Dissolved metal ion removal by online hollow fiber ultrafiltration for enhanced size characterization of metal-containing nanoparticles with single-particle ICP-MS

Single particle-inductively coupled plasma mass spectrometry (SP-ICP-MS) is a powerful tool for size-characterization of metal-containing nanoparticles (MCNs) at environmentally relevant concentrations,however,coexisting dissolved metal ions greatly interfere with the accuracy of particle size analysis.The purpose of this study is to develop an online technique that couples hollow fiber ultrafiltration (HFUF) with SP-ICP-MS to improve the accuracy and size detection limit of MCNs by removing metal ions from suspensions of MCNs.Through systematic optimization of conditions including the type and concentration of surfactant and complexing agent,carrier pH,and ion cleaning time,HFUF completely removes metal ions but retains the MCNs in suspension.The optimal conditions include using a mixture of 0.05 vol.%FL-70 and 0.5 mmol/L Na2S2O_(3)(pH=8.0) as the carrier and 4 min as the ion cleaning time.At these conditions,HFUF-SP-ICP-MS accurately determines the sizes of MCNs,and the results agree with the size distribution determined by transmission electron microscopy,even when metal ions also are present in the sample.In addition,reducing the ionic background through HFUF also lowers the particle size detection limit with SP-ICP-MS (e.g.,from 28.3 to 14.2 nm for gold nanoparticles).This size-based ion-removal principle provided by HFUF is suitable for both cations (e.g.,Ag+) and anions (e.g.,AuCl_(4)^(-)) and thus has good versatility compared to ion exchange purification and promising prospects for the removal of salts and macromolecules before single particle analysis.

A review on hollow fiber membrane module towards high separation efficiency:Process modeling in fouling perspective

Hollow fiber microfiltration(MF)and ultrafiltration(UF)membrane processes have been extensively used in water purification and biotechnology.However,complicated filtration hydrodynamics wield a negative influence on fouling mitigation and stability of hollow fiber MF/UF membrane processes.Thus,establishing a mathematical model to understand the membrane processes is essential to guide the optimization of module configurations and to alleviate membrane fouling.Here,we present a comprehensive overview of the hollow fiber MF/UF membrane filtration models developed from different theories.The existing models primarily focus on membrane fouling but rarely on the interactions between the membrane fouling and local filtration hydrodynamics.Therefore,more simplified conceptual models and integrated reduced models need to be built to represent the real filtration behaviors of hollow fiber membranes.Future analyses considering practical requirements including complicated local hydrodynamics and nonuniform membrane properties are suggested to meet the accurate prediction of membrane filtration performance in practical application.This review will inspire the development of high-efficiency hollow fiber membrane modules.

Determination of free ceftriaxone concentration and its application in predicting lung tissue concentration

The purpose of this study was to establish a method for determining the free concentration of ceftriaxone based on hollow fiber centrifugal ultrafiltration(HFCF-UF)technology in combination with high-performance liquid chromatography(HPLC)for free pharmacokinetic studies and the prediction of ceftriaxone concentrations in lung tissue.This method only required centrifugation for a short time,and the filtrate could be injected directly for HPLC analysis without further treatment.The specificity,linearity,precision and stability of this method were validated for quantification of free ceftriaxone.Under the optimized conditions,the absolute recoveries were more than 92.5%.The intraday and interday precision RSDs were less than 3.6%.Additionally,nonspecific adsorption(NSB)between the analyte and the ultrafiltration membrane was considered.This method was successfully applied to the analysis of the free ceftriaxone concentration in rat plasma and lung tissue.The free ceftriaxone concentration of lung tissue could be predicted by using the linear formula Cfl=Cfp(0.342 x–0.0129)(x:time).This method also provides a reliable alternative for accurate monitoring of the free ceftriaxone concentration in therapeutic drug monitoring(TDM).