Hand-held instrument

Block diagram for a filter photometer with photo showing a typical hand-held instrument suitable for field work. Colorimeterrw is manufactured by Hach Company/photo courtesy of Hach Company. 

The nature of electrochemical instruments makes them very attractive for decentralized testing. For example, compact, battery-operated voltammetric analyzers, developed for on-site measurements of metals (9,10), readily address the growing needs for field-based environmental studies. Similarly, portable (hand-held) instruments are being designed for decentralized clinical testing (11). 

Selection of on-site analytical techniques involves evaluation of many factors including the specific objectives of this work. Numerous instrumental techniques, GC, GC-MS, GC-MS-TEA, HPLC, HPLC-MS-MS, IR, FTIR, Raman, GC-FTIR, NMR, IMS, HPLC-UV-IMS, TOF, IC, CE, etc., have been employed for their laboratory-based determination. Most, however, do not meet on-site analysis criteria, (i.e., are not transportable or truly field portable, are incapable of analyzing the entire suite of analytes, cannot detect multiple analytes compounded with environmental constituents, or have low selectivity and sensitivity). Therefore, there exists no single technique that can detect all the compounds and there are only a few techniques exist that can be fielded. The most favored, portable, hand-held instrumental technique is ion mobility spectrometry (IMS), but limitations in that only a small subset of compounds, the inherent difficulty with numerous false positives (e.g., diesel fumes, etc.), and the length of time it takes to clear the IMS back to background are just two of its many drawbacks. 

The Mobile Universal Surface Explorer (MOUSE) is described as a new-generation, hand-held instrument with exciting potential for use on-line." MOUSE devices are based on the principles of inside-out NMR where open magnet designs are used for measurements within the held. Essentially the unit... 

The excitation lamp is enclosed within a compartment which is designed to shield the detector and its associated electronic circuits from the heat generated by the lamp. A small fan flushes cool air into the upper compartment that houses the detection devices. The trigger mounted at the instrument s handle is used to operate a dual shutter that opens and closes the excitation and emission apertures simultaneously. The hand-held instrument is low cost (a/ 2,000), simple to operate, and weighs only a little over 1 kg without the power supply ( 5 kg). A photograph of the prototype instrument is shown in Figure 2. 

Cylindrical probe (either a hand-held instrument or a fixture for a mechanical testing machine), flat or rounded end (Magness-Taylor)... 

Distell Industries (1993) has developed hand-held instruments for the measurement of fat content in fish and meat. The technology evolved from the knowledge that the dielectric loss factor of fish has a reasonably linear dependence on water content (Ohlsson et al. 1974). In fish, fat accumulates at the expense of water and protein, making estimation of fat content based on water content practical (Kent 1990). In meat products, fat accumulation is independent of water and protein, i.e., it is additive, and thus makes the calculation of fat based on water amount more difficult. A hand-held meat instrument has been developed, but requires calibration depending on the type of meat measured. 

The unit works on the principal that the microwave attenuation of a strip transmission line depends upon the loss factor of the material with which it is in contact. Data indicates accuracies of 5% can be attained by the hand-held instruments, depending upon the range of fat measured. The instruments sell for approximately 5000.00. Copies of references are available from Distell. 

Kent, M. 1990. Hand-held instrument for fat/water determination in whole fish. Food Control, Jan. 1990, pp. 47-53. 

J.P. Hart, S. Serban, L.J. Jones, N. Biddle, R. Pittson and G.A. Drago, Selective and rapid biosensor integrated into a commercial hand-held instrument for the measurement of ammonium ion in sewage effluent, Anal. Lett., 39 (2006) 1657-1667. 

It is proposed that the survey of the interior of the main hall will be carried out manually using hand held instruments. This will be supplemented using the bridge crane mounted equipment to examine the hall walls up to crane rail height. 

Cytoplasmic Male Sterility. Unfortunately, large-scale mechanical emasculation cannot be applied to all crops of interest. In wheat, for example, the pollen-bearing anthers and female stigmas lay side by side within each floret of a spikelet. Removal of anthers with small, hand-held instruments obviously has utility only for small-scale hybridization experiments. Nevertheless, by crossing a female parent endowed with cytoplasmic male sterility with a male parent that has fertility-restoring genes, one can achieve hybrid wheat seed production. This technology, however, has limitations compared to... 

The Testmate is a hand-held instrument designed to rapidly assess the acetylcholinesterase level in blood samples. Fluctuations in the acetylcholinesterase level may indicate potential exposure to nerve agent. The Testmate can be utilized prior to deployments to determine baseline levels so potential exposures are better quantified. It is also used in the field as a rapid assessment tool for potential nerve agent exposure. Results from a sample can determine whether or not further investigations are needed. It recently received FDA approval. Two units have been fielded to the TAML. 

Brochure of Bruker RAID series and 1MS2000 hand-held instruments, Bruker-Saxonia, Germany, http //www.anny-technology.com/contractors/nbc/bruker/. 

Data collection is far more rapid than using cover meters or other hand-held instruments. However, interpretation is far more complex as many features... 

Current flat-panel display technology primarily revolves aroimd inorganic LEDs, backlit liquid crystal displays (LCDs) and vacuum fluorescent displays. Although these technologies are trim and efficient compared with cathode ray tubes, they can be bulkier and much more power consuming than required for many applications. In many battery-operated devices, such as laptop computers, cellular telephones and other hand-held instruments, the illuminated display is the primary energy consumer. Furthermore, LED displays are expensive to fabricate because of the many individual diodes required to make up an alphabet, each with its own contacts and interconnections. These problems forced researchers to look for other materials. 

Figure 28.14 Remote open-path TOLAS measurement, using a hand-held instrument. The data displayed are for simulated gas leak detection, measured from (a) a brick wall at distance 21 ft (b) a grassy embankment at 22 ft and (c) a hedge at 17 ft. The arrows indicate the nozzle release of CH4. Adapted from Frish et at, SPIE 4199-05, 2000, with permission of the International Society for Optical Engineering...

A number of photographs illustrate typical measurement situations. A collimated detector, detector hoist, and cart-mounted readout were usually used. A compact, hand-held Instrument was also used extensively. Some special calibration source arrangements were made to simulate some of the more common situaUons encountered in Hie measurements. 

The automobile company Ford has developed, in conjunction with Southampton University, a hand-held instrument for identifying the basic types of polymers and additives, and the research agency PIRA is reported to be working on similar equipment, in conjunction with Bayer AG. 

A hand-held instrument to measure colour quickly, easily and accurately on almost any type of surface - claimed to be the only such device - has been... 

Portable. Hand-held instruments intended for field applications offer extensive capabihties in a portable, rugged package. Some hand-held meters include true-RMS measurements, 1 msec response times, capacitance and frequency modes, and recording capabihties. 

Hand-Held Instruments, The utility of a hand-held analytical instrument should be an ability to respond quickly to physiologically important concentrations of toxic chemicals. A greater degree of uncertainty in response can be tolerated although this uncertainty must be minimized. The safety of Treaty Inspectors is a basic application where hand-held analytical instruments can be of benefit. It must be re-emphasized that the response characteristics of a device used to warn an inspector of potential chemical hazards must be directly related to human physiological response characteristics. 

Hand-held instruments can also be useful in chemical screening or for determination of presence or absence of specific chemicals in or near a chemical facility. Hand-held instruments, because of limited analytical power, should prove useful in this regard because identification of materials other than those for which they are programmed is difficult. 

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