Detection and identification

The JCAD shall automatically and simultaneously detect, identify, and quantify chemical vapor by class (nerve, blister, and blood, and TIC) and specific agent (GA, GB, GD, GF, VX, HD, L, HNS, AC, CK, and possibly some TICs). It shaU detect and provide an alert for nerve agent vapors, blister agent vapors, and blood agent vapors within the response times at constant concentration exposures listed in Table 3.9. These requirements are to be incorporated in requirements for future detector certification. TICs alerts are not a requirement at present. Ability to detect TICs may be desirable however. 

---

A significant advantage of the PLM is in the differentiation and recognition of various forms of the same chemical substance polymorphic forms, eg, brookite, mtile, and anatase, three forms of titanium dioxide calcite, aragonite and vaterite, all forms of calcium carbonate Eorms I, II, III, and IV of HMX (a high explosive), etc. This is an important appHcation because most elements and compounds possess different crystal forms with very different physical properties. PLM is the only instmment mandated by the U.S. Environmental Protection Agency (EPA) for the detection and identification of the six forms of asbestos (qv) and other fibers in bulk samples. 

Analytical and Test Methods. In addition to the modem spectroscopic methods of detection and identification of pyrroles, there are several chemical tests. The classical Runge test with HCl yields pyrrole red, an amorphous polymer mixture. In addition, all pyrroles with a free a- or P-position or with groups, eg, ester, that can be converted to such pyrroles under acid conditions undergo the Ehrlich reaction with p-(dimethylamino)henzaldehyde to give purple products. 

The mass spectrometer (ms) is a common adjunct to a chromatographic system (see Mass spectrometry). The combination of a gas chromatograph for component separation and a mass spectrometer (gc/ms) for detection and identification of the separated components is a powerful tool, particularly when the data are collected usiag an on-line data-handling system. QuaUtative information inherent ia the separation can be coupled with the identification of stmcture and relatively straightforward quantification of a mixture s components. 

Hyphenation of HPLC with NMR combines the power of sepai ation with a maximum of stiaictural information by NMR. HPLC-NMR has been used in the detection and identification of diaig metabolites in human urine since 1992. The rapid and unambiguous determination of the major metabolites of diaigs without any pretreatment of the investigated fluid represents the main advantage of this approach. Moreover the method is non-destmctive and without the need to use radiolabelled compounds. 

The most useful application of ISS is in the detection and identification of sur-fece contamination, which is one of the major causes of product failures and problems in product development. The surface composition of a solid material is almost always different than its bulk. Therefore, surface chemistry is usually the study of unknown surfaces of solid materials. To better understand the concept of surface analysis, which is used very loosely among many scientists, we must first establish a definition for that term. This is particularly Important when considering ISS... 

SERS substrates with bare metal surfaces irreversibly adsorb thioorganics (Eig. 4.59) and other compounds and can thus serve for the detection and identification of very low gas or solution concentrations of these substances [4.303]. SERS is especially well suited for the analysis of traces of gases, because it combines measurement of surface concentration with extremely high sensitivity. A monolayer in a typical focus of a laser with a diameter of 10 pm has a mass in the range of 10 femtograms even smaller amounts of substance are easily detectable, because 1% of a monolayer in a region 1-pm in diameter results in SERS of sufficient intensity. 

There are many reports of the use of mass spectroscopy coupled to chromatography outlets for detection and identification of dmgs and metabolites. An example is compound 126 (99MI2, 99MI3). Carboxylic acids have been converted into hydrazides and hence into 3-substituted [l,2,4]triazolo... 

Infrared absorption spectra can be employed for the identification of pure compounds or for the detection and identification of impurities. Most of the applications are concerned with organic compounds, primarily because water, the chief solvent for inorganic compounds, absorbs strongly beyond 1.5//m. Moreover, inorganic compounds often have broad absorption bands, whereas organic substances may give rise to numerous narrower bands. 

Harden T.C. Imeson, Detection and Identification of Trace Quantities of Organic Vapors in the Atmosphere by Ion Cluster Mass Spectrometry and the Ionization Detector System ,... 

When problems do arise, detection and identification of the causes, together with suitable remedies that will prevent reoccurrence, are required. 

Detection and identification of Helicobacter pylori and Demodex folliculorum (Fig. 17.13). 

The ultimate goal of microarray-based expression analysis is to acquire a comprehension of the entire cellular process, in order to exploit and to standardize the multidi-menisional relations between genotype and phenotype. However, an increasingly important parameter, which has not yet been substantially taken into account, is the role of cellular translation. This means that mRNA expression data need to be correlated with the assortment of proteins actually present in the cell. One approach is based on the use of microarrays containing double-stranded DNA probes for the analysis of DNA-protein interaction and, thus, the detection and identification of DNA-binding proteins by means of fluorescence [130] or mass spectrometry analysis [131]. Moreover, substantial efforts are currently under way to develop protein, antibody, or even cell arrays, applicable to the cor-... 

Ramsey JD, Flanagan RJ. 1982. Detection and identification of volatile organic compounds in blood by headspace gas chromatography as an aide to the diagnosis of solvent abuse. J Chromatogr 240 423-444. 

