Lipid extracts of sherds of archaeological late Roman cooking pots were analysed using high temperature–gas chromatography coupled to a mass spectrometer and liquid chromatography with atmospheric ...pressure chemical ionization mass spectrometer detection (LC–APCI-MS). With these advanced techniques the use of beeswax was shown through identification of the constituting alkanes, mono and diesters. The detection of high amounts of saturated triacylglycerols (TAGs) further indicated that animal fat was processed in these pots. Part of the animal fat was characterised as originating from ruminants due to the presence of
trans-fatty acids. The distribution of saturated TAGs and the higher concentration of stearic acid compared to palmitic acid in the transesterified lipid extract indicated that this was sheep fat. The results illustrate how complex mixtures can be unravelled and original contents of ancient ceramic vessels can be determined using specialised analytical equipment.
The lipid fraction of residues in ancient oil lamps found at the archaeological site of Sagalassos (south-west Turkey) was analysed by gas chromatography (GC) coupled to mass spectrometry (MS). The ...identification of plant sterols and long chain alcohols suggested that a vegetable oil was used in these lamps. The lipid sample was also analysed with reversed-phase liquid chromatography (LC) coupled to MS with atmospheric pressure chemical ionization (APCI). The identification of TAG’s detected with LC–APCI–MS showed that predominantly olive oil was used as a fuel for the antique oil lamps. The presence of large quantities of multiply unsaturated triacylglycerol (TAG) and traces of saturated TAG indicated that also other oils and animal fat were added. Summarizing, the analysis of TAG’s with LC–APCI–MS in lipid extracts of ancient ceramics proved to be a valuable method to reconstitute the original contents.
Summary
Identifying ‘functional' pools of soil organic matter and understanding their response to tillage remains elusive. We have studied the effect of tillage on the enriched labile fraction, ...thought to derive from microbes and having an intermediate turnover time. Four soils, each under three regimes, long‐term arable use without tillage (NT), long‐term arable under conventional tillage (CT), and native vegetation (NV), were separated into four aggregate size classes. Particle size fractions of macro‐ (250–2000 μm) and microaggregates (53–250 μm) were isolated by sonication and sieving. Subsequently, densiometric and chemical analyses were made on fine‐silt‐sized (2–20 μm) particles to isolate and identify the enriched labile fraction. Across soils, the amounts of C and N in the particle size fractions were highly variable and were strongly influenced by mineralogy, specifically by the contents of Fe and Al oxides. This evidence indicates that the fractionation procedure cannot be standardized across soils. In one soil, C associated with fine‐silt‐sized particles derived from macroaggregates was 567 g C m−2 under NV, 541 g C m−2 under NT, and 135 g C m−2 under CT, whereas C associated with fine‐silt‐sized particles derived from microaggregates was 552, 1018, 1302 g C m−2 in NV, NT and CT, respectively. These and other data indicate that carbon associated with fine‐silt‐sized particles is not significantly affected by tillage. Its location is simply shifted from macroaggregates to microaggregates with increasing tillage intensity. Natural abundance 13C analyses indicated that the enriched labile fraction was the oldest fraction isolated from both macro‐ and microaggregates. We conclude that the enriched labile fraction is a ‘passive' pool of soil organic matter in the soil and is not derived from microbes nor sensitive to cultivation.
Lipid extracts of different types of pottery from the archaeological site Sagalassos (southwest Turkey) were investigated using several analytical techniques. The usefulness of lipid analysis in the ...functional analysis of a broad spectrum of pottery from one archaeological site was evaluated. The results establish indeed a relationship between vessel use and form. Based on the analyses a determination table could be drawn relating vessel use and form and separating the different types of vessels. This research shows that lipid analysis can be a valuable contribution to classify different ceramic pots.
Mixed complexation of the lanthanide(III) chelates of the 1,7-disubstituted tetraazacyclododecane macrocycles DO2A and DO2P with phosphate, acetate and fluoride anions was studied in aqueous ...solutions using high resolution
1H and
31P NMR spectroscopy. The La(DO2A)(H
2O)
2−3
+ and Ce(DO2A)(H
2O)
2−3
+ chelates readily decompose in aqueous solutions containing phosphate anions. Nd(DO2A)(H
2O)
2−3
+ and Eu(DO2A)(H
2O)
2−3
+ chelates remain stable in an acetate environment. Association constants for the 1:1 adduct were obtained via
1H NMR titrations. In a fluoride environment, La(DO2A)(H
2O)
2−3
+ was found to be unstable, in contrast to Eu(DO2A)(H
2O)
2−3
+, for which the association constant for the 1:1 adduct was calculated. Chelate formation, as well as mixed complexation with fluoride and phosphate was studied for Eu(DO2P)(H
2O)
2−3
−. The
31P chemical shifts of Eu(DO2P)(H
2O)
2−3
− indicate that the DO2P macrocycle forms an ‘in-cage’ complex with binding through all four nitrogens. The Eu(DO2P)(H
2O)
2−3
− chelate gradually decomposes in a phosphate environment, but remains stable in an fluoride environment.
