scholarly journals Water Uptake by Evaporating pMDI Aerosol Prior to Inhalation Affects Both Regional and Total Deposition in the Respiratory System

Pharmaceutics ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 941
Author(s):  
Victoria Legh-Land ◽  
Allen E. Haddrell ◽  
David Lewis ◽  
Darragh Murnane ◽  
Jonathan P. Reid
Keyword(s):  
Water Activity ◽  
Volatile Components ◽  
Radiological Protection ◽  
Hygroscopic Growth ◽  
Analytical Treatment ◽  
Drug Deposition ◽  
Core Composition ◽  
Aerosol Particle Size ◽  
Dramatic Shift ◽  
Dose Deposition

As pulmonary drug deposition is a function of aerosol particle size distribution, it is critical that the dynamics of particle formation and maturation in pMDI sprays in the interim between generation and inhalation are fully understood. This paper presents an approach to measure the evaporative and condensational fluxes of volatile components and water from and to solution pMDI droplets following generation using a novel technique referred to as the Single Particle Electrodynamic Lung (SPEL). In doing so, evaporating aerosol droplets are shown capable of acting as condensation nuclei for water. Indeed, we show that the rapid vaporisation of volatile components from a volatile droplet is directly correlated to the volume of water taken up by condensation. Furthermore, a significant volume of water is shown to condense on droplets of a model pMDI formulation (hydrofluoroalkane (HFA), ethanol and glycerol) during evaporative droplet ageing, displaying a dramatic shift from a core composition of a volatile species to that of predominantly water (non-volatile glycerol remained in this case). This yields a droplet with a water activity of 0.98 at the instance of inhalation. The implications of these results on regional and total pulmonary drug deposition are explored using the International Commission of Radiological Protection (ICRP) deposition model, with an integrated semi-analytical treatment of hygroscopic growth. Through this, droplets with water activity of 0.98 upon inhalation are shown to produce markedly different dose deposition profiles to those with lower water activities at the point of inspiration.

Evaluation Of Precision Estimates For Fiber-Dimensional And Electrical Hygrometers For Water Activity Determinations

1987 ◽  
Vol 70 (6) ◽  
pp. 955-957
Author(s):  
William H Stroup ◽  
James T Peeler ◽  
Kent Smith
Keyword(s):  
Water Activity ◽  
Soy Sauce ◽  
Volatile Components ◽  
Sweetened Condensed Milk ◽  
A Value ◽  
Condensed Milk ◽  
Collaborative Studies ◽  
Percent Difference ◽  
Aoac Method ◽  
The Mean

Abstract The precision of instruments used in 3 collaborative studies conducted within the Food and Drug Administration over a 4-year period (1981, 1982, 1984) for water activity (a„) determinations according to the official AOAC method is evaluated. Calibration responses of the instruments were tested for linearity over the a„ range from 0.75 to 0.97. Average absolute percent difference between predicted and assigned a, values for the linear model ranged from 0.3 to 0.7% for a fiber-dimensional hygrometer (Abbeon) and 3 electrical hygrometers (Beckman, Rotronics, and Weather Measure). The calibration responses for another electrical hygrometer (Hygrodynamics) were nonlinear. The fiber-dimensional hygrometer yielded mean a„ values and precision estimates that did not differ significantly from those obtained with the electrical hygrometers for (NH4)2S04 slush, KN03 slush, sweetened condensed milk, pancake syrup, and cheese spread. However, the mean a„ value for a soy sauce was 0.838 for the electrical hygrometers compared with 0.911 for the fiber-dimensional hygrometer. The fiber-dimensional hygrometer was affected by a volatile components) in the soy sauce that caused an erroneously high a„ value. Pooled estimates of reproducibility (5X) in the 3 studies were 0.008 for the fiber-dimensional hygrometer and 0.010 for the electrical hygrometers; these values were not significantly different from those reported in the study that verified the current official AOAC method.

scholarly journals Towards closing the gap between hygroscopic growth and activation for secondary organic aerosol – Part 2: Theoretical approaches

2009 ◽  
Vol 9 (12) ◽  
pp. 3999-4009 ◽  
Author(s):  
M. D. Petters ◽  
H. Wex ◽  
C. M. Carrico ◽  
E. Hallbauer ◽  
A. Massling ◽  
...  
Keyword(s):  
Water Activity ◽  
Secondary Organic Aerosol ◽  
Cloud Condensation Nuclei ◽  
Organic Aerosol ◽  
Water Soluble ◽  
Water Mixture ◽  
Hygroscopic Growth ◽  
Ideal Behavior ◽  
Hygroscopic Properties ◽  
Theoretical Approaches

