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Banana pulps at any ripening stage can be completely dissolved in solvent systems based on the ionic liquid (IL) 1-n-butyl-3-methylimidazolium chloride ([C4mim]Cl), and variations in the carbohydrate composition of the fruit analyzed directly on the resulting solutions using high-resolution 13C NMR spectroscopy.
Solvent yellow (2-(2'-quinolinyl)-1,3-indandione) and solvent green (1,4-di-p-toluidinoanthraquinone) are components of colored smoke munitions and may become airborne and be inhaled by workers during the manufacture of the munitions. Little is known about the disposition of either dye after inhalation. To obtain this information, we exposed male F344/N rats to 14C-solvent yellow aerosols (160 nmol solvent yellow/liter air) or a mixture of 14C-solvent yellow and unlabeled solvent green (340 nmol solvent yellow and 370 nmol solvent green/liter air) for 60 min. After either exposure, solvent yellow was rapidly cleared from the respiratory tract, with a t1/2 of 2-3 hr. Solvent green was retained in the lungs with a minimum estimated t1/2 for clearance of 22 days. Solvent green was not detected in other tissues during the 70-hr postexposure period. After either exposure, high-pressure liquid chromatography analysis of tissues extracts indicated that 40 to 75% of the 14C in liver and kidney consisted of solvent yellow metabolites. Greater than 90% of the 14C in the lungs was unmetabolized solvent yellow. The major pathway for excretion of solvent yellow and solvent yellow metabolites was the feces (74% of the initial body burden); the t1/2 for excretion was 14 hr. Urinary 14C accounted for 14% of the initial body burden and the t1/2 for excretion was 10 hr. Over 90% of the 14C excreted in the urine was solvent yellow metabolites. Very little solvent yellow (2%) was metabolized to 14CO2. By 72 hr after exposure, only 10% of the initial 14C deposited remained in the body.
The repeated-dose inhalation toxicity of a smoke containing a mixture of three dyes was tested in female mice, rats and guinea pigs. The green component dye (Solvent Green 3) was retained in the lungs. Particularly in the rats marked collections of alveolar macrophages were found. In the same species several other adverse findings were noted: these included adenocarcinomas of the breast in the high-dose group and a dose-related incidence of biliary hyperplasia. Fatty change was noted in the livers of the test-group mice. A large proportion of the high-dose guinea pigs died during the exposure period, for which reason exposure was stopped early in that group, otherwise the guinea pigs were little affected. However, all test groups of all species showed reductions in growth during the exposure period.
The quinoline dye 2-(2'-quinolyl)-1,3-indandione or Solvent Yellow 33 (SY) and the anthraquinone dye 1,4-di-p-toluidinoanthraquinone or Solvent Green 3 (SG) are used in many manufactured products including military smoke grenades. During manufacturing, SY or a combination of both SY and SG can be released into the air, exposing factory workers by inhalation to these dye compounds. The potential inhalation toxicity of these compounds was tested by exposing F344/N rats to different concentrations of SY or SY/SG dye mixture (30:70 w/w) for 6 hr/day, 5 days/week for 4 or 13 weeks. In the 4-week studies, rats were exposed to SY aerosols at average concentrations of 10 +/- 5, 51 +/- 10, or 230 +/- 30 mg/m3 (means +/- SD) or SY/SG aerosols at average concentrations of 11 +/- 5, 49 +/- 11, or 210 +/- 50 mg/m3 (means +/- SD). Rats exposed to the highest concentration of SY or SY/SG had body weights that were approximately 8% or 7% less, respectively, than their controls after exposure. Rats exposed to the highest concentration of SY/SG for 4 weeks also had reduced pulmonary gas exchange efficiency, airflow obstruction, mild pulmonary inflammation, slight Type II pulmonary epithelial cell hyperplasia, and proliferation of vacuolated alveolar macrophages. In the 13-week studies, rats were exposed to SY aerosols at average concentrations of 1.0 +/- 0.2, 10.8 +/- 1.8, or 100 +/- 17 mg/m3 (means +/- SD) or SY/SG aerosols at average concentrations of 1.1 +/- 0.5, 10.2 +/- 3.1, or 101 +/- 23 mg/m3 (means +/- SD). Animals exposed to the highest concentration of SY or SY/SG for 13 weeks had body weights that were approximately 5 or 9% less, respectively, than their controls after exposure and had accumulation of vacuolated alveolar macrophages in lungs. Rats exposed to the highest concentration of SY/SG dye mixture for 13 weeks also had indications of mild pulmonary inflammation and slight Type II pulmonary epithelial cell hyperplasia. Very little SY was found in lungs after any exposures, indicating its clearance from lungs was at a rapid rate. However, significant amounts of the SG component of the SY/SG mixture were detected in lungs after each exposure. Lung clearance half-times of SG from the 13-week exposure were estimated to be approximately 280 days. In summary, neither test material appeared to be highly toxic following inhalation. However, the slightly higher toxicity observed for SY/SG over SY alone is probably related to the longer lung retention of the SG component of the dye mixture.
