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PubMedDate not supplied

Effect of recirculation of 99mTc-Sn colloid in estimating mean transit time of soft-tissue vascular anomalies by direct puncture scintigraphy: a simulation analysis.

We have reported direct puncture scintigraphy, a novel method to estimate mean transit time (MTT) of soft-tissue vascular anomaly. In the examination, 99mTc-Sn colloid is infused percutaneously into the lesion, and MTT is calculated using the time-activity curve for the lesion. Recirculation of 99mTc-Sn colloid is neglected in computing MTT, and this may cause error. The aim of this study was to assess this error by simulation analysis. Data simulating direct puncture scintigraphy were produced for lesions with various blood volumes and various blood flows, considering recirculation and blood clearance of 99mTc-Sn colloid, and MTT was estimated by the same method used in the patient examination. Although MTT was overestimated in large lesions with intermediate or long MTT, the error was small except in extremely large lesions. It was suggested that recirculation of 99mTc-Sn colloid does not cause a serious problem in the clinical use of direct puncture scintigraphy.

Arteriovenous Malformations↗
PubMed1998

Effect of dual and triple energy window scatter correction methods on image quality in liver scintigraphy.

AIM: To investigate the effect of two scatter correction methods on lesion detectability for both planar and tomographic hepatic imaging. METHODS: All planar and tomographic acquisitions involved simultaneous collection of photons in the main photopeak window (126-154 keV) and three additional windows (92-116, 116-126 and 154-164 keV). Uncorrected and corrected for scatter images were obtained from the same acquisition data. The dual energy window (DEW) and the triple energy window (TEW) scatter compensation methods were used to obtain two sets of corrected images. The DEW method was implemented with main photopeak window 126-154 keV, Compton scatter window 92-126 keV and scatter multiplier k = 0.5. A modified TEW method was also applied with main photopeak window 126-154 keV and scatter subwindows 116-126 keV and 154-164 keV. Phantoms were used to study the effect of scatter correction on contrast and signal-to-noise ratio. The observer's ability to identify lesions was studied on uncorrected and corrected for scatter patient images. RESULTS: In planar imaging, both scatter compensation methods yielded contrast enhancement. However signal to noise ratio (SNR) was degraded to 0.63 and 0.67 when DEW and TEW were applied respectively. In SPECT images, contrast was increased by a factor of 2.4 and 1.7, while SNR was degraded to 0.60 and 0.64 when DEW and TEW methods were used respectively. CONCLUSIONS: Scatter correction using DEW and TEW methods may improve observer's ability to distinguish lesions in planar (p < 0.05 for both methods) and SPECT (p < 0.05 for both methods) liver studies.

Adult↗
PubMed1993

Gas chromatographic determination of inorganic tin in rat urine after a single oral administration of stannous chloride and mono-, di-, and triphenyltin chloride.

A method is described for the determination of inorganic tin by gas chromatography with flame photometric detection. The inorganic tins, stannous and stannic, were extracted with hydrochloric acid and n-hexane-benzene in the presence of 0.05% tropolone, and both inorganic tins were pentylated to tetrapentyltin with a Grignard reagent prior to gas chromatography. The absolute limit of detection for tetrapentyltin was 3 pg as tin. The recovery of stannous chloride added to rat urine samples was 80.2 +/- 2.4% (mean +/- S.D., n = 8). The application of this method to the study of urinary excretion of inorganic tin and organotin compounds in rats following oral administration of tin compounds is presented. The urinary excretion of tin compounds was observed over a period of 96 h following administration of stannous chloride or phenyltin compounds. Most of the inorganic tin was excreted into urine within 24 h after administration of stannous chloride. In the experiments on organotin administration, the level of the excretion as total tin for monophenyltin reached a maximum ca. 0-24 h after administration, whereas the maxima for di- and triphenyltin were found after 24-48 h and 48-72 h, respectively. The predominant excretion product of these tin compounds found in urine was monophenyltin.

