal to implement portable instruments. Externally modulated solid state microlasers are a... 

These miniaturized sensors are suitable for flow-injection analysis [130]. Similar systems have also been used in portable instruments [56]. A micro-ISFET was constructed for intracellular determination of K [53]. 

Batteries are needed to power small, portable instruments such as flashlights, cameras, and computers. In many flashlight batteries, the two electrodes—attached to the plus and minus ends of the battery—... 

Nevertheless, it was only starting from the seventies and the eighties that the technology began to deploy highly sophisticated devices, which are continuously evolving toward an increasing miniaturization and the development of portable instrumentation. 

This paper reports on research involved the design, construction, and evaluation of a portable instrument, a "luminoscope", for detecting skin contamination by coal tars via induced fluorescence. The instrument has been used in the laboratory to measure the fluorescence of various coal tars and recycle solvents from liquefaction processes spotted on filter paper on rat and on hamster skin. The practical use of the devices in field test measurements to monitor skin contamination of workers at coal gasifier is discussed. The paper also discusses the practicality and usefulness of the luminescence method for detecting skin contamination. 

Development of a Diffusion Head Sensor Cell. The use of air sampling pumps in portable electrochemical gas detection apparatus introduces potential problems into the instrument. First, the sensor cell response is dependent on gas flow rate. The sample flow rate, therefore, must be accurately controlled to obtain reproducible results, or the sample flow rate must be set high enough to insure a flow independent response. Secondly, failure of the pump itself could prevent a sample from reaching the sensor cell. Thirdly, the pumps are usually one of the largest users of current in a portable instrument and thereby limit usable battery life. 

Production Gas Detection Instruments. A family of portable instruments has been developed for the detection and monitoring of CO levels in air (7 > The instrument family consists of a direct reading detector with LCD display of actual CO concentration and a personal CO dosimeter. Both the detector and the dosimeter measure the accumulated CO exposure of personnel in industrial environments and provide both visible and audible alarms if instantaneously unsafe levels of CO are encountered. An accompanying support console is used for integrated cumulative CO dosage readout and battery charging. 

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