Combination Of Acetone Research Articles

Performance study and tunnel waterproofing application of polyurethane prepolymer prepared by prepolymer and acetone combination

Performance study and tunnel waterproofing application of polyurethane prepolymer prepared by prepolymer and acetone combination

Use of Photo isomers to enhance the removal of lignin from woody biomass hydrolysate: UV irradiated photo isomerization of 4,4-diethoxy-azobenzene enhances precipitation of organosolv lignin from extraction solvents

Conversion of lignocellulose to bioproducts and biofuels is often initiated with a hydrolytic pretreatment process that helps to depolymerize the native polymers in biomass and produce a cellulose rich pulp stream. Extracting dissolved components (lignin) from this hydrolysate is an important step to derive value from the biomass components other than cellulose. In this investigation we propose a novel method to enable precipitation of desired solutes using photo-isomers in the extraction solvent. This photo-switchable solvent enables dissolution or precipitation of desired components using alternating UV or visible light to modify the solubility of the compounds of interest. It was found that among different combinations of three solvents and three photo-isomers, the combination of acetone with 4,4′-diethoxy azobenzene solution was most efficient at precipitating dissolved Organosolv lignin in response to UV light exposure. To our knowledge this is the first demonstration of this approach to separating lignin from organic solvents. This method is significant because it minimizes the high energy demands of traditional lignin extraction methods that involve distillation or large amounts of dilution using antisolvents.

Custom-Shaped Carbon Xerogel Materials by 3D Printing

Sol–gel-based carbon xerogels possess very promising properties for pollution abatement, using processes that associate adsorption and on-site electrochemical oxidation. However, combining a high exterior surface area (for efficient diffusion) and a monolithic shape (necessary for electrochemical processes) poses challenges. In this work, the shape of monolithic carbon xerogels was contrived by the use of 3D-printed molds. Several parameters were optimized: the choice of mold design, the choice of plastic, the 3D printer parameters, the solvent, and the process of dissolving the plastic. A design combining fine sticks and plates made of ABS was printed; a sol–gel carbon xerogel monolith was synthesized in it, and the mold was removed by using a combination of acetone and pyrolysis. Dissolving the plastic could be carried out by placing the material on a metallic net and leaving the dissolved ABS to settle. The resulting carbon material exhibits a high exterior surface area and good strength, leading to potential uses in the aforementioned process. The research shows that 3D printing is an efficient method of parameter optimization in pre-industrialization research, thanks to its flexibility, low cost, and ease of use.

Selected mechanical properties of human cancellous bone subjected to different treatments: short-term immersion in physiological saline and acetone treatment with subsequent immersion in physiological saline

BackgroundPhysiological saline (0.9% NaCl) and acetone are extensively used for storage (as well as hydration) and removal of bone marrow, respectively, of cancellous bone during preparation and mechanical testing. Our study aimed to investigate the mechanical properties of cancellous bone subjected to short-term immersion in saline and acetone treatment with subsequent immersion in saline.MethodsCylindrical samples (Ø6 × 12 mm) were harvested from three positions (left, middle, and right) of 1 thoracic vertebral body, 19 lumbar vertebral bodies, and 5 sacral bones, as well as from 9 femoral heads. All samples were divided into two groups according to the different treatments, (i) samples from the left and middle sides were immersed in saline at 4℃ for 43 h (saline-immersed group, n = 48); (ii) samples from the respective right side were treated with a combination of acetone and ultrasonic bath (4 h), air-dried at room temperature (21℃, 15 h), and then immersed in saline at room temperature (21℃, 24 h) (acetone and saline-treated group, n = 38). All samples were subjected, both before and after treatment, to a non-destructive compression test with a strain of 0.45%, and finally destructive tests with a strain of 50%. Actual density (ρact), initial modulus (E0), maximum stress (σmax), energy absorption (W), and plateau stress (σp) were calculated as evaluation indicators.ResultsBased on visual observation, a combination of acetone and ultrasonic bath for 4 h failed to completely remove bone marrow from cancellous bone samples. The mean values of ρact, σmax, W, and σp were significantly higher in the femoral head than in the spine. There was no significant difference in E0 between non-treated and saline-immersed samples (non-treated 63.98 ± 20.23 vs. saline-immersed 66.29 ± 20.61, p = 0.132). The average E0 of acetone and saline-treated samples was significantly higher than that of non-treated ones (non-treated 62.17 ± 21.08 vs. acetone and saline-treated 74.97 ± 23.98, p = 0.043).ConclusionShort-term storage in physiological saline is an appropriate choice and has no effect on the E0 of cancellous bone. Treatment of cancellous bone with acetone resulted in changes in mechanical properties that could not be reversed by subsequent immersion in physiological saline.

