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PubMed1985

Autoradiography of high affinity uptake of catecholamines by primary astrocyte cultures.

Uptake of D.L-[3H]norepinephrine ([3H]NE) and [3H]dopamine ([3H]DA) by primary astrocyte cultures prepared from neonatal rat brains, which are greater than or equal to 95% glial fibrillary acidic protein (GFAP(+)), was studied by measuring accumulation of tritium label, and localizing such uptake at the cellular level by autoradiography. Uptake of [3H]NE was 95% Na+ dependent at 10(-7) M and 80% Na+ dependent at 7.5 X 10(-7) M [3H]NE. Uptake of [3H]DA at 7.5 X 10(-7) M was 58% Na+ dependent, but total uptake of [3H]DA was greater than uptake of [3H]NE. Autoradiography of cells incubated with 7.5 X 10(-7) M [3H]NE or [3H]DA showed that a high proportion of all the cells in these cultures had a grain density which was clearly above background. When Na+ was omitted from the medium, the temperature was lowered to 4 degrees C, or 10(-7) M desmethylimipramine or 10(-7) M amitryptyline were present, cellular grain density after exposure to both [3H]NE and [3H]DA was greatly reduced, to close to background levels. It also appeared necessary to have inhibitors of both monoamine oxidase (pargyline) and catecholamine-O-methyltransferase (tropolone) present to see clear cellular localization for [3H]DA. In the case of [3H]NE the presence of tropolone alone was adequate to observe cellular localization. These results confirm our previous findings of the existence of a high affinity uptake process for catecholamines in primary astrocyte cultures based on uptake properties, and in the present study also localizes such uptake to the major, astrocytic cell type.

Amitriptyline↗
PubMed1988

Extraneuronal accumulation of isoproterenol in atria and ventricle of perfused rat heart.

Extraneuronal accumulation of isoproterenol in atria and ventricle of perfused rat heart was investigated. Rat hearts were perfused with various concentrations of 3H-isoproterenol for 30 min in the absence and the presence of catechol-O-methyltransferase (COMT) inhibitor (tropolone). When COMT was intact, the accumulation of 3H-isoproterenol in both atria and ventricle after perfusion with low concentration of 3H-isoproterenol (0.01 to 1 mumol/l) was less than that of perfusing concentration; the tissue/medium ratio (T/M) of isoproterenol for artia was lower than that for ventricle. The T/M of isoproterenol after perfusion with 10 and 20 mumol/l of 3H-isoproterenol were 0.94 and 1.76 for atria and 3.25 and 2.95 for ventricle, respectively. When COMT was inhibited by tropolone, the T/M increased 6.3-9.0 folds for atria and 5.1-6.7 folds for ventricle after perfusion with 3H-isoproterenol (0.01 to 1 mumol/l). From these results, it was concluded that both atria and ventricle of the rat heart have an extraneuronal O-methylating system as reported in rat whole heart, and was suggested that there might be different capacities of extraneuronal uptake and COMT between them.

Animals↗
PubMed1985

A new model of ventricular fibrillation induced by isoprenaline and catechol-O-methyl transferase inhibitor at a high perfusion temperature in isolated rat hearts.

Isolated rat hearts were perfused with various concentrations of isoprenaline (0.01-10 mumol/liter) for 30 min at a constant flow rate (6.5 ml/min) at 37-44 degrees C. The occurrence of ventricular fibrillations was isoprenaline concentration dependent and also perfusion temperature dependent in the combined treatment with various concentrations of isoprenaline and high perfusion temperatures. When the hearts were perfused with isoprenaline (1 mumol/liter) in the presence of tropolone (100 mumol/liter) at 40-41 degrees C, the duration of ventricular fibrillations was significantly prolonged, but the incidence of ventricular fibrillations was similar to that produced with isoprenaline (1 mumol/liter) alone. The antiarrhythmic drugs such as quinidine sulfate, lidocaine hydrochloride, dl-propranolol hydrochloride, carteolol hydrochloride, atenolol, dl-verapamil hydrochloride, and diltiazem hydrochloride, given at a concentration of 10 mumol/liter, significantly suppressed the incidence and duration of such ventricular fibrillations. Bretylium tosylate (10 mumol/liter) significantly suppressed the duration of the ventricular fibrillations but not their incidence. These results indicate that ventricular fibrillation induced by combined treatment with a high concentration of isoprenaline and tropolone at a high perfusion temperature in isolated rat hearts is a more useful experimental model of arrhythmia than conventional models.

