Mixture Of Formic Acid Research Articles

Proceeding toward the development of poly(ɛ-caprolactone)/cellulose microfibrils electrospun biocomposites using a novel ternary solvent system

In the current study, a mixture of formic acid (FA), acetic acid (AA), and acetone was used, for the first time, as a ternary solvent system to dissolve poly(ɛ-caprolactone) (PCL). In addition, as a biomaterial reinforcement, various amounts of cellulose microfibrils (CMF) (1.5, 3, and 5 wt.%), extracted from rice husk, were added to PCL solution, and subsequently the prepared suspensions were individually electrospun. Adding acetone to FA/AA solvent system led to fabrication of uniform electrospun nanofibers with the average diameter of 178 ± 38 nm. Upon CMF incorporation, the mean electrospun fiber diameter was increased to 320 ± 132 nm at 5 wt.% CMF mostly due to the solution viscosity rise. In addition, scanning electron microscopy (SEM) confirmed wider diameter distribution in the presence of CMF. The electrospun fibers were also analyzed via wide angle X-ray scattering (WAXS) and differential scanning calorimetry (DSC) to study the supermolecular structure and thermal behavior of fibrous bionanocomposites, respectively. Both the characterizations positively affect the PCL crystallinity as a result of CMF incorporation. The DSC measurements showed the highest crystallinity (70.11%) at 1.5 wt.% CMF incorporation. The effect of CMF addition on the hydrophilicity of PCL was also investigated by contact angle measurement, where a decreasing trend in contact angle was observed upon CMF loading. Moreover, in vitro degradability of the bionanocomposite nonwoven mats was studied in PBS solution. The rate of degradation was enhanced in the presence of CMF. Moreover, tensile mechanical analysis was carried out and CMF inclusion had a reinforcing impact on electrospun PCL. The highest modulus (19.17 ± 0.8 MPa) and ultimate tensile strength (UTS) (4.45 ± 0.32 MPa) were achieved at 1.5 wt.% CMF addition to PCL.

Electrospinning process optimization for Nylon 6,6/Epoxy hybrid nanofibers by using Taguchi method

In this study, Taguchi method has been exploited to optimize the electrospinning process to produce hybrid nanofibers composed from Nylon 6, 6 (NY) and Epoxy (EP) polymers. Both polymers has been dissolved, with a sequence technique, in 80:20 mixture of Formic acid (FA)/Dichloromethane (DCM) solvent to form a homogenous electrospinnable (NY/EP/solvent) polymer solutions. Naylon 6, 6 was added to epoxy with weight ratio of 1, 2, 3, 4 and 5. NY/EP/solvent solutions were prepared and design of experiment was utilized to determine the optimal factors which affect the average electrospun hybrid nanofibers diameter of Nylon 6, 6/epoxy. The effect of two main factors (NY/EP ratios and Nylon 6, 6/solvent concentration) on the electrospun hybrid fiber diameter and its morphology was investigated. An extensive study for the effect of Berry’s number on the formation of hybrid fibers has been conducted too. Taguchi method and ANOVA results indicate that the Nylon 6, 6/solvent concentration is the most significant factor exhibiting best morphology and optimum diameter for the electrospun hybrid nanofibers. The minimum hybrid nanofiber diameter and its standard deviation was found to be 180 ± 35 nm corresponds to 8 wt% Nylon 6, 6/solvent and NY/EP ratio of 5:1. Infrared spectra and Nuclear magnetic resonance spectroscopy were used to confirm the coexistence of both epoxy and Nylon 6, 6 polymers in the electrospun hybrid nanofibers. Glass transition temperature of hybrid nanofibers was measured by differential scanning calorimeter. Incorporation of the epoxy in the fibers resulted in 5% increase in glass transition temperature indicating that the addition of epoxy has confined the mobility of the polymer chains. Also, an improvement in both tensile strength and modulus of elasticity of the electrospun NY/EP hybrid nanofibers has been notified and reported.

