Acid Hydrolysis Conditions Research Articles

Xylitol-Sweetener Production from Barley Straw: Optimization of Acid Hydrolysis Condition with the Energy Consumption Simulation

Barley straw from brewing process is an attractive and renewable raw material for the production of biofuel and useful chemicals, such as xylitol. It is necessary to determine the best conditions of biomass hydrolysis and fermentation for boosting the incorporation of this biomass in a biorefinery. We optimized the conditions for acid hydrolysis of barley straw to obtain a hemicellulosic hydrolysate rich in xylose with low energy consumption. Moreover, the energy consumption was simulated per quantity of xylose extracted. In order to obtain a hydrolysate with the highest xylose extraction efficiency (99%), low inhibitors concentration and energy consumption (8.41 KW/Kg Xylose), we used 1.0% H2SO4 (w/v) at 120 °C, with 1:10 dry-weight/acid solution for 40 min. We also optimized the medium composition to improve xylitol production by Candida guilliermondii. The hemicellulosic hydrolysate was used as a fermentation medium and the best condition showing the highest xylitol volumetric productivity (0.69 g L−1 h−1) by C. guilliermondii was found to be 60 g L−1 initial xylose supplemented with 1.5 g L−1 (NH4)2SO4, 0.75 CaCl2 and 8.75 g L−1 rice bran extract. It can be concluded that barley straw can be used in biorefinery, wherein the hemicellulose fraction would be utilized to produce xylitol and the cellulosic fraction (more accessible to enzymatic hydrolysis after pre-treatment) would be used for the production of cellulosic ethanol.

Application of the Severity Factor and HMF Removal of Red Macroalgae Gracilaria verrucosa to Production of Bioethanol by Pichia stipitis and Kluyveromyces marxianus with Adaptive Evolution.

Gracilaria verrucosa, red seaweed, is a promising biomass for bioethanol production due to its high carbohydrate content. The optimal hyper thermal (HT) acid hydrolysis conditions are 12% (w/v) G. verrucosa with 0.2M H2SO4 at 130°C for 15min, with a severity factor of 1.66. This HT acid hydrolysis produces 50.7g/L monosaccharides. The maximum monosaccharide concentration of 58.0g/L was achieved with 96.6% of the theoretical monosaccharide production from 120g dry weight/L G. verrucosa slurry after HT acid hydrolysis and enzymatic saccharification. Fermentation was carried out by removing an inhibitory compound and via yeast adaptation to galactose. Both Pichia stipitis and Kluyveromyces marxianus adapted to galactose were excellent producers, with the ethanol yield (YEtOH) of 0.50 and 29.0g/L ethanol production. However, the bioethanol productivity with Pichia stipitis adapted to galactose is higher than that with Kluyveromyces marxianus adapted to galactose, being 0.81 and 0.35g/L/h, respectively. The results from this study can be applied to industrial scale bioethanol production from seaweed.

A NEW STABILITY-INDICATING RP-HPLC-PDA METHOD FOR SIMULTANEOUS ESTIMATION OF TRIPLICATE MIXTURE OF RAMIPRIL, ATORVASTATIN AND CLOPIDOGREL IN TABLET DOSAGE FORM