Administration, Oral↗
PubMed2000

Electron impact and chemical ionisation mass spectrometry in the characterisation of organometallic silicon, germanium, tin and lead compounds

The electron impact and chemical ionisation mass spectra of a number of organometallic derivatives of silicon, germanium, tin and lead, incorporating inter alia 2-bis(trimethylsilyl)methylpyridyl or cyclopentadienyl ligands have been recorded. Representative spectra are presented and illustrate the utility of these mass spectrometric techniques in the characterisation of such compounds, particularly so in light of the highly informative nature arising from their fragmentation patterns and the numerous isotopes of the nuclei involved. Copyright 2000 John Wiley & Sons, Ltd.

Journal Article↗
PubMed2002

Speciation of mercury, tin, and lead compounds by gas chromatography with microwave-induced plasma and atomic-emission detection (GC-MIP-AED).

Because of their high toxicity and widespread distribution, the reliable selective quantification of alkyl and aryl species containing mercury, tin, or lead has been one of the goals of speciation analysis in recent years. Since becoming commercially available, GC-MIP-AED has been one of the most-used tools in this work. In this paper, the value and limitations of GC-MIP-AED for the speciation of Hg, Sn, and Pb compounds in environmental samples are reviewed and compared with the analytical characteristics of other hyphenated GC-based techniques. Because quantification of Hg, Sn, and Pb species by GC techniques normally requires complex sample preparation involving several steps, the effect of sample-preparation methods on the accuracy and precision of the results is discussed. Finally, we describe the current status of a rapid, low-cost GC-MIP-PED system specifically designed for routine quantification of Hg, Sn, and Pb species in environmental control laboratories.

Journal Article↗
PubMed1997

Synthesis of Cage Compounds Containing Boron, Tin, and Phosphorus Atoms.

The 1:1 reactions of [((i)()Pr(2)N)BP(H)B(N(i)()Pr(2))PLi.DME] (1) and [(tmp)BP(H)B(tmp)PLi.DME] (2; tmp = 2,2,6,6-tetramethylpiperidino) with organylhalostannanes have been examined, and stannyl-substituted diphosphadiboretanes, (R(2)N)BP(H)B(NR(2))PSn(Cl)R'(2) (R(2)N = (i)()Pr(2)N, tmp; R' = Me, (t)()Bu) have been isolated and characterized. Dehydrohalogenation of these compounds with (t)()BuLi produced bicyclic cage compounds P(2)(R(2)NB)(2)SnR'(2) (R(2)N = (i)()Pr(2)N (9), tmp (8); R' = (t)()Bu) or an oligomer [-P(R(2)NB)(2)PSn(R'(2))-] (R(2)N = tmp; R' = Me). The 2:1 reactions of R'(2)SnCl(2) with 1 and 2 have been studied, and with a small R' group (Me) a disubstitution product, [HP(tmpB)(2)P](2)SnMe(2) (11), is obtained. With a larger R' group ((t)()Bu), cage products P(2)(tmpB)(2)Sn(t)()Bu(2) and P(2)((i)()Pr(2)NB)(2)Sn(t)()Bu(2) are isolated. The molecular structures of 8 and 9 have been determined by single crystal X-ray diffraction techniques, and these structures and their spectroscopic features are discussed in relation to other boron-phosphorus cage compounds.

Journal Article↗
PubMed2003

Addition of organometallic compounds to tin-containing cyclic ketones. Remote stereocontrol induced by the stannyl group.

