Amines analysis

A drawback to conventional amino analysis by chromatography is the need for pre- or post-column derivatization to improve sensitivity. Ninhy-drin, the reagent originally applied for detection, has been increasingly displaced by other reagents such as phenylisothiocyanate,71 9-fluorenylethyl chloroformate,72 and o-phthaldialdehyde (OPA). OPA allows fluorimetric detection, which offers the potential for greater sensitivity.73 A limitation of OPA is that it doesn t derivatize secondary amines, so an additional reaction must be added for proline detection. And, as noted for amine analysis in section A5.4.2, such derivatization adds to the analysis time and may yield unstable products. 

Preparation of commercial fatty acid-DETA derivatives the previously described procedure (11) was slightly modified, using a 5% excess fatty acid to ascertain that all BETA was consumed. Amine analysis was conducted, according to AOCS test method (13). The reaction products were used without purification. 

Berberine,acrino1 Quaternary alkyl amines Analysis pharmaceuticals Determination by using UV-absor-bing counter-ions(Fig,15.2)... 

Knize M. and Salmon C. Heterocyclic amine analysis of process flavors. Unpublished report submitted to FEMA. 1998. 

Diaminobutane, DAB (Aldrich), Di-n-Butylamine, DBA (Aldrich), and Tri-n-Butylamine, TBA (Eastman Organic Chemicals), were used as curing agents. Each was distilled under Helium at one atmosphere and sealed. The amine analysis of Critchfield and Johnson (15)was conducted to determine purity. Table I. The purity and the theoretical equivalence were used to determine the weight of amine needed for a given weight of resin. 

Analytical Methods. The analytical methods utilized for this paper were a combined epoxy-amine analysis as described by Bell (16) and a spectrophotometric determination for primary and secondary amines based on work by Toome and Manhart (17). 

Catalytic asymmetric transfer hydrogenation is an efficient method for producing optically active alcohols and amines. Analysis of launched and development pharmaceuticals show that these types of chiral centers occur most frequently, so this technology is proving particularly valuable. The chapter will describe the background, development, and application of asymmetric transfer hydrogenation, with particular emphasis on Avecia s proprietary CATHy catalysts. 

Riederer P, Woketich S. Time course of nigrostriatal degeneration in Parkinson s disease. A detailed study of influential factors in human brain amine analysis. J Neural Transm 1976 38 277-301. 

Analysis of dimethyl- and diethylamine in air may be performed in accordance to NIOSH Method 2010 (NIOSH 1984, Suppl. 1989). About 3-30 L of air at a fiow rate of 10-1000 mL/min is passed through a silica gel (20/40 mesh, 150 mg front and 75 mg back) sorbent tube. The analytes are desorbed with dilute sulfuric acid in 10% aqueous methanol (3-h ultasonication) and injected into a GC equipped with a FID. A packed column, 4% Carbowax M over 0.8% KOH on Carbosieve B (60/80 mesh) was used in the NIOSH laboratory. A nitrogen-specific detector may be used for amine analysis instead of an FID, using a DB-5 fused-silica capillary column. This method may be applied for the analyses of other aliphatic amines in air and also for certain ethanolamines (NIOSH 1984, Suppl. 1989, Method 2007). Alternatively, ethanolamines may be analyzed by NIOSH Method 3509 (NIOSH 1984, Suppl. 1989). These compounds present in air (5-300 L of air) are... 

Fig. 1, Confirmation that the cell bodies shown to contain octopamine (in Table 1) belong to PM4 neurons. The photomontage shows the major projections of a Lucifer yellow-stained PM4 neuron revealed by anti-Lucifer yellow immunohistochemistry. The cell body is missing because it was removed for biogenic amine analysis. See Note 9 for additional commentary. Scale 100 pm.

The crosslink structure was analyzed and quantified by thiol-amine analysis, which is based on treatment of the crosslinked material with a set of thiol-amine chemical probes, specifically cleaving particular crosslinks types [23], Polysulfide crosslinks are cleaved by treatment of crosslinked rubber samples with 2-propanethiol (0.4 M) and piperidine (0.4 M) in toluene for 2 h under inert gas atmosphere (argon) at room temperature, while polysulfide and disulfide crosslinks can be cleaved by treatment under the same conditions with 1-dodecanethiol (1 M) in piperidine for 72 h. 

FIGURE 11.3 Crosslink structure of samples 2/0 and 2/1.5, irradiated with 122 and 198 kGy. Network density formed in the samples irradiated with a dose of 50 kGy was very low and the results on crosslink structure obtained from the thiol - amine analysis... 

Lovely AE, Wenzel TJ. Chiral NMR discrimination of amines analysis of secondary, tertiary and prochiral amines using (18-crown-6)-2,3,ll, 12-tetracarboxylic acid. Chirality 2008 20 370-378. 

When one needs to determine the optical purity of a compound that is not amenable to salt formation (i.e., not a carboxylic acid or amine), analysis by NMR becomes slightly more difficult. It is frequently necessary to determine the enantiomeric excesses of chiral secondary alcohols, for example. In these cases, derivatization of the alcohol through covalent attachment of an optically pure auxiliary provides the mixture of diastereomers for analysis. This requires reacting a (usually small, a few milligrams) sample of sample alcohol with the optically pure derivatizing agent. Sometimes, purification of the products is necessary. In the example shown below, a chiral secondary alcohol is reacted with (5)-2-methoxyphenylacetic acid [(5)-MPA] using dicyclohexylcarbodiimide (DCC) to form diastereomeric esters. After workup, the NMR spectrum of product mixture is acquired, and the res-... 

High-field NMR may be used to obtain the approximate percentage of free amine in an amine oxide. For some products, the analysis can also be performed by GC, using any of a number of columns recommended by suppliers for amine analysis. However, most amine oxides are heat sensitive and decompose to the free amine in the GC injection port. The methods described below are generally selected for routine quality control. 

A problem with the analysis of surfactants with two hydroxyl groups is the possibility of formation of two different derivatives of each oligomer the mono- and the Wjtrimeth-ylsilyl ether. This leads to more complex chromatograms than for underivatized nonionics. Therefore, for low MW EO adducts of primary amines, analysis without derivatization is sometimes preferred (50). 

As mentioned under amine analysis, it is best to react any residual amine hydrogen by addition of chlorotrimethylsilane to the bw(trimethylsilyl)acetamide solution (83). Direct GC analysis of underivatized monoethanolamides has been demonstrated using MS detection (84). 

Surmann P, Peter B (1996) Carbon electrodes in amine analysis effect of chemically modified carbon surfaces on signal quality and reproducibility. Electroanalysis 8 685-691... 

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