Objective: To develop a novel, accurate, precise and linear reverse phase high performance liquid chromatographic (RP-HPLC) method for simultaneous quantitative estimation of ramipril, atorvastatin and clopidogrel in Atamra-CV tablet and validate as per international conference on harmonization (ICH) guidelines and to perform the force degradation studies using the developed method.Methods: In the present work, the good chromatographic separation was achieved isocratically using a shim-pack HPLC Kromasil 150 mm x 4.6 mm, 5 m. m. And mobile phase consisting of 0.05 M potassium dihydrogen orthophosphate pH 3 adjusted with orthophosphoric acid and acetonitrile in the ratio (52:48), at flow rate 1 ml/min and column temperature (30 °C). The effluents obtained were monitored at 210 nm with the UV-visible detector.Results: The retention time of ramipril, atorvastatin and clopidogrel was found to be 2.893 min, 5.012 min and 6.102 min respectively. The linearity of ramipril, atorvastatin and clopidogrel was found in the range of 25-150 % and the correlation coefficient for ramipril, atorvastatin and clopidogrel were>0.999. The high recovery values (98%-101%) indicate a satisfactory accuracy. The low percent relative standard deviation (% RSD) values in the precision study reveals that the method is precise. The three-drug samples were subjected to stress conditions of acidic and alkaline hydrolysis, oxidation, photolysis and thermal degradation. The proposed method proved to be stability-indicating by resolution of the analytes from their forced-degradation products.Conclusion: The developed method is novel, simple, precise, rapid, accurate and reproducible for simultaneous estimation of ramipril, atorvastatin and clopidogrel tablet dosage form. Hence the proposed method may find practical applications as a quality-control tool in the simultaneous analysis of the three drugs in combined dosage forms in quality-control laboratories. The proposed method was made use of photodiode array (PDA) as a tool for peak identification and purity confirmation.

Development and Validation of a Stability-Indicating Liquid Chromatographic Method with Mass-Spectrometric Detection for the Analysis of Apixaban and Determination of Production Related Impurities

Apixaban is a novel anticoagulant drug acting as a direct, selective and reversible inhibitor of coagulation factor Xa. The purpose of this work was to develop and validate a sensitive, stability-indicating LC-MS method for the analysis of apixaban and estimation of production-related substances in the active pharmaceutical ingredient (API) and pharmaceutical dosage forms. The analyses were carried out on a Macherey-Nagel Nucleodur C18 column (250 × 4.6 mm, 5 μm particle size) with a mobile phase containing acetonitrile and water in gradient program at a flow rate of 0.8 mL/min, the column oven temperature 25°C, and the UV detection tuned to 270 nm. Apixaban was subjected to stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation, and found susceptible to acid and base hydrolysis conditions, while it was stable under thermal, photolytic, and oxidative degradation conditions. The degradation products were well resolved from the main peak and its impurities, proving the stability-indicating power of the proposed method. The proposed method was validated as per International Conference on Harmonization (ICH) guidelines. The method is suitable for practical routine analysis and it has been successfully applied to analyze apixaban in eliquis brand preparations. All analytical results were acceptable according to the pharmaceutical requirements.

Mild Acid Hydrolysis of Rice Straw for Highly Efficient Methane Generation with Hydrolysates

Glucose and xylose are the dominant hydrolysis products of lignocellulose, and they can be used as a potential substrate for biogas generation. To reveal the acid hydrolysis metabolism and enhance the methane production, mild acid hydrolysis of rice straw was conducted to obtain hydrolysates with different glucose to xylose ratios. The methane production and microbial metabolism process using mixed sugars and hydrolysates were investigated. The results showed that the cellulose and hemicellulose in the rice straw were converted to the desired sugars by controlling the acid hydrolysis conditions. The glucose to xylose ratios tested were 70:30, 60:40, 50:50, 40:60, and 30:70. The anaerobic digestion process had the highest methane yield with the 40:60 glucose to xylose ratio in the mixed sugars and hydrolysate, which were 334.1 mL/g and 318.2 mL/g based on the chemical oxygen demand (COD), respectively. The metabolic process with the 40:60 glucose to xylose ratio had good butyrate type fermentation and a high COD removal rate. The corresponding acid hydrolysis conditions were 1% HCl and a 7.5% solid loading at 60 °C for 48 h. Therefore, the mild acid hydrolysis conditions can adjust the glucose to xylose ratio in the hydrolysate for high methane production.

Development and application of degradation kinetics of thin layer chromatographic densitometry and conductometric methods for butoconazole nitrate determination

Two simple methods were developed for determination of butoconazole nitrate (BN). The first developed method was stability-indicating HPTLC-densitometric method (method A) which is based on the quantitative densitometric separation of butoconazole nitrate (BN) from its degradation products on silica gel 60 F254 and measurement of the bands at 290nm. The developed stability study of BN was performed under different stress conditions including oxidative, hydrolytic, thermal and photolytic. Degradation was observed under acidic hydrolytic and oxidative conditions. Moreover, the HPTLC method was used to study the kinetics of BN acid degradation, determining as first order kinetics. The degradation rate constant of BN was found to be 0.076 hr-1 and t 1/2 value was determined at 9.12 hr in acidic medium. The second method (Method B) was conductometric method which is based on the reaction of BN with phosphotungstic acid (PTA) to form an ion associate in 50% methanol-water system. Validation of the proposed methods was carried out. All proposed methods were successfully applied for the commercial dosage form of BN. Statistical analysis of the results has been carried out revealing high accuracy and good precision.