Animals↗
PubMed1998

IKP104-induced decay of tubulin: role of the A-ring binding site of colchicine.

Tubulin, the major subunit protein of microtubules, has a tendency to lose its ability to assemble or to interact with ligands in a time-dependent process known as decay. Decay involves the increase in exposure of sulfhydryl groups and hydrophobic areas. The antimitotic drug IKP104 [2-(4-fluorophenyl)-1-(2-chloro-3, 5-dimethoxyphenyl)-3-methyl-6-phenyl-4(1H)-pyridinone] accelerates the decay of tubulin [Ludueña et al. (1995) Biochemistry 34, 15751-15759]. In the presence of colchicine, however, IKP104 stabilizes tubulin against decay. We have shown that the stability and the acceleration of the decay of tubulin are mediated respectively by the high- and low-affinity binding site(s) of IKP104 [Chaudhuri et al. (1998) J. Protein Chem. 17, 303-309]. To better understand the mechanism by which colchicine protects tubulin from IKP104-induced decay, we examined the effect of colchicine and its analogues on this process. We found that IKP104 unfolds tubulin in a process involving a specific domain where colchicine interacts, although the binding sites of these two drugs are distinctly different. 2-Methoxy-5-(2',3',4'-trimethoxyphenyl) tropolone (MTPT), the bicyclic analogue of colchicine that lacks the B-ring, can also protect tubulin from IKP104-induced decay. An A-ring analogue of colchicine, 3,4,5-trimethoxybenzaldehyde (TMB), can also stop IKP104-induced unfolding of tubulin significantly. Interestingly, the C-ring analogue of colchicine, tropolone methyl ether (TME), does not prevent this process. Our results thus suggest that neither the B-ring nor the C-ring binding regions of colchicine are involved in the IKP104-induced decay and that the A-ring binding site of colchicine on tubulin plays a crucial role in IKP104-induced decay.

Alkylation↗
PubMed1984

On the metabolism of [3H]noradrenaline in different compartments of rat brain with respect to the role of catechol-O-methyltransferase.

Rats were pretreated with either reserpine or desmethylimipramine, either alone or in combination with tropolone. At either 10 min or 1 h after the intraventricular injection of [3H]noradrenaline, in several brain regions the complete metabolic patterns were determined: normetanephrine; the glycol metabolites (methylated and nonmethylated) and their sulfate conjugates; and the acidic metabolites (methylated and non-methylated). A reserpine-induced increase in the turnover of [3H]noradrenaline caused a transient increase of the catechol glycol followed by elevated levels of the two glycol sulfates. The stimulated [3H]noradrenaline turnover if achieved by desmethylimipramine caused a transient increase of normetanephrine and initially lowered values of catechol glycols (both free and sulfated), which were followed by elevated levels. Drug-pretreated rats compensated for the inhibition of catechol-O-methyl-transferase by tropolone in different ways: Reserpine caused an early increase of the catechol glycol beyond the measurements in other treatment groups, whereas desmethylimipramine increased the nonmethylated carboxylic acid and glycol sulfates rather slowly to levels beyond those of other groups. The results support the existence of two compartments with a fast metabolism (an intraneuronal monoamine oxidase compartment and an extraneuronal catechol-O-methyltransferase compartment). In addition, there seems to exist another extra-neuronal space with a slow, monoamine oxidase-dependent noradrenaline turnover.

Animals↗
PubMed1997

Utilization of iron-catecholamine complexes involving ferric reductase activity in Listeria monocytogenes.

Listeria monocytogenes is a ubiquitous potentially pathogenic organism requiring iron for growth and virulence. Although it does not produce siderophores, L. monocytogenes is able to obtain iron by using either exogenous siderophores produced by various microorganisms or natural catechol compounds widespread in the environment. In the presence of tropolone, an iron-chelating agent, growth of L. monocytogenes is completely inhibited. However, the growth inhibition can be relieved by the addition of dopamine or norepinephrine under their different isomeric forms, while the catecholamine derivatives 4-hydroxy-3-methoxyphenylglycol and normetanephrine did not relieve the inhibitory effect of tropolone. Preincubation of L. monocytogenes with chlorpromazine and yohimbine did not antagonize the growth-promoting effect of catecholamines in iron-complexed medium. In addition, norepinephrine stimulated the growth-promoting effect induced by human transferrin in iron-limited medium. Furthermore, dopamine and norepinephrine allowed 55Fe uptake by iron-deprived bacterial cells. The uptake of iron was energy dependent, as indicated by inhibition of 55Fe uptake at 0 degrees C as well as by preincubating the bacteria with KCN. Inhibition of 55Fe uptake by L. monocytogenes was also observed in the presence of Pt(II). Moreover, when assessed by a whole-cell ferric reductase assay, reductase activity of L. monocytogenes was inhibited by Pt(II). These data demonstrate that dopamine and norepinephrine can function as siderophore-like compounds in L. monocytogenes owing to their ortho-diphenol function and that catecholamine-mediated iron acquisition does not involve specific catecholamine receptors but acts through a cell-bound ferrireductase activity.

