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Abstract Solubility of pharmaceutical drugs in organic solvents is one of the important parameters to understand the equilibrium concentration of solute-solvent, which helps optimize and design crystallization conditions to obtain the desired product crystals. In the present study, Chlorzoxazone (CHZ) is used as a model pharmaceutical compound to investigate the equilibrium solubility, the influence of solvent and the operating conditions on the shape, and the size distribution. The solubility of CHZ is determined in organic solvents like Isopropanol, Ethanol, and 2-Ethoxyethylacetate, Ethylacetate and Ethyllactate using shake flask method from -5ºC to 60ºC. The solubility of CHZ in these solvents shows an increasing trend as the temperature increases in the following order: ethyllactate + water (0.5+0.5) < ethylacetate < isopropanol < ethanol < 2-ethoxyethylacetate < ethyllactate + water (0.75+0.25). The solvents, isopropanol, ethanol, and ethyl lactate, produce needle-shaped crystals, while 2-ethoxyethylacetate and ethyl acetate tend to produce plate shaped crystals. CHZ crystals obtained from 2-ethoxyethylacetate tend to have plate shaped crystals with a lower aspect ratio and are selected for batch cooling crystallization experiments performed at different cooling rates, and agitation. It is found that the agitation at 300 rpm and the cooling rate 0.2ºC/min produce more uniform crystal size distribution
Subject(s)
Solvents/classification , Chlorzoxazone/analysis , Crystallization/classification , Solubility , Pharmaceutical Preparations/administration & dosageABSTRACT
@#Population bioequivalence (PBE) is a statistical approach recommended by FDA to evaluate the consistency of particle size distribution of numerous nanoparticle products.However, when particle size distribution (PSD) profile exhibits multiple peaks or other complex distributions, the traditional descriptors D50 and SPAN are no longer suitable to describe PSD.Earth mover''s distance (EMD) is a new statistical metric for assessing the difference between distributions.In this study, we used EMD to measure the discrepancy between PSD and then PBE was applied to perform statistical test to establish equivalence.Our results showed that the proposed method can effectively reject an unequivalent product and pass an equivalent product, thus indicating its helpfulness in guiding the optimization of formulation and preparation process.
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Objective:To investigate the factors that could influence the particle size and size distribution of mRNA vaccines.Methods:The influences of several factors including the ionic strength and pH values of buffers, solutions, dilution folds and testing equipments on the particle size and size distribution of three batches of mRNA vaccines were analyzed by dynamic light scattering.Results:The particle size increased with increasing ionic strength, but no significant change in size distribution was observed. The particle size also increased with increasing pH values and the size distribution showed significant change when the buffer solution was weakly alkaline. Solution types could affect the particle size, but had no influence on size distribution. There was no significant change in the particle size or size distribution when the dilution was limited to 100 folds. Moreover, the particle size and size distribution detected by different equipments showed no significance difference.Conclusions:The particle size and size distribution of mRNA vaccines could be affected by solution, dilution fold and testing equipment, which should be concerned during the vaccine production and quality control.
