Isopropanol Concentration Research Articles

Graphene Oxide Thin Films for Detection and Quantification of Industrially Relevant Alcohols and Acetic Acid

Industrial environments are frequently composed of potentially toxic and hazardous compounds. Volatile organic compounds (VOCs) are one of the most concerning categories of analytes commonly existent in the indoor air of factories' facilities. The sources of VOCs in the industrial context are abundant and a vast range of human health conditions and pathologies are known to be caused by both short- and long-term exposures. Hence, accurate and rapid detection, identification, and quantification of VOCs in industrial environments are mandatory issues. This work demonstrates that graphene oxide (GO) thin films can be used to distinguish acetic acid, ethanol, isopropanol, and methanol, major analytes for the field of industrial air quality, using the electronic nose concept based on impedance spectra measurements. The data were treated by principal component analysis. The sensor consists of polyethyleneimine (PEI) and GO layer-by-layer films deposited on ceramic supports coated with gold interdigitated electrodes. The electrical characterization of this sensor in the presence of the VOCs allows the identification of acetic acid in the concentration range from 24 to 120 ppm, and of ethanol, isopropanol, and methanol in a concentration range from 18 to 90 ppm, respectively. Moreover, the results allows the quantification of acetic acid, ethanol, and isopropanol concentrations with sensitivity values of (3.03±0.12)∗104, (-1.15±0.19)∗104, and (-1.1±0.50)∗104 mL-1, respectively. The resolution of this sensor to detect the different analytes is lower than 0.04 ppm, which means it is an interesting sensor for use as an electronic nose for the detection of VOCs.

Use of yogurt bacteria as a model surrogate to compare household cleaning solutions

With the growing number of pathogens that are responsible for human disease, there is an urgent need to compare the relative efficacy of various household cleaning chemicals. These chemicals play an important role in preventing the spread of disease in the home setting, but there is no uniform way of comparing these cleaning products. In addition, there is no readily available guidance for the consumer while purchasing household cleaning products in terms of their efficacy in destroying bacteria. This research addresses this need by studying the inactivation of yogurt bacteria in the presence of a variety of cleaning products. We found that several of the cleaning products (Citrus II Hospital Germicidal Deodorizing Cleaner, Lysol All-Purpose Cleaner, and Earth Essentials Multipurpose Cleaner) were very effective at rapidly destroying bacteria. On the other hand, several other cleaning products including soap and alcohol-based hand sanitizer were only partially efficacious. Water as a control and one other cleaner were not at all effective at destroying bacteria. We compared the efficacy of cleaning products on bacteria isolated from common public surfaces and found good correlation with the results from the yogurt model. The effective concentration of isopropyl alcohol in hand sanitizer was studied using this model system. The results support our hypothesis that yogurt bacteria are a safe and readily available model system that can be used to rank the relative efficacy of several commonly used household cleaning products, as well as potentially for other studies on bacterial inactivation.

On the oxidation of isopropanol on platinum single crystal electrodes. A detailed voltammetric and FTIR study

Isopropanol oxidation is studied on platinum single crystals using electrochemical techniques and FTIR spectroscopy at different isopropanol concentrations. Isopropanol oxidation is found to be facilitated by the presence of adsorbed OH on the electrode surface, which reacts with an isopropanol molecule to yield the adsorbed alkoxide. Thus, when sulfuric acid is used as the supporting electrolyte instead of perchloric acid, oxidation currents diminish drastically since sulfate hinders OH adsorption. Kinetic measurements reveal that the chemical reaction between adsorbed OH and isopropanol is the rate-determining step in the mechanism. Voltammetric and FTIR experiments show that acetone is the major product of the reaction. On the Pt(111) surface, acetone is produced exclusively, and oxidation currents are controlled by diffusion since, on this electrode, acetone is not adsorbed and the adsorbed OH mobility is high. The adsorption of acetone-related species on the Pt(110) surface, which partially block the surface, leads to slightly lower currents. On the other hand, the Pt(100) electrode is the one showing significant rates for the C–C bond cleavage, yielding adsorbed CO and other species. Although this route is a minor path, the surface blockage by these species leads to a significant diminution of the currents.