Catecholamines↗
PubMed2003

Low-level iron-dependent mutants of Listeria monocytogenes and their virulence in macrophages.

Listeria monocytogenes is an opportunistic intracellular pathogen capable of growth that requires iron for growth within phagocytic cells and virulence expression. In the presence of an appropriate concentration tropolone, an iron-chelating agent, growth of L. monocytogenes is completely inhibited. However, this inhibition can be relieved by addition of dopamine, norepinephrine, or ferric citrate. By selection on streptonigrin medium supplemented with tropolone and norepinephrine, we have obtained two spontaneous mutants, Lm-8 and Lm-15, with the same iron dependence but lower iron dependence than the wild-type Lm-B38. The association between iron requirement and virulence of the two mutants and the wild type was studied in the J774 macrophage cell line. One hour after phagocytosis by the J774 macrophage cell line, the two mutants and the parental strain displayed no difference in the number of phagocytosed bacteria. Twenty-four hours after phagocytosis, the number of bacteria within the surviving macrophages was identical for the wild strain and the two clones. However, only 40% of macrophage cells infected with Lm-8 and 90% of those infected with Lm-15 were alive after 24 h in comparison with macrophage cells infected with the parental strain Lm-B38. These data demonstrate that there is no direct correlation between iron requirement and virulence of L. monocytogenes in the J774 macrophage cell line.

Catecholamines↗
PubMed1995

Hinokitiol induces differentiation of teratocarcinoma F9 cells.

Hinokitiol, a constituent of the wood of Chamaecyparis taiwanensis, was found to induce differentiation of teratocarcinoma F9 cells. When examined by the agar-overlay method, in which expression of plasminogen activator as a differentiation marker protein was detected, this compound exhibited a dose- and time-dependent induction. Induction of differentiation by hinokitiol occurred irreversibly and required its addition for more than 12h. Among its structure-related compounds tested, tropolone and two colchicine-related compounds exerted potent activities comparable to that of hinokitiol. These findings indicate that free tropolone structure in the molecules plays an essential role in inducing differentiation of F9 cells. Hinokitiol showed a strong inhibitory effect of DNA synthesis in very early stages of culture, suggesting that this effect may be responsible for triggering differentiation of F9 cells.

Animals↗
PubMed1990

Effects of extraneuronal accumulation of isoprenaline on cAMP production in perfused rat heart.

The effects of extraneuronal accumulation of isoprenaline on the level of cAMP in perfused rat hearts were investigated. When catechol-O-methyl transferase (COMT) was intact, perfusion with isoprenaline (10(-6) M) for 5 min and 30 min (low accumulation of isoprenaline in the heart) enhanced the cAMP level. Propranolol (10(-6) M) significantly decreased the high level of cAMP produced by the perfusion with isoprenaline for 5 min and 30 min (low accumulation of isoprenaline). When COMT was inhibited by tropolone, perfusion with isoprenaline (10(-6) M) for 5 min (slight accumulation of isoprenaline in the heart) slightly increased the level of cAMP, while perfusion for 30 min (high accumulation of isoprenaline in the heart) did not increase the level of cAMP. Propranolol (10(-6) M) significantly decreased the cAMP level produced by 5 min perfusion with isoprenaline, but did not change the level by 30 min perfusion. The perfusion length (5 min and 30 min) and COMT inhibition by tropolone (10(-4) M) in the absence of isoprenaline did not affect cAMP levels. These results suggest that extraneuronally accumulated isoprenaline may inhibit the adenylate cyclase in perfused rat hearts.

Animals↗
PubMed1976

The effect of chelating agents on iron mobilization in Chang cell cultures.