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Objective:To study the extraction method and characteristics of vesicle-like nanoparticles （VLNs） in Astragali Radix decoction， and to explore the mechanism of the VLNs in reducing blood glucose by regulating the gut microbiota of db/db diabetic mice. Method:Ultracentrifugation and size exclusion chromatography were used to enrich VLNs from Astragali Radix decoction， and the morphology， particle size and concentration of the VLNs were analyzed by transmission electron microscope and nanoparticle tracking analyzer. The db/db diabetic mice were randomly divided into model group， Astragali Radix VLNs high-， medium- and low-dose （21.1， 10.6， 5.3 g·kg<sup>-1</sup>） groups and metformin group （0.25 g·kg<sup>-1</sup>） according to their blood glucose levels. There were 7 mice in each group， and another 7 C57BL/6 mice were set as the normal group. The mice were given intragastrically for 3 weeks （once a day）， and the changes of fasting blood glucose were observed every week. Hematoxylin-eosin （HE） staining was used to observe the pathological morphology of liver and pancreas of diabetic mice. The feces of mice were collected for 16S rRNA diversity detection of intestinal microbes. Result:The size of the nanoparticles obtained by the two methods was about 200 nm. Astragali Radix VLNs extracted by ultracentrifugation had a typical saucer-like shape with the concentration of 3.0×10<sup>11</sup> particles·mL<sup>-1</sup>. The morphology of Astragali Radix VLNs obtained by size exclusion chromatography was relatively poor with the concentration of 2.2×10<sup>11</sup> particles·mL<sup>-1</sup>. After 3 weeks of administration， compared with the model group， Astragali Radix VLNs high-， medium- and low-dose groups could significantly reduce the fasting blood glucose of diabetic mice （<italic>P</italic><0.05， <italic>P</italic><0.01）. The VLNs could improve the gut microbiota dysbiosis， significantly decrease the ratio of Firmicutes/Bacteroidota， and increase the relative abundance of beneficial bacteria and reduce the relative abundance of harmful bacteria. Conclusion:Astragali Radix VLNs may reduce the blood glucose of db/db diabetic mice by adjusting the ratio of Firmicutes/Bacteroidota in the intestinal flora.
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ABSTRACT: This study evaluated the effects of the physically effective fiber (peNDF) content on nutrient composition of the total mixed ration (TMR), orts and fecal parameters in 15 commercial beef feedlots. The particle size distribution of TMR was measured adopting Penn State Particle Size Separator (PSPS). Samples were evaluated for dry matter (DM), ash, ether extract (EE), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF) and starch content. Fecal samples were also evaluated for pH and score. The feedlots were categorized into peNDF<20% and peNDF ≥ 20%. Data were analyzed by a model that included fixed effects of treatment and covariates (sex and genetic groups). Levels of DM, CP, EE and starch were lower in TMR with peNDF ≥ 20% (P<0.05). Fecal dry matter was higher and morning fecal pH was lower for TMR with peNDF<20% (P<0.05). Physically effective fiber changed nutrient levels in TMR, orts, fecal pH and DM. So, using PSPS and fecal parameters are practical and indirect tools for measuring fecal starch and assessing the effectiveness of the diet supplied to ruminants.
RESUMO: O objetivo desse estudo foi avaliar o teor de fibra fisicamente efetiva (FDNfe) de dietas totais e seus efeitos nos nutrientes da dieta, das sobras e nos parâmetros fecais de bovinos de corte em 15 confinamentos comerciais. As amostras da dieta foram separadas utilizando a peneira Penn State Particle Size Separator (PSPS). As amostras foram analisadas quanto aos teores de matéria seca (MS), matéria mineral (MM), extrato etéreo (EE), proteína bruta (PB), fibra em detergente neutro (FDN), fibra em detergente ácido (FDA) e amido. Nas amostras de fezes também foram avaliadas o escore e pH fecal. Os confinamentos foram categorizados em dois tratamentos: FDNfe<20% e FDNfe≥20%. Os dados foram analisados por um modelo que incluiu os efeitos de grupo e covariável (sexo e grupo genético). Os teores de MS, PB, EE e amido foram menores nas dietas com FDNfe≥20%(P<0,05). A MS fecal foi maior e pH fecal matinal foi menor nas dietas com FDNfe<20% (P<0,05). Sendo assim a efetividade da fibra alterou os nutrientes da dieta total e sobras, bem como as variáveis pH e MS fecal. Com isso, o uso de PSPS e parâmetros fecais são ferramentas práticas e indiretas para medir o amido fecal e a efetividade da dieta em confinamentos de bovinos comerciais.