Application of organic acids in Clarias gariepinus Burchell, 1822 aquafeed: impacts on fish relative growth rate, condition factor and cannibalism ratio

The present research was performed to determine the relative growth rate (RGR), condition factor (K) and cannibalism ratio (CR) of Catfish (Clarias gariepinus Burchell, 1822) fed different level and types of organic acid addition in the fish. Eighty fish were randomly assigned into five group triplicates, reared, and fed different type organic acid supplemented viz: control diet with no organic acid addition (B1); mixture of formic, acetic and propionic acid at level 0.05% (B2); mixture of formic, acetic and propionic acid at level 0.1% (B3); 0.05% butyric acid (B4); 0.1% butyric acid (B5), for 8 weeks. At the end of the 8th week, RGR, K, and CR were determined. Fish fed 0.1% mix of formic, acetic and propionic acid or 0.1% butyric acid in the diet had the significantly higher (p<0.05) RGR than control or other groups. Meanwhile, the K and CR of fish during the trial were not affected by any various and levels of the organic acid. In conclusion, the supplementation of 0.1% mix organic acid or 0.1% butyric acid in the diet of C. gariepinus for 8 weeks enhanced the RGR of the catfish but no effect on the condition factor and cannibalism ratio.

Postmortem analysis of human bone marrow aspirate - Quantitative determination of SSRI and SNRI drugs

For the first time the MAE/UHPLC-TOFMS method was developed and used in order to determine the antidepressant drugs within the human bone marrow aspirate in real forensic cases. The following drugs, belonging to the group of selective serotonin (or serotonin-norepinephrine) reuptake inhibitors, were tested in this study: venlafaxine, citalopram, fluoxetine, sertraline and paroxetine. The sample preparation proposed in the present article included several steps: homogenization in ultrasound bath, liquid-liquid extraction, fat removal and evaporation under nitrogen. The extraction involved microwave-assisted extraction, performed for 15 min at 55 °C, with hexane-isoamyl alcohol (99:1, v/v) mixture, as an extraction solvent. Time and temperature of extraction were optimized using the simplex method. The fat removal step was introduced because of the fatty nature of the bone marrow that resulted in insufficiently purified samples, impossible to analyze using HPLC. It was achieved by adding a mixture of ethanol, water and formic acid to samples consisting of hexane and isoamyl alcohol, so that the analytes could diffuse to polar phase and fat could stay in non-polar phase. The method was validated and parameters such as: LOD, LOQ, linearity, matrix effect, recovery were determined. The validation parameters obtained allowed to recognize the method as quantitative. Due to lack of the data on therapeutic and toxic levels of considered drugs in bone marrow, data regarding serum has been used for reference. Under this assumption, the developed method allows for quantification of all mentioned drugs at therapeutic levels. Moreover this method has been used in real cases. Finally four analytes: venlafaxine (104 ng/mL), fluoxetine (84 ng/mL), paroxetine (about 3.6 μg/mL) and citalopram (68 ng/mL) were found in three case samples.

Surfactant-Assisted Selective Oxidation of Aromatic Amines to Nitro Compounds by in Situ-Formed Performic Acid.

Development of novel and greener methods for the selective oxidation of various organic compounds is a challenging task. Herein, a novel protocol for the selective oxidation of aromatic amines to nitroaromatics at room temperature is developed. The oxidation reaction was carried out using a mixture of formic acid and aqueous hydrogen peroxide, which resulted in the in situ formation of performic acid. Further, improvement of selectivity was studied using different surfactants, of which cetyltrimethylammonium bromide (CTAB) gave the highest selectivity (85%) toward nitrobenzene. The role of CTAB in achieving higher selectivity is discussed. Under optimized reaction conditions, various substituted amines were successfully oxidized to corresponding nitro compounds. It is worth mentioning that this is the first report on oxidation of amines to nitro compounds in an aqueous medium with high selectivity.