Experimental study of homogeneous charge compression ignition combustion in a light-duty diesel engine fueled with isopropanol–gasoline blends

Homogeneous charge compression ignition (HCCI) is a high-efficiency, ultra-low emission generating combustion technique that can potentially phase out conventional diesel combustion (CDC). Due to wide misfire and knocking limits, a limited load range impedes its commercial success. The present work addresses HCCI limitations using isopropanol–gasoline blends in a port fuel injected light-duty diesel engine. A cetane booster additive, 2-ethylhexyl nitrate (2-EHN), at 5vol.% was mixed with the test fuels to broaden the HCCI lower load limits. The tested fuels include biofuel isopropanol that replaced non-renewable gasoline in 20% increments to achieve higher loads during HCCI. The results show a substantial increment in HCCI operating load range (24%–86%) with test fuels over diesel HCCI (20%–38%). The characteristics of HCCI combustion in the modified test engine were benchmarked with CDC in the unmodified production engine. The significant benefits of HCCI over CDC were the concomitant reduction of indicated specific energy consumption (ISEC), oxides of nitrogen (NOx), and soot emissions, especially at higher loads. For instance, at 80% load, the ISEC, soot, and NOx were decreased by 5%, 99%, and 77%, respectively, for 60% isopropanol/35% gasoline/5% 2-EHN fueled HCCI than CDC. The exergy analysis was conducted to gain insight into irreversibility sources in thermodynamic processes during HCCI and CDC. The second law efficiency of HCCI improved with increased isopropanol content in the test fuels at a specific load. Overall, the present work shows that isopropanol–gasoline blends are viable alternatives to diesel to operate the HCCI engine that meets the desired emission and performance targets.

Formation of in-situ microemulsion and its efficiency for residual PCE removal in low temperature aquifers

Microemulsion is used extensively for enhanced oil recovery due to its efficient solubilization. Recently, in-situ microemulsion has been considered to have great potential for remediation of dense non-aqueous phase liquid contaminated aquifers. However, the temperature of aquifers is substantially below that of oilfields (30–120 °C), and the influence of temperature variation on in-situ microemulsion formation and solubilization is unclear. In this work, the efficient in-situ microemulsion for low temperature aquifers were established via the ε-β fishlike phase diagram; the solubilization capacity and size distribution of microemulsion at low temperature of about 10 °C were investigated; and the remediation efficiency of microemulsion flushing for residual tetrachloroethylene (PCE) removal was evaluated. Microemulsion precursor composition of 6.0 wt% compound surfactants (Tween80: SDS=3:2), 8.0 wt% isopropyl alcohol (IPA) and 3.0 wt% NaCl was prepared to form microemulsion with PCE in situ. The PCE apparent solubility was determined to be 80.28 g L−1 at 10 °C, which was three orders of magnitude higher than that in water at the same temperature, about 0.06 g L−1. The solubilization capacity was inversely proportional to temperature and IPA concentration, whereas proportional to Na+ concentration. The microemulsion droplets size were enlarged with the increase of IPA concentration, Na+ concentration and PCE solubilization by DLS experiments. Besides, sand column flushing using various eluents (water, micelle solution, in-situ microemulsion) was conducted to determine the removal efficiency for residual PCE. It was determined that in-situ microemulsion formulations can achieve removal efficiency of 97.1% for residual PCE, which was higher than that flushed via water and micelle solution, about 54.6% and 1.1%. In summary, the results confirm great feasibility of in-situ microemulsion for DNAPLs polluted aquifer remediation.

Selective and Efficient Photoextraction of Aqueous Cr(VI) as a Solid-State Polyhydroxy Cr(V) Complex for Environmental Remediation and Resource Recovery

Aqueous hexavalent chromium (Cr(VI)) treatment and chromium resource recovery toward Cr-containing wastes are of significant importance and necessity to both wastewater remediation and resource recovery. Herein, via mild photoreaction conditions with isopropanol (IPA) as an electron donor, a catalyst-free strategy for aqueous Cr(VI) extraction to form an insoluble polyhydroxy Cr(V) complex is developed for the first time. Aqueous Cr(VI) with concentration from 5 to 150 ppm can be efficiently extracted with high selectivity even in the presence of coexisting ions, and the total Cr concentration in residue solution can be as low as 0.5 ppm. The Cr resource could be efficiently recovered as pure Cr2O3 by calcinating the resulting Cr(V) precipitate. Outstanding extraction efficiency could be realized with various IPA concentrations (1.3-12.0 mol/L) by coordinately tuning the pH value to promote the formation of Cr(VI)-IPA ester. The formed ester undergoes intramolecular electron transition under visible light irradiation, resulting in a polyhydroxy solid-state Cr(V) intermediate complex. The controlled pH value blocks further reduction of Cr(V) to soluble Cr(III); thus the insoluble Cr(V) intermediate complex is stabilized thermodynamically under ambient conditions. Because of its electric neutrality property and the strong intermolecule interaction via hydrogen bonds, a dioxo-bridged di-nuclear Cr(V) complex {Cr2(μ-O)2(OH)4[OCH(CH3)2]2} is finally precipitated as the main product. Satisfactory extraction and recovery of Cr from chromium-plating wastewater and discarded stainless steel verify that this approach is ideal for both one-step purification of Cr(VI)-containing wastewater and selective resource recovery from Cr-containing solid wastes in practical application.