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RESUMO Neste artigo, buscou-se avaliar a sensibilidade da função contínua de distribuição de tamanho de partículas (DTP) diante da modificação decorrente da floculação. Para tal, foram investigadas seis configurações discretas, subdivididas em 3, 4, 5, 6, 7, 8, 10 e 15 classes de tamanho. As configurações investigadas diferem na frequência de partículas presentes por faixa de tamanho e no comportamento, sendo este monotônico ou unimodal. O ajuste da função contínua na forma linearizada aos dados discretos foi avaliado por meio do coeficiente de determinação (R2). O coeficiente de potência da função (β) e o centro de massa (C.M) da distribuição foram tomados como representativos da DTP para a análise de sensibilidade, realizada por meio do estudo da correlação múltipla entre as variáveis. Experimentos em escala de bancada foram conduzidos visando a avaliar a simulação. Os resultados demonstraram que os parâmetros β e C.M foram sensíveis às variações da DTP, todavia os ajustes das funções para distribuições unimodais carecem de aprimoramento.
ABSTRACT In this paper, the sensitivity of the continuous particle size distribution function (PSD) was evaluated, as flocculation occurs. To this end, six discrete configurations were investigated, subdivided into 3, 4, 5, 6, 7, 8, 10 and 15 classes. The distribution studied here differ in the particles presented by size range and behavior, whether monotonic or unimodal. The adjustment of the continuous function in linearized form to the discrete data was evaluated by means of R2. The power law coefficient (β) and the center of mass (C.M) were taken as representative of PSD during the sensitivity analysis, which was carried out by means of multiple correlation between the variables. Batch essays were performed in order to evaluate simulations. Results showed that β and C.M were both sensitive to PSD variations; however, the function adjustments for unimodal distributions need improvement.
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OBJECTIVE: To investigate the enzymatic hydrolysis characteristics of five medicinal starches, i.e.,waxy corn starch, potato starch, pea starch, wheat starch and common corn starch,using gravitational field flow fractionation (GrFFF) and other technologies. METHODS: Firstly, the enzymatic hydrolysis rates of the five medicinal starches were characterized by GrFFF, and the results of GrFFF were verified by determination of the reducing sugar.Secondly, scanning electron microscopy (SEM) and particle size analyzer were used to characterize the changes of particle morphology and size distribution during amylase hydrolysis. RESULTS: The experiments showed that the enzymatic hydrolysis rates of the five medicinal starches were successively decreased. The former two as well as the latter three reached the maximum enzymatic rate at 6-12 h and 12-24 h, respectively. As the enzymatic hydrolysis time increased, the particle size distribution range became wider and the average size increased. The results of reducing sugar quantitation, SEM and particle size analysis were almost identical to those of GrFFF. CONCLUSION: This study proves that GrFFF is an effective analytical technology to characterize the enzymatic hydrolysis of medicinal starch, which expands the application range of GrFFF and provides useful reference for the application of starch in medicine and food sciences.
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The mass concentration and size distribution of atmospheric particulate matter (PM) was measured in three major towns in Plateau state. The CW-HAT200 PM2.5, PM10 dust particle counter was used to measure the particle size in each major location within Jos, Shendam and Pankshin. The results revealed that both PM2.5 and PM10 concentration were high in morning hours in most of the measured locations. These values were however found decreasing in the afternoon. The higher value of PM2.5 and PM10 observed in the morning hours in some locations within the study area can be attributed to the high volume of motorists plying the roads during those hours. However, some locations within the study area their PM2.5 and PM10 were higher in the afternoon hours than morning hours. The PM sampling respirable dust sampler (AMP460NL model) was placed on the elevated platform of 1.5 m high and 20 cm away from obstacles in order to avoid any obstruction of the air from tall buildings and trees etc. Measurements were taken after 8-hours per location and the average air flow rate, sample time, initial and final mass of the filter paper were used to calculate the mass concentration of the suspended particulate matter in each locations. The mass concentration of the suspended particulate matter were higher in dry season than in the rain season for all locations. This can be attributed to the dust usually experienced during the dry season on the Plateau.