Abstract. We examine the hygroscopic properties of secondary organic aerosol particles generated through the reaction of α-pinene and ozone using a continuous flow reaction chamber. The water activity versus composition relationship is calculated from measurements of growth factors at relative humidities up to 99.6% and from measurements of cloud condensation nuclei activity. The observed relationships are complex, suggesting highly non-ideal behavior for aerosol water contents at relative humidities less than 98%. We present two models that may explain the observed water activity-composition relationship equally well. The first model assumes that the aerosol is a pseudo binary mixture of infinitely water soluble compounds and sparingly soluble compounds that gradually enter the solution as dilution increases. The second model is used to compute the Gibbs free energy of the aerosol-water mixture and shows that the aerosol behaves similarly to what can be expected for single compounds that contain a certain fraction of oxygenated and non-polar functional groups.

scholarly journals Ion production rate in a boreal forest based on ion, particle and radiation measurements

2004 ◽  
Vol 4 (4) ◽  
pp. 3947-3973 ◽  
Author(s):  
L. Laakso ◽  
T. Petäjä ◽  
K. E. J. Lehtinen ◽  
M. Kulmala ◽  
J. Paatero ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Production Rate ◽  
Radiation Energy ◽  
External Radiation ◽  
Hygroscopic Growth ◽  
Production Rates ◽  
Particle Measurements ◽  
Ion Production ◽  
Aerosol Particle Size ◽  
Concentration Measurements

Abstract. In this study the ion production rates in a boreal forest are studied based on two different methods: 1) cluster ion and particle concentration measurements, 2) external radiation and radon concentration measurements. Both methods produce reasonable estimates for ion production rates. The average ion production rate calculated from aerosol particle size distribution and air ion mobility distribution measurements was 2.6 cm−3s−1 and based on external radiation and radon measurements 4.5 cm−3s−1. The first method based on ion and particle measurements gave lower values for the ion production rates especially during the day. A possible reason for this is that particle measurements started only from 3 nm, so the sink of small ions during the nucleation events was underestimated. Another reason is that the possible fogs, which caused an extra sink of small ions are not taken into account in the calculations. It may also be possible that the hygroscopic growth factors of aerosol particles were underestimated. A fourth possible reason for the discrepancy is the nucleation mechanism itself. If the ions were somehow present in the nucleation process, there could have been an additional ion sink during the nucleation days. On the other hand, not all the radiation energy is converted to ions and the possible effect of alpha recoil is also omitted.

scholarly journals Towards closing the gap between hygroscopic growth and activation for secondary organic aerosol – Part 2: Theoretical approaches

2008 ◽  
Vol 8 (6) ◽  
pp. 20839-20867 ◽  
Author(s):  
M. D. Petters ◽  
H. Wex ◽  
C. M. Carrico ◽  
E. Hallbauer ◽  
A. Massling ◽  
...  
Keyword(s):  
Water Activity ◽  
Secondary Organic Aerosol ◽  
Cloud Condensation Nuclei ◽  
Organic Aerosol ◽  
Water Soluble ◽  
Water Mixture ◽  
Hygroscopic Growth ◽  
Ideal Behavior ◽  
Hygroscopic Properties ◽  
Theoretical Approaches

Abstract. We examine the hygroscopic properties of secondary organic aerosol particles generated through the reaction of alpha-pinene and ozone using a continuous flow reaction chamber. The water activity versus composition relationship is calculated from measurements of growth factors at relative humidities up to 99.6% and from measurements of cloud condensation nuclei activity. The observed relationships are complex, suggesting highly non-ideal behavior for aerosol water contents at relative humidities less than 98%. We present two models that may explain the observed water activity-composition relationship equally well. The first model assumes that the aerosol is a pseudo binary mixture of infinitely water soluble compounds and sparingly soluble compounds that gradually enter the solution as dilution increases. The second model is used to compute the Gibbs free energy of the aerosol-water mixture and shows that the aerosol behaves similarly to what can be expected for single compounds that contain a certain fraction of oxygenated and non-polar functional groups.

scholarly journals Extension of the AIOMFAC model by iodine and carbonate species: applications for aerosol acidity and cloud droplet activation

2021 ◽  
Author(s):  
Hang Yin ◽  
Jing Dou ◽  
Liviana Klein ◽  
Ulrich K. Krieger ◽  
Alison Bain ◽  
...  
Keyword(s):  
New Species ◽  
Functional Groups ◽  
Water Activity ◽  
Activity Coefficients ◽  
Open System ◽  
Interaction Parameters ◽  
Estimation Methods ◽  
Volatile Components ◽  
Extended Model ◽  
Carbonate Species