The investigation of chelating agents with potential therapeutic value in patients with transfusional iron overload has been facilitated by the use of Chang cell cultures. These cells have been incubated with [59Fe]transferrin for 22 hr, following which most of the intracellular radioiron is found in the cytosol, distributed between a ferritin and a nonferritin form. Iron release from the cells depends on transferrin saturation in the medium, but when transferrin is 100% saturated, which normally does not allow iron release, desferrioxamine, 2,3-dihydroxybenzoic acid, rhodotorulic acid, cholythydroxamic acid, and tropolone all promote the mobilization of ferritin iron and its release from cells. They are effective to an approximately equal degree. The incubation of [59Fe]transferrin with tropolone in vitro at a molar ratio of 1:500 results in the transfer of most of the labeled iron to the chelator, reflecting the exceptionally high binding constant of this compound. How far these phenomena relate to therapeutic potentially remains to be seen.

Anemia, Hypochromic↗
PubMed1989

A thermodynamic study of the interaction of tubulin with colchicine site ligands.

The bicyclic colchicine analogue 2-methoxy-5-(2',3',4'-trimethoxyphenyl)-2,4,6-cycloheptatrien-1-on e (MTC) has been used to study the thermodynamics of specific ligand binding to the colchicine site of tubulin, employing isothermal reaction microcalorimetry. The binding of MTC to purified calf brain tubulin, in 10 mM sodium phosphate buffer, pH 7.0, is characterized by delta H degree = -19 +/- 1 kJ.mol-1, delta G degree = -31.8 +/- 0.6 kJ.mol-1, and delta S degree = 43 +/- 5 J.mol-1.K-1 at 298 K, with a slight variation in the temperature range from 283 to 308 K. The binding thermodynamics of colchicine and allocolchicine are similar to MTC under the conditions examined, suggesting related molecular interactions of the three ligands with the protein binding site. The standard enthalpy changes of binding of colchicine and MTC at 308 K coincide within experimental error. Therefore the more favorable free energy change of binding of colchicine must come from a larger binding entropy change (by about 20 J.mol-1.K-1). This difference could be attributed to the presence of the middle ring of colchicine, which is absent in MTC. Consistently, a similar entropy change is observed by the comparison of allocolchicine to MTC binding at several temperatures. In addition, allocolchicine binding is about 6 kJ.mol-1 less exothermic than MTC binding, which could be attributed to the presence in allocolchicine of a substituted phenyl ring instead of the colchicine-MTC tropolone ring. The present results and analysis are fully compatible with the previously proposed bifunctional binding of colchicine and MTC (through their trimethoxybenzene and tropolone moieties) to a bifocal protein binding site, and also with a partial immobilization of intramolecular rotation of MTC upon binding, which in colchicine is already constrained by its middle ring (Andreu, J. M., Gorbunoff, M. J., Lee, J. C., and Timasheff, S. (1984) Biochemistry 23, 1742-1752).

Animals↗
PubMed1978

Sensitization to the generalized Shwartzman reaction by catechol-O-methyltransferase inhibitors.

The generalized Shwartzman reaction (GSR) was produced by a single injection of endotoxin in male rats pretreated with catechol-o-methyltransferase (COMT) inhibitors (tropolone, pyrogallol). Such a result was not obtained with inhibitors (pargyline, phenelzine, isocarboxazide) of the monoamine oxidase (MAO). The inhibitors of the COMT were found to enhance the action of endotoxin on the coagulation system such as evidenced by the increased consumptions of Hageman factor, fibrinogen, and platelets. Tropolone-treated rabbits did not require exogenous stimulation of alpha-adrenergic receptor sites by norepinephrine to localize thrombi in the glomerular capillaries when Hageman factor was activated by ellagic acid and fibrinolysis inhibited by epsilon-amino-caproic acid. It is concluded that interference with the degradation of circulating catecholamines results in sensitization to the generalized Shwartzman reaction.

Animals↗
PubMed1995

Induction of differentiation of embryonal carcinoma F9 cells by iron chelators.

The effects of several chelators, including hinokitiol, on embryonal carcinoma F9 cell differentiation were assessed by assaying the production of plasminogen activator (PA) as a differentiation marker protein. Hinokitiol and tropolone which were potent differentiation inducers lost their activity following preincubation with Fe2+ and Fe3+ ions. Other metal ions had no or little effect on the hinokitiol-induced differentiation. Of several chelators examined, dithizone induced differentiation as effectively as did hinokitiol and tropolone. Dithizone-induced differentiation was also inhibited by preincubation with Fe3+ ions. It was concluded that some potent iron chelators could trigger the teratocarcinoma F9 cells to differentiate through the chelation with intracellular iron ions.