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ABSTRACT Lippia alba (Mill.) N.E.Br. ex Britton & P. Wilson, Verbenaceae, is considered a great source of a bioactive volatile oil. Due to the wide range of known chemotypes, its chemical analysis is very important. Among the several activities of this volatile oil, a potential larvicidal action against Culicidae species is highlighted. However, the low water miscibility of volatile oils limits their application in aqueous media. Oil in water nano-emulsions are in the spotlight of novelty to solve this main problem. Thus, the aim of the present study was to obtain this nanostructured system with L. alba volatile oil (citral chemotype) and evaluate its larvicidal activity against Aedes aegypti and Culex quinquefasciatus larvae. The major compounds were geranial (30.02%) and neral (25.26%). Low mean droplet size (117.0 ± 1.0 nm) and low polydispersity index (0.231 ± 0.004) were observed and no major changes were observed after seven days of storage. LC50 values against C. quinquefasciatus and A. aegypti third-instar larvae were respectively 38.22 and 31.02 ppm, while LC90 values were, respectively, 59.42 and 47.19 ppm. The present study makes use of a low energy, solvent-free and ecofriendly method with reduced costs. Thus, this paper contributes significantly to phyto-nanobiotechnology of larvicidal agents, opening perspectives for the utilization of L. alba volatile oil in integrated practices of vector control.
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The particle diameters of active pharmaceutical ingredient (API) and excipients are important factors to the quality of preparations and have great significances in the reverse engineering to brand products and the consistent evaluation of generic drugs. In this study, a novel method was established for particle size determination to identify the selected component and eliminate other interferential particles by comparing the microscopic images before and after fusion caused by controllable heating. Stearic acid (SA) particles in irregular and spherical shape were selected as a typical excipient to demonstrate the methodology, which were identified from the mixed particles based upon its melting characteristics to detect their particle sizes as well as the size distributions. In the same approach, the morphology and particle size of fenofibrate particles as API in tablets were analyzed. The results illustrated that the particle diameters and particle size distributions of the selected components in the mixture of particles can be detected via the hot-melting characteristics under the prerequisite of proper pretreatment to separate selected components from other particles in microscopic field. In conclusion, this research provides a practical approach for the reverse engineering purpose to brand products and the consistent evaluation of generic drugs.
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Municipal sewage treatment plants (STPs) are thought to be important point sources of microplastics in freshwater systems and many peer-reviewed articles have been published on this issue since mid-2010s. In this review, we summarize existing literature on the occurrence of microplastics in STPs and experimental methods used for isolation and identification of microplastics. The number concentrations of microplastics in STP influents were 15.1-640 L⁻¹, whereas those in the STP effluents were highly variable and ranged from not detectable to 65 L⁻¹. For most of cases, conventional STPs are removing microplastics very effectively. Fragments and fibers are dominant shapes of microplastics. Thermoplastics (polyethylene and polypropylene) and polyester are the predominant materials recovered. Although further research is needed, size distribution of microplastics in STPs is likely to follow a power law, implying that different studies using different size cutoffs may be compared after establishing a power law relationship.
Subject(s)
Fresh Water , Jurisprudence , Polyesters , SewageABSTRACT
Objective: To establish a method for the determination of the particle size of nifedipine and study the effect of particle size on the in vitro dissolution behaviors of nifedipine sustained release tablets. Methods: Light scattering was used to study the parti-cle size of nifedipine API. Nifedipine APIs with different particle sizes were prepared by a portable high-speed grinder. The in vitro dis-solution curve of nifedipine sustained released tablets (Ⅰ) was determined by HPLC. The similarity was evaluated using the similarity factor ( f2) with the original drug (trade name: Adalat-L, specification: 10mg) as the reference preparation. Results: The granulo-metric conditions were as follows: the pump speed of laser size analyzer was 1 800 r·min-1, the shading rate was 8%-20% , the bal-ance time was 0 s, the media was 0. 3% Tween 80, and the ultrasonic time was 1 min. The in vitro dissolution of nifedipine sustained released tablets (Ⅰ) showed that the smaller particle size of nifedipine API, the better the dissolution was. As the Dv90 ( the particle size accounting for 90% of the total particle quantity) was reduced from 118. 781 μm to 3. 471 μm, the cumulative dissolution in 0. 25 h of nifedipine sustained released tablets (Ⅰ) increased from 11. 2% to 44. 0% , the similarity factor ( f2) compared with the dis-solution cruve of the original drug increased firstly and then decreased, and f2value was 77 when the Dv90 was 29. 823 μm. Conclu-sion: The in vitro dissolution of nifedipine sustained released tablets is improved remarkably by micronization technology. In order to produce nifedipine sustained released tablets (Ⅰ) with the same bioavailability as the original drug preparation, the particle size of nife-dipine API should be controlled within the range of 15 μm≤Dv90≤45 μm.