TLC fingerprint with chemometrics and antioxidant activity of selected lichens

Selected lichens, collected in forests near Lublin (Poland) were extracted using Soxhlet apparatus with dichloromethane and methanol as solvents. The obtained extracts were analyzed using the Thin Layer Chromatography with silica gel as adsorbent and the mixture of toluene, ethyl acetate and formic acid (10/10/0.5; v/v/v, respectively) as mobile phase. Developed chromatographic plates were sprayed using the Naturstoff reagent to confirm the presence of some phenolic compounds. The images of plates were digitalized using TLC Analyzer software and the obtained chromatograms were exported to Excel and converted to csv files. Next csv files were loaded to SpecAlign program, where the smoothing, subtraction (original word misspelled) of background and normalization were performed. The chemical differences between samples were confirmed using the similarity (Pearson correlation coefficient) and distance (Euclidean distance) indices with cluster analysis and Principal Component Analysis (PCA). Additionally, the preliminary evaluation of the antioxidant activity of the examined extracts of lichens was performed by use of the DPPH TLC test.

Immune Response of Piglets Receiving Mixture of Formic and Propionic Acid Alone or with Either Capric Acid or Bacillus Licheniformis after Escherichia coli Challenge.

This study aims to evaluate whether diets containing mixture of formic and propionic acid alone or supplemented with either capric acid or Bacillus Licheniformis can alleviate immune inflammatory response of piglets challenged with enterotoxigenic Escherichia coli (ETEC). A total of 30 weaning pigs were assigned to 5 diets, without additive (CON), with antibiotics (ATB), with 1% organic acid (OA; 64% formic and 25% propionic acid), with OA plus 0.2% capric acid (OA + CRA), and with OA plus 0.02% probiotic (Bacillus Licheniformis; OA + PB). After oral challenge with ETEC on day 10, the feces and plasma of all pigs were collected at different time points. Four additive treatments all decreased rectal temperature (RT) at 9 h and fecal scores (FS) at 24 h after challenge (P < 0.05), while at 9 h after challenge, inclusion of OA induced a decrease of RT compared with OA + CRA and OA + PB (P < 0.05). In plasma, concentration of interleukin (IL)-1β was reduced with the addition of ATB and OA at 24 h and 48 h after challenge and it is lower in OA group than OA + CRA group at 24 h after challenge (P < 0.05). Diets with ATB, OA, and OA + PB caused a decrease of the concentrations of IL-6 in plasma at 9 h after challenge (P < 0.05). The four additives treated piglets showed decreased concentrations of plasma tumor necrosis factor-α and interferon-γ at 9 h and 24 h after challenge, respectively (P < 0.05). In conclusion, OA supplementation alleviated the inflammatory response and reduced diarrhea incidence in piglets challenged with ETEC. However, no further improvements were observed when OA supplemented with CRA or probiotics.

Fractionation of Lignocellulosic Biomass over Core-Shell Ni@Al2 O3 Catalysts with Formic Acid as a Cocatalyst and Hydrogen Source.

Highly dispersed, core-shell Ni@Al2 O3 on activated carbon (AC) catalysts were prepared to develop an effective, external-hydrogen-free fractionation process for various types of lignocellulosic biomass. In a mixture of formic acid, ethanol, and water at 190 °C, the conversion of oak wood produced 23.4 C% lignin-derived phenolic monomers (LDPMs) and highly delignified pulp-rich solid. At an early stage, formic acid acted as a cocatalyst to enhance the delignification by solvolysis, and at a later stage, it acted as a hydrogen source to stabilize the phenolic monomers by hydrodeoxygenation and hydrogenation. Based on the positive correlation between spillover hydrogen on the catalysts and LDPM yields, a new suite of catalyst design criteria was proposed to develop highly active, non-noble-metal based catalysts for realizing economically viable biorefineries. Enzymatic saccharification of the pulp-rich solid indicated that the pulp-rich solid is an excellent source of fermentable sugars.

Measurement and Modeling of Solid–Liquid Equilibria of l-Glutamic Acid in Pure Solvents and Aqueous Binary Mixtures

