Several studies have been performed so far for the effective recovery, detection and quantification of specific compounds and their degradation products in archaeological materials. According to the ...literature, lipid molecules are the most durable and widespread biomarkers in ancient pottery. Artificial ageing studies to simulate lipid alterations over time have been reported. In this review, specific lipid archaeological biomarkers and well-established sampling and extraction methodologies are discussed. Although suitable analytical techniques have unraveled archaeological questions, some issues remain open such as the need to introduce innovative and miniaturized protocols to avoid extractions with organic solvents, which are often laborious and non-environmentally friendly.
Deferiprone, generally, is considered an important chelating agent for Fe3+ overload. From a literature data analysis, a lack of information on the interaction of this molecule toward a series of ...metal cations emerged, inducing to fill out the topic. The complexing ability of deferiprone toward Ca2+, Mg2+, Cd2+ and Pb2+ was studied by potentiometry and 1H NMR spectroscopy, in KCl aqueous solutions at different ionic strength values (0.1 ≤ I/mol dm−3 ≤ 1.0) and T = 298.15 K. The same speciation model featured by the ML, ML2, ML3 and ML(OH) (M = metal and L = deferiprone or DFP) species was obtained for Cd2+ and Pb2+; the formation constants calculated at infinite dilution are: logTβ = 7.23±0.02, 12.47±0.03, 16.70±0.04, and −2.53±0.04, respectively for Cd2+ and 9.91±0.01, 15.99±0.02, 19.93±0.05 and 0.99±0.02 for Pb2+. Only two species, namely ML and ML2, were determined for Ca2+ and Mg2+, whose formation constants at infinite dilution are respectively: 3.72±0.01 and 6.50±0.02, for the first one, 5.31±0.01 and 9.58±0.01, for the second. The ligand sequestering ability and affinity toward M2+ were evaluated by determining the pL0.5 and pM parameters at different pHs and ionic strengths. The results suggest that deferiprone has the best complexing and sequestering ability toward Pb2+, followed by Cd2+, Mg2+ and Ca2+, respectively. 1H NMR studies confirmed the DFP affinity for Cd2+ and Pb2+, and in combination with DFT calculations showed that metal cations are bound to the hydroxo-oxo moiety of the pyridinone ring. The data reported in this study provide information on the possible employment of a small molecule like deferiprone, as a chelating and sequestering agent for Pb2+ accumulation or overload from environmental and biological matrices.
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•Speciation study on the deferiprone interactions toward Ca2+, Mg2+, Cd2+, Pb2+.•Potential use of deferiprone ligand to remove Pb2+ contamination.•Future applications on real environmental matrixes.
Protonation of nicotinic acid has been investigated by means of potentiometric titrations at different temperatures 283.15 ≤
T
(K) ≤ 383.15 and ionic strengths of NaCl
(aq)
, 0.12 ≤
I
(mol·kg
−1
) ...≤ 4.84 and mixed NaCl with MgCl
2
or CaCl
2
. Stability constants of the CaL
+
and MgL
+
species were obtained by means of the Δp
K
method. Different models (e.g. Debye–Hückel type equation, Specific Ion Interaction Theory, Pitzer and van’t Hoff) were applied to account for the ionic strength and temperature dependences, in order to obtain data in a standard state and parameters to calculate stability constants in any point of our experimental domain. Speciation studies were performed simulating the conditions of natural fluids. Literature data were investigated for comparison with the experimental results here obtained.