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To measure particle size distribution of phenols in mainstream cigarette smoke aerosol,the particles of cigarette smoke aerosol were divided into 12 stages using single channel smoking machine coupled electrical low-pressure impactor (ELPI) and collected by 12 polyester films.The collected particles were weighted and then analyzed by ultra-high performance liquid chromatography-fluorescence detection (UPLC-FLD) to determine the 14 phenols in the different size particles.The results showed that the aerosols collecting method had good stability with relative standard deviation (RSD) of collected particles mass less than 10%.The analyzing results of 14 phenols by UPLC-FLD showed that the linear correlation coefficients(R2) were greater than 0.9959,with detection limits were less than 1.2 ng/cig and recoveries were 80.1%-115.0%.The distributions of 14 phenols with respect to smoke aerosol particle size were investigated.The results indicated that except 4-ethyl-2-methoxy-phenol not detected,the other 13 phenols were detected in mainstream cigarette smoke aerosol.The content of 13 phenols appeared increasing at first and then decreasing with increase of the particle size which distributed in a pattern similar to that of particle mass.All of 13 phenols were present in higher amounts in the medium size particles (0.261-0.722 μm) with peak content in particles 0.431 μm.The distribution of concentrations (ratio of content to particle mass) of 13 phenols in different size particles was different.The concentrations of phenol and mono-substituted phenol appeared to first increase and then decrease with increasing smoke aerosol particle size and were higher in medium size particles (0.261-0.772 μm).The concentrations of benzenediol and mono-substituted benzenediol were uniformly distributed in medium size particles (0.144-1.166 μm),and the concentration of disubstituted phenol was uniform throughout the particles of varying sizes.
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@#Aims: This study is focused to explore Pseudomonas aeruginosastrain mass transport andassessment of the water quality.Methodology and results:Pseudomonas aeruginosahave been detected in the real location at the RBF study areabyusing molecular method. The bacterium strain was cultivated in the river water sample and column study was performed using soil aquifer collected from the RBF study site.Conclusions, significance and impact of the study:The column experiments show the removal of the bacteria was achieved almost 99%. Concentration of cultured bacteria was detected in range 0.26 g/Lto 0.33 g/Land reduced after flow through the soilpassage in range 0 to 0.148 g/L. This study also examines the water qualities that affected during the transport such as turbidity and color. The range of turbidity for initial concentration for both influents was 84-96 NTU was reduced to range 2.88-49.29 NTU. Meanwhile for color, the initial concentration was 51-58 PtCo was reduced to range 1-18 PtCo
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OBJECTIVE: To discuss whether the difference in dissolution profile in vitro may cause different bioavailability in vivo and investigate the effects of the key quality parameters of leflunomide on bioavailability. METHODS: Using SANOFI product as the reference preparation and domestic product as the test preparation, the disintegration solution of leflunomide tablets was analyze by Morphologi G3-ID automated measurement to get the paricile size and size distribution of the API; using pH 6.5 FaSSIF solution without adding ox-gall sulfonic acid sodium and lecithin as the dissolution medium, the dissolution and permeation profiles of the reference and test preparations and raw material were compared at 37 ℃ with rotate speed of 150 r•min-1. The influence of quality parameters on the process of API's release and absorption was investigated, then the difference between the reference and test preparations were compared to preliminarily predict the bioavailability and bioequivalence. RESULTS: The particle size Dv(50)of domestic leflunomide tablets was 79.80 μm, while the particle size Dv(50)of the reference product was 17.60 μm; the dissolution rate and penetration rate of the test preparation were about 70% of the reference preparation, the tmax was basically identical,but the ρmax and AUC0-t were lower than the reference preparation. The bioavailability of the test preparation was about 90% of the reference preparation. CONCLUSION: Though the dissolution profile of domestic leflunomide tablets is not identical to the reference preparation, but the two products were predicted to be bioequivalent.