Solvents are widely used in commercial manufacturing and service industries. Despite abundant precaution, they inevitably contaminate our air, land, and water because they are difficult to contain and recycle. Researchers have therefore focused on reducing solvent use through the development of solvent-free processes and more efficient recycling protocols. However, these approaches have their limitations, necessitating a pollution prevention approach and the search for environmentally benign solvent alternatives. This report highlights opportunities for the practical implementation of such green solvents.
The first examples of room temperature ionic liquids, containing N-alkyl-N-vinyl-2-pyrrolidinonium (N-alkyl-N-vinyl-gamma-butyrolactam) cations in combination with bromide and tetrafluoroborate anions, have been synthesized and the spectroscopic and physical characteristics of this family of ionic liquids have been investigated for intended use as liquid electrolytes and green solvents.
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Thin-layer chromatography and high-performance liquid chromatography (HPLC) with linear photodiode array detection (LPDA) were used to separate impurities from two commercial dyes. Gravity flow liquid chromatography was used to purify reference standards of the dyes. Normal phase HPLC with LPDA detection was used to determine purities of submitted samples by comparing responses to those of the reference standards. Electron impact mass spectrometry and nuclear magnetic resonance were utilized to confirm structures of the dyes and their impurities.
We demonstrate the use of room-temperature ionic liquids as catalysts and solvents for the cracking reaction of alkoxypropanes, eliminating the need for a volatile organic solvent and hazardous catalyst disposal.
Compressed air-powered jet mills are used in the chemical and food industries for grinding and classifying powders. We adapted one type of these fluid energy mills as a powder generator for inhalation experiments. The generating system included a jet mill and a screw feeder, the jet mill consisting of an elongated channel, a feeding jet to deliver the material into the channel, and two high-speed air jets. High speed air circulating in the channel created turbulence and centrifugal forces to disperse powder. The jet mill used can be operated from 25 to 100 psig at flow rates of 300 to 900 L/min. Two test materials--a solvent yellow dye and a dye mixture of solvent green and solvent yellow--were used. Both dyes were soft and sticky and could not be dispersed with several other powder generators tested at the concentrations required for toxicity studies. Aerosol concentrations ranging from 10 to 1500 mg/m3 at a flow rate of 400 L/min were obtained by adjusting the feed rate to the jet mill. Stability of aerosol concentration during six-hour continuous generation was 15 to 20%. Comparisons of several generators for producing sticky organic powders are also discussed.
A self-aspirating heated nebulizer probe is described and demonstrated for use in the direct analysis of analytes on surfaces and in liquid samples by atmospheric pressure chemical ionization (APCI) mass spectrometry. Functionality and performance of the probe as a self-aspirating APCI source is demonstrated using reserpine and progesterone as test compounds. The utility of the probe to sample analytes directly from surfaces was demonstrated first by scanning development lanes of a reversed-phase thin-layer chromatography plate in which a three-component dye mixture, viz., Fat Red 7B, Solvent Green 3, and Solvent Blue 35, was spotted and the components were separated. Development lanes were scanned by the sampling probe operated under computer control (x, y plane) while full-scan mass spectra were recorded using a quadrupole ion trap mass spectrometer. In addition, the ability to sample the surface of pharmaceutical tablets (viz., Extra Strength Tylenol and Evista tablets) and to detect the active ingredients (acetaminophen and raloxifene, respectively) selectively was demonstrated using tandem mass spectrometry (MS/MS). Finally, the capability to sample analyte solutions from the wells of a 384-well microtiter plate and to perform quantitative analyses using MS/MS detection was illustrated with cotinine standards spiked with cotinine-d3 as an internal standard.
