Cellulose mini-membranes modified with TiO2 for separation, determination, and speciation of arsenates and selenites

Sorptive and selective mini-membranes based on TiO2 directly synthesized onto cellulose filters (TiO2@cellulose) have been developed. The in situ synthesis of TiO2@cellulose applied is simple and economically advantageous. The obtained membranes can be useful for (1) separating arsenic(V) and selenium(IV) from other ions and organic matter, (2) speciation of arsenic and selenium, and (3) determining ulratraces of these ions in water samples. The membranes exhibit good stability and high maximum adsorption capacities for Se(IV) (71 mg g−1) and As(V) (41 mg g−1). A monolayer chemical adsorption of analytes on the membranes was confirmed. The structure of membranes was examined with scanning electron microscopy, x-ray diffractometry, and micro energy-dispersive x-ray fluorescence spectrometry (μ-EDXRF). The membranes were characterized by homogenous distribution of TiO2 onto cellulose. The TiO2@cellulose was used as a new sorbent in micro-solid phase extraction for determination of Se(IV) and As(V) by EDXRF. Using direct analysis of mini-membranes after sorption of analytes avoids the elution step. Thus, the proposed procedure is an attractive and solvent-free option for quantitative monitoring of Se(IV) and As(V) in different materials. Both analytes were quantitatively and simultaneously separated/determined from samples at pH 2 with very good recovery (close to 100%), precision (4.5%), and detection limits (0.4 ng mL−1 Se and 0.25 ng mL−1 As). TiO2@cellulose membranes were applied to water analysis.

Membrane Adsorber for the Fast Purification of a Monoclonal Antibody Using Protein A Chromatography

Monoclonal antibodies are conquering the biopharmaceutical market because they can be used to treat a variety of diseases. Therefore, it is very important to establish robust and optimized processes for their production. In this article, the first step of chromatography (Protein A chromatography) in monoclonal antibody purification was optimized with a focus on the critical elution step. Therefore, different buffers (citrate, glycine, acetate) were tested for chromatographic performance and product quality. Membrane chromatography was evaluated because it promises high throughputs and short cycle times. The membrane adsorber Sartobind® Protein A 2 mL was used to accelerate the purification procedure and was further used to perform a continuous chromatographic run with a four-membrane adsorber-periodic counter-current chromatography (4MA-PCCC) system. It was found that citrate buffer at pH 3.5 and 0.15 M NaCl enabled the highest recovery of >95% and lowest total aggregate content of 0.26%. In the continuous process, the capacity utilization of the membrane adsorber was increased by 20%.

AAV Purification by anion-exchange chromatography

We describe a new optimized, scalable and reproducible method based on anion exchange chromatography to obtain high titers of rAAV vectors without empty capsids contamination. The method takes advantage of Q-sepharose matriz to development a scalable procedure. After the virus harvest from supernatant and lysate cells, virus crude was subjected to anion exchange chromatography with Q-sepharose column. Three different protocols were tested, and the elution peaks were evaluated through qPCR rAAV titration and 260/280 nm ratio determination in order to identified empty capsid-containing fractions. A 150 mM NH4Ac wash step fallowing by 1 M NaCl elution step generate a a high titer eluted fraction of rAAV with 1.334 260/280 nm ratio. The described method makes rAAV vector purification an easily adapted for a large scale GMP production format to produce empty capsid free rAAV for clinics.

Breaking down scats: degradation of DNA from greater bilby (Macrotis lagotis) faecal pellets

Isolating DNA from scats (faeces) of threatened species is a valuable, non-invasive method for identifying individuals. To establish whether genotyping of greater bilby (Macrotis lagotis) individuals from faecal pellets collected in the field can be useful for population monitoring, an understanding of the DNA degradation rates is necessary. To determine the relationship between time and degradation of bilby faecal DNA, and assess whether a two-step elution process during extraction results in better-quality DNA, faecal pellets were collected from captive individuals, maintained under seminatural conditions, then harvested at known periods. DNA was amplified from faecal pellets with a 99% success rate and error rates of less than 5% up to 14 days after deposition. The amplification rate decreases, and the rate of allelic dropout increases with time, but DNA can still be amplified at rates above 60% and error rates below 15% at 90–180 days. We found that a second elution step was unnecessary, with more DNA amplified over a longer period using the first eluate. Viable DNA exists on bilby faecal pellets for a long period after deposition, which is useful for obtaining genetic samples for population monitoring programs and studies on population genetics.

Selective Adsorption and Pre-Concentration of Morin by Molecularly Imprinted Polymers with Chitosan Beads as Functional Matrix

To separate and enrich morin, a molecularly imprinted polymer (MIP) was synthesized on chitosan by surface molecular imprinting technique and characterized with Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The results showed that MIP possessed better selectivity and recognition for morin in a mixture than that of non-imprinted polymer (NIP). The saturated adsorption amount of MIP was 8.0 mg/g, which was 4-fold than that of NIP, and the recovery in the elution step was 94.87% and 10.97% for MIP and NIP, respectively. These findings indicate MIP could realize the separation and pre-concentration of morin in real sample and may be used for solid phase extraction (MIP-SPE) protocol.