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OBJECTIVE: To establish a determination method of molecular-size distribution of human serum albumin (HSA) by ultra performance liquid chromatography (UPLC). METHODS: An UPLC method was developed to specifically determine the polymers and other components in HSA on UPLC PROTEIN BEH SEC analysis column with Waters Alliance UPLC system and Waters UPLC TUV detector. The separation was performed using a mobile phase consisting of PBS at a flow rate of 0.6 mL•min-1 and the UV detection wavelength was set at 280 nm. HSA samples were diluted to different concentrations (0.5-20 mg•mL-1) to confirm the optimal concentration range of the injection. The change of component percentage and the linear relationship between HSA concentration and chromatographic peak height were confirmed and the molecular-size distribution was calculated by area normalization method. Within the optimum injection concentration range, the national control sample for HSA was diluted to 12 mg•mL-1 and tested by UPLC method and the methodology was confirmed. Twenty batches of HSA samples were determined by both UPLC and existing HPLC methods, and the samples were determined in parallel. The consistency of the methods was compared and the method was reconfirmed. RESULTS: The UPLC retention time of HSA polymer was 1.469 min, of dimer was 1.972 min, and of monomer was 2.267 min, respectively. The resolution of dimer and monomer was 2.20 and the USP tailing of monomer peak was 1.18 respectively. In the range of the injection concentrations, 0.5-20 mg•mL-1, there was linear relationship between the concentrations of the components of 11 HAS samples, including polymer, dimer and monomer peak, and the peak area%, peak height, peak area, and the squares of linear correlation coefficient were all greater than 0.997 0. The components peak area percentage of HSA samples remained relatively stable within the concentration range of 10-16 mg•mL-1 (total injection amount of 100-160 μg). The RSDs of the percentage of polymers were 0.00% (n=3, 10 mg•mL-1), 0.10% (n=3, 12 mg•mL-1), and 0.10% (n=3, 16 mg•mL-1), respectively. The UPLC method was used to determine the national control sample for human albumin of 12 mg•mL-1, and the mean value of peak area% was 5.62% (n=10). The results were consistent with those of the parallel determination by HPLC (5.58%), both of which were in accordance with the quality control range of the national standard for human albumin. The RSD of the percentage of the peak area of the polymers in national standard for human albumin by UPLC was 0.40% (n=10). The HPLC and UPLC methods were used to determine the polymer peak area percentage of 20 batches of HSA samples from 7 domestic and foreign enterprises at the concentration of 12 mg•mL-1. The correlation coefficient of the two methods was 0.996 0 (P> 0.05) and there was no significant difference between the two methods (P>0.05). CONCLUSION: Compared with the traditional HPLC method, the detection time of HSA SEC by the proposed UPLC method is shortened by at least 10 times, and the accuracy and repeatability of the determination are satisfactory. UPLC method can save much more analysis time, is simple and much faster, and can be used for high-throughput determination of molecular-size distribution of human serum albumin.
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Municipal sewage treatment plants (STPs) are thought to be important point sources of microplastics in freshwater systems and many peer-reviewed articles have been published on this issue since mid-2010s. In this review, we summarize existing literature on the occurrence of microplastics in STPs and experimental methods used for isolation and identification of microplastics. The number concentrations of microplastics in STP influents were 15.1-640 L⁻¹, whereas those in the STP effluents were highly variable and ranged from not detectable to 65 L⁻¹. For most of cases, conventional STPs are removing microplastics very effectively. Fragments and fibers are dominant shapes of microplastics. Thermoplastics (polyethylene and polypropylene) and polyester are the predominant materials recovered. Although further research is needed, size distribution of microplastics in STPs is likely to follow a power law, implying that different studies using different size cutoffs may be compared after establishing a power law relationship.