Animals↗
PubMed1986

Application of anion-exchange resin to remove lipophilic chelates from liposomes.

Lipophilic chelates such as 8-hydroxyquinoline, acetylacetone, and tropolone are useful to load high levels of radioactive cations into the inner aqueous compartments of liposomes for investigating the fate of liposomes by the technique of gamma imaging or gamma-ray perturbed angular correlation measurements. However, if lipophilic chelates are not completely removed from liposomes the very same lipophilic chelates can also cause leakage of the entrapped cations from liposomes. Thus, it is essential to make sure that all the lipophilic chelates are removed from liposomes after the loading process. The results of the present study show that more than 99.85% of acetylacetone in liposomal suspension can be removed by a minicolumn of AG1-X8 (phosphate form) anion exchange resin. Virtually all the 8-hydroxyquinoline and tropolone in liposomal suspension are adsorbed tightly to the resin. The procedure is rapid, and the dilution of liposomes is minimal. For experiments involving high levels of gamma-emitting radionuclides, the cleaning up process of removing lipophilic chelates from liposomes can be conveniently operated behind a lead glass.

Chelating Agents↗
PubMed1994

The effect of inhibition of synthesis, release, metabolism and uptake on the microdialysis extraction fraction of dopamine.

The present study was designed to determine the effects that synthesis, release, metabolism and uptake have on the in vivo extraction fraction (relative recovery) of dopamine (DA) in the nucleus accumbens of the rat. The extraction fraction and extracellular concentration of DA were established for rats that were perfused with artificial cerebrospinal fluid (aCSF) with or without substances inhibiting synthesis (100 microM alpha-methylparatyrosine (alpha-MPT)), release (1 microM tetrodotoxin (TTX)), uptake (1 microM, 20 microM cocaine or 1 microM GBR-12909) or metabolism (100 microM tropolone or 100 microM pargyline) with DA concentrations ranging from 0 to 200 nM. Inhibiting synthesis with alpha-MPT or release with TTX had no effect on the extraction fraction of DA. Inhibiting intracellular or extracellular metabolism with pargyline or tropolone, respectively, did not cause any changes in the extraction fraction. However, inhibiting uptake with 20 microM cocaine or 1 microM GBR-12909 decreased the extraction fraction by one-third and one-half, respectively. These results provide evidence that uptake is the primary neuronal process affecting the extraction fraction of DA in the nucleus accumbens and indicate that the extraction fraction may be useful as an index of DA uptake in vivo.

Animals↗
PubMed1989

Release and metabolism of dopamine in a clonal line of pheochromocytoma (PC12) cells exposed to fenthion.

The effects of an organophosphate (OP) pesticide, fenthion (FEN), on the release and metabolism of dopamine were evaluated in a clonal line of rat pheochromocytoma (PC12) cells. HPLC was used to determine media concentrations of DA and the DA metabolites norepinephrine (NE), 3,4-dihydroxyphenylacetic acid (DOPAC), and homovanillic acid (HVA). The FEN formulation solvent did not significantly affect DA metabolism. In the first study, cultures were treated with 10(-5) or 10(-6) M FEN or 10(-5) M neostigmine, a non-OP acetylcholinesterase inhibitor. Concentrations of both catecholamines were elevated in cultures treated with 10(-5) M FEN by 2.8-fold for DA and 3.5-fold for NE. Neostigmine effects were of smaller magnitude and DA was decreased after 24 hr. Cultures were also treated with depolarizing levels of K+, but the effect of FEN was not altered, suggesting that FEN does not act by increasing DA release. In the second study, the effect of 10(-6) M FEN was evaluated in cultures treated with the DA uptake inhibitor benztropine, the monoamine oxidase (MAO) inhibitor pargyline, or the catechol-O-methyltransferase (COMT) inhibitor tropolone. Inhibitor effects were consistent with their known mechanisms of action. In all cultures treated with FEN, the ratio HVA/DOPAC was decreased after 3 and 6 hr of exposure. A decrease in HVA/DOPAC was also observed in cultures treated with neostigmine and tropolone. In combination with pargyline, FEN decreased DA in contrast to its usual effect of increasing DA. Neither the stimulation of DA release nor the inhibition of DA uptake affected the observed action of FEN in PC12 cultures.(ABSTRACT TRUNCATED AT 250 WORDS)

3,4-Dihydroxyphenylacetic Acid↗
PubMed1999

Effects of tolcapone upon soluble and membrane-bound brain and liver catechol-O-methyltransferase.

