Impact Of Sample Preparation Research Articles

Quantitative determination of 1,4-Dioxane in a novel three-dimensional (3D) porous scaffold by GC-MS

Event Abstract Back to Event Quantitative determination of 1,4-Dioxane in a novel three-dimensional (3D) porous scaffold by GC-MS Ling Li1, Jing Long1, Long Li1, Yuxiao Lai1, Ling Qin1, 2 and Xinluan Wang1, 2, 3 1 Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences, Translational Medicine R&D Center, China 2 The Chinese University of Hong Kong, Department of Orthopedics and Traumatology, Hong Kong, SAR China 3 Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedics, China Introduction: A novel three-dimensional(3D) porous scaffold PLGA/TCP/Mg was made by 3D printing for bone defect repair. 1,4-dioxane was used during scaffolds preparation process and it was hard to be removed completely. As Chinese Pharmacopoeia specified 1,4-dioxane should be limited below 380 ppm in order to protect patients from potential adverse effects. It is mandatory to test residual 1,4-dioxane for PLGA/TCP/Mg registration in CFDA. The aim of this paper was to describe a quantitative determination of 1,4-dioxane in scaffold, focusing on the impact of sample preparation. Materials and Methods: Porous scaffolds were cut into 3 mm3 of particles with the weight of 0.15g for each one，Process of sample preparation was stated in Table.1[1]. Calibration curves for 1,4-dioxane were established according to sample preparation. Sample for experiment of blank matrix effect following the method in Table. 1. External standard method was used in the quantification of 1,4-dioxane. Paraments of GC-MS for all detections were summarized in Table. 2. Temperature and cycle time of head space of sample dissolved in DMF were 90℃ and 45 min, respectively. Temperature and cycle time of head space of Na2CO3 aqueous solution were 70℃ and 40min, respectively[2]. Results and Discussion: This study compared direct injection and headspace injection, and found that direct injection had more interference, worse separation, and large molecule of PLGA in the material can pollute the instrument, so that it was more suitable for test of 1,4-dioxane using headspace injection. In the Na2CO3 aqueous solution, processed under headspace condition, the detecting sensitivity is 5 times higher than that in DMF, but in the Na2CO3 aqueous solution, it can be disturbed by the matrix strongly, and due to the propriety of the sample, this method can not promise high accuracy. Dissolving sample in DMF, was able to remove the matrix effect (the linear correlation coefficient and the corresponding concentration area were also close), and achieve more accurate quantitative method. The linear correlation coefficient of this method is 0.9998,(Fig.1) and the recovery per cent is 105.41%-107.99%. Conclusions: Porous of the scaffolds affected the remove of the organic solvents. So the sample preparation is essential for the accuracy of the determination of remained 1,4-dioxane. In this study, we found the most effective preparation was that porous scaffolds were disolved with DMF and injected by Head Space. Our results provided basis for determination of residual solvent of porous scaffolds. National Natural Science Foundation of China (81302782，81171771); NSFC-DG-RTD Joint Scheme (51361130034); The Opening Project of Shanghai Key Laboratory of Orthopaedic Implants（KFKT2014001）

Fractionation of biogas plant sludge material improves metaproteomic characterization to investigate metabolic activity of microbial communities.

With the development of high resolving mass spectrometers, metaproteomics evolved as a powerful tool to elucidate metabolic activity of microbial communities derived from full-scale biogas plants. Due to the vast complexity of these microbiomes, application of suitable fractionation methods are indispensable, but often turn out to be time and cost intense, depending on the method used for protein separation. In this study, centrifugal fractionation has been applied for fractionation of two biogas sludge samples to analyze proteins extracted from (i) crude fibers, (ii) suspended microorganisms, and (iii) secreted proteins in the supernatant using a gel-based approach followed by LC-MS/MS identification. This fast and easy method turned out to be beneficial to both the quality of SDS-PAGE and the identification of peptides and proteins compared to untreated samples. Additionally, a high functional metabolic pathway coverage was achieved by combining protein hits found exclusively in distinct fractions. Sample preparation using centrifugal fractionation influenced significantly the number and the types of proteins identified in the microbial metaproteomes. Thereby, comparing results from different proteomic or genomic studies, the impact of sample preparation should be considered. All MS data have been deposited in the ProteomeXchange with identifier PXD001508 (http://proteomecentral.proteomexchange.org/dataset/PXD001508).

Impact of Sample Preparation on Determination of Hydrogen Content in TC4 Titanium Alloys

Impact of sample preparation on determination of hydrogen content in TC4 titanium alloys is studied through the experimental test method which was developed according to ASTM E 1447-2009. The simulation of the heating process in sample preparation process verifies the slight warming (60°C ~ 80 °C) will affect the test result of hydrogen content in TC4 titanium alloys. The heating process makes the result be lower than the actual content.

