Mass Balance Experiments Research Articles

Detection of Resin Acid Compounds in Airborne Particulate Generated from Rosin Used as a Soldering Flux

Various uses of rosin and exposure to its resin acid constituents have been associated with dermal and pulmonary sensitization. Methodology is presented to detect resin acids common to rosin (such as abietic and dehydroabietic acid) found in aerosol from heated rosin flux. Air filtration, solvent filter extraction, and gas chromatography/mass spectrometry were used to provide qualitative and quantitative information on the resin acid content of aerosol produced during soldering with rosin flux. Abietic acid and dehydroabietic acid were identified and quantified in aerosol derived from heated rosin flux, in samples collected in the field and in laboratory generated samples. Other resin acids (including several apparently oxidized resin acids) were detected, but not quantified. Laboratory mass balance experiments using soldering temperatures and liquid rosin flux showed that much of the nonvolatile material originally present in unheated flux may be captured on a sampling filter following heating and aerosolization. The data presented suggest that resin acids are a major component (with regard to mass) of the airborne contaminants produced during soldering with rosin flux. Abietic acid was shown to be unstable on sampling filters held for a period of weeks, while dehydroabietic acid and total solvent-soluble material were not found to degrade under the same conditions. Rosin aerosol produced in the laboratory using a soldering iron and liquid rosin flux produced particles shown to be of respirable size using scanning electron microscopy.

Detection of Resin Acid Compounds in Airborne Particulate Generated from Rosin Used as a Soldering Flux

Various uses of rosin and exposure to its resin acid constituents have been associated with dermal and pulmonary sensitization. Methodology is presented to detect resin acids common to rosin (such as abietic and dehydroabietic acid) found in aerosol from heated rosin flux. Air filtration, solvent filter extraction, and gas chromatography/mass spectrometry were used to provide qualitative and quantitative information on the resin acid content of aerosol produced during soldering with rosin flux. Abietic acid and dehydroabietic acid were identified and quantified in aerosol derived from heated rosin flux, in samples collected in the field and in laboratory generated samples. Other resin acids (including several apparently oxidized resin acids) were detected, but not quantified. Laboratory mass balance experiments using soldering temperatures and liquid rosin flux showed that much of the nonvolatile material originally present in unheated flux may be captured on a sampling filter following heating and aerosolization. The data presented suggest that resin acids are a major component (with regard to mass) of the airborne contaminants produced during soldering with rosin flux. Abietic acid was shown to be unstable on sampling filters held for a period of weeks, while dehydroabietic acid and total solvent-soluble material were not found to degrade under the same conditions. Rosin aerosol produced in the laboratory using a soldering iron and liquid rosin flux produced particles shown to be of respirable size using scanning electron microscopy.

Biodegradation of Sorbed Fluorene in Sediment Slurries

The bioavailability of sorbed organic chemicals is a deciding factor in the applicability of bioremediation processes to contaminated sediments and soils. Sorption of pollutants may prevent contact between the microbes and the contaminant, or it may simply maintain the aqueous phase contaminant concentrations at levels too low to support growth. Studies presented herein investigate the biodegradation and desorption of fluorene, a 3-ringed polynuclear aromatic hydrocarbon (PAH), in estuarine sediment-water slurries. Adsorption of fluorene to sediments with 1.4% organic carbon was characterized with a linear isotherm. Desorption was characterized through step-desorption and temporal-desorption tests, which showed that desorption was both completely reversible and rapid. Further studies evaluated the rate and extent of fluorene removal in systems containing a fluorene-degrading culture. Fluorene biodegradation was confirmed with 14C mass balance experiments, and fluorene disappearance was monitored in both the sediment and aqueous phase. In biologically active systems fluorene was rapidly degraded, after a lag period, to levels below detection limits. The rate of fluorene disappearance in biologically active systems was controlled by microbial degradation rates and was not limited by desorption.

Ammonia volatilization from nitric-acid-treated cattle slurry surface applied to grassland

The reduction in NH3 loss from HNO3 treated cattle slurry, surface applied to grassland, was measured on different soil types throughout the Netherlands from 1989 to 1992. Thirteen micro-meteorological mass balance and 10 small wind tunnel experiments were carried out. Amounts varying between 7-17 and 10-30 m-3 ha-1 were applied, resp. and measurements were performed for 4 and 10 days, resp. The pH of treated slurry ranged from 3.9 to 6.6. A mean total of 60% (range: 29-98%) of the NH4-N from untreated slurry was volatilized in the mass balance experiments. A reduction in NH3 volatilization of 85, 72 and 55% was achieved for acidified slurry with a respective pH of c. 4.5, 5.0 and 6.0. Approx 55% (range: 7-91%) of the total loss from acidified slurry was measured on the day of application. A mean total of 66% (range: 21-90%) of NH4-N from untreated slurry volatilized in the tunnel experiments. The reduction in NH3 volatilization was 73% for slurry with pH 4.5. Approx 27% (range: 6-91%) of the total loss from acidified slurry was measured on the first day. The smaller reduction and the different pattern in NH3 volatilization observed in the wind tunnel experiments might be the consequence of different climatic conditions in and outside the tunnels or they might be related to the higher rates of slurry application in these experiments. Regression analysis indicated that high temperature, slurry pH, potential water evaporation and NH4+ concn stimulated NH3 loss in the mass balance experiments (Rsuperscript 2 = 87%). It is suggested that the results obtained with acidified slurry were independent of the grassland soil type at the application levels employed.