Exhaled volatile organic compounds for diagnosis of hepatocellular carcinoma

Volatile organic compounds (VOCs) profile for diagnosis and monitoring therapeutic response of hepatocellular carcinoma (HCC) has not been well studied. We determined VOCs profile in exhaled breath of 97 HCC patients and 111 controls using gas chromatography–mass spectrometry and Support Vector Machine algorithm. The combination of acetone, 1,4-pentadiene, methylene chloride, benzene, phenol and allyl methyl sulfide provided the highest accuracy of 79.6%, with 76.5% sensitivity and 82.7% specificity in the training set; and 55.4% accuracy, 44.0% sensitivity, and 75.0% specificity in the test set. This combination was correlated with the HCC stages demonstrating by the increased distance from the classification boundary when the stage advanced. For early HCC detection, d-limonene provided a 62.8% sensitivity, 51.8% specificity and 54.9% accuracy. The levels of acetone, butane and dimethyl sulfide were significantly altered after treatment. Patients with complete response had a greater decreased acetone level than those with remaining tumor post-treatment (73.38 ± 56.76 vs. 17.11 ± 58.86 (× 106 AU, p = 0.006). Using a cutoff of 35.9 × 106 AU, the reduction in acetone level predicted treatment response with 77.3% sensitivity, 83.3% specificity, 79.4%, accuracy, and AUC of 0.784. This study demonstrates the feasibility of exhaled VOCs as a non-invasive tool for diagnosis, monitoring of HCC progression and treatment response.

The effectiveness of the Fucus virsoides and Cystoseira barbata fucoidan isolation as a function of applied pre-treatment and extraction conditions

Fucus virsoides and Cystoseira barbata are important sources of sulfated polysaccharide fucoidan which shows a wide range of biological activities. These activities are significantly dependent on chemical composition which is influenced by species, anatomical part of the seaweed, growing location and conditions, extraction procedures and analytical methods. The objective of this study was to evaluate influence of various pre-treatment solvents and conventional extraction parameters (solvent, temperature and time) on polysaccharide yield and chemical composition (total sugar, fucose, sulfate group and uronic acid content) of the fucoidan from F. virsoides and C. barbata. Combination of acetone and ethanol was chosen for pre-treatment since it removed the most interfering compounds and resulted with the highest polysaccharide yield. Applying acid (0.1 M HCl and 0.1 M H2SO4) instead of water for polysaccharide extraction improved yield and resulted with fucoidan with higher sulfate group content, lower uronic acid content but lower fucose content. Extraction at higher temperatures and longer time resulted with higher polysaccharide yield, uronic acid and total sugars content. However, they had the opposite effect on fucose and sulfate group content between F. virsoides and C. barbata.

Basalt Fiber-Based Flame Retardant Epoxy Composites: Preparation, Thermal Properties, and Flame Retardancy.

We aimed to study the impact of surface modification of basalt fiber (BF) on the mechanical properties of basalt fiber-based epoxy composites. Four different types of pretreatment approaches to BF were used; then a silane coupling agent (KH550) was applied to further modify the pretreated BF, prior to the preparation of epoxy resin (EP)/BF composites. The combination of acetone (pre-treatment) and KH550 (formal surface treatment) for basalt fiber (BT-AT) imparted the EP/BF composite with the best performance in both tensile and impact strengths. Subsequently, such modified BF was introduced into the flame-retardant epoxy composites (EP/AP750) to prepare basalt fiber reinforced flame-retardant epoxy composite (EP/AP750/BF-AT). The fire behaviors of the composites were evaluated by vertical burning test (UL-94), limiting oxygen index (LOI) test and cone calorimetry. In comparison to the flame-retardant properties of EP/AP750, the incorporation of BF-AT slightly reduced LOI value from 26.3% to 25.1%, maintained the good performance in vertical burning test, but increased the peak of the heat release rate. Besides, the thermal properties and mechanical properties of the composites were investigated by thermogravimetric analysis (TGA), universal tensile test, impact test and dynamic mechanical analysis (DMA).