The very fast oxidation of the radical precludes its detection and identification by esr however, reacting mixtures are capable of initiating polymerisation of acrylonitrile. The oxidations of allylic alcohols by V(V) perchlorate are ca. thirty times faster than those of saturated alcohols. This is supporting evidence for radical intermediates in view of the expected delocalisation of the free electron... 

Frischenschlager, S., Hellwig, E., and Peteuly, R, Detection and identification of caramel colors in some liquid foodstuffs, Dtsch. Lebensm. Rundsch., 78, 385, 1982. Hellwig, E. et al., Detection and identification of caramel by gel-permeation chromatography, Dtsch. Lebensm. Rundsch, 77, 165, 1981. 

Takahashi H, B Kimura, M Yoshikawa, T Fuji (2003) Cloning and sequencing of the histidine decarboxylase genes of Gram-negative, histamine-producing bacteria and their application in detection and identification of these organisms in fish. Appl Environ Microbiol 69 2568-2579. 

Voinov VG, YuN ETkin, TA Kuznetsova, II Mal tsev, VV Mikhailov, VA Sasunkevich (1991) Use of mass spectrometry for the detection and identification of bromine-containing diphenyl ethers. J Chromatogr 586 360-362. 

In some cases a principal components analysis of a spectroscopic- chromatographic data-set detects only one significant PC. This indicates that only one chemical species is present and that the chromatographic peak is pure. However, by the presence of noise and artifacts, such as a drifting baseline or a nonlinear response, conclusions on peak purity may be wrong. Because the peak purity assessment is the first step in the detection and identification of an impurity by factor analysis, we give some attention to this subject in this chapter. 

R. P. Lcite, G. U. Miinsavage, U. Bonas, and R. E. Stall, Detection and identification of phytopathogenic Xanthomonas species by amplification of DNA-.sequences related to the HRP genes of Xanthomonas-campestris pv. vesicatoria. Appl. Environ. Microbiol. 60 1077 (1994),... 

In the case of the low abundance of some compounds, there are difficulties with signal overlap. To overcome these difficulties, there have been developments involving NMR hyphenation with techniques such as HPLC and mass spectrometry. In LC/NMR methods of analysis, NMR is used as the detector following LC separation and this technique is capable of detecting low concentrations in the nanogram range. This technique has been reported for the detection and identification of flavanoids in fruit juices and the characterization of sugars in wine [17]. 

The primary technology mission and expertise of TSA s laboratories and personnel involve the detection of weapons and concealed explosives. The TSA does not have the resources or expertise to develop detection and identification systems for chemical/biological agents. However, TSA s... 

The distinction between detection and identification is important, since it may affect the overall response time and options. A detection occurs when a chosen parameter exceeds its threshold value. The detection may be nonspecific—that is, it registers the occurrence of an anomaly but does not necessarily indicate the presence of a particular threat substance. By contrast, identification establishes the identity of the threat substances in a given set. Nonspecific detection systems may have a relatively rapid response time compared with that of specific identification systems, but the former typically provide a lower confidence level that a threat substance is in fact present. In some cases, an alarm from a rapid but nonspecific detection system may be used... 

TLC plates are of particular interest as substrates for spectroscopy (i) as a storage device for offline spectroscopic analysis (ii) for efficient in situ detection and identification and (iii) for exploitation of spectroscopic techniques that cannot be used in HPLC. Thin-layer chromatography combined with HR MAS (NMR) can be used for compound identification without the need for elution from the stationary phase [413]. Recently also TLC-XRF was found suitable for in situ TLC imaging of elements [414]. The combination... 

Various LC-PB-MS and LC-APCI-MS comparisons have been reported on polymer additive extracts [540, 563,629,630]. The complementary character of the El and APCI modes was confirmed. Yu et al. [630] compared LC-PB-MS and RPLC-UV-APCI-MS for detection and identification of unknown additives (in the 252 to 696 Da range) in an acetonitrile extract from PP (containing Irganox 1076, Naugard XL-1 and a degradation product, NC-4, 3-(3,5-di-f-butyl-4-hydroxyphenyl) propanoic acid, 7,9-di-f-butyl-l-oxaspiro [4,5] deca-6,9-diene-2,8-dione and octadecanol-1). Comparison was based on El data (identification of chemical structure), APCI (MW information CID spectrum with limited fragmentation) and PDA (210 nm). The components were identified by El and confirmed by APCI- (with better sensitivity and linearity) MS and PDA showed... 

The use of Raman microscopy in the detection and identification of pigments on manuscripts, paintings, ceramics and papyri was reviewed by Clark (1999). He concludes that it is arguable the best single technique to be applied to this area, since it combines the attributes of reproducibility and sensitivity with those of being nondestructive and immune to interference from both pigments and binders. He points... 

Kuhn, H. (1960), Detection and identification of waxes, including punic wax, by infrared spectrography, Stud. Conserv. 5, 71-80. 

Rottlander, R. C. A. (1985), Detection and identification of archaeological fats, Fette, Seifen 87, 314-317. 

Peruski, L. F. Peruski, A. H. Rapid diagnostic assays in the genomic biology era Detection and identification of infectious disease and biological weapon agents. BioTechniques 2003, 35, 840-846. 

---