Key parameters controlling an adsorption process for the selective removal of arsenic from drinking water

Arsenic can be selectively removed from water through adsorption on a natural manganese oxide. This paper presents some of the key parameters controlling such a process. Both production and regeneration steps were studied and the influence of three main controlling parameters was put to light. The water pH greatly influenced the adsorption capacity. Low water pH highly improved the treatment. The adsorption being under mass transfer limitation, flow rate influence was measured and optimization solutions were proposed. Finally, the impact of the regeneration procedure was evaluated on the adsorbent stability. It gave good arsenic elution results but the caustic elution step generated fine particles that could not be avoided. The following neutralization could however be adjusted in order to minimize further adsorbent dissolution.

Immunoaffinity Column as Sample Cleanup Method for Determination of the Beta-Adrenergic Agonist Ractopamine and Its Metabolites

A monoclonal antibody-based immunoaffinity column (RAC-IAC) was developed as a cleanup method for the determination of ractopamine and ractopamine glucuronides. [14C]Ractopamine (5 μg) and [14C]ractopamine glucuronides (5 μg) were fortified into 10 mL cattle urine, and loaded onto an RAC-IAC (5 mg IgG/mL) column. The column was washed and the bound analytes were eluted. In the initial loading and washing, 22% of the radioactivity was washed off and the subsequent elution step recovered 78%. A blank column prepared from nonspecific IgG retained <10% of the radioactivity. The RAC-IACs were damaged by high methanol concentrations, preventing reuse. Elution of the analytes with 50mM glycine buffer, pH 2.8, prevented damage, and the columns could be reused at least 20 times with no change in performance. They were stored >3 months in phosphate- buffered saline with 0.02% sodium azide at 4°C. The method was used with fortified cattle muscle, liver, and kidney samples with recoveries of 82.1 ± 7.6, 87.8 ± 1.9, and 92.5 ± 0.4%, respectively (n = 3). Similar studies with sheep muscle, liver, and kidney samples gave recoveries of 91.8 ± 0.2, 91.7 ± 0.3, and 92.3 ± 0.3, respectively ( n = 3). Liver and kidney samples were diluted to prevent column plugging, but all of the eluants were suitable for liquid chromatography analysis. This IAC is a selective, efficient, and economical cleanup method in a variety of matrixes for ractopamine determination.

Efficient and predictable recovery of viruses from water by small scale ultrafiltration systems

Current methods to concentrate viruses from large volumes of water are prone to inconsistent results and are costly and complex procedurally. Ultrafiltration can utilize size exclusion rather than adsorption and (or) elution to concentrate viruses and, therefore, may offer greater flexibility in developing methods that can provide more consistent recoveries among different viruses and widely varying water conditions. Two small scale ultrafiltration systems (hollow fiber and tangential flow) were tested with a virus suspended in 2 L of reagent grade, tap, ground, or surface water. Three model viruses were used (bacteriophages PP7 and T1 and poliovirus) to compare and characterize the recovery of viruses with the two ultrafiltration systems. Pretreatment of the ultrafilters with blocking agents and the use of elution agents can serve to prevent viral adsorption to the filter surface or to elute bound virus and keep viral agents suspended in the retentate. The use of a blocking and elution step concentrated viruses (>60% recovery) from widely varying water qualities, including surface water, such that a single method can be used to efficiently concentrate viruses from all of the water types tested. Both ultrafiltration systems appear to be able to efficiently recover viruses; however, the hollow fiber systems provided slightly better results in the 2-L volumes tested.Key words: ultrafiltration, waterborne virus, poliovirus, enterovirus.

Influence of US EPA 1622 method successive steps on the viability of Cryptosporidium oocysts

Viable Cryptosporidium parvum oocysts were processed by the US EPA 1622 method to determine if the procedure that requires successive filtration, elutionand centrifugation alters their integrity and viability (determined by in vitro excystation). Oocyst seeded in tap water samples were also used to evaluate recovery efficiencies and impact of the whole procedure on oocyst viability. Filtration through Envirochek Gelman cartridge was found not to damage oocysts. The use of Laureth-12 buffer during the elution step was shown to lead to greater spontaneous oocysts excystation than other phosphate buffers containing between 80 and/or SDS (like the Gelman buffer). However, this drawback was widely balanced against the best efficiency of this buffer to elute oocysts captured by the cartridge filter and therefore against its high recovery efficiency. Thus, in water samples in which the oocyst concentration is expected to be low, it is more advantageous to employ the Laureth-12 buffer for the elution through it can influence viability. Centrifugation speeds (1,000–5,000 g) did not alter oocysts.