The experimental solubility data of l-glutamic acid in pure water, formic acid, methanol, 1-propanol, 2-propanol, acetonitrile, and binary mixtures (formic acid + water, methanol + water, 2-propanol + water, acetonitrile + water) with different compositions were carried out at temperatures ranging from (283.15 to 328.15) K by the static analytic method. The solubility measurements showed that formic acid and its aqueous mixtures recorded a higher solubility than methanol + water, 2-propanol + water, and acetonitrile + water for the same composition at each temperature. Moreover, except formic acid the addition of methanol, 2-propanol, and acetonitrile to its aqueous mixtures resulted in the decrease in solubility of l-glutamic acid. The experimental data was fitted using different thermodynamic models such as the Buchowski-Ksiazczak equation, the Van't Hoff equation, the modified Apelblat equation, and the NRTL model, and the optimum values of the regressed parameters were obtained. The modified Apelblat equation, Buchowski-Ksiazczak equation, and NRTL activity coefficient model were fitted to the pure solvents solubility data, while the modified Apelblat, modified Apelblat-Jouyban-Acree, and NRTL models were used for the binary solvent systems. The results demonstrated formic acid as a cosolvent in the dissolution of l-glutamic acid in formic acid + water binary mixtures, while others exhibited an antisolvent effect on the solubilization of l-glutamic acid in their respective aqueous mixtures.

Electrospun polycaprolactone/silk fibroin nanofibrous bioactive scaffolds for tissue engineering applications

Degumming of Bombyx mori silk cocoons by a novel and mild process using aqueous ammonia and fabrication of electrospun polycaprolactone/silk fibroin (PCL/SF) nanofibrous scaffolds is reported. Cocoons were degummed in 0.3% w/w solutions of boiling ammonia (28–30%) for 45 min. Degummed SF fibers were dissolved in phosphoric and formic acid (7/3 v/v) mixture, coagulated in methanol, filtered and dried. PCL solutions containing different amounts of SF were electrospun in formic acid, a green solvent. Scaffolds were characterized to confirm the successful incorporation of SF and to demonstrate formation of nanofibrous webs with good biomechanical properties. Cell viability assay was performed by seeding Human BJ fibroblast cells on scaffolds. In vitro analysis showed that the scaffolds produced were non-toxic and incorporation of SF resulted in enhanced cell proliferation. Nanofibrous PCL/SF scaffolds with good biomechanical properties developed through dialysis free processing of silk fibroin can be promising substrates for tissue engineering applications.

A diethylpyrocarbonate-based derivatization method for the LC-MS/MS measurement of plasma arginine and its chemically related metabolites and analogs

BackgroundChanges in NO metabolism correlate with cardiovascular risk factors and are associated with endothelial dysfunction. NO availability is regulated by nitric oxide synthase (NOS) and arginine and some chemically related metabolites and analogs have the capacity to alter NOS activity. Hence the need for analytical methods for the simultaneous assessment of these analytes. MethodsAnalytes (L-arginine (Arg), NG-monomethyl-L-arginine (MMA), L-homoarginine (hArg), asymmetric dimethyl-L-arginine (ADMA), symmetric dimethyl-L-arginine (SDMA), and L-citrulline (CIT)) were isolated from human plasma by thermal coagulation of plasma followed by a derivatization with diethylpyrocarbonate. Carbetoxy derivatives were separated on a C18 reversed-phase column in <10 min using an aqueous solution of 0.4% v/v formic acid and acetonitrile (95:5, v/v) mixture as a mobile phase. Positive electrospray ionization and tandem mass spectrometry in combination with specific multiple reaction monitoring transitions were used for detection of analytes and three deuterated forms of the analytes used as internal standards. ResultsIntra- and inter-day precision %RSD values ranged between 3 and 5.5% and percentage recoveries were close to 100% for all analytes. Plasma concentrations in 20 healthy male volunteers were 58.62 ± 8.81 μmol/L for Arg, 105.08 ± 21.66 nmol/L for MMA, 1.88 ± 0.57 μmol/L for hArg, 0.612 ± 0.140 μmol/L for ADMA, 0.581 ± 0.172 μmol/L for SDMA, and 28.62 ± 11.60 μmol/L for Cit, respectively. ConclusionThis LC–MS/MS method provides the capacity to quantify the plasma concentrations of arginine and some of its chemically related metabolites. Sample preparation was simple, inexpensive and effortless. Overall, given the short sample preparation and chromatographic run time, the method may be suitable for the fast and reproducible quantitative determination of the analytes in large clinical trials and routine analysis.