Isolation and Characterization of Cellulose Nanocrystals Created from Recycled Laser Printed Paper

This article presents the development of a method to prepare nanocrystalline cellulose (NCCs) from laser-printed waste paper using factorial design 23 experiments by controlled acid hydrolysis of the waste paper. The method applies high gain ultrasound and subsequent flotation, washing, and bleaching stages. Characterization of the raw material, prepared pulp, test sheets, and NCCs is presented. Optimum conditions to obtain high quality NCCs were found to be 65% acid, for 40 min time of treatment, and residual load in the range of 130 to 570 mmol/kg of NCCs. The obtained NCCs were 80 to 700 nm long depending on the acid hydrolysis conditions. They exhibited high values of whiteness (90.3% Elrepho), -cellulose contents (95%), degree of polymerization (731), viscosity (9.59 cP), and chemical compositions similar to that of Whatman paper.

Renewable Isohexide-Based, Hydrolytically Degradable Poly(silyl ether)s with High Thermal Stability.

Several degradable poly(silyl ether)s (PSEs) have been synthesized by dehydrogenative cross-coupling between bio-based 1,4:3,6-dianhydrohexitols (isosorbide and isomannide) and commercially available hydrosilanes. An air-stable manganese salen nitrido complex [MnV N(salen-3,5-tBu2 )] was employed as the catalyst. High-molecular-weight polymer was obtained from isosorbide and diphenylsilane (Mn up to 17000 g mol-1 ). Thermal analysis showed that these PSEs possessed high thermal stability with thermal decomposition temperatures (T-5 % ) of 347-446 °C and glass transition temperatures of 42-120 °C. Structure-property analysis suggested that steric bulk and molecular weight have a significant influence to determine the thermal properties of synthesized polymers. Importantly, these polymers were degraded effectively to small molecules under acidic and basic hydrolysis conditions.

Synthesis and Structure of New gem-Diols with 1,2,3-Triazole Fragment

α-(1,2,3-Triazole)-substituted acetals were obtained using the click procedure. Under acid hydrolysis conditions these acetals were converted into earlier unknown stable gem-diols containing a triazole ring.

Stability-Indicating UV-Spectrophotometric Assay of Diethylcarbamazine Citrate in Pharmaceuticals

Diethylcarbamazine citrate (DEC) is a piperazine anthelmintic agent indicated for the treatment of individual patients with lymphatic filariasis. Two simple and sensitive UV-spectrophotometric techniques have been developed and validated for the determination of this drug in bulk parent substance and tablets, based on the measurement of the absorbance of DEC solution either in 0.1M HCl at 210 nm (method A) or in 0.1M H2SO4 at 209 nm (method B). Beer’s law was obeyed over the concentration ranges of 1.25 – 25.0 and 2.5 – 30.0 μg · mL-1, for method Aand method B, respectively, and the corresponding molar absorptivity values were 2.02 × 104 and 1.21 × 104 L mol-1 · cm-1. The limits of detection (LOD) and quantification (LOQ) were, respectively, 0.26 and 0.78 μg · mL-1 (method A), and 0.16 and 0.49 μg · mL-1 (method B). These methods were assessed for intra-day and inter-day accuracy and precision, as well as robustness and ruggedness. Both methods were applied to one brand of tablets with percentage label claim of 101.7 and 100.8 for method A and method B, respectively, and the standard deviation was below 2%. In order to establish the stability-indicating ability of these methods, the drug was analyzed after subjecting it to acid and base hydrolysis, oxidation, heat and light stress conditions and the results indicated that the drug degraded extensively under both base- and oxidative-stress conditions, and remained intact under other stress conditions.