Biological productivity determined from oxygen mass balance and incubation experiments

The flux of metabolic products from the surface ocean regulates the carbon dioxide concentration in the atmosphere on time scales shorter than millennia and is central to our perception of how the global ecosystem works. There are many different approaches for estimating the net production of organic matter in the euphotic zone. We compare net biological oxygen production derived from a study of oxygen, nitrogen, and argon mass balance with nitrate uptake determined in 15N incubation experiments in the mixed layer of the subarctic Pacific Ocean. Net community production rates determined by these two methods are within a factor of two with the incubations being, in one case, greater. This indicates that chemical mass balance and in vitro incubation measurements give similar results under circumstances where averaging over different time scales does not bias the comparison.

Effect of minoxidil concentration on the deposition of drug and vehicle into the skin

Minoxidil dissolved in propylene glycol/ethanol/water (20:60:20; v/v) was more efficiently delivered into hairless mouse skin from a 0.02% solution than from a 2% formulation during in vitro mass balance experiments. Evaporation of the vehicle after application of the 2% minoxidil solution led to compositional changes so drastic that saturation is attained quickly. The shifting compositions of the vehicle were experimentally profiled and the drug's solubility was measured in media reflecting these changes over time. The original 2% formulation has excess capacity to dissolve minoxidil but, following its application, the solution rapidly saturates through evaporation, reaching saturation within 30 minutes. While the 2% formulation definitely functions at a proportionally higher thermodynamic activity than the 0.02% formulation at early times, most of this thermodynamic advantage is lost abruptly upon precipitation of the drug. The driving force following drug precipitation only reflects the dissolved minoxidil, and thus the relative delivery rate of the 2% formulation eventually drops to only several multiples of the delivery rate of the 0.02% solution which never quite attains saturation.

Electrochemical oxidation of elemental indium in liquid ammonia media

The electrochemical oxidation of indium metal in solutions of NH4X (X = Cl, Br or I) in liquid ammonia proceeds with an electrochemical efficiency which implies the formation of indium(II) species at the anode. In the case of NH4I–NH3, Raman spectroscopy confirmed the presence of In2I4 in solution; it was not possible to isolate neutral or anionic derivatives of indium(II), since disproportionation occurs on removal of solvent to give indium-(0), -(I) and -(III) derivatives. Mass-balance experiments have been made for these systems. Solutions of NH4I + substituted o-quinone (But2H2C6O2-o or Br4C6O2-o) yielded InI3·3NH3, while with substituted catechols [X4C6(OH)2; X = Cl or Br] the products were [NH4]3[In(O2C6X4)3]·Et2O. In the case of a solution of But2H2C6(OH)2-o(H2dbc) in liquid NH3–Et2O media, the final product is a derivative of the dimeric anion [In2(dbc)4(NH3)2]2–, in a lattice which also contains NH4+, Hdbc– and Et2O. The crystal parameters of [NH4]4[In2(dbc)4(NH3)2]·(2Hdbc)·2Et2O are monoclinic, space group P21/n, a= 14.464(10), b= 19.194(5), c= 19.560(7)A, β= 103.72(4)°, Z= 4, R= 0.055. The anion involves two InO5N kernels, with In2O2 cross-linking responsible for the dimerization.

Cross‐flow filtration of colloids from aquatic environments

In recognition of problems associated with traditional ultrafiltration techniques, cross‐flow ultrafiltration has been adapted to isolate colloidal material from natural aquatic environments, both freshwater and marine. The procedure is capable of delivering filtration rates on the order of tens of liters per hour without introducing significant quantities of organic or trace‐metal contaminants, and thus is suitable for large‐volume and trace‐component applications. Mass balance experiments in which concentrations were measured in ultrafiltrate and retained fractions show that both organic material and several trace metals are recovered without significant losses on the filters.