Subject(s)
Fresh Water , Jurisprudence , Polyesters , SewageABSTRACT
OBJECTIVE:To establish the method for the determination of particle size distribution of Budesonide nasal spray, and to analyze the consistency of particle size distribution of spray samples. METHODS:Water was used as dispersant for mixing and dispersing(1800 r/min). The particle sizes [d(0.1),d(0.5),d(0.9)] corresponded to accumulative particle size of 10%,50%and 90%were used as characteristic value. The distribution of granularity was determined by laser scattering method. The consisten-cy of particle size distribution of samples from 2 manufacturers (A,B) were analyzed among different batches or same batch of same manufacturer by SAS 9.3 statistical software. RESULTS:The mean values of d(0.1),d(0.5) and d(0.9) were 3.96 μm, 29.58 μm and 67.10 μm in manufacturer A. The mean values of d(0.1),d(0.5)and d(0.9)were 2.00 μm,7.53 μm and 28.51 μm in manufacturer B. By analysis,there was great difference in particle size of samples from 2 manufacturers. The particle size of the samples from manufacturer A were larger than that of manufacturer B. The consistency among different batches from manufacturer B was better,and the consistency among same batch were all good from 2 manufacturers. CONCLUSIONS:The established meth-od is suitable for particle size distribution of Budesonide nasal spray and the consistency analysis of particle size distribution.
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Objective To establish an effective and reliable method for analysis of uhratrace uranium in multi-stage atmospheric particles providing the monitoring and evaluation of the content of radioactive uranium in the atmosphere.Methods A large volume six-stage-impactor sampler of atmosphere particles was used to collect aerosol samples,and uhratrace uranium in particles was digested using microwave and measured by inductively coupled plasma mass spectrometry.The filter material,digestion conditions and microwave digestion system had been optimized.Results The background of uranium level on the cellulose filter was the lowest,and the samples were digested by using HNO3-HCI (aqua regia)-H2O2 solution.Reference material SRM2783 was used to validate the accuracy of the method,and the relative error of the 238U was 7％,The detection limit of the method was 2 × 10-4ng/m3.The aerosol actual samples were analyzed using the established method.The mass concentrations of uranium in PM2.5 was in the range of 0.023-0.065 ng/m3.Conclusions The established method was effective and reliable to monitor the concentration level of ultratrace uranium in multi-stage atmospheric particles.
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Objective:To establish a laser light scattering method for the determination of the particle size distribution of clostridium butyricum enterococcus triple viable powder and compare the results of the sieving method.Methods:The conditions of laser scattering method were as follows:the vibration sampling rate of 80%,the dispersion pressure of 0.05 MPa,the background and sample scan time of 15 s,the shading of 0.5%-5%,the refractive index of the particles of 1.55,the particle absorption rate of 0.01,and the injection volume of 0.1-0.2 g.The eigenvalues of the particle size distribution were determined,which were the particle size cumulative distribution map of 10%,50% and 90% of the particle size value and the volume average particle diameter D.Results:The RSDs of d(0.1),d(0.5) and d(0.9) were less than 5% in the methodology study.The results of laser light scattering method showed that the particle size of 93.3% samples was below 250 μm,that of 64.2% samples was below 150 μm,that of 51.4% samples was below 125 μm,and that of 31.3% samples was below 90 μm.The results of sieving method showed that the particle size of 96.6% was below 250 μm,that of 46.4% samples was below 150 μm,that of 23.5% samples was below 125 μm,and that of 1.4% samples was below 90 μm.Conclusion:Sieving method and laser light scattering method both can characterize the particle size distribution of the sample.The laser light scattering method is simple,accurate and producible,which is suitable for the particle size control of clostridium butyricum enterococcus triple viable powder.