Preparation of alumina precursor sols with a high solid content for alumina fibers

Precursor sol with a high solid content is significant for alumina fiber synthesis. In the present work, alumina precursor sols used for preparing alumina fibers were synthesized by dissolving aluminum powder (AP) into a mixture of formic acid, acetic acid and deionized water. The effects of preparation temperatures on solubility of AP, structure of the synthesized sols and gels were investigated. The reaction mechanism of hydrolysis and polymerization was also studied. Based on the reaction mechanism, alumina precursor sol with a high solid content was acquired through the adjustment of temperature. The results revealed that all the sols synthesized at the temperature from 85 °C to 115 °C consisted of polymers, linear oligomers and monomeric species. Colloidal particles presented spherical shape with a uniform size. However, AP cannot dissolve entirely at 85 °C and white precipitates (HO)Al(CH3COO)2 was produced at 105 °C and 115 °C. AP had the highest dissolution degree at 95 °C. A colorless and transparent alumina sol with the highest solid content was acquired at this temperature. The structure of concentrated gels was also discussed. It was revealed that network polymers increased when using sols synthesized at temperature above 105 °C, which were negative for spinning. Continuous green fibers were obtained successfully using the alumina sol prepared at 95 °C.

Dietary acidifiers blend enhanced the production of Nile tilapia (Oreochromis niloticus), striped mullet (Mugil cephalus), and African catfish (Clarias gariepinus) polycultured in earthen ponds

Organic acids and/or their salts could be used as acidifiers to improve the performance, health, and immunity status of aquatic organisms. Generally, a single acidifier is used as a feed additive but the present study used a multiple acidifiers blend (Latibon®), which is a mixture of formic acid (25.7%), lactic acid (11.5%), and citric acid (7.0%). In the present study, each pond (3 acres) of nine earthen ponds was stocked with 15,000 Nile tilapia (NT; 2.1 ± 0.2 g), 3000 striped mullet (SM; 10.7 ± 1.7 g), and 300 African catfish (AC; 218.0 ± 10.3 g) representing a fish biomass of 10.5–11.5, 10.9–11.2, and 5.4–5.5 kg/acre, respectively. Latibon® was incorporated to a floating diet at levels of 0.0 (control), 1.5, and 3.0 g/kg diet. Fish fed one of the tested diets up to apparent satiation for a period of 20 min thrice a day at 9:00, 12:00, and 16:00 h for 28 weeks. At the end of the feeding period, each pond was drained and fish of each cultured species were collected, counted, and group-weighed. No significant difference was observed in fish survival among the different treatments and its range was 92.1–93.4% for NT, 86.2–87.6% for SM, and 87.3–90.3% for AC. The production of NT, SM, and AC increased significantly as levels of Latibon® increased from 0.0 (828.9, 273.9, and 68.2 kg/acre, respectively) to 3.0 g/kg diet (1204.4, 304.3, and 77.8 kg/acre, respectively). The total fish yield in the control ponds was 1171.0 kg/acre, while it was maximized in ponds fed 3.0 g/kg diet of Latibon® (1586.5 kg/acre). This is because fish consumed more feed with increasing the levels of Latibon® from 0.0 (4614.0 kg feed/pond) to 3.0 g/kg diet (6256.0 kg feed/pond) with insignificant differences in feed conversion ratios per ponds (1.34–1.35). Nile tilapia was the target fish; however, its production percentage to the total fish yield was 75.9%, whereas those of SM and AC were 19.2% and 4.9%, respectively, in ponds received 3.0 g/kg of Latibon®. Additionally, in this treatment, the sale of NT represented 62.8% of the total fish sale, whereas these of SM and AC were 34.1 and 3.1%, respectively. The simple economic analysis revealed that the net profit of ponds received 3.0 g/kg diet of Latibon® increased by 23.3% over that received the control diet. Thus, the present study recommends the incorporating of 3.0 g/kg diet of Latibon® to fish diets.