The coupling of a rotation planar preparative thin-layer chromatography system on-line with mass spectrometry is demonstrated using a simple plumbing scheme and a self-aspirating heated nebulizer probe of a corona discharge atmospheric pressure chemical ionization source. The self-aspiration of the heated nebulizer delivers approximately 20 microL/min of the 3.0 mL/min eluate stream to the mass spectrometer, eliminating the need for an external pump in the system. The viability of the coupling is demonstrated with a three-dye mixture composed of fat red 7B, solvent green 3, and solvent blue 35 separated and eluted from a silica gel-coated rotor using toluene. The real-time characterization of the dyes eluting from the rotor is illustrated in positive ion full-scan mode. Other self-aspirating ion source systems including atmospheric pressure photoionization, electrospray ionization, and inductively coupled plasma ionization, for example, might be configured and used in a similar manner coupled to the chromatograph to expand the types of analytes that could be ionized, detected, and characterized effectively.
Two dyes (C.I. Solvent Yellow No. 33 and a mixture of C.I. Solvent Yellow No. 33 and C.I. Solvent Green No. 3) were tested for mutagenicity in the Salmonella reversion assay and the L5178Y/TK+/- mouse lymphoma assay, and also for sister chromatid exchange (SCE) induction in vivo in C57B1/6J mice. In addition, a greater than 99.9% pure sample of the yellow dye [2-(2'-quinolyl)-1,3-indandione] was tested with and without exogenous activation in the Salmonella reversion assay and the L5178Y/TK+/- mouse lymphoma assay. Neither C.I. Solvent Yellow No. 33 nor the C.I. Solvent Yellow No. 33 and Solvent Green No. 3 mixture was positive for inducing SCEs in vivo. All three dyes were tested in the standard plate incorporation test in seven Salmonella strains TA98, TA100, TA102, TA104, TA1535, TA1537, and TA1538. The dyes were negative with and without exogenous activation in TA98, TA1535, and TA1538. One test with TA1537 was positive with the greater than 99.9% purified yellow dye. All three dyes gave weakly positive results (less than a twofold increase) with S-9 in TA100 and were clearly positive in TA102 and TA104 both with and without S-9. They also induced mutation at the thymidine kinase locus in mouse lymphoma cells, produced both large- and small-colony trifluorothymidine-resistant mutants, and were clastogenic. The purified yellow dye was further tested for SCE induction in mouse lymphoma cells and was determined to give a slightly positive response in the presence of S-9.
This paper presents an environmentally friendly, inexpensive, rapid, and efficient process for size-selective fractionation of polydisperse metal nanoparticle dispersions into multiple narrow size populations. The dispersibility of ligand-stabilized silver and gold nanoparticles is controlled by altering the ligand tails-solvent interaction (solvation) by the addition of carbon dioxide (CO2) gas as an antisolvent, thereby tailoring the bulk solvent strength. This is accomplished by adjusting the CO2 pressure over the liquid, resulting in a simple means to tune the nanoparticle precipitation by size. This study also details the influence of various factors on the size-separation process, such as the types of metal, ligand, and solvent, as well as the use of recursive fractionation and the time allowed for settling during each fractionation step. The pressure range required for the precipitation process is the same for both the silver and gold particles capped with dodecanethiol ligands. A change in ligand or solvent length has an effect on the interaction between the solvent and the ligand tails and therefore the pressure range required for precipitation. Stronger interactions between solvent and ligand tails require greater CO2 pressure to precipitate the particles. Temperature is another variable that impacts the dispersibility of the nanoparticles through changes in the density and the mole fraction of CO2 in the gas-expanded liquids. Recursive fractionation for a given system within a particular pressure range (solvent strength) further reduces the polydispersity of the fraction obtained within that pressure range. Specifically, this work utilizes the highly tunable solvent properties of organic/CO2 solvent mixtures to selectively size-separate dispersions of polydisperse nanoparticles (2 to 12 nm) into more monodisperse fractions (+/-2 nm). In addition to providing efficient separation of the particles, this process also allows all of the solvent and antisolvent to be recovered, thereby rendering it a green solvent process.