The addition of organometallic reagents to cyclic ketones bearing stannyl groups at an appropriate distance to the carbonyl group occurs with a high level of stereocontrol, giving alcohols resulting from attack of the nucleophile syn to the tin center. This remarkable remote control is a consequence of the anchoring of the organometallic reagent by the tin and carbonyl groups. The degree of selectivity observed depends on the spatial distance between the carbonyl group and the tin center. (Z)-beta-Stannylvinyl ketones (Sn/CO separation: 5 bonds) react with organolithium reagents, showing a high degree of stereocontrol. On the contrary, the analogous ketones with E stereochemistry do not show selectivity at all. In the case of beta-stannyl ketones (Sn/CO separation: 3 bonds), the long distance between the tin center and the carbonyl group does not favor selective addition except when allyllithium derivatives are used. A chelation-controlled pathway assisted by the three-carbon chain of the allyl anion, which compensates the distance between tin and carbonyl groups, has been proposed. The selectivity found for ketones 34-36 (Sn/CO separation: 4 bonds) depends on their structure and varies with the hybridization of the carbon atom linked to the trialkyltin group. Deuterium labeling experiments as well as ab initio molecular-orbital analysis support the mechanistic hypothesis of an intramolecular delivery. Grignard reagents are less selective than organolithium compounds.

Journal Article↗
PubMed2002

Towards alpha- or beta-D-C-glycosyl compounds by tin-catalyzed addition of glycosyl radicals to acrylonitrile and vinylphosphonate, and flexible reduction of tetra-O-acetyl-alpha-D-glucopyranosyl bromide with cyanoborohydride.

Photo-induced radical addition of acetylated alpha-D-glucopyranosyl bromide (1). to acrylonitrile or diethyl vinylphosphonate, in the presence of catalytic amounts of tri-n-butyltin chloride and sodium (or tetra-n-butylammonium) cyanoborohydride in excess, allowed efficient preparations of alpha-configurated nonononitrile and 2-(alpha-D-glucopyranosyl)-ethylphosphonate (79, 70% yields, respectively). These conditions led to 2-(alpha-D-manno-, and galactopyranosyl)-ethylphosphonates in 68 and 76% yields. Similarly, radical addition of acetylated 1-bromo-beta-D-glucopyranosyl chloride (2). to acrylonitrile or diethyl vinylphosphonate afforded mainly intermediate chlorides which, upon radical reduction with excess tri-n-butyltin hydride, afforded the corresponding beta anomers (40 and 38%, respectively) by sequential C-C and C-H bond formation. Stereocontrol relies on the alpha-stereoselective quenching of D-glycopyranos-1-yl radicals. We found also that UV light irradiation of 1 with excess NaBH(3)CN in tert-butanol afforded either 1,3,4,6-tetra-O-acetyl-2-deoxy-alpha-D-arabino-hexopyranose (65% after crystallization) or, when 10% mol thiophenol was added, 2,3,4,6-tetra-O-acetyl-1,5-anhydro-D-glucitol (79%). These are simple, tin-free, and easily controlled conditions, which compare well with known preparations of these reduced sugars.

Acetylation↗
PubMed2001

Species-specific isotope-ratio measurements of volatile tin and antimony compounds using capillary GC-ICP-time-of-flight MS.

The analytical performance of an axial inductively-coupled-plasma time-of-flight mass spectrometer (ICP-TOFMS) as a detector for fast transient chromatographic signals resulting from the coupling to capillary gas chromatography (CGC) was investigated. A cryotrapping GC-ICP-TOFMS method for the determination of volatile metal(loid) compounds (VOMs) in gases was used and the suitability of the TOF mass analyzer for multielemental speciation analysis and multi-isotope ratio determinations was studied in terms of accuracy and precision. Isotope ratios 118Sn/120Sn and 121Sb/123Sb have been determined in in-house gas standard atmospheres in Tedlar bags at two different levels (100 pg and 1 ng) for different elemental species (SnH4, MeSnH3, Me2SnH2, Me3SnH, BuSnH3, SbH3, and MeSbH2). A limitation arising from counting statistics in both detection modes could be shown. A solution containing rhodium (10 ng mL(-1)) and cadmium (40 ng mL(-1)) was introduced simultaneously to the GC outlet. Rhodium acts as a continuous internal standard and Cd is used for mass-bias correction (by measuring the 111Cd/113Cd ratio). The detection system in both pulse counting and analog mode was examined. The best attainable precision was established for Me2SnH2 (analog mode, 12 replicates, 1 ng, RSD 0.34%, accuracy 0.31%) whereas most other species ranged between 0.4 and 0.5% RSD if higher concentrations were used. The limitations of the pulse counting system are clearly seen, with peak heights of more than 2000 counts reaching saturation (for an integration time of 100 ms), which reduces the accuracy of isotope ratio determinations. A dozen VOM could be detected in an aged landfill gas sample; several unidentified Sn compounds were present. Although their isotope ratios are within the confidence value of the standards, it is not yet clear if the acquired precision is good enough to identify isotopic fractionation of metal(loid)s through biovolatilization processes. With the precision achieved, the combination of cryotrapping GC and ICP-TOFMS is a powerful tool for monitoring volatile multi-element species in multi-tracer experiments and isotope dilution methodology.

