Detection instrumentation

ISA RP 12.13. Part II. 1987. Installation, Operation, and Maintenance of Combustible Gas Detection Instruments. Instrument Society of America, Research Triangle Park, NC. 

Various calibration schemes similar to those given in Section 2.2.8 were simulated. The major differences were (1) the assumption of an additional 100% calibration sample after every fifth determination (including replications) to detect instrument drift, and (2) the cost structure outlined in Table 4.6, which is sununarized in Eq. (4.2) below. The results are depicted graphically in Figure 4.5, where the total cost per batch is plotted against the estimated confidence interval CI(X). This allows a compromise involving acceptable costs and error levels to be found. 

MSn are of particular interest. MSn stands for the n-fold coupling of mass spectrometers, alternatively serving as separation and detection instrument. By hyphenated techniques the dimensionality of analytical information (see Sect. 3.4) and, therefore, also the information amount (see Sect. 9.3) is significantly increased (Eckschlager and Danzer [1994]). 

They allow sensing at a distance from analyzed object. Because the fluorescence reporter and the detecting instrument are connected via emission of light, the sensing may occur in an essentially noninvasive manner and allow formation of... 

Fluorescent detection technology applicable to biochips is evolving rapidly, resulting in detection instruments that are more powerful, user-friendly, and less expensive. Most systems employ photomultiplier tube (PMT) technology in conjunction with multiple colors, lasers, and a variety of filters. It is essentially a fluorescent microscope that... 

Canadian Standards Association (CSA), Standard C22.2 No. 152 M1984. Combustible Gas Detection Instruments. CSA, Rexdale, Ontario, Canada, 1984. 

Factory Mutual (FM), FM Class No. 6310-6330, Combustible Gas Detection Instruments. 

A wide variety of commercial equipment is available for detection of hazardous chemicals, including a number of chemical warfare agents. For example, ion mobility spectroscopy is used to detect nerve, blister, and blood agents. The Chemical Agent Monitor is a portable, hand-held point detection instrument that uses ion mobility spectrometry to monitor nerve or blister agent vapors. However, minimum detection limits are approximately 100 times the acceptable exposure limit for nerve agents, and approximately 50 times the acceptable exposure limit for blister agents. 

In order to protect against these radioactive materials being brought on-site, a facility may set up monitoring sites outfitted with radiation detection instrumentation at entrances to the facility. Depending on the specific types of equipment chosen, this equipment would detect radiation emitted from people, packages, or other objects transported through an entrance. 

In recent years, also the number of articles concerning HILIC stationary phases has enormously increased, especially as regards the hydrophilic interactions that resolve some important problems separation and resolution of less retained compound in reversed phase chromatography. With this novel stationary phase, where the silica surface is covered with cross-linked diol groups to increase polar selectivity in hydrophilic conditions, is possible obviate to the use of normal phase with high water content. This allows facilitating the interfacing with sensible and selective detection instruments, such as mass spectrometer with ESI source. The HILIC stationary phase was often chosen to interface the mass spectrometry detector, because it would be... 

As an inert gas with heat-transfer capability, hehum is used in gas-cooled nuclear power reactors, which operate at a higher efficiency than liquid-cooled nuclear reactors. The worlds largest particle accelerators use hquid hehum to cool their superconducting magnets. Astronomers use hquid hehum to cool their detecting instruments. If this equipment is kept cool, the thermal noise produced at higher temperatures is reduced. 

Selecting the placement of Q.C. samples within the anaytical run depends upon the purpose of the Q.C. program. While random placement is statistically justified, it may not provide sufficient diagnostic information. If instrumental drift is an important concern (as it is in many automated, operator unattended techniques) the two Q.C. samples should be spaced at intervals that are appropriate to detect the anticipated drift. Placement near the beginning and end of the analytical run has been been beneficial in detecting instrumental drift. By bracketing groups of routine samples with Q.C. samples it is easy to identify specific samples that require re-analysis. 

Before moving on to excerpt 4E, we call your attention to two ways in which the concept of zero is addressed in excerpt 4D. First, we consider the concept of zero in measured concentrations (i.e., the concentrations reported in the last column of Table 1). Recall that no chromium oxalate was detected in the cells however, the authors do not report this with a zero. Rather, they use the phrase below the detection limit in the text and the less-than symbol (e.g., <0.025 mg/g) in Table 1, which puts an upper limit on the amount of chromium oxalate present. Novice writers might (incorrectly) suggest that no chromium was present in the text and use a zero in the table (0 mg/g). Such uses of zero, however, are incorrect, because (for measured concentrations) zero varies with the sensitivity of the detecting instrument. For example, on one instrument, zero will be less than one part per million on a more sensitive instrument, zero will be less than one part per billion. Instead of reporting zero, authors report that the measurement was below the detection limit for that instrument. Some common ways to express this concept in the text and table are as follows ... 

Neptunium is not found in nature in any extractable quantities. However, it occurs in uranium ores in exceedingly small concentrations resulting from neutron capture of uranium isotopes. No major application is known for this element. Its isotope, Np-237, is used in neutron detection instruments. 

Complete calibration of the personal monitors using the NIST secondary standards for all irradiation conditions is not done routinely. More often, the physical response of the components of the personal monitor is compared to the response of other calibrated radiation detection instruments to assess whether the personal monitor components respond the same as during complete calibration. This comparative calibration usually involves fewer radiation fields. 

Electrochemical gas detection instruments have been developed which use a hydrated solid polymer electrolyte sensor cell to measure the concentration of specific gases, such as CO, in ambient air. These instruments are a spin-off of GE aerospace fuel cell technology. Since no liquid electrolyte is used, time-related problems associated with liquid electrolytes such as corrosion or containment are avoided. This paper describes the technical characteristics of the hydrated SPE cell as well as recent developments made to further improve the performance and extend the scope of applications. These recent advances include development of NO and NO2 sensor cells, and cells in which the air sample is transported by diffusion rather than a pump mechanism. 

The intended use of the SPE detectors is by military, government and industrial personnel involved in air quality measurements. The commercial SPE CO dosimeter and direct-reading detection instruments are being widely used by steel mills, fire departments and various city, state and government regulatory agencies. 

Life testing conducted on N0 SPE sensor cells showed a 1 /day increase in signal over the first 20 to 30 days followed by a leveling in performance. Typical initial sensor response for the NO sensor cell is 3 /ppm N0. With daily- calibrations, high accuracy levels can be maintained throughout sensor life. For example, a prototype N0 detection instrument has operated for one year with the response to N0-in-air within 15 of the original calibration value. 

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. 

Dempsey, R.M. LaConti, A.B. Nolan, M.E. lGas Detection Instrumentation Using Electrically-Biased Fuel Cell Sensor Technology11, PB25W23, NTIS, Springfield, Va., 1978... 

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