Amino acids extraction

GC-C-IRMS instrumentation enables the compound-specific isotope analysis of individual organic compounds, for example, n-alkanes, fatty acids, sterols and amino acids, extracted and purified from bulk organic materials. The principle caveat of compound-specific work is the requirement for chemical modification, or derivatisation, of compounds containing polar functional groups primarily to enhance their volatility prior to introduction to the GC-C-IRMS instrument. Figure 14.7 summarises the most commonly employed procedures for derivatisation of polar, nonvolatile compounds for compound-specific stable isotope analysis using GC-C-IRMS. 

Amino acids Extraction of dried salts Paper FAA [248]... 

As a result of these inconsistencies, the very same amino acid extracts that had been used to produce the contentious AAR dates were independently dated by the AMS method at the Oxford Radiocarbon Accelerator Unit of the Research Laboratory for Archaeology and the History of Art, University of Oxford (OxA numbers Bada et al., 1984) and the NSF Accelerator Facility for Radioisotope Analysis, University of Arizona, Tucson (AA numbers). 

Bada, J.L., Gillespie, R., Gowlett, J.A.J. and Hedges, R.E.M. (1984). Accelerator mass spectrometry radiocarbon ages of amino acid extracts from Californian Palaeoindian skeletons. Nature 312 442 144. 

The painstaking procedures and special instrumentation required for manipulating nanoliter range volumes were described for the determination of amino acids in single cells218 and the amino acid analysis of subnanogram amounts of protein219. The amino acid extract... 

A dating technique for fossils is based on the measurement of the d l ratio of amino acids extracted from the fossil sample. The hypothesis is that over very long periods... 

An alternative general process involves coextraction of palladium and platinum, followed by selective stripping (see Fig. 11.12). A novel amino acid extractant, made by the reaction between chloracetic acid and Amberlite LA-2, a secondary amine, is used to extract the two elements from the leach liquor. However, in the given flow sheet, no selective stripping is employed, both elements being stripped by hydrochloric acid. The resulting chloroanions are then separated by using di- -hexylsulfide to extract PdCll. ... 

The most interesting point is that extraction of amino acids into IL occurs without addition of a counterion. Typically, for amino acid extraction into conventional solvents (including extraction with crown ether), a hydrophobic counterion is required. Moreover, in most cases, even the presence of such a counteranion does not provide an efficient recovery. 

The ion-exchange mechanism of exfracfion does nof occur only for amino acids. We observed if also for cafecholamines [26]. These compounds are efficiently extracted into ILs in the cationic form, af pH 1-8. Af fhese pH, the primary (dopamine) or secondary (adrenaline and dobutamine) amino groups are protonated (catecholamines are oxidized in alkaline solutions at pH > 8). By analogy with amino acids, extraction may be described by the cation-exchange reaction ... 

Hexane Amino acid extracted MAW-HE° Commercial meal Laboratory prepared Commercial meal... 

Despite its ionic structure 12 is almost insoluble in water. The affinity toward amino acids was studied by extraction experiments, where the enantiomers of Phe, Val, and Trp were extracted into CD2C12 from aqueous solutions. The amounts of amino acids extracted were determined by NMR integration . As expected, the aromatic amino acids were preferred (40% extraction efficiency for L-Phe and L-Trp). In the organic phase, no valine was detected. Moreover, almost no D-enantiomers were extracted by (S,S)-12 (D-Trp<0.5%,D-Phe<2%). 

Table 7 Amounts and enantiomeric excesses of amino acids extracted by 63-66...

Fig. 39. Chemical structure of the glyco amino acid extracted from ovomucoid...

Reports of the presence of methionine sulfoxide are less frequent with respect to protein hydrolyzates than to free amino acid extracts. This is at least partially due to the fact that reduction and other changes occur upon hydrolysis with hydrochloric acid (16). The extent of decomposition depends on the conditions of hydrolysis and may approach 100%. One occasionally finds a published report of an amino acid analysis of protein in which data for methionine sulfoxide but not methio-... 

Amino acid racemization analyses on shell are carried out in two ways sampling all the amino acids extracted from the shell (called total) and sampling only the protein-bound amino acids (referred to as protein). The first method is essentially identical to the processing... 

Radiocarbon Dating of Amino Acids Extracted from Chione Shell. We attempted to resolve the question of which dating method produced more accurate shell dates by submitting amino acids extracted from Chione shell for a radiocarbon analysis (20). Because of the possibility of exchange with groundwater carbonates, the inorganic carbon in mollusc shell can be contaminated easily. We reasoned that the carbon in the amino acids would provide a more reliable age estimate than the carbon-... 

This interpretation has been questioned by Chang and Mack (1978), who found that water-soluble organics, especially amino acid extracts from the Murchison meteorite, were almost as heavy as carbonate C [8C (PDB) = -1-23 to -l-44%o vs. +44.4%o], in contrast to the much lighter insoluble polymer (—15.3 to —16.8%o) or benzene-methanol extracts ( + 5.0%o)- They suggested that these various forms of carbon represent several stages of carbon condensation in the solar nebula, in different environments separated in space and possibly in time . 

Conversion of the ATZ-amino acids (extracted with TFA) to the PTH form was carried out off-line. After cleavage, the extract from each Edman degradation cycle was collected into a 2(X)-pL vial, to which 25 lL of 25% aqueous TFA solution was added and mixed. The solution was heated at 67°C for 10 min. and then dried on a vacuum centrifuge. The residue in the vial was dissolved in 1 pL... 

The separation of 20 amino acids extracted from a root cell culture is shown in Figure 767 and a full description of the experimental conditions is given in Section 9.16.5.2. 

Figure 7. Time course of the distribution of in amino acids extracted after assimilation of for 1,15,120, and 900 s by (A) A. cylindrica,...

A recent study with biotechnology applications relates to amino acid extraction. Schugerl and co-workers (71 ) used a quaternary ammonium carrier in an emulsion liquid membrane system for enzyme catalyzed preparation of L-amino acids. Frankenfield et al. (72) discuss a wide variety of biomedical ELM applications including enzyme encapsulation, blood oxygenation, and treatment of chronic uremia. 

The identification of a naturally occurring phosphonate was by Horiguchi and Kandatsu [134], who identified 2-aminoethylphosphonic acid in an amino acid extract from a hydrolysate of rumen protozoal lipid. Subsequently, it has been shown that phosphonates occur naturally in a variety of organisms. Consequently, there is a growing need to develop new and efficient synthetic methods for preparation of organophosphorus compounds bearing a P-C bond. 

---