Classification of VOC Vapors Using Machine Learning Algorithms

Detection of volatile organic compound (VOC) vapors, which are known to have carcinogenic effects, is extremely important and necessary in many areas. In this work, the sensing properties of a cobalt phthalocyanine (CoPc) thin film at six different VOC vapors (methanol, ethanol, butanol, isopropyl alcohol, acetone, and ammonia) concentrations from 50 to 450 ppm are investigated. In this sense, it is observed that the interaction between the VOC vapors and the CoPc surface is not selective. It is shown that using machine learning algorithms the present sensor, which is poorly selective, can be transformed into a more efficient one with better detection ability. As a feature, 10 seconds of responses taken from the steady state region are used without any additional processing technique. Among classification algorithms, k-nearest neighbor (KNN) reaches the highest accuracy of 96.7%. This feature is also compared with the classical steady state response feature. Classification results indicate that the feature based on 10 seconds of responses taken from the steady state region is much better than that based on the classical steady state response feature.

Label-free viability assay using in-line holographic video microscopy

Total holographic characterization (THC) is presented here as an efficient, automated, label-free method of accurately identifying cell viability. THC is a single-particle characterization technology that determines the size and index of refraction of individual particles using the Lorenz–Mie theory of light scattering. Although assessment of cell viability is a challenge in many applications, including biologics manufacturing, traditional approaches often include unreliable labeling with dyes and/or time consuming methods of manually counting cells. In this work we measured the viability of Saccharomyces cerevisiae yeast in the presence of various concentrations of isopropanol as a function of time. All THC measurements were performed in the native environment of the sample with no dilution or addition of labels. Holographic measurements were made with an in-line holographic microscope using a 40times objective lens with plane wave illumination. We compared our results with THC to manual counting of living and dead cells as distinguished with trypan blue dye. Our findings demonstrate that THC can effectively distinguish living and dead yeast cells by the index of refraction of individual cells.

Sanitizing Equipment and Personnel to Prevent the Spread of Hibiscus Mealybug [Nipaecoccus viridis (Hemiptera: Pseudococcidae)] in Florida Citrus.

Hibiscus mealybug (Nipaecoccus viridis, Newstead) is an emerging and serious pest of citrus in Florida. Preventing the spread of hibiscus mealybug by sanitizing personnel and equipment such as individual protective covers can help limit new infestations. Two mealybug life stages, first instars (crawlers) and eggs inside ovisacs, were tested as they are the most likely to be accidentally transported on people and tools. Isopropanol sprays in 3 commercially available concentrations (50%, 70%, and 90%) were tested against crawlers and ovisacs, and steam treatments and hot water immersion were tested against ovisacs. All concentrations of isopropanol resulted in >90% incapacitation of mealybug crawlers, especially when two sprays of isopropanol were applied. However, no concentration of isopropanol reliably killed all mealybug eggs within ovisacs. Steam treatments and hot water immersion for 10 min or longer at 49°C and for 5 min or longer at 54.5°C resulted in 100% mortality of mealybug adults and eggs inside ovisacs. However, adults and ovisacs insulated inside of individual protective covers did not experience 100% mortality until 30 min or longer at 49°C, 10 min or longer at 54.5°C, and 5 min or longer at 60°C for steam treatments. Isopropanol sprays can effectively incapacitate the majority of hibiscus mealybug crawlers on personnel and tools, but are not effective against ovisacs. Steam treatments and hot water immersion can reliably lead to 100% mortality of ovisacs, but longer times and higher temperatures must be used for steam treatments if ovisacs are insulated by equipment.