The thermodynamics of the interaction of L-glutamic-N,N-diacetic acid (GLDA) with protons was studied potentiometrically at different temperatures, ionic strengths and ionic media. Four protonation ...constants and corresponding enthalpy changes occurred at infinite dilution together with temperature and ionic strength coefficients. The medium effect was also interpreted in terms of the formation of weak complexes between the ligand and the cations of supporting electrolytes, resulting in a greater tendency of GLDA to chemically interact with Na+ rather than K+ and, in turn, (CH3)4N+. Formation constants of GLDA with Cd2+ were determined in NaCl(aq) at different ionic strength values. Five complex species were found, namely CdL2−, CdHL−, CdH2L0(aq), Cd2L0(aq), and Cd(OH)L3−, whose formation constant values at infinite dilution were log β = 12.68, 17.61, 20.76, 17.52, and 1.77, respectively. All the species results were relevant in the pH range of natural waters, although the Cd2L0(aq) was observed only for CCd ≥ CGLDA and concentrations of >0.1 mmol dm−3. The sequestering ability of GLDA toward Cd2+, evaluated by means of pL0.5, was maximum at pH~10, whereas the presence of a chloride containing a supporting electrolyte exerted a negative effect. Among new generation biodegradable ligands, GLDA was the most efficient in Cd2+ sequestration.
Potentiometric measurements were carried out to study the protonation constants of risedronic acid (RA) in NaCl
(aq)
, (CH
3
)
4
NCl
(aq)
and (C
2
H
5
)
4
NI
(aq)
at different ionic strengths and ...temperatures (283.15 ≤
T
/K ≤ 318.15). In the same conditions, solubility measurements were also performed. Calorimetric measurements were done in NaCl to determine the protonation enthalpy values at
I
= 0.15 mol·dm
−3
and 298.15 K. Generally, the proton binding process was endothermic and the driving force was entropic in nature. The values of the protonation constants determined in NaCl
(aq)
are lower than those obtained in the two tetraalkylammonium salts. The medium effect was interpreted using different thermodynamic models in terms of variation of the activity coefficients with ionic strength (Debye–Hückel type and SIT), or formation of weak complexes between risedronate (Ris
4−
) and the ions of the supporting electrolytes. Specific interaction coefficients (
ε
) and the stability of five (CH
3
)
4
N
+
/Ris
4−
(at different temperatures and ionic strengths) species are reported. The total solubility of risedronic acid is higher in NaCl
(aq)
than in the other two ionic media and, in all cases, increases with increasing temperature. Setschenow and activity coefficients of the neutral species were also computed in all ionic media.
This work is focused on the design and preparation of polymer inclusion membranes (PIMs) for potential applications for stannous cation sequestration from water. For this purpose, the membranes have ...been synthesized employing two polymeric matrices, namely, polyvinylchloride (PVC) and cellulose triacetate (CTA), properly enriched with different plasticizers. The novelty here proposed relies on the modification of the cited PIMs by selected extractants expected to interact with the target cation in the membrane bulk or onto its surface, as well as in the evaluation of their performances in the sequestration of tin(II) in solution through chemometric tools. The composition of both the membrane and the solution for each trial was selected by means of a D-Optimal Experimental Design. The samples such prepared were characterized by means of TG-DTA, DSC, and static contact angles investigations; their mechanical properties were studied in terms of tensile strength and elastic modulus, whereas their morphology was checked by SEM. The sequestering ability of the PIMs toward stannous cation was studied by means of kinetic and isotherm experiments using DP-ASV. The presence of tin in the membranes after the sequestration tests was ascertained by μ-ED-XRF mapping on selected samples.
The current work investigates the protonation constants of gabapentin (GP), 2-1-(aminomethyl)cyclohexylacetic acid and the stability constants for the binding of GP to Ca
2+
and Mg
2+
in a wide range ...of temperature and ionic strength conditions 283.15 ≤
T
/K ≤ 318.15 and ionic strengths of NaCl(aq), 0.12 ≤
I
/mol·dm
−3
≤ 4.84. The pH-potentiometric titration method was applied for gathering experimental data and determination of solution equilibrium constants. The Δp
K
method was used for the determination of calcium and magnesium stability constants due to the low values which were predicted. A Debye–Hückel type equation, Specific Ion Interaction Theory, Pitzer and van’t Hoff equations were used for the modeling of ionic strength and temperature effects. Two species, ML and MHL, were found according to the best model for Ca
2+
and Mg
2+
. Both protonation processes are exothermic based on the enthalpy values at 298.15 K and infinite dilution. A case study has been performed taking into account the speciation of GP in seawater.
