Amines detection

IEC was applied to determine biogenic polyamines such as putrescine (4a), cadaverine (4b), tyramine (5), histamine (6), spermidine (38), agmatine (39) and tryptamine (40), contained in aqueous trichloroacetic extracts of leafy vegetables, such as cabbage and lettuce. A cation exchange column loaded with potassium ions and a special buffer were used. Spermidine (38) was the major amine detected in this group (7-15 Xg/g fresh weight)144. 

The molecular absorption intensity of polar compounds is usually small, but highly sensitive detection can be obtained after pre- or post-column derivatiza-tions. The use of ultraviolet absorption or fluorescence-active counter-ions makes it possible to achieve highly sensitive detection of polar compounds and enhance the capability of ion-pair liquid chromatography. For example, N,N-dimethylprotriptyline has been used as a counter-ion for carboxylic acids12 and picric acid for quaternary amines13 in normal-phase ion-pair partition liquid chromatography. Phenethylammonium, cetylpyridinium, l-phenethyl-2-pyco-linium, and naphthalene-2-sulfonic acid have been used for sulfonic acid and alkyl amines detection.14,15 Ion-pair post-column extraction was applied on-line for fluorescence detection.16... 

Generally, the detector response will depend on the type of aromatic amine detected. Table I shows that response to N,N-di-methylaniline is about twice as high as the response to its primary isomer 2,6-dimethylaniline. Sensitivity for a selected number of aromatic amines was found to be increased by a factor 5-16 in comparison to a flame-ionization detector. 

A succinylated casein derivative that has nearly all its amines blocked can be used as a substrate in protease assays (Hatakeyama etal., 1992). As the casein is degraded by a protease, free amines are created from a-chain cleavage and release of a-amino groups. The creation of amines can be monitored by an amine detection reagent such as trinitrobenzene sulfonic acid (TNBS Section 4.3). The procedure forms the basis for a highly sensitive assay for protease activity. 

O-Phthaldialdehyde (OPA) is an amine detection reagent that reacts in the presence of 2-mercaptoethanol to generate a fluorescent product (for preparation, see Section 4.1, 2-mercaptoethanol) (Fig. 91). The resultant fluorophore has an excitation wavelength of 360 nm and an emission point at 455 nm. OPA can be used as a sensitive detection reagent for the HPLC separation of amino acids, peptides, and proteins (Fried et al., 1985). It is also possible to measure the amine content in proteins and other molecules using a test tube or microplate format assay with OPA. Detection limits are typically in the microgram per milliliter range for proteins. 

Blocking of amine groups on proteins also has been used to create a sensitive reagent for measuring protease activity (Hatakeyama etal., 1992). With nearly all the primary amines of casein blocked, an amine detection reagent such as trinitrobenzene sulfonic acid (TNBS) will only minimally react with the protein and form its typical orange derivative. As proteases cleave the protein, however, primary a-amines are created from cleavage of the a-chain peptide bonds, and TNBS can react with them. The more protease activity present, the more color is formed. 

Hinsberg test To 0.5 ml of the amine (0.5 g, if solid) in a test tube add 1 ml of benzenesulfonyl chloride and 8 ml of 10% NaOH. Stopper the tube and shake for 3 to 5 min. Remove the stopper and warm the tube while shaking in a hot water bath ( 7CPC) for about 1 min. No reaction is indicative of a 3° amine the amine becomes soluble upon acidification (pH = 2 to 4) with 10% HC1. If a precipitate is present in the alkaline solution, dilute with 5 to 8 ml of H20 and shake. If the precipitate does not dissolve, the original amine is probably a 2° one. If the solution is clear, acidify (pH = 4) with 10% HC1. The formation of a precipitate is indicative of a 1° amine (detection limit, 100 mg compounds tested, C, to C10). 

Amides Basic (reflux) hydrolysis All amides yield ammonia or the corresponding amine detected by odor or by placing wet blue litmus paper on top of the condenser... 

Endo et al. reported a precolumn derivatization method with sodium p-naphtoquinone-4-sul-fonate for stimulant amines. Detection of the coloured derivatives at 450 nm increased the sensitivity about 25-fold, when compared with UV-detection of the underivatized compounds.UV detection of the coloured derivatives at 245 and 280 nm was also more sensitive - 2.4 and 3.7-fold increase in sensitivity respectively. However, interfering peaks made it less suitable for the analysis of urine extracts. 

Song X, Boga R, and Chidebelu-Eze CO, Diagnostic kit and one-step enzymatic and amine detection technique, U.S. Patent US 2006003336 Al 01/05. 2006. 

Table 11.10 shows popular methods of amine detection used in GC analyses, while Table 11.11 shows examples of GC-MS analyses depending on the selection of column type, temperature, carrier gas, as well as the conditions of injection and detection. 

The APD 2000 provides semi-quantitative identification of nerve agents. Colorimetric tubes are available which are designed to qualitatively detect vapors of phosphoric acid esters as well as the key decomposition products hydrogen fluoride (HP) and organic amines. Detection of agents with PIDs or FIDs may be possible. Detection and identification with FT-IR is possible provided that the appropriate reference spectra are available. 

Maldnen, M. Sillanpaa, M. Viitanen, A-K. Knap, A. Makela, J.M. Puton J., The effect of humidity on sensitivity of amine detection in ion mobility spectrometry, Talanta 20n, 84, 116-21. 

Table 12.3 Maximum levels (mg/kg) of biogenic amines detected in foodstuffs purchased from retail markets... 

Alberto, M. R., Arena, M. E., De Nadra, M. C. (2004). Differences between biogenic amine detection by HPLC methods using OPA and dansyl derivates. Methods in Molecular Biology, 268,481-487. 

Caillouette, J. C. Amine detection by color change, inhuman body moisture. US Patent 5998161,1999 Chem. Abstr. 1999,132, 1805. 

Li DQ, Ma M (2000) Surface acoustic wave microsensors based on cyclodextrin coatings. Sens Actuators B 69 75-84 Liu CJ, Lin JT, Wang SH, Jiang JC, Lin 03 (2005) Chromogenic calixarene sensors for amine detection. Sens Actuators... 

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