Abstract. Iodine and carbonate species are important components in marine and dust aerosols, respectively. The non-ideal interactions between these species and other inorganic and organic compounds within aqueous particle phases affect hygroscopicity, acidity, and gas–particle partitioning of semi-volatile components. In this work, we present an extended version of the Aerosol Inorganic–Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) model by incorporating the ions I−, IO3−, HCO3−, CO32−, OH−, and CO2(aq) as new species. First, AIOMFAC ion interaction parameters for aqueous solutions were determined based on available thermodynamic data, such as water activity, mean molal activity coefficients, solubility, and vapor–liquid equilibrium measurements. Second, the interaction parameters for the new ions and various organic functional groups were optimized based on experimental data or, where data are scarce, alternative estimation methods such as multiple linear regression or a simple substitution by analogy approach. Additional bulk water activity and electrodynamic balance measurements were carried out to augment the database for the AIOMFAC parameter fit. While not optimal, we show that the use of alternative parameter estimation methods enables physically sound predictions and offers the benefit of a more broadly applicable model. Our implementation of the aqueous carbonate/bicarbonate/CO2(aq) system accounts for the associated temperature-dependent dissociation equilibria explicitly and enables closed- or open-system computations with respect to carbon dioxide equilibration with the gas phase. We discuss different numerical approaches for solving the coupled equilibrium conditions and highlight critical considerations when extremely acidic or basic mixtures are encountered. The fitted AIOMFAC model performance for inorganic aqueous systems is considered excellent over the whole range of mixture compositions where reference data are available. Moreover, the model provides physically meaningful predictions of water activity under highly concentrated conditions. For organic–inorganic mixtures involving new species, the model–measurement agreement is found to be good in most cases, especially at equilibrium relative humidities above ~70 %; reasons for deviations are discussed. Several applications of the extended model are shown and discussed, including: the effects of ignoring the auto-dissociation of water in carbonate systems, the effects of mixing bisulfate and bicarbonate compounds in closed- or open-system scenarios on pH and solution speciation, and the prediction of critical cloud condensation nucleus activation of NaI or Na2CO3 particles mixed with suberic acid.

scholarly journals Hygroscopic properties of aminium sulfate aerosols

2017 ◽  
Vol 17 (6) ◽  
pp. 4369-4385 ◽  
Author(s):  
Grazia Rovelli ◽  
Rachael E. H. Miles ◽  
Jonathan P. Reid ◽  
Simon L. Clegg
Keyword(s):  
Water Activity ◽  
Cloud Droplet ◽  
Droplet Surface ◽  
Volatile Components ◽  
Hygroscopic Properties ◽  
Electrodynamic Balance ◽  
Solution Droplet ◽  
Dependent Growth ◽  
Activity Dependent ◽  
Evaporation Kinetics

Abstract. Alkylaminium sulfates originate from the neutralisation reaction between short-chained amines and sulfuric acid and have been detected in atmospheric aerosol particles. Their physicochemical behaviour is less well characterised than their inorganic equivalent, ammonium sulfate, even though they play a role in atmospheric processes such as the nucleation and growth of new particles and cloud droplet formation. In this work, a comparative evaporation kinetics experimental technique using a cylindrical electrodynamic balance is applied to determine the hygroscopic properties of six short-chained alkylaminium sulfates, specifically mono-, di-, and tri-methylaminium sulfate and mono-, di-, and tri-ethyl aminium sulfate. This approach allows for the retrieval of a water-activity-dependent growth curve in less than 10 s, avoiding the uncertainties that can arise from the volatilisation of semi-volatile components. Measurements are made on particles > 5 µm in radius, avoiding the need to correct equilibrium measurements for droplet-surface curvature with assumed values of the droplet-surface tension. Variations in equilibrium solution droplet composition with varying water activity are reported over the range 0.5 to > 0.98, along with accurate parameterisations of solution density and refractive index. The uncertainties in water activities associated with the hygroscopicity measurements are typically < ±0.2 % at water activities > 0.9 and  ∼  ±1 % below 0.9, with maximum uncertainties in diameter growth factors of ±0.7 %. Comparison with previously reported measurements show deviation across the entire water activity range.

scholarly journals Measuring and modeling the hygroscopic growth of two humic substances in mixed aerosol particles of atmospheric relevance

2013 ◽  
Vol 13 (17) ◽  
pp. 8973-8989 ◽  
Author(s):  
I. R. Zamora ◽  
M. Z. Jacobson
Keyword(s):  
Sodium Chloride ◽  
Succinic Acid ◽  
Ammonium Sulfate ◽  
Water Activity ◽  
Water Uptake ◽  
Water Vapor Pressure ◽  
Water Soluble ◽  
Hygroscopic Growth ◽  
Inorganic Species ◽  
Pure Salt