A dinuclear gadolinium(III) complex of an amphiphilic chelating ligand, containing two diethylenetriamine‐N,N,N′,N′′,N′′‐pentaacetate (DTPA) moieties bridged by a bisindole derivative with three ...methoxy groups, has been synthesized and evaluated as a potential magnetic resonance imaging (MRI) contrast agent. Nuclear magnetic relaxation dispersion (NMRD) measurements indicate that at 20 MHz and 37 °C the dinuclear gadolinium(III) complex has a much higher relaxivity than Gd(DTPA) (6.8 vs 3.9 s−1 mmol−1). The higher relaxivity of the dinuclear gadolinium(III) complex can be related to its reduced motion and larger rotational correlation time relative to Gd(DTPA). In the presence of human serum albumin (HSA) the relaxivity value of the noncovalently bound dinuclear complex increases to 15.2 s−1 per mmol of Gd3+, due to its relatively strong interaction with this protein. The fitted value of the binding constant to HSA (Ka) was found to be 104 M−1. Because of its interaction with HSA, the dinuclear complex exhibits a longer elimination half‐life from the plasma, and a better confinement to the vascular space compared to the commercially available Gd(DTPA) contrast agent. Transmetalation of the dinuclear gadolinium(III) complex by zinc(II) has been investigated. Biodistribution studies suggest that the complex is excreted by the renal pathway, and possibly by the hepatobiliary route. In vivo studies indicated that half of the normal dose of the gadolinium(III) complex enhanced the contrast in hepatic tissues around 40 % more effectively than Gd(DTPA). The dinuclear gadolinium(III) complex was tested as a potential necrosis avid contrast agent (NACA), but despite the binding to HSA, it did not exhibit necrosis avidity, implying that binding to albumin is not a key parameter for necrosis‐targeting properties.
Gadolinium complexes as imaging agents: A dinuclear gadolinium(III) complex of an amphiphilic chelating ligand, containing two diethylenetriamine‐N,N,N′,N′′,N′′‐pentaacetate (DTPA) moieties bridged by a bisindole derivative with three methoxy groups (see formula), has been synthesized and evaluated as a potential MRI contrast agent.
Three amphiphilic DTPA bisamide derivatives containing long-chain phenylalanine esters (with 14, 16 and 18 carbon atoms in the alkyl chain) were synthesized and their corresponding gadolinium(III) ...complexes were prepared. The attempts to form paramagnetic micelles carrying the gadolinium(III) complexes yielded unstable or polydisperse micelles implying that the presence of the bulky aromatic side groups in the amphiphilic Gd-DTPA bisamide complexes results in an inefficient packing of the paramagnetic complex into micelles. All complexes were efficiently incorporated into liposomes consisting of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), yielding stable and monodisperse paramagnetic liposomes. All liposomes had a comparable size, typically between 120 and 160 nm. As a result of the reduced mobility of the gadolinium(III) complexes, solutions of these supramolecular structures show a higher relaxivity than solutions of Gd-DTPA. However, the relaxivity gain is lower compared to compounds consisting of purely aliphatic chains of the same length, most likely due to the less efficient packing or increased local mobility of the gadolinium(III) complex. In the case of the Gd-DTPA bisamide complex with 18 carbon atoms, the immobilization inside the liposomal structure is less effective, probably because the aliphatic chains of the complex are longer than the alkyl chains of the DPPC host, resulting in a relatively high local mobility. The paramagnetic liposomes containing the Gd-DTPA bisamide complexes with 14 carbon atoms showed the highest relaxivity because the optimal length match between the hydrophobic chains of the DPPC and the ligand allowed very efficient packing of the paramagnetic complex into the liposome.
A derivative of diethylenetriamine-
N,
N,
N′,
N″,
N″-pentaacetic acid (DTPA), carrying two catechol functional groups has been synthesised by the reaction between DTPA-bis(anhydride) and ...3-hydroxytyramine (dopamine). The ligand DTPA-bis(3-hydroxytyramide), DTPA(HTA)
2, is able to form stable heterobimetallic complexes with gadolinium(III) and iron(III) ions. The gadolinium(III) occupies the internal coordination cage of DTPA formed by three nitrogens, two carboxylate and two amide oxygens, while the Fe(NTA)(H
2O)
2 (nitrilotriacetic acid, NTA) binds to catechol units by the substitution of two water ligands. The formation of polymeric species was avoided by using the tripodal NTA ligand. The heterobimetallic complex was characterised by means of visible absorption spectroscopy, electron spray ionisation–mass spectrometry (ESI–MS), and nuclear magnetic resonance (NMR) spectroscopy.
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