Synthesis and Spectro-Electrochemical Properties of New Metallophthalocyanines Having High Electron Transfer Capability

It is important to synthesis and examine the redox properties of phthalocyanines and related macrocycles in order to reveal their possible applications. In this paper, new Zn2+, Co2+ and Mn2+ phthalocyanine complexes containing substituted 1,2,4-triazole groups on peripheral positions have been prepared and characterized by classical methods and electrochemistry in detail. The use of triethylamine and acetone combination in the synthesis of nitrile structures 3a and 3b, the starting compounds for phthalocyanines, both increased yield of products and shortened reaction time compared to classical synthesis of nitrile structures. The electron transfer capability of new metallophthalocyanines (ZnPcs, CoPcs and MnPcs) was investigated in detail via cyclic voltammetry (CV), square wave voltammetry (SWV) and in situ UV–vis spectroelectrochemistry. For ZnPcs, these experiments demonstrated that the complexes exhibited three well-defined reductions and two oxidations waves based on the Pc ring electroinactive nature of the Zn metal coordinated to the macrocycle. For CoPcs showed three reductions and one oxidation based on both the Pc ring and electroactive nature of Co center. Furthermore, MnPcs displayed three well-defined reductions and two oxidations waves based on either the Pc ring or electroactive Mn center.

Influence of organic solvents in the extraction and purification of torularhodin from Sporobolomyces ruberrimus.

This work aimed at evaluating the influence of organic solvents and stationary phases in the extraction with glass beads and chromatographic purification of carotenoids, especially torularhodin, from Sporobolomyces ruberrimus. The combinations of acetone:hexane (1:1 v/v) and acetone:ethyl ether (1:1 v/v) yielded 171.74 and 172.19 μg of total carotenoids.g of cells-1, respectively. The first blend resulted in the highest percent of cell lysis of 57.4%. Among different proportions of acetone:hexane, the 9:1 v/v mixture showed a significant difference (p < 0.05), resulting in a recovery of total carotenoids of 221.88 μg.g of cells-1. The purification of carotenoids was made by preparative chromatography and the yield of the silica-containing stationary phase was higher (24 μg torularhodin.g cells-1). The analyses of the purified fractions in thin layer chromatography and high performance liquid chromatography indicated that the purification of carotenoids, especially of torularhodin, was successfully performed. The combination of polar (acetone) and non-polar solvents (hexane) and the use of silica as stationary phase was efficient to recover and purify torularhodin from the intracellular pigments of Sporobolomyces ruberrimus.

Synthesis of 4‐Acylchromene via Highly Chemoselective Iodine‐Catalyzed Cyclization of Alkynylarylether Dimethylacetals

4-Acylchromene is an important core structure found in bioactive natural products and bioactive synthetic compounds. Moreover, this core structure is frequently used as a key precursor for the synthesis of more complex molecules. In this work, we discovered that a combination of acetone and catalytic I2 could lead to selective activation of acetal in alkynylarylether dimethylacetal substrates while alkyne moiety remained intact. This activation of acetal led to the generation of oxonium ion intermediate which triggered intramolecular cyclization and elimination of methanol to provide the desired 4-acylchromene as the sole product in up to 95% yield. Moreover, this method could be applied in a broad range of substrates under a mild and metal-free catalytic conditions for the synthesis of 4-acylchromene derivatives.

CFD multiphase modelling of the acetone condensation and evaporation process in a horizontal circular tube

With increasing demands on energy efficiency, the use of low grade waste heat using vapour absorption refrigeration systems (VARS) are receiving renewed interest. One idea is to use the combination of acetone and zinc bromide as the salt solution, which allows use of temperatures in the order of 10 s of °C above ambient conditions. This work numerically models acetone phase change in the evaporator and condenser in order to indicate how improvements can be made in these components of the system. ANSYS® Fluent finite volume method CFD is used to produce volume of fluid (VOF) and mixture multiphase flow models to investigate the evaporation and the condensation of acetone in a horizontal circular tube. Different velocities and temperatures were taken in each process to explore the effect of these variables in the system. A user defined function (UDF) is used to calculate the volume fraction of the phases. For the evaporation case, the heat transfer coefficient increases with increasing velocity and the temperature difference between the inlet flow and the wall, as expected. The mass transfer rate decreases with increasing the flow rate or decreasing the wall temperature, from 0.045 kg/m3·s at 0.01 m/s to 0.016 kg/m3·s at 0.06 m/s and it drops from 0.044 to 0.023 kg/m3·s by reducing the temperature just from 300 to 298 K. There is a reduction in specific heat transfer to the liquid despite the higher wall heat transfer coefficient. In the condenser, vapour quality decreases along the tube as liquid acetone is created when the flow rate is reduced. Vapour volume fraction at the outlet section drops from 0.74 to 0.168 by increasing the ingoing velocity from 0.01 to 0.06 m/s. Increasing the rate of condensation will increase the liquid supplied to the evaporator, which increases the evaporation rate and then increases the performance of the VARS. This demonstrates the importance of controlling the temperature and the flow rate in the VARS for generating more refrigerant in the vapour generator.