Failure Modes of Sand in Undrained Cyclic Loading: Impact of Sample Preparation

This paper presents a systematic experimental investigation into the impact of specimen preparation on the cyclic loading behavior of saturated sand, including the deformation pattern, pore-water pressure generation, stress-strain relationship, and cyclic shear strength. Moist tamping and dry deposition were used in the laboratory to prepare sand specimens with distinct fabrics for cyclic triaxial tests under a range of conditions. It is found that the soil fabric formed by dry deposition can lead to unique failure modes different from those of moist-tamped sam- ples in certain situations. These failure modes are hybrid in nature, characterized by a contractive response in the form of limited flow followed by cyclic strain hardening in the form of either cyclic mobility or plastic-strain accumulation. The hybrid nature of the failure patterns makes defining failure for liquefaction-resistance evaluation crucial; the conventional failure criteria based on a certain level of strain or pore-water pressure do not appear to properly represent the failure mechanism involved and may lead to a substantial overestimation of liquefaction re- sistance. The experiments reveal that the method used to reconstitute specimens or the soil fabric they form plays a role that is far more com- plicated than previously thought. Depending on the combination of relative density, confining stress, and degree of stress reversal in cyclic loading, a change of reconstitution method can have a marked or little effect on the nature of the response in terms of deformation pattern and failure mechanism; nevertheless, the two reconstitution methods always give significantly different liquefaction-resistance values under otherwise similar testing conditions. DOI: 10.1061/(ASCE)GT.1943-5606.0000971. © 2014 American Society of Civil Engineers.

Reproducibility of NMR Analysis of Urine Samples: Impact of Sample Preparation, Storage Conditions, and Animal Health Status

Introduction. Spectroscopic analysis of urine samples from laboratory animals can be used to predict the efficacy and side effects of drugs. This employs methods combining 1H NMR spectroscopy with quantification of biomarkers or with multivariate data analysis. The most critical steps in data evaluation are analytical reproducibility of NMR data (collection, storage, and processing) and the health status of the animals, which may influence urine pH and osmolarity. Methods. We treated rats with a solvent, a diuretic, or a nephrotoxicant and collected urine samples. Samples were titrated to pH 3 to 9, or salt concentrations increased up to 20-fold. The effects of storage conditions and freeze-thaw cycles were monitored. Selected metabolites and multivariate data analysis were evaluated after 1H NMR spectroscopy. Results. We showed that variation of pH from 3 to 9 and increases in osmolarity up to 6-fold had no effect on the quantification of the metabolites or on multivariate data analysis. Storage led to changes after 14 days at 4°C or after 12 months at −20°C, independent of sample composition. Multiple freeze-thaw cycles did not affect data analysis. Conclusion. Reproducibility of NMR measurements is not dependent on sample composition under physiological or pathological conditions.

Impact of Sample Preparation on Dissolution Testing: Drug Binding and Extractable Impurities and Their Effect on Dissolution Data

Dissolution testing is a key pharmaceutical QC test required for release of oral dosage forms. It is also commonly used to predict in vivo behavior of the formulation. Filtration is a key sample preparation step that follows the drug dissolution test before sample analysis. Because of the simplicity of the filtration process, the choice of filtration devices is often ignored, leading to inaccurate and irreproducible results. This paper discusses the effects of drug binding and extractable impurities from syringe filters on dissolution data. The data presented here demonstrate that various basic and acidic drugs bind strongly to nylon membrane filters, thereby reducing drug recovery and giving an incorrect dissolution profile. On the other hand, various drugs with different physicochemical properties do not bind to hydrophilic polytetrafluoroethylene (PTFE) syringe filters, thereby leading to quantitative drug recovery. In combination with its very low extractable profile, hydrophilic PTFE is an ideal filtration choice for dissolution testing.

Impact of sample preparation in peptide/protein profiling in human serum by MALDI-TOF mass spectrometry

The low molecular weight (LMW) serum proteome (<15 kDa) is the most generally informative from a medical point of view. Different sample pre-treatment approaches and devices for serum depletion in high-abundant proteins were tested in order to analyze, by MALDI-TOF-MS (both in “linear” and “reflectron” acquisition mode), the serum low molecular weight proteins/peptides. The best results in terms of detected ions number and abundance were obtained by using ultrafiltration of serum on 30 kDa molecular weight cut off membranes followed by miniaturized reverse-phase solid-phase extraction (μ-SPE) as sample pre-treatment; this procedure yielded also satisfactory within-sample and sample-to-sample repeatability (on both m/ z values and peak intensity of the main observable ions). The procedure was finally applied to serum samples of breast cancer patients, and the relevant results compared to “normal” samples seem to be promising for the individuation of different profiles (“linear” and “reflectron” mode) and/or peptides capable of differentiating for malignancies (“reflectron” mode).