Abstract. The hygroscopic growth of atmospheric particles affects atmospheric chemistry and Earth's climate. Water-soluble organic carbon (WSOC) constitutes a significant fraction of the dry submicron mass of atmospheric aerosols, thus affecting their water uptake properties. Although the WSOC fraction is comprised of many compounds, a set of model substances can be used to describe its behavior. For this study, mixtures of Nordic aquatic fulvic acid reference (NAFA) and Fluka humic acid (HA), with various combinations of inorganic salts (sodium chloride and ammonium sulfate) and other representative organic compounds (levoglucosan and succinic acid), were studied. We measured the equilibrium water vapor pressure over bulk solutions of these mixtures as a function of temperature and solute concentration. New water activity (aw) parameterizations and hygroscopic growth curves at 25 °C were calculated from these data for particles of equivalent composition. We examined the effect of temperature on the water activity and found a maximum variation of 9% in the 0–30 °C range, and 2% in the 20–30 °C range. Five two-component mixtures were studied to understand the effect of adding a humic substance (HS), such as NAFA and HA, to an inorganic salt or a saccharide. The deliquescence point at 25 °C for HS-inorganic mixtures did not change significantly from that of the pure inorganic species. However, the hygroscopic growth of HA / inorganic mixtures was lower than that exhibited by the pure salt, in proportion to the added mass of HA. The addition of NAFA to a highly soluble solute (ammonium sulfate, sodium chloride or levoglucosan) in water had the same effect as the addition of HA to the inorganic species for most of the water activity range studied. Yet, the water uptake of these NAFA mixtures transitioned to match the growth of the pure salt or saccharide at high aw values. The remaining four mixtures were based on chemical composition data for different aerosol types. As expected, the two solutions representing organic aerosols (40% HS/40% succinic acid/20% levoglucosan) showed lower water uptake than the two solutions representing biomass burning aerosols (25% HS/27% succinic acid/18% levoglucosan/30% ammonium sulfate). However, interactions in multicomponent solutions may be responsible for the large variation of the relative water uptake of identical mixtures containing different HSs above a water activity of 0.95. The ZSR (Zdanovskii, Stokes, and Robinson) model was able to predict reasonably well the hygroscopic growth of all the mixtures below aw = 0.95, but produced large deviations for some multicomponent mixtures at higher values.

Lung deposition of aerosolized anticancer drugs with a novel inhalation system: AKITA

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 12037-12037
Author(s):  
E. Hofstetter ◽  
H. Ehlich ◽  
B. Muellinger ◽  
G. Scheuch
Keyword(s):  
Particle Size ◽  
Cancer Therapy ◽  
Anticancer Drugs ◽  
Breathing Pattern ◽  
Scintillation Counter ◽  
Lung Deposition ◽  
Positive Pressure ◽  
Radiological Protection ◽  
Aerosol Particle Size ◽  
Jet Nebulizer

12037 Background: Inhalation of anticancer drugs might be a helpful route of delivery in cancer therapy, particularly for lung tumors and metastasis in the lungs. In this experimental setup 12 different drugs (including antineoplastic drugs and immunotherapeutics) were nebulized with two different jet nebulizer systems. Aerosol particle size (MMD) and mass output were characterized. Methods: MMD was measured using a laser diffraction system (Sympatec, Clausthal-Zellerfeld, Germany). Mass output measurements were performed after CEN Standard using a Flow/volume simulator with radiolabelled (99m Tc) solution/suspension. The amount of radioactivity on the filters was detected with a scintillation counter. For aerosolization two nebulizer systems were used: Pari LC Plus with Pari compressor (PARI) and Pari LC Star with AKITA compressor (AKITA). To determine lung deposition a lung deposition model (International Commission of Radiological Protection, ICRP66, 1994) was used, taking into account: mass output, particle size and breathing pattern of patients. The AKITA guides the patient with a positive pressure through the inhalation maneuver, it is breath activated and delivers the medication only during inspiration. The PARI nebulizes continuously and the patient inhales with different individual breathing pattern. Results: MMD with PARI was found to be 4.2 ± 0.4 μm compared to 3.40 ± 0.3 μm for AKITA. After filling 2.5 ml into the nebulizers we found 1.4 ml residual volume with PARI and 1.0 ml for AKITA. The output rate was 0.15 ± 0.02 ml/min for PARI and 0.29 ± 0.03 ml/min for AKITA. Lung deposition relative to the emitted dose was determined to be 28 ± 10% for PARI and 85 ± 4% for AKITA. This is because the AKITA nebulizes only during inspiration and guides the patient through the inhalation maneuver, where as the PARI is running continuously and patients inhale with different breathing pattern. The result is that from 2.5 ml filled into the nebulizer, on average 0.3 ml will be deposited in the lungs with the PARI and 1.3 ml with the AKITA. To deposit 1 ml in the lungs with AKITA it will take 7 min, with PARI about 24 min. Conclusions: By use of modern inhalation devices with controlled inhalation lung deposition for cancer therapy can be optimized. [Table: see text]

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