Oxone®-Mediated Direct α-Hydroxylation of β-Dicarbonyl Compounds: Racemic Synthesis of Harzialactone A

An environmentally benign method is described for the α-hydroxylation of malonates and cyclic analogues in aqueous medium at room temperature under mild conditions, based on the in situ generation of dimethyldioxirane through the combination of acetone and Oxone®. This procedure was found to be substrate-dependent and was successfully performed to provide α-hydroxylated γ-lactones. To demonstrate the synthetic potential of this mild α-hydroxylation, two different concise routes were developed to synthesize harzialactone A in the racemic form with a moderate (3:1) diastereomeric ratio.

AN INNOVATIVE APPROACH TO ENVIRONMENTAL SAMPLE PREPARATION FOR DETERMINATION OF POLYCYCLIC AROMATIC HYDROCARBONS BY GC-MS USING NEW SORBENTS IN QUECHERS TECHNIQUE

Polycyclic aromatic hydrocarbons (PAHs) have been considered as environmental pollutants of a great concern. Regardless of the method of quantitative analysis to be applyied, sample preparation is essential for the accurate determination of PAHs. Due to the extreme complexity of the soil samples, caused primarily by the presence of hundreds of compounds, many of them have similar physical and / or chemical properties as well as the analyzed compounds, and preparation of environmental samples for analysis is crucial for validity of the PAHs analysis. No matter which method will be applied for later analysis, sample preparation has to fulfill a number of conditions such as, adequate selectivity, efficiency, availability, easy to perform, short duration of the procedure. QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method of sample preparation is a relatively new method that uses different sorbents and solvent systems. In this paper, the possibility of application of sorbents (diatomaceous earth, clinoptilolite and carbon black), which are not usually used in QuEChERS clean-up step of sample preparation, using 3 different solvent mixtures hexane / acetone (1:1, v / v) cyclohexane / acetone (1: 1, v / v) and acetonitrile / methanol (2:1, v / v) was investigated. Standard solutions of PAHs were treated with selected sorbents and solvent systems in all combinations, and then analyzed by GC-MS method. The overall accuracy of the method varied depending of compound and used sorbent/solvent system, while precision of the method was constantly good. Highest mean recovery for all PAHs (49.22%) was recorded for clinoptilolite, hexane / acetone combination. Diatomaceous earth showed lower recoveries in comparison with clinoptilolite, with all solvent systems, while recoveries for carbon black were almost zero. Among tested sorbents, clinoptilolite was identified as good starting sorbent which characteristics could be modified with aim to achieve higher accuracy, precision and selectivity of the method, and enable its new application in analytical chemistry. Key words: PAHs, QuEChERS, sorbents, GC-MC.

Non-labeling multiplex surface enhanced Raman scattering (SERS) detection of volatile organic compounds (VOCs)

In this paper, we report multiplex SERS based VOCs detection with a leaning nano-pillar substrate. The VOCs analyte molecules adsorbed at the tips of the nano-pillars produced SERS signal due to the field enhancement occurring at the localized surface plasmon hot spots between adjacent leaning nano-pillars. In this experiment, detections of acetone and ethanol vapor at different concentrations were demonstrated. The detection limits were found to be 0.0017ng and 0.0037ng for ethanol and acetone vapor molecules respectively. Our approach is a non-labeling method such that it does not require the incorporation of any chemical sensing layer for the enrichment of gas molecules on sensor surface. The leaning nano-pillar substrate also showed highly reproducible SERS signal in cyclic VOCs detection, which can reduce the detection cost in practical applications. Further, multiplex SERS detection on different combination of acetone and ethanol vapor was also successfully demonstrated. The vibrational fingerprints of molecular structures provide specific Raman peaks for different VOCs contents. To the best of our knowledge, this is the first multiplex VOCs detection using SERS. We believe that this work may lead to a portable device for multiplex, specific and highly sensitive detection of complex VOCs samples that can find potential applications in exhaled breath analysis, hazardous gas analysis, homeland security and environmental monitoring.

Preparation and In Vitro Evaluation of Ethylcellulose and Polymethacrylate Resins Loaded Microparticles Containing Hydrophilic Drug.