Characterization of Forced Degradation Products of Rufinamide by LC/QTOF/MS/MS, NMR and IR studies

Rufinamide is a triazole derivative used as an anticonvulsant was subjected to stress degradation under various stress conditions of hydrolysis, oxidation, photolysis and thermal stress as per ICH guideline Q1A (R2). The drug was highly susceptible to acidic and alkaline hydrolytic stress conditions while it remained stable under neutral hydrolytic, oxidative, thermal and photolytic stress conditions. Overall, two degradation products (DP1 and DP2) were formed. DPs were separated by using simple isocratic mode of water and acetonitrile (50: 50, %v/v) on Xbridge C18 (250 mm × 4.6 mm; 5 μm) column. Characterization of DPs was done by using LC/MS/MS, NMR and FT-IR. Further, the mechanistic pathway for formation of two DPs and their fragmentation pathways were postulated. The developed HPLC isocratic method was validated as per ICH guidelines.

Preparation of Oligosaccharides by Degradation of Polysaccharides from Chinese Jujube and Its Biological Activity

This study examined the degradation of polysaccharides to oligosaccharides in Chinese jujube fruits. Using a response surface model, the degradation conditions of polysaccharides under acid hydrolysis and enzymatic hydrolysis were optimized in laboratory conditions. A degradation rate of 66.9% was obtained under optimum acid hydrolysis conditions: 0.6 mol/L hydrochloric acid, 3% substrate concentration, and 1 h reaction time. A degradation rate of 41.4% was obtained under optimum enzyme hydrolysis conditions: 4.0 mL cellulose solution (10 mg/mL), 0.3 mL substrate solution (20 mg/mL), 0.7 mL citric acid buffer solution (pH 5), and 7.3 h reaction time. Using the stimulation effect for strain J-4 intestinal probiotic proliferation, the biological activity of oligosaccharides was determined. The results showed that the oligosaccharides from enzyme hydrolysis encouraged intestinal probiotic proliferation.

Determination of Polysaccharide Hydrolyzates in Chinese Herbal Medicine by UltraHigh-Performance Liquid Chromatography-Quadrupole Time-of-Flight Mass Spectrometry and Evaporative Light Scattering Detection

ABSTRACTUltrahigh-performance liquid chromatography coupled with evaporative light scattering detector was used to optimize acid hydrolysis conditions of polysaccharides from Dendrobium candidum. The optimized conditions were the concentration of H2SO4, 0.4 M, hydrolysis temperature, 90°C, and hydrolysis time, 1 h. Ultrahigh-performance liquid chromatography-quadrupole time-of-flight mass spectrometry was used to obtain the total ion current chromatograms and determine the hydrolyzates of polysaccharides, such as monosaccharides, oligosaccharides, and some low-molecular weight polysaccharides from D. candidum, Cordyceps sinensis, and Ganoderma atrum. The accurate mass data were analyzed by chemometric tools, including an unsupervised analytical method, principal component analysis (one-way ANOVA, p < 0.05), and five supervised analytical methods, partial least square discriminant analysis, support vector machine, naïve Bayes, decision tree, and neural network. The results showed that D. candidum polysaccharides from different locations and grades can be discriminated effectively by the principal component analysis scores. The quality predictive models showed a high value with a low prediction error calculated from both validation and training sets.

Enhancement of Ethanol Production via Hyper Thermal Acid Hydrolysis and Co-Fermentation Using Waste Seaweed from Gwangalli Beach, Busan, Korea.