Antimony↗
PubMedDate not supplied

Erythrocyte hemolysis by organic tin and lead compounds.

The effect of trialkyllead and trialkyltin on pig erythrocyte hemolysis has been studied and compared. The results of experiments showed that the hemolytic activity of organoleads increases with their hydrophobicity and follows the sequence: triethyllead chloride < tri-n-propyllead chloride < tributyllead chloride. And similarly in the case of organotins: triethyltin chloride < tri-n-propyltin chloride < tributyltin chloride. Comparison of the hemolytic activity of organoleads and organotins indicates that the lead compounds exhibit higher hemolytic activity. The methods of quantum chemistry allowed to determine the maximum electric potential of the ions R3Pb+ and R3Sn+, and suggest a relationship between the potential and toxicity.

Animals↗
PubMed2005

Speciation of organometallic compounds in environmental samples by gas chromatography after flow preconcentration on fullerenes and nanotubes.

The development of a simple speciation method for the determination of lead (trimethyllead(I), dimethyllead(II), triethyllead(I), and diethyllead(II)), mercury (methylmercury(I), ethylmercury(I), mercury(II)), and tin (n-butyltin(III), di-n-butyltin(II), tri-n-butyltin(I), tin(IV)) compounds in environmental samples was described. The potential of C70 fullerenes and multiwalled carbon nanotubes (MWNTs) as sorbents was investigated for the first time; this study revealed that there are no significant differences between them in terms of sensitivity, selectivity, precision, and reusability. Comparative studies showed that MWNTs and C60 and C70 fullerenes were superior to graphitized carbon black and RP-C18 for the extraction of the 11 compounds studied. The accuracy of the MWNT method was evaluated from recovery values with two standard reference coastal sediments, and good concordance in the results were obtained. Detection limits of 0.5-2 pg/mL were obtained when using a sorbent column containing 160 mg of MWNTs (sample breakthrough, 50 mL of water). The method was successfully applied to the determination of lead, mercury, and tin compounds in water and coastal sediment samples with satisfactory results.

Chromatography, Gas↗
PubMed2004

Tin-chalcogen double-bond compounds, stannanethione and stannaneselone: synthesis, structure, and reactivities.

The first isolation of diarylstannanethione (tin-sulfur double-bond compound) and diarylstannaneselone (tin-selenium double-bond compound), Tbt(Ditp)Sn=X (Tbt = 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl; Ditp = 2,2' '-diisopropyl-m-terphenyl-2'-yl; X = S and Se) was accomplished by dechalcogenation of the corresponding highly hindered tetrachalcogenastannolanes, Tbt(Ditp)SnX(4). The (119)Sn NMR of stannanethione, Tbt(Ditp)Sn=S, and stannaneselone, Tbt(Ditp)Sn=Se, showed only one low-field broad signal at 531 and 440 ppm, respectively, characteristic of a tricoordinated tin, and hence, the stannanethione and stannaneselone display an intrinsic nature of tin-chalcogen double-bond compounds. The X-ray crystallographic analysis of the isolated stannaneselone, Tbt(Ditp)Sn=Se 5a, revealed a completely trigonal geometry around the central tin with a remarkably short Sn-Se bond length, indicative of structural similarity to a ketone.

Journal Article↗