Validated isocratic liquid chromatographic method for the quantification of teneligliptin in the presence of internal standard

Introduction: Teneligliptin (TGP) is an oral dipeptidyl peptidase inhibitor used for the treatment of type 2 diabetes mellitus. A simple liquid chromatographic method has been established on isocratic mode for the quantification of TGP in pharmaceutical formulations in the presence of internal standard (IS) eplerenone, and the method was validated. Materials and Methods: Methanol and formic acid mixture was used with a flow rate of 0.4 ml/min (detection at 244 nm) using Agilent column on Shimadzu high-performance liquid chromatography system. Results and Discussion: TGP was eluted at 5.099 min and that of IS at 8.535 min. TGP has shown linearity 1–100 μg/mL with regression equation, y = 95722x–6775.4 correlation coefficient 0.9999. The limit of detection and limit of quantification are found to be 0.2598 μg/mL and 0.8134 μg/mL, respectively. Conclusion: It is observed that this reverse-phase ultra-fast liquid chromatography method is accurate and precise and can be used for the estimation of TGP tablets.

Electrochemical and Mass Transport Characteristics of the Strongly Basic MA-41 Membrane Modified by Poly-N,N-Diallylmorpholinium

Poly-N,N-diallylmorpholinium bromide is synthesized and characterized using the methods of IR and NMR spectroscopy. The surface modification of MA-41 industrial heterogeneous membranes (Russia) by this polyelectrolyte is carried out from an equivalent mixture of N-methylpyrrolidone and anhydrous formic acid and also from aqueous solutions. The electrochemical characteristics of the modified membranes are studied on the setup with a rotating membrane disk. It is found that the reaction of water dissociation on modified membranes occurs less intensively than on the initial membrane and the main mass transport mechanism in the superlimiting current modes in systems with modified membranes is electroconvection.

Mixtures of 5-hydroxymethylfurfural, levulinic acid, and formic acid have different impact on H2-producing Clostridium strains

Fermentative hydrogen production allows the use of renewable biomasses as feedstocks. However, biomass saccharification results not only in carbohydrates, but also in products that can inhibit fermentation. Although biomass hydrolysates contain mixtures of inhibitors, most studies are performed with a single inhibitor. This study evaluates how 5-hydroxymethylfurfural (HMF, 0.60 g/L), levulinic acid (LA, 2.10 g/L), and/or formic acid (FA, 0.80 g/L) mixtures affect two H2-producing clostridia, Clostridium beijerinckii Br21 and Clostridium acetobutylicum ATCC 824. Fermentation assays with and without (control) the inhibitors helped to calculate the specific H2 production, substrate consumption, and bacterial cell growth rates for Clostridium beijerinckii Br21 or Clostridium acetobutylicum ATCC 824. HMF + AL, HMF + AF, AL + AF, and HMF + AL + AF mixtures inhibited H2 production by C. beijerinckii Br21 by 58.7, 60.0, 46.9, and 83.0%, respectively, and by C. acetobutylicum ATCC 824 by 68.1, 71.4, 58.2, and 89.0%, respectively. Clostridium acetobutylicum ATCC 824 metabolized HMF more efficiently. However, organic acids and their combination with HMF inhibited H2 production by C. beijerinckii Br21 to a lesser extent, which highlighted that this microorganism is robust for H2 production from biomass hydrolysates.

Development of LC-MS and LC-MS/MS Methods for Free Asparagine in Grains

New analytical methods for the determination of free asparagine （Asn）, which is a precursor of acrylamide, in grains were developed using LC-MS and LC-MS/MS. Asn was extracted from a sample with 5％ （w/v） aqueous trichloroacetic acid solution, appropriately diluted with 0.1％ （v/v） formic acid solution, and then analyzed by LC-MS or LC-MS/MS. HPLC separation was performed by isocratic elution on a Penta Fluoro Phenyl （PFP） column using 0.1％ （v/v） formic acid and acetonitrile mixture as the mobile phase. The calibration curve was linear in the range of 0.005-0.1 μg/mL. The mean recoveries from potato starch, non-glutinous rice flour and whole wheat flour ranged from 95.4 to 100.9％, repeatability （RSD） ranged from 0.9 to 6.0％, and within-laboratory reproducibility （RSDwr） ranged from 2.8 to 7.1％. Limits of quantitation （LOQs） were 7 mg/kg for potato starch, and 5 mg/kg for non-glutinous rice flour. In addition, an inter-laboratory study was performed in 10 laboratories using 5 kinds of grains （non-glutinous brown rice flour, corn flour, strong flour, whole wheat flour, and whole rye flour）, which naturally contained free asparagine. The HORRATR values ranged from 0.4 to 1.0. These results are within the range of the procedural manual of the Codex Alimentarius Commission, confirming the effectiveness of the developed procedures.