Objective. The purpose of the recent study was to prepare and estimate sustained release of Ethylcellulose (300 cps) and Eudragit (RS 100 and RL 100) microparticles containing Propranolol hydrochloride used as a treatment of cardiovascular system, especially hypertension. Method. Propranolol hydrochloride was microencapsulated with different polymers (Ethylcellulose, Eudragit RS, and Eudragit RL) using modified hydrophobic (O/O) solvent evaporation method using 1 : 1 combination of acetone and isopropanol as the internal phase. Obtained microparticles were showing higher batch yield with higher encapsulation efficiency. Microparticles were prepared with different ratios of 1 : 1, 1 : 3, 1 : 5, and 1 : 7 (%, wt/wt) using span 80 (%, v/v) as a surfactant. Results. The influence of formulation factors like drug: polymer ratio, internal phase, and type of polymers on obtained microparticles was characterized with respect to particle size distribution, encapsulation efficiency, percentage yield, FTIR, and FE-SEM. Higher encapsulation efficiencies were obtained with various polymers like Ethylcellulose (96.63 ± 0.5) compared to Eudragit RS 100 (83.70 ± 0.6) and RL 100 (89.62 ± 0.6). The in vitro release study was characterized by initial burst. Conclusion. The result of study displays that Ethylcellulose and Eudragit loaded microparticles of Propranolol hydrochloride can be effectively prepared using modified hydrophobic emulsification solvent evaporation technique. Therefore, the modified hydrophobic emulsion technique can also be applied to the preparation of microparticles for low molecular weight and highly water soluble drugs.

METHOD DEVELOPMENT FOR DETERMINATION OF CYAZOFAMID IN SOIL AND WATER BY HPLC

A rapid, sensitive, and accurate method for analysis of cyazofamid has been developed using SPE in texturally different soils and water. The method involved using different solvents or their combinations for the extraction of fungicide from soil and water. The cleanup was done with C-18/florisil/alumina SPE cartridges and finally analyzed by high performance liquid chromatography (HPLC) using different columns, namely, C-18/diol/cyano and mobile phase using methanol/acetonitrile:water in different ratios with UV detection at 279 nm. The best results in terms of recovery, cleanup efficiency, and independence of soil characteristics were obtained with combination of acetone:methanol followed by cleanup with florisil for soil and chloroform for water. Most suited column was C-18 with mobile phase acetonitrile:water for HPLC. Calibration curve for quantification were linear (R2 = 0.999) over the dynamic range of 0.1–10.0 µg mL−1 and percent relative standard deviation (RSD) was 1.72%. The limit of detection for instrument and limit of quantification for method were 0.01 and 0.05 µg g−1.

Optimizing Human Synovial Fluid Preparation for Two-Dimensional Gel Electrophoresis

BackgroundProteome analysis is frequently applied in identifying the proteins or biomarkers in knee synovial fluids (SF) that are associated with osteoarthritis and other arthritic disorders. The 2-dimensional gel electrophoresis (2-DE) is the technique of choice in these studies. Disease biomarkers usually appear in low concentrations and may be masked by high abundant proteins. Therefore, the main aim of this study was to find the most suitable sample preparation method that can optimize the expression of proteins on 2-DE gels that can be used to develop a reference proteome picture for non-osteoarthritic knee synovial fluid samples. Proteome pictures obtained from osteoarthritic knee synovial fluids can then be compared with the reference proteome pictures obtained in this study to assist us in identifying the disease biomarkers more correctly.ResultsThe proteomic tool of 2-DE with immobilized pH gradients was applied in this study. A total of 12 2-DE gel images were constructed from SF samples that were free of osteoarthritis. In these samples, 3 were not treated with any sample preparation methods, 3 were treated with acetone, 3 were treated with 2-DE Clean-Up Kit, and 3 were treated with the combination of acetone and 2-D Clean-Up Kit prior to 2-DE analysis. Gel images were analyzed using the PDQuest Basic 8.0.1 Analytical software. Protein spots that were of interest were excised from the gels and sent for identification by mass spectrometry. Total SF total protein concentration was calculated to be 21.98 ± 0.86 mg/mL. The untreated SF samples were detected to have 456 ± 33 protein spots on 2-DE gel images. Acetone treated SF samples were detected to have 320 ± 28 protein spots, 2-D Clean-Up Kit treated SF samples were detected to have 413 ± 31 protein spots, and the combined treatment method of acetone and 2-D Clean-Up Kit was detected to have 278 ± 26 protein spots 2-DE gel images. SF samples treated with 2-D Clean-Up Kit revealed clearer presentation of the isoforms and increased intensities of the less abundant proteins of haptoglobin, apolipoprotein A-IV, prostaglandin-D synthase, alpha-1B-glycoprotein, and alpha-2-HS-glycoprotein on 2-DE gel images as compared with untreated SF samples and SF samples treated with acetone.ConclusionsThe acetone precipitation method and the combined treatment effect of acetone and 2-DE Clean-Up Kit are not preferred in preparing SF samples for 2-DE analysis as both protein intensities and numbers decrease significantly. On the other hand, 2-D Clean-Up Kit treated SF samples revealed clearer isoforms and higher intensities for the less abundant proteins of haptoglobin, apolipoprotein A-IV, prostaglandin-D synthase, alpha-1B-glycoprotein, and alpha-2-HS-glycoprotein on 2-DE gels. As a result, it is recommended that SF samples should be treated with protein clean up products such as 2-D Clean-Up Kit first before conducting proteomic research in searching for the relevant biomarkers associated with knee osteoarthritis.