Investigation on isopropanol sensing properties of LnFeO3(Ln = Nd, Dy, Er) perovskite materials synthesized by microwave-assisted hydrothermal method

The early detection of lung cancer by breath analysis has attracted more and more attention. In this work, high-performance LnFeO3 (Ln = Nd, Dy, Er) based isopropanol sensors were synthesized by microwave-assisted hydrothermal method. X-ray diffraction, field-emission scanning electron microscope, transmission electron microscope, and UV–visible-near infrared absorption spectrometer were used to analyze the material phase composition, microstructure, and other physical properties. The sensing performance was tested by using a four-channel gas testing chamber. The sensors were tested with low concentrations of isopropanol at high humidity to simulate a real human exhaled breath environment. The low binding energy of the Ln-O bond makes it easy to have chemical reactions, which leads to excellent isopropanol sensing performance. Finally, the gas sensing mechanism of the LnFeO3 sensor was discussed.

Formulation and Characterization of Metformin-Loaded Ethosomes for Topical Application to Experimentally Induced Skin Cancer in Mice.

To achieve the best treatment of skin cancer, drug penetration inside the deepest layers of the skin is an important scientific interest. We designed an ethosome formulation that serves as a carrier for metformin and measured the in vitro skin permeation. We also aimed to measure the antitumor activity of the optimal ethosomal preparation when applied topically to chemically induced skin cancer in mice. We utilized a statistical Box–Behnken experimental design and applied three variables at three levels: lecithin concentration, cholesterol concentration and a mixture of ethanol and isopropyl alcohol concentrations. All formulations were prepared to calculate the entrapment efficiency %, zeta potential, size of the vesicles and drug release % after 1, 2, 4, 8 and 24 h. The size of the vesicles for the formulations was between 124 ± 14.2 nm and 560 ± 127 nm, while the entrapment efficiency was between 97.8 ± 0.23% and 99.4 ± 0.24%, and the drug release % after 8 h was between 38 ± 0.82% and 66 ± 0.52%. All formulations were introduced into the Box–Behnken software, which selected three formulations; then, one was assigned as an optimal formula. The in vivo antitumor activity of metformin-loaded ethosomal gel on skin cancer was greater than the antitumor activity of the gel preparation containing free metformin. Lower lecithin, high ethanol and isopropyl alcohol and moderate cholesterol contents improved the permeation rate. Overall, we can conclude that metformin-loaded ethosomes are a promising remedy for treating skin cancers, and more studies are warranted to approve this activity in other animal models of skin cancers.

Hybrid nanophotonic-microfluidic sensor for highly sensitive liquid and gas analyses.

Today, a lab-on-a-chip is one of the most promising ways to create sensor devices for gas and liquid analysis for environmental monitoring, early diagnosis, and treatment effectiveness assessment. On the one hand, this requires a large number of measurements and, on the other hand, involves minimum consumption of the test analytes. Combination of highly sensitive photonic integrated circuits (PICs) with microfluidic channels (MFCs) is necessary to solve this problem. In this work, PICs based on a silicon nitride platform integrated with MFCs for studying liquids and gases were developed. Different concentrations of isopropanol in de-ionized water were used as the analyte. Based on this, the sensitivity (S) and detection limit (DL) of the analyzed solution were evaluated. Entire system calibration was carried out to calculate S and DL, considering experimental and numerical simulation data. This development may be of interest as a promising platform for environmental monitoring and realization of point-of-care strategy for biomedical applications.

Spraying Characteristics of Alcohol‐Coal‐Water Slurries with Low Coal Content

AbstractThe results of spraying characteristics of alcohol‐coal‐water slurries are presented. It has been experimentally proved that the lowest viscosity value of the studied slurries varies from 54 to 329 mPa s. The density value of alcohol‐coal‐water slurries decreases to 1130 kg m−3 when the content of isopropyl alcohol in the fuel composition is 8 wt %. The largest value of jet spraying angle corresponds to alcohol‐coal‐water fuel with an isopropyl alcohol content of 8 wt %. The number of sufficiently large droplets decreases in comparison with a typical two‐component coal‐water fuel. The calorific value of alcohol‐coal‐water slurries rises when the third liquid fuel component is introduced into the composition of coal‐water fuel.