Determination of tocopherols and tocotrienols in human breast adipose tissue with the use of high performance liquid chromatography-fluorescence detection.

Tocopherols and tocotrienols have been extensively studied owing to their anticancer potential, especially against breast cancer. Therefore, the aim of this study was to quantitatively determine tocochromanols in human breast adipose tissue with the use of HPLC-FLD. The sample preparation procedure included homogenization and solvent extraction with isopropanol-ethanol-0.1% formic acid mixture prior to solid-phase extraction. After implementation of central composite design, satisfactory separation of all eight target compounds was achieved within 10.5 min. Chromatographic runs were carried out with the use of a naphthylethyl chromatographic column with methanol-water mixture (89:11, v/v) as the mobile phase. Fluorescence detection of tocochromanols was performed with excitation and emission wavelengths 298 and 330 nm, respectively. The method was validated in terms of linearity, carryover, recovery, precision, accuracy and stability. Extraction yield was also determined for accurate evaluation of vitamin E content in human breast adipose tissue samples. Finally, concentrations of particular tocochromanols compounds were assessed in human breast adipose tissue samples obtained from 99 patients, including women with breast cancer, healthy volunteers and deceased women who had died as a result of accidents. The raw data was transformed according to the newly developed equation for accurate estimation of the concentrations of tocochromanols in breast adipose tissue samples. Results obtained in the study indicated that the proposed analytical assay could be useful in breast cancer research.

Functional transformation of Fourier-transform mid-infrared spectrum for improving spectral specificity by simple algorithm based on wavelet-like functions

Herein a simple algorithm for the mathematical transformation of FTIR spectrum was developed, evaluated, and applied for description of different systems. Water, ethanol, n-butanol, n-hexanol, formic acid, acetic acid, citric acid, and water-acetic acid mixtures at different concentrations were used as model systems. We found that functional transformation of FTIR spectrum can be performed by functionally-enhanced derivative spectroscopy approach using the Function P, which is defined as P = (1 + aj)(s)−0.5 where aj and s are the absorbance and the scale factor, respectively. It is also demonstrated that Function P can be used for qualitative and quantitative analysis of pure substances and mixtures. It is concluded that Function P can be understood as a wavelet transformation, which is evaluated at small times and displacements, with scaling factor given by the change of absorbance inverse.

Nickel determination in oily sludge leachates using isotope dilution inductively coupled plasma mass spectrometry following photochemical vapor generation: A feasibility study

The feasibility of photochemical vapor generation for the production of volatile Ni species was evaluated and applied to the analysis of acetic acid leachates obtained from oily sludge samples. Sludge samples originating from a petrochemical plant were submitted to extraction using standardized procedures with solutions adjusted to pH 2.88 or 4.93, with acetic acid. The leachate solutions were subsequently treated with a mixture of acetic and formic acid and exposed to UV radiation from a Hg discharge lamp; the irradiated solution was pumped to a gas-liquid separator and the volatile species were transported by a stream of argon for detection using inductively coupled plasma mass spectrometry. Experimental variables, including the nature and concentration of low molecular weight acids, irradiation interval, carrier gas flow rate and the effect of concomitant species on the efficiency of photochemical production of volatile Ni species were systematically evaluated. Oxygenated anions, particularly nitrate, were found to suppress the analytical signal, whereas the effect of cationic species depended on the nature of the cation. Lead was found to induce substantial signal suppression even at ppb levels. Considering the significant influence of concomitant species on the overall efficacy of the photochemical process, isotope dilution calibration was adopted as a strategy to overcome non-spectral interferences. Under optimized conditions, relative standard deviations better than 8.5% were achieved, along with detection limits better than 40 μg L−1. The accuracy was statistically attested upon comparison of the results to those obtained from the analysis of leachates using sample introduction via pneumatic nebulization. The proposed photochemical vapor generation setup was proven efficient to carry out the determination of Ni in the leachates, although the technique is highly sensitive to the presence of concomitants.