Antioxidant potential of bitter cumin (Centratherum anthelminticum (L.) Kuntze) seeds in in vitro models

BackgroundBitter cumin (Centratherum anthelminticum (L.) Kuntze), is a medicinally important plant. Earlier, we have reported phenolic compounds, antioxidant, and anti-hyperglycemic, antimicrobial activity of bitter cumin. In this study we have further characterized the antioxidative activity of bitter cumin extracts in various in vitro models.MethodsBitter cumin seeds were extracted with a combination of acetone, methanol and water. The antioxidant activity of bitter cumin extracts were characterized in various in vitro model systems such as DPPH radical, ABTS radical scavenging, reducing power, oxidation of liposomes and oxidative damage to DNA.ResultsThe phenolic extracts of bitter cumin at microgram concentration showed significant scavenging of DPPH and ABTS radicals, reduced phosphomolybdenum (Mo(VI) to Mo(V)), ferricyanide Fe(III) to Fe(II), inhibited liposomes oxidation and hydroxyl radical induced damage to prokaryotic genomic DNA. The results showed a direct correlation between phenolic acid content and antioxidant activity.ConclusionBitter cumin is a good source of natural antioxidants.

A simple approach for the selective enzymatic synthesis of dilauroyl maltose in organic media

A selective synthesis of dilauroyl maltose was developed using lipase-catalyzed condensation of lauric acid and maltose in two-solvent mixtures. The characteristics of different solvent combination were tested and it was found that the combination of acetone with n-hexane has a good selectivity for the synthesis of dilauroyl maltose. The highest diester conversion of 69% (i.e. 36.5 g/L of dilauroyl maltose) was obtained under optimal conditions: 25.65 g/L maltose, 60 g/L lauric acid, 60 g/L molecular sieve and 10 g/L lipase at 150 rpm and 50 °C for 72 h in 10 mL of mixed solvent of acetone: n-hexane (60:40, v/v).

Evaluation of the Value of Frozen Tissue Section Used as “Gold Standard” for Immunohistochemistry

To examine the use of acetone- or ethanol-fixed frozen tissue sections as the "gold standard" for immunohistochemical analysis, we evaluated frozen sections with various conditions of fixation and antigen retrieval (AR). Fresh human tissues were frozen in OCT. An adjacent tissue block was fixed in 10% neutral buffered formalin (NBF) and paraffin embedded (FFPE). Frozen sections were fixed by 6 protocols: acetone, ethanol, NBF (2 durations), and NBF + calcium chloride (2 durations). AR was used for all NBF-fixed sections. More than half of the antibodies (16/26 [62%]) showed immunohistochemical results indistinguishable between acetone- and NBF-fixed sections; 8 (31%) showed better immunohistochemical signals following NBF and AR; 2 gave better immunohistochemical results for acetone-fixed sections. Most cytoplasmic proteins (10/13) showed comparable immunohistochemical signals between acetone- and NBF-fixed sections. For nuclear proteins, NBF-fixed sections gave better immunohistochemical signals than did acetone-fixed sections. In most cases, NBF yielded stronger signals with less background and better morphology. The data do not support the use of acetone-fixed frozen tissue sections as the gold standard for immunohistochemical analysis. In evaluating new antibodies, a combination of acetone- and NBF-fixed frozen sections should be used, although in practice, FFPE tissue sections may serve as the standard for most antigens for immunohistochemical analysis.