Human Serum and Plasma Protein Binding of Enoximone and Its Sulfoxide Metabolite

Experimental factors and determinants of the protein binding of enoximone (a new cardiotonic agent) were investigated in human serum from healthy, drug-free subjects using a rapid ultrafiltration method; these factors and determinants included nonspecific binding to the apparatus, ultrafiltrate volume, temperature, serum pH, enoximone serum concentration, and enoximone sulfoxide (metabolite) concentration. It was demonstrated from mass balance experiments that nonspecific binding to the apparatus did not occur. Within the range investigated, ultrafiltrate volume did not affect the binding result. However, serum pH and temperature were critical variables. At pH 7.4 and 37 °C, enoximone serum binding occurred to the extent of ~70%; over the therapeutic serum concentration range, this binding was concentration independent. Experiments with purified albumin solutions indicated that much of the serum binding could be accounted for by albumin. At concentrations exceeding those observed clinically, enoximone sulfoxide did not affect enoximone serum binding. In another experiment, enoximone binding to serum was compared with that from plasma containing either heparin or disodium EDTA. There were essentially no differences. Enoximone sulfoxide serum protein binding was also investigated in serum from healthy, drug-free human subjects; binding occurred to the extent of ~5%.

The water gas shift reaction catalyzed by Rh 6(CO) 16 adsorbed on alumina or [Rh(CO) 2Cl] 2 adsorbed on alumina, Na-Y zeolite and H-Y zeolite

Rh 6(CO) 16 chemisorbed on η-alumina or [Rh(CO) 2Cl] 2 chemisorbed on η-alumina, Na-Y zeolite and H-Y zeolite catalyze the water gas shift reaction to various degrees. The following order of activity was observed: alumina > Na-Y > H-Y zeolite. With alumina the reaction occurs between 25 and 100°C. Turnover numbers as high as 255/Rh atom/h are obtained at 50°C and under 50 atm. These turnover numbers are the same whether the precursor complex is Rh 6(CO) 16 or [Rh(CO) 2Cl] 2. The mechanism of such a reaction has been deduced from infrared studies, mass balance and labeling experiments. It involves three steps: electrophilic attack by surface protons on the metallic frame with formation of Rh I(CO) 2(OAl ▪)(HOAl ▪) and possibly Rh III(H)(H)(OAl ▪)HOAl ▪); reductive elimination of H 2 from Rh(H)(H)(OAl ▪)(HOAl ▪) under CO pressure; and nucleophilic attack by water on CO coordinated to rhodium(I) with formation of CO 2, H + and regeneration of Rh 6(CO) 16. If the CO pressure is too low or if liquid water is used, aging of the catalyst occurs which seems to be due to the formation of metallic rhodium. The intermediacy of [Rh(CO) 4] − is also suspected in the step of metal-metal bond formation.

Peritoneal lymphatic uptake of fibrinogen and erythrocytes in the rat.

Intact and thoracic duct-cannulated rats were dialyzed at various intraperitoneal pressures with 5% bovine serum albumin solutions containing 125I-fibrinogen or 51Cr-erythrocytes. Lymphatic transport rates were calculated from the mass of tracer passing into the plasma space as function of tracer concentration in the peritoneal fluid during dialysis periods ranging between 143 and 360 min. Peritoneal protein concentrations were constant over the duration of the experiments. The calculated lymph flow rate was independent of intraperitoneal pressure and in intact rats averaged 2.85 +/- 1.22 microliters/min for uptake of 125I-fibrinogen and 2.60 +/- 1.17 for uptake of 51Cr-erythrocytes. However, the observed fluid loss rates from the peritoneal cavity were sensitive to the intraperitoneal pressure and were 5 to 20 times the calculated lymph flow rate. Mass balance experiments in two rats dialyzed with 125I-fibrinogen indicated that a significant proportion (28%) of tracer leaving the peritoneal cavity is absorbed by the anterior muscle wall of the abdomen and is probably trapped there because of its large molecular weight. Results from 125I-fibrinogen and 51Cr-erythrocyte uptake experiments both indicated that only approximately 30% of the total lymphatic drainage of the peritoneal cavity passes through the thoracic duct in rats.

A Comparative Study of the Gas-Phase Radiation Chemistry of Phosphine and Ammonia

Comparison studies of the decomposition in the gas phase of pure phosphine and pure ammonia by cobalt-60 gamma rays show that both compounds are broken down to their elemental constituents. Results of mass balance experiments with pure phosphine indicate that the overall radiolysis reaction is ${\rm PH}_{3}\rightarrow {\rm P}_{\text{red}}+{\textstyle\frac{3}{2}} {\rm H}_{3}$. G for hydrogen production is 11.3 (molecules formed per 100 eV absorbed energy), over the dose range $0.4\times 20^{20} {\rm eV}$ to $5\times 10^{20} {\rm eV}$, beyond which the G value decreases. From 50 Torr to 1 atm the product yield is proportional to phosphine pressure, extrapolating to zero yield at zero pressure. Yields of nitrogen and hydrogen from the radiolysis of gaseous ammonia are proportional to dose from $1\times 20^{20} {\rm eV}$ to $5\times 10^{20} {\rm eV}$, with G values of 1.5 and 4.5, respectively. The total product yields extrapolate to zero yield at zero dose. The G values are not dependent on ammonia pres...