A potentiometric method has been used for the determination of the protonation constants of
N
-(2-hydroxyethyl)iminodiacetic acid (HEIDA or L) at various temperatures 283.15 ≤
T
/K ≤ 383.15 and ...different ionic strengths of NaCl
(aq)
, 0.12 ≤
I
/mol·kg
−1
≤ 4.84. Ionic strength dependence parameters were calculated using a Debye–Hückel type equation, Specific Ion Interaction Theory and Pitzer equations. Protonation constants at infinite dilution calculated by the SIT model are
log
10
T
K
1
H
=
8.998
±
0.008
(amino group),
log
10
T
K
2
H
=
2.515
±
0.009
and
log
10
T
K
3
H
=
1.06
±
0.002
(carboxylic groups). The formation constants of HEIDA complexes with sodium, calcium and magnesium were determined. In the first case, the formation of a weak complex species, NaL, was found and the stability constant value at infinite dilution is log
10
K
NaL
= 0.78 ± 0.23. For Ca
2+
and Mg
2+
, the CaL, CaHL, CaL
2
and MgL species were found, respectively. The calculated stability constants for the calcium complexes at
T
= 298.15 K and
I
= 0.150 mol·dm
−3
are: log
10
β
CaL
= 4.92 ± 0.01, log
10
β
CaHL
= 11.11 ± 0.02 and
log
10
β
CaL
2
= 7.84 ± 0.03, while for the magnesium complex (at
I
= 0.176 mol·dm
−3
): log
10
β
MgL
= 2.928 ± 0.006. Protonation thermodynamic functions have also been calculated and interpreted.
The interaction of the biodegradable ligand,
l
-glutamic acid
N
,
N
-diacetic acid tetrasodium salt (GLDA) with molybdenum(VI) was studied by determining stability constants at pH 6.00,
T
= ...298.15 K, and ionic strength 0.0992 <
I
/mol·dm
−3
< 2.5689 of sodium chloride. The ionic strength dependence of the stability constants was fitted to both extended Debye–Hückel and specific ion interaction models. Job’s method confirmed the formation of one species, MoO
3
GLDA
4−
. The values of the stability constants are in agreement with the other data in the literature for the complex formation of aminopolycarboxylic acids with molybdenum(VI). Experimental data were obtained by using UV spectrophotometric method. The formation constant in pure water is 18.96 ± 0.08 on the molal concentration scale.
The archaeological excavations at Villa San Pancrazio (Taormina, Italy) are bringing to light a vast Roman-Imperial residential quarter featuring luxurious dwellings decorated with wall paintings and ...mosaic floors, pointing it out as one of the most significant archaeological sites of the city. The polychrome and black and white mosaics recovered date back to the middle Imperial period, during the 2nd century AD. This work deals with the first archaeometric investigations of the materials employed for the tesserae production with the aim of elucidating the mineralogical composition and obtaining analytical evidence that can contribute to extracting information related to their production technology. For that purpose, a non-invasive methodology, based on micro energy dispersive X-ray fluorescence (μ-EDXRF) spectrometry and Raman spectroscopy, was used to characterize a wide selection of stone, ceramic and glass tesserae. Chemometric tools were exploited to manage the large set of elemental data collected on black and white lithic samples, providing essential clues for the subsequent investigations. The results evidenced the employment of natural lithotypes (calcareous sedimentary, dolomitic and volcanic) local and imported, and also artificial materials, such as ceramic made firing magnesium-rich clays, soda-lime-silica glasses made with different opacifying and coloring agents (such as calcium antimoniate, cobalt and copper).
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