Near infrared reflectance spectroscopy (NIRS) to predict biological parameters of maize silage: effects of particle comminution, oven drying temperature and the presence of residual moisture

Maize silage nutritive quality is routinely determined by near infrared reflectance spectroscopy (NIRS). However, little is known about the impact of sample preparation on the accuracy of the calibration to predict biological traits. A sample population of 48 maize silages representing a wide range of physiological maturities was used in a study to determine the impact of different sample preparation procedures (i.e., drying regimes; the presence or absence of residual moisture; the degree of particle comminution) on resultant NIR prediction statistics. All silages were scanned using a total of 12 combinations of sample pre-treatments. Each sample preparation combination was subjected to three multivariate regression techniques to give a total of 36 predictions per biological trait. Increased sample preparations procedure, relative to scanning the unprocessed whole plant (WP) material, always resulted in a numerical minimisation of model statistics. However, the ability of each of the treatments to significantly minimise the model statistics differed. Particle comminution was the most important factor, oven-drying regime was intermediate, and residual moisture presence was the least important. Models to predict various biological parameters of maize silage will be improved if material is subjected to a high degree of particle comminution (i.e., having been passed through a 1 mm screen) and developed on plant material previously dried at 60 °C. The extra effort in terms of time and cost required to remove sample residual moisture cannot be justified.

Impact of sample preparation on the determination of crude fat content in corn

AbstractSample preparation is an important step in any analysis as it directly affects the assay results. The effect of sample preparation on the extraction of crude fat from 10 corn samples with varying fat content was studied. Samples were ground on seven different grinders, namely, the Mega‐grinder, Knifetec, Cyclotec, Cemotec, Mikro‐mill, UDY, and Brinkmann‐Retsch mill. The crude fat was extracted from ground samples using Soxtec and/or Butt‐tube extraction procedures and was determined gravimetrically after evaporation of the extraction solvent. The lowest amount of crude fat was extracted from samples ground on a Cemotec grinder. However, similar yields of crude fat were obtained with the other six sample preparation mills by using the proper screen size and grinding conditions. We observed an increase of 0.3% in the grand mean of crude fat extracted from samples ground on a Cyclotec grinder fitted with a 1.0‐mm screen as compared with a 2.0‐mm screen. Modifying the grinding time from 5 to 10 s/cycle and increasing the number of cycles from 2 to 3 resulted an increase of 0.4% in the grand mean of crude fat extracted from 10 corn samples. No significant differences were observed in crude fat content when samples were ground with a Monsanto‐built Mega‐grinder, located at two different sites. The efficiency of crude fat extracted from ground samples was found to increase with the decrease in particle size.

Impact of Sample Preparation on Residual Moisture Analyses for a Lyophilized Protein Formulation

This study compares residual moisture data obtained by thermogravimetric (TG) and Karl Fischer (KF) analyses of freeze-dried recombinant Desmodus rotundus salivary plasminogen activator (DSPA) and the protein free placebo. Significant changes in water content were observed depending on the sample type as well as the relative humidity of the exposure environment prior to analysis. The TG and KF analyses gave identical results only when the samples were handled identically. The method of choice for the determination of the true total moisture content of these samples is the KF analysis since it can be performed without any opportunity for water exchange with the environment.

Comparative magnetic-field imaging, electric-field imaging, and scanning Auger microscopy study of metal–matrix composites

Abstract X-ray photoelectron emission microscopy (XPEEM) provides valuable chemical information at the micron or submicron level and has been successfully applied to a wide range of materials. We have initiated a study of metal–matrix composites (MMCs) using this technique, aimed at understanding the interfacial interactions that occur between the metal matrix and the ceramic reinforcement. The experiments have been performed on Ti/SiC (fiber) MMCs and SiC fibers. We have found that the method of preparing the sample plays a critical role in understanding the results of the measurements. Samples prepared by polishing and sputtering were examined using an electric-field imaging photoelectron microscope (EFIPM), and fractured samples were studied with a magnetic-field imaging photoelectron microscope (MFIPM). While the EFIPM exhibited exellent elemental contrast and resolution, the data were flawed by artifacts introduced by both the polishing and the sputtering. Although the spatial resolution of the MFIPM was lower than the EFIPM, the ability to study fractured samples greatly facilitated interpretation of the data, which revealed the intrinsic chemical states of the sample. These results will be interpreted in terms of the impact of sample preparation on the application of XPEEM to MMCs and other complex systems.