The waste seaweed from Gwangalli beach, Busan, Korea was utilized as biomass for ethanol production. Sagassum fulvellum (brown seaweed, Mojaban in Korean name) comprised 72% of the biomass. The optimal hyper thermal acid hydrolysis conditions were obtained as 8% slurry contents, 138 mM sulfuric acid, and 160°C of treatment temperature for 10 min with a low content of inhibitory compounds. To obtain more monosaccharides, enzymatic saccharification was carried out with Viscozyme L for 48 h. After pretreatment, 34 g/l of monosaccharides were obtained. Pichia stipitis and Pichia angophorae were selected as optimal co-fermentation yeasts to convert all of the monosaccharides in the hydrolysate to ethanol. Co-fermentation was carried out with various inoculum ratios of P. stipitis and P. angophorae. The maximum ethanol concentration of 16.0 g/l was produced using P. stipitis and P. angophorae in a 3:1 inoculum ratio, with an ethanol yield of 0.47 in 72 h. Ethanol fermentation using yeast co-culture may offer an efficient disposal method for waste seaweed while enhancing the utilization of monosaccharides and production of ethanol.

Improved fermentation performance to produce bioethanol from Gelidium amansii using Pichia stipitis adapted to galactose.

This study employed a statistical method to obtain optimal hyper thermal acid hydrolysis conditions using Gelidium amansii (red seaweed) as a source of biomass. The optimal hyper thermal acid hydrolysis using G. amansii as biomass was determined as 12% (w/v) slurry content, 358.3mM H2SO4, and temperature of 142.6°C for 11min. After hyper thermal acid hydrolysis, enzymatic saccharification was carried out. The total monosaccharide concentration was 45.1g/L, 72.2% of the theoretical value of the total fermentable monosaccharides of 62.4g/L based on 120g dry weight/L in the G. amansii slurry. To increase ethanol production, 3.8g/L 5-hydroxymethylfurfural (HMF) in the hydrolysate was removed by treatment with 3.5% (w/v) activated carbon for 2min and fermented with Pichia stipitis adapted to high galactose concentrations via separate hydrolysis and fermentation. With complete HMF removal and the use of P. stipitis adapted to high galactose concentrations, 22g/L ethanol was produced (yield 0.50). Fermentation with total HMF removal and yeast adapted to high galactose concentrations increased the fermentation performance and decreased the fermentation time from 96 to 36h compared to traditional fermentation.

Surface Charge Influence on the Phase Separation and Viscosity of Cellulose Nanocrystals.

A series of four cellulose nanocrystal (CNC) suspensions were prepared from bleached softwood kraft pulp using different conditions of sulfuric acid hydrolysis. The CNCs were identical in size (95 nm in length × 5 nm in width) but had different surface charges corresponding to the harshness of the hydrolysis conditions. Consequently, it was possible to isolate the effects of surface charge on the self-assembly and viscosity of the CNC suspensions across surface charges ranging from 0.27%S to 0.89%S. The four suspensions (never-dried, free of added electrolyte) all underwent liquid crystalline phase separation, but the concentration onset for the emergence of the chiral nematic phase shifted to higher values with increasing surface charge. Similarly, suspension viscosity was also influenced by surface charge, with suspensions of lower surface charge CNCs more viscous and tending to gel at lower concentrations. The properties of the suspensions were interpreted in terms of the increase in effective diameter of the nanocrystals due to the surface electrostatic repulsion of the negative sulfate half-esters, as modified by the screening effects of the H+ counterions in the suspensions. The results suggest that there is a threshold surface charge density (∼0.3%S) above which effective volume considerations are dominant across the concentration range relevant to liquid crystalline phase formation. Above this threshold value, phase separation occurs at the same effective volume fraction of CNCs (∼10 vol %), with a corresponding increase in critical concentration due to the decrease in effective diameter that occurs with increasing surface charge. Below or near this threshold value, the formation of end-to-end aggregates may favor gelation and interfere with ordered phase formation.

Effect of acid hydrolysis and OSA esterification of waxy cassava starch on emulsifying properties in Pickering-type emulsions

The emulsifying properties of waxy cassava starch modified by acid hydrolysis and esterification with octenyl succinic groups in Pickering-type emulsions were evaluated using zeta potential, emulsification index, light microscopy and rheology behavior. The optimal conditions of acid hydrolysis to achieve the highest emulsification index were determined to be a hydrochloric acid concentration of 4 mol/L for 5.20 h. After that, the starch was esterified to obtain a double modification. The emulsification index values were acid treated/succinated starch > optimal acid treated starch > native starch. The acid treated/succinated starch emulsion presented higher storage modulus (G′) values, without G’ and loss modulus (G”) crossing point in the evaluated frequency range. Acid hydrolysis modified the emulsifying properties of waxy cassava starch improving its interaction at the oil/water interface. According to observations by light microscopy and rheology behavior, the double modification formed a more uniform and stable network over time through granule-granule and granule-interface interactions.