THE INFLUENCE OF ISOPROPYL ALCOHOL CONCENTRATION ON THE CHANGE OF PHASE BEHAVIOR IN THE MIXTURE OF OIL - SURFACTANT - ISO PROPYL ALCOHOLFORMATION WATER

Surfactant is surface active agent chemical that has two types of properties; lyophobic (like water) and hydrophobic (like oil). One of enhanced oil recovery methods that is used to improve oil recovery factor, is surfactant flooding. Oil and water are two separated phases and have high interfacial tension value (around 30-40 dyne/cm). Addition of surfactant solution at certain concentration into the mixture of oil-surfactant-formation water will change the phase behavior. In this case, four types possibilities of emulsion formed, these are: • Upper phase; Middle phase (microemulsion); Lower phase; Macroemulsion. According to Prince, L.M (Theory and Practice of Microemulsions), change of phase behavior in the oil-surfactant-formation water mixture is influenced by several factors, one of them is concentration of alcohol. The main focus of this research is to study influence of isopropyl alcohol (IPA) concentration on phase behavior in the oil-surfactant-IPA-formation water mixture.Concentration Behavior Oil - Surfactant - Iso

Understanding the Working Mechanism of the Novel HKUST-1@BPS Composite Materials as Stationary Phases for Liquid Chromatography.

Composite materials have been used based on coordination polymers or microporous metal-organic frameworks (MOFs) combined with mesoporous matrices for adsorption-related techniques, which enable outflanking some adverse phenomena manifested during pristine components operation and enhance the performance and selectivity of the resulting materials. In this work, for the first time, the novel HKUST-1@BPS composites synthesized by the microwave-assisted (MW) technique starting from microporous HKUST-1 (Cu3(btc)2) MOF and biporous silica matrix (BPS) with bimodal mesopore size distribution were comparatively studied as materials for liquid-phase adsorption techniques utilizing the high-performance liquid chromatography (HPLC) method and benzene as a model adsorbate. It was established that the studied HKUST-1@BPS composites can function as stationary phases for HPLC, unlike the pristine HKUST-1 and bare BPS materials, due to the synergetic effect of both components based on the preliminary enhanced adsorbate mass transfer throughout the silica mesopores and, subsequently, its penetrating into HKUST-1 micropores. The suggested mechanism involves the initial deactivation of open metal Cu2+ sites in the HKUST-1 framework structure by isopropanol molecules upon adding this polar component into the mobile phase in the region of the isopropanol concentration of 0.0 to 0.2 vol.%. Thereafter, at the medium range of varying the isopropanol concentration in the eluent of 0.2 to 0.3 vol.%, there is an expansion of the previously inaccessible adsorption centers in the HKUST-1@BPS composites. Subsequently, while further increasing the isopropanol volume fraction in the eluent in the region of 0.3 to 5.0 vol.%, the observed behavior of the studied chromatographic systems is similar to the quasi-normal-phase HPLC pattern. According to the obtained thermodynamic data, benzene adsorption into HKUST-1 micropores from solutions with a vol.% of isopropanol in the range of 0.4 to 5.0 follows the unique entropy-driven mechanism previously described for the MIL-53(Al) framework. It was found that HKUST-1 loading in the composites and their preparation conditions have pronounced effects on their physicochemical properties and adsorption performance, including the adsorption mechanism.

Characterizing surface porosity of porous membranes via contact angle measurements

This investigation attempts to establish and verify a novel method for quantifying surface porosity of porous polymeric membranes via contact angle measurements. Herein, we fabricate a series of porous membranes via nonsolvent induced phase separation (NIPS) comprising different concentrations of polyvinylidene fluoride (PVDF) and PVDF-poly (methyl methacrylate) block co-polymer (PVDF-PMMA) with different concentrations of water and isopropyl alcohol (IPA) in the coagulation bath. Both sessile drop and captive bubble contact angle measurements are used to determine contact angles (and porosity) for both dry and wet membranes, respectively. The former method is probably applicable for membrane distillation, aeration and de-aeration where liquid water does not saturate the membrane, whereas the latter may be more indicative of pressure-driven aqueous membrane separations where the membrane is saturated through its cross-section. Image analysis of scanning electron microscope (SEM) images quantified dry membrane surface porosity. We propose a simple analytical model to obtain wet and dry membrane surface porosity from contact angle measurements. Our results suggest that the surface porosity calculated from both wet and dry contact angle data correlates strongly with the surface porosity calculated from SEM values. However, wet contact angles of the membranes with high porosities produce significantly higher porosity values, which also establishes the importance of porous membrane swelling in determining membrane porosity for aqueous membrane separations.