The work summarized here demonstrates a new concept for exploiting dense phase CO(2), media considered to be "green" solvents, for homogeneous catalytic oxidation reactions. According to this concept, the conventional organic solvent medium used in catalytic chemical reactions is replaced substantially (up to 80 vol %) by CO(2), at moderate pressures (tens of bars), to create a continuum of CO(2)-expanded solvent media. A particular benefit is found for oxidation catalysis; the presence of CO(2) in the mixed medium increases the O(2) solubility by ca. 100 times compared to that in the neat organic solvent while the retained organic solvent serves an essential role by solubilizing the transition metal catalyst. We show that CO(2)-expanded solvents provide optimal properties for maximizing oxidation rates that are typically 1-2 orders of magnitude greater than those obtained with either the neat organic solvent or supercritical CO(2) as the reaction medium. These advantages are demonstrated with examples of homogeneous oxidations of a substituted phenol and of cyclohexene by molecular O(2) using transition metal catalysts, cobalt Schiff-base and iron porphyrin complexes, respectively, in CO(2)-expanded CH(3)CN.
Chloroethenes like tetrachloroethene (PCE) are the most prevalent groundwater contaminants in the USA. Their presence as nonaqueous phase liquids (NAPLs) makes remediation difficult. Among options for NAPL cleanup, co-solvent injection has demonstrated success. However, the process has the potential to leave considerable residue of the co-solvent as well as residual chloroethene. Our rationale in this study was to examine whether this residual solvent could be a potential electron donor for the remediation of the residual chloroethene. We hypothesized that ethyl lactate, a "green" solvent, could serve both as a NAPL extraction solvent and an electron donor for reductive dechlorination of residual chloroethene. We examined whether a mixed culture known to degrade PCE with lactate could also grow on ethyl lactate and whether it could stimulate PCE dechlorination. Biomass growth and PCE dechlorination were observed by protein and chloride production, respectively, in the culture; with a specific dechlorination rate of 50 150 microg (mg cell d)(-1). Ethyl lactate abiotically breaks down to ethanol and lactate, the latter being a rich source of hydrogen fo reductive dechlorination. The results demonstrate that ethyl lactate may be promising for in situ bioremediation following NAPL extraction.
Polyethylene glycol (400) with 90% glycerol (aqueous) is introduced as an efficient solvent system for lipid stains. Various lipid-soluble dyes were dissolved in this solvent system and tested for their intensity, contrast, and specificity of staining of suberin lamellae in plant tissue. The stability (i.e., lack of precipitation) of the various staining solutions in the presence of fresh tissue was also tested. When dissolved in polyethylene glycol-glycerol, Sudan red 7B (fat red) was the best nonfluorescent stain and fluorol yellow 088 (solvent green 4) was an excellent fluorochrome. These two dyes formed stable staining solutions which efficiently stained lipids in fresh sections without forming precipitates. Estimations of the solubilities of these dyes in the solvent compared with their solubilities in lipids of various chemical types indicated that they should both be effective stains for lipids in general.
An ionic liquid/aqueous two-phase system based on the hydrophilic ionic liquid 1-butyl-3-methylimidazolium chloride (BmimCl) and K(2)HPO(4) has been employed for direct extraction of proteins from human body fluids for the first time. Proteins present at low levels were quantitatively extracted into the BmimCl-rich upper phase with a distribution ratio of about 10 between the upper and lower phase and an enrichment factor of 5. Addition of an appropriate amount of K(2)HPO(4) to the separated upper phase results in a further phase separation, giving rise to an improved enrichment factor of 20. FTIR and UV spectroscopy demonstrated that no chemical (bonding) interactions between the ionic liquid and the protein functional groups were identifiable, while no alterations of the natural properties of the proteins were observed. The partitioning of proteins in the two-phase system was assumed to have been facilitated by the electrostatic potential difference between the coexisting phases, as well as by salting out effects. The system could be applied successfully for the quantification of proteins in human urine after on-line phase separation in a flow system. The use of an ionic liquid, as a green solvent, offers clear advantages over traditional liquid-liquid extractions, in which the use of toxic organic solvents is unavoidable.