HPTLC determination of diosgenin in fenugreek seeds.

A new HPTLC-densitometric method for diosgenin determination in fenugreek seeds was established after optimization of the conditions for efficient saponin extraction and acid hydrolysis. Several procedures were tested, the best of which was a three-step Soxhlet extraction, followed by hydrolysis of the obtained methanolic extract with 2 mol L-1 H2SO4. Best diosgenin separation from other hydrolysis products was obtained on HPTLC Si60F254 plates u sing a mixture of n-heptane/ethyl acetate (7:3, V/V) and modified anisaldehyde as a spraying reagent. The method was preliminarily validated and the determined amounts of diosgenin in fenugreek seeds of Polish and African origin were found to be similar and ranged from 0.12-0.18 %.

Optimization of the polysaccharide hydrolysate from Auricularia auricula with antioxidant activity by response surface methodology

An efficient acid-hydrolysis method was developed and optimized for the hydrolyses of polysaccharide from Auricularia auricula with the ABTS· scavenging ability as the detective marker. Based on the single factor experimental results, Box-Behnken design (BBD) were applied for the optimization of acid-hydrolysis conditions. The possible antioxidant mechanism of the hydrolyses (AAPs-F) in vivo was performed using the C. elegans model. The acid-hydrolysis conditions were found to be the optimal hydrolyzing time 2.78h (166.8min), hydrolyzing temperature 95.04°C and the acid concentration 14.03mol/L, respectively. Under the optimal acid-hydrolysis conditions, the ABTS· scavenging ability of AAPs-H was 97.94±0.87%, which was well matched with the predicted value (99.77%) of the BBD model. AAPs-F was the main fraction of AAPs-H separated through Sephadex G-10 as the stationary phase. AAPs-F was a kind of heteropolysaccharide and comprised of glucose, galactose and fucose with the molar ratio of 50:1:2. The molecular weight of AAPs-F was 143.15kDa. AAPs-F showed a remarkable protective effect to the injury induced by hydrogen peroxide or paraquat (p<0.01), and it could up-regulate stress-resistance related enzymes including superoxide dismutase (SOD) by 109.74% and CAT by 106.84% at concentration of 0.2mg/mL in C. elegans.

Characterization of forced degradation products of canagliflozine by liquid chromatography/quadrupole time-of-flight tandem mass spectrometry and in silico toxicity predictions.

Forced degradation studies are useful for better understanding of the stability of active pharmaceutical ingredients and drugs and to generate information about drug degradation pathways and formation of degradation products (DPs). Identification of DPs plays a vital role in establishing the safety and therapeutic benefit of a drug. Canagliflozin (CAN) was subjected to different stress conditions as per International Conference on Harmonization guidelines (Q1A R2). All the DPs and the drug were well separated on an Aquity CSH C18 (100 × 2.1mm, 1.7 μm) column using acetonitrile-methanol (70:30, v/v) and formic acid in gradient mode. The same UPLC method was employed for LC/HRMS for the characterization of DPs. In addition, in silico toxicity was predicted for all the DPs by using TOPKAT and DEREK software tools. CAN was found to degrade under oxidative stress condition and formed DP1 and DP2. This is a typical case of degradation where co-solvents acetonitrile-water (50:50, v/v) and methanol-water (50:50, v/v) react with CAN under acid hydrolytic conditions leading to the formation of pseudo-DPs, DP3 and DP4, respectively. Among these, DP2 and DP3 showed ocular irritancy whereas DP1 showed skin sensitization. The drug was labile under oxidative stress condition. CAN reacted with co-solvent under acid hydrolytic conditions and gave pseudo-DPs. All the DPs were separated using UPLC and characterized by LC/QTOF/MS/MS. Toxicity of DPs was evaluated using TOPKAT and DEREK software tools.