The present study was aimed to evaluate the sensitivity of soluble (S) and membrane bound (MB) catechol-O-methyltransferase (COMT) from rat brain and liver to inhibitors which interact with the enzyme as competitive (tropolone), non-competitive (S-adenosyl-l-homocysteine; SAHC) and tight-binding (tolcapone and 3,5-dinitrocatechol) inhibitors. COMT activity was evaluated by the ability to methylate adrenaline (0.1 to 2000 microM) to metanephrine in the presence of a saturating concentration of the methyl donor (S-adenosyl-l-methionine). When using a fixed amount of total protein (2 micrograms/ml), but variable concentrations of COMT, the inhibitory potency of tolcapone upon S- and MB-COMT activity in the brain was in the low nM range (IC50's of 2 and 3 nM, respectively), whereas in liver the IC50 values for tolcapone against liver MB- and S-COMT (IC50's of 123 and 795 nM, respectively) were markedly higher than those observed in the brain. By contrast, when inhibition studies were performed with a fixed concentration of COMT (15 nM), as determined by the Ackermann-Potter equation, tolcapone was found to be endowed with the same potency (in the low nM range) in inhibiting S- and MB-COMT from both brain and liver. As for tolcapone, 3,5-dinitrocatechol was more potent against MB- than against S-COMT when a fixed amount of total protein was used, but showed the same potency when a fixed concentration of COMT was used. Tropolone, a competitive inhibitor, was much less potent than tolcapone and 3,5-dinitrocatechol in inhibiting S- and MB-COMT from both brain and liver and its potency was found not to depend on enzyme concentration. SAHC, a non-competitive inhibitor, behaved similarly to tight-binding inhibitors when a fixed amount of total protein was used. By contrast, when a fixed amount of enzyme was used, SAHC was found to be endowed with the same potency against S- and MB-COMT from brain and liver. In the final series of experiments the inhibitory effect of tolcapone was examined under in vitro ex vivo conditions, using the same concentration of COMT (15 nM). One hour after its oral administration, tolcapone (0.3 to 30 mg/kg) was found to be much more potent against MB-COMT than against S-COMT. In the liver, 0.3 mg/kg tolcapone resulted in 82% inhibition of MB-COMT and 31% inhibition of S-COMT. In the brain, 3.0 mg/kg tolcapone inhibited 78% MB-COMT, whereas S-COMT activity was reduced by 38% only. In conclusion, the results reported here show that tolcapone is particularly potent in inhibiting MB-COMT from liver and brain under in vivo experimental conditions, though it does not discriminate between MB- and S-COMT under in vitro experimental conditions when using the same amount of enzyme in the assay.

Animals↗
PubMed2000

Speciation of butyl- and phenyltin compounds in sediments using pressurized liquid extraction and liquid chromatography-inductively coupled plasma mass spectrometry.

A liquid chromatographic method with inductively coupled plasma mass spectrometry is proposed for the speciation of butyl- (monobutyltin, dibutyltin, tributyltin) and phenyl- (monophenyltin, diphenyltin, triphenyltin) tin compounds in sediments. After evaluation of different additives in the mobile phase, the use of 0.075% (w/v) of tropolone and 0.1% (v/v) of triethylamine in a mobile phase of methanol-acetic acid-water (72.5:6:21.5) allowed the best chromatographic separation of the six compounds. Pressurized liquid extraction (PLE) with a methanolic mixture of 0.5 M acetic acid and 0.2% (w/v) of tropolone was suitable for the quantitative extraction of butyl- and phenyltin compounds with recovery values ranging from 72 to 102%. This analytical approach was compared to conventional solvent extraction methods making use of acids and/or organic solvent of medium polarity. The main advantages of PLE over conventional solvent extraction are: (i) the possibility to extract quantitatively DPhT and MPhT from sediments, which could not be done by a solvent extraction approach; (ii) to preserve the structural integrity of the organotin compounds; (iii) to reduce the extraction time from several hours in case of solvent extraction techniques to just 30 min. For spiked sediments, limits of detection ranged from 0.7 to 2 ng/g of tin according to the compound. The relative standard deviations were found to be between 8 and 15%. The developed analytical procedure was validated using a reference material and was applied to various environmental samples.

Chromatography, High Pressure Liquid↗