Non-deuterated 1H NMR Spectrometric Method for the Rapid and Direct Analysis of Alcohol Content in Hand Sanitizers

In this study, a 1H nuclear magnetic resonance (NMR) method to quantify the alcohol content of alcohol-based hand sanitizers was developed and validated in non-deuterated solvent and unlocked mode conditions. Deionized water was used to prepare the solutions for the no-D method, which also matched the matrix of the samples. The generated integration areas were used to quantify the ethanol and isopropanol content of the sanitizer samples. The no-D method presented well-correlated calibration curves with a detection limit of 1.41% (v/v) and 2.61% (v/v) for isopropanol and ethanol, respectively. The experimental alcohol content in no-D conditions was compared to the results using the D2O method and was not significantly different (p > 0.05). Although there is no additional precautionary measure when handling D2O, non-deuterated solvents are more easily accessible, which makes a 1H NMR-based analysis more cost-effective.

Synthesis of Sn doped-Bi2WO6 nanoslices for enhanced isopropanol sensing properties

Bi2WO6 has sparked a lot of attention as a gas sensor in recent years. However, in most cases, the working temperature is quite high. The Sn doped- Bi2WO6 slice-shaped nanostructure material was generated using a cost-effective one-step hydrothermal process in this study. The material was evaluated using X-ray diffraction (XRD), field emission scanning microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) and an energy-dispersive X-ray detector (EDX). The results show that the 5 wt% Sn doped- Bi2WO6 sensor has outstanding isopropanol gas sensitivity. The sensor's optimal operating temperature is 260 °C, and it responds to low isopropanol concentrations. The unique interfacial interaction between 2D slice-shaped nanostructures and Sn doping, which provides additional catalytic active sites on the Bi2WO6 surface and improves electrical responsiveness and gas sensitivity, is responsible for the improved gas sensitivity.

A New Setup for the Measurement of Total Organic Carbon in Ultrapure Water Systems.

With the increasing demand for ultrapure water in the pharmaceutical and semiconductor industry, the need for precise measuring instruments for those applications is also growing. One critical parameter of water quality is the amount of total organic carbon (TOC). This work presents a system that uses the advantage of the increased oxidation power achieved with UV/O3 advanced oxidation process (AOP) for TOC measurement in combination with a significant miniaturization compared to the state of the art. The miniaturization is achieved by using polymer-electrolyte membrane (PEM) electrolysis cells for ozone generation in combination with UV-LEDs for irradiation of the measuring solution, as both components are significantly smaller than standard equipment. Conductivity measurement after oxidation is the measuring principle and measurements were carried out in the TOC range between 10 and 1000 ppb TOC. The suitability of the system for TOC measurement is demonstrated using the oxidation by ozonation combined with UV irradiation of defined concentrations of isopropyl alcohol (IPA).

Effect of dietary isopropanol on the performance and milk quality of dairy cows

The objective of this study was to examine the effects of isopropanol alone or in combination with ethanol on performance, metabolism, and milk quality of dairy cows. Eight crossbred Jersey × Holstein cows (527 ± 98 kg body weight; 152 ± 44 days in milk) were allocated in two 4 × 4 balanced-Latin squares to receive one of four dietary treatments. Four cows were surgically adapted with rumen cannula. Diets contained 450 g/kg concentrates and 550 g/kg corn silage either added with (DM basis) 15 g/kg isopropanol, 15 g/kg ethanol, 15 g/kg isopropanol + 15 g/kg ethanol, or water (control). Immediately before feeding, corn silage was sprayed with alcohols, mixed with concentrates, and fed as total mixed rations twice daily. Dry matter intake, total tract digestibility, ruminal fermentation pattern (pH, volatile fatty acids and NH3), urinary purine derivatives, milk yield, solids composition and oxidative capacity were not affected by treatments. However, gamma-glutamyl transferase activity increased (P < 0.01) in blood of cows supplemented with alcohols, indicating that isopropanol and ethanol were absorbed. Moreover, milk concentration of isopropanol and acetone increased (P < 0.01) in cows receiving isopropanol, but not ethanol. Consequently, milk from cows fed corn silage treated with isopropanol tested false-positive at the ethyl alcohol test in raw milk. In conclusion, dietary isopropanol and ethanol did not impair the performance of dairy cows, but isopropanol was imparted to milk and induced false-positive results at the ethyl alcohol test in raw milk.