Small Amounts Of Formaldehyde Research Articles

Synergistic fire retardancy of melamine resin modified with pentaerythritol and ammonium polyphosphate in PP

AbstractThe synergistic fire retardancy of modified melamine resin with pentaerythritol (MF‐PER, a novel green and effective triazine charring agent), and ammonium polyphosphate (APP) in polypropylene was investigated by UL‐94 test, LOI measurement, and cone calorimetry test. It is found that the synergism of MF‐PER is obviously better than pentaerythritol (PER). MF‐PER/APP imparts a fire retardancy mainly by the following mode: in burning process, MF‐PER, and APP are first pyrolyzed respectively into polyols and polyphosphoric acid, which is esterified to form phosphoric ester, and the inert gases make the molten residues foaming; When the temperature increases, and polyphosphoric acid is dehydrated to polymetaphosphoric acid, which dehydrates phosphoric ester to form an intumescent char layer, inducing a fire retardant effect by barrier effect. The graphitization degree of the cone calorimetry test residues of the FR‐PP with MF‐PER is higher than that with PER, which leads to a better synergism.Highlights Melamine formaldehyde resins modified with pentaerythritol (MF‐PER) as a novel triazine charring agent was designed and synthesized. MF‐PER is synthesized by solid phase method and using hexahydroxymethyl melamine (HMM) instead of cyanuric chloride as raw material, so the emission of three wastes in its synthesis process is very little, only a small amount of formaldehyde and water are produced. MF‐PER has excellent synergistic fire retardancy with APP in polypropylene. The highly efficient and environmentally benign charring agent show great potential for developing more efficient and eco‐friendly IFR.

Hydrogenation of Formate Species Using Atomic Hydrogen on a Cu(111) Model Catalyst.

The reaction mechanism of the CH3OH synthesis by the hydrogenation of CO2 on Cu catalysts is unclear because of the challenge in experimentally detecting reaction intermediates formed by the hydrogenation of adsorbed formate (HCOOa). Thus, the objective of this study is to clarify the reaction mechanism of the CH3OH synthesis by establishing the kinetic natures of intermediates formed by the hydrogenation of adsorbed HCOOa on Cu(111). We exposed HCOOa on Cu(111) to atomic hydrogen at low temperatures of 200-250 K and observed the species using infrared reflection absorption (IRA) spectroscopy and temperature-programmed desorption (TPD) studies. In the IRA spectra, a new peak was observed upon the exposure of HCOOa on Cu(111) to atomic hydrogen at 200 K and was assigned to the adsorbed dioxymethylene (H2COOa) species. The intensity of the new peak gradually decreased with heating from 200 to 290 K, whereas the IR peaks representing HCOOa species increased correspondingly. In addition, small amounts of formaldehyde (HCHO), which were formed by the exposure of HCOOa species to atomic hydrogen, were detected in the TPD studies. Therefore, H2COOa is formed via hydrogenation by atomic hydrogen, which thermally decomposes at ∼250 K on Cu(111). We propose a potential diagram of the CH3OH synthesis via H2COOa from CO2 on Cu surfaces, with the aid of density functional theory calculations and literature data, in which the hydrogenation of bidentate HCOOa to H2COOa is potentially the rate-determining step and accounts for the apparent activation energy of the methanol synthesis from CO2 on Cu surfaces.

Are cellulose ethers safe for the conservation of artwork? New insights in their VOC activity by means of Oddy testing

Cellulose ethers, like methyl cellulose (MC) or hydroxypropyl cellulose (HPC), are widely used in conservation. They also occur as additives and rheology modifiers in various products like dispersions or gels. Do such products release harmful volatile organic compounds (VOC) during their accelerated aging? A mass testing series utilizing the Oddy test of 60 commercial cellulose ethers ranks the products in safe for permanent use (P, no corrosion), only for temporary use (T, slight corrosion), and unsuitable at all (F, heavy corrosion). Results show that 55% of the products passed the test whereas 33% are for temporary use as slight corrosion occurred on at least one metal coupon and only 11% failed the Oddy test. Raman measurements of the corrosion products identified oxides like massicot, litharge, cuprite, and tenorite among carbonates (hydrocerussite, plumbonacrite), and acetates like basic lead acetate, lead acetate trihydrate as well as lead formate as main phases. For example, commercial, industrial Klucel® G (HPC) scored a T rating through slight corrosion on the lead coupon. Basic lead acetate among other phases indicates the presence of acetic acid. Additional measurements of the sample with thermal desorption GC–MS utilizing the BEMMA scheme confirm the high acetic acid outgassing and reveal the presence of a small amount of formaldehyde.

Mechanistic study of methanol oxidation on Pt(1 1 1) single crystal

The oxidation of methanol on a Pt(111) single crystal was studied using X-ray photoelectron spectroscopy and polarization-modulation infrared reflection absorption spectroscopy in a temperature range between 300 and 600 K. It was shown that the oxidation starts at approximately 350 K, and methanol is oxidized mainly to CO2 and methyl formate. CO was not found among gas-phase products in the whole temperature range. A small amount of formaldehyde was detected in the gas phase only at 350–450 K. On the platinum surface, methyl formate, CO, formates, carbonates, and carbon atoms were detected under reaction conditions. Their concentrations depended on the reaction temperature and the methanol/oxygen molar ratio. Formates were detected only at 300 K, indicating their low thermal stability. Both CO and formate are the key intermediates in the total oxidation of methanol, which can proceed via two different pathways: a CO-based route and a non-CO-included route. Carbonates are formed from formates and demonstrate extremely high thermal stability. This leads us to propose that not only CO but also carbonates can poison the platinum surface and prevent the oxidation of methanol. The overall mechanism of the oxidation of methanol on platinum is discussed.

Effect of salting time on formaldehyde content of dried salted Indo-Pacific mackerel

This paper reports an analysis of formaldehyde in dried salted short mackerel (Rastrelliger brachysoma) which was intentionally added with formaldehyde compared to those that was not. The purpose was to see whether salting could cover up the illegal use of formaldehyde. Mackerel was obtained from one day fishing landed at Karangantu Fishing Port, Serang-West Java. The fish was transported in ice by road (3 hours) to the laboratory in Jakarta, and divided into two groups upon arrival. One group was soaked in 3% (w/v) formaldehyde solution for 30 minutes, while another group was not (control treatment). They were then salted in saturated brine for 12 and 24 hours at ambient temperature and sun dried subsequently to 40% moisture content or less. The formaldehyde content of raw materials was in the range of 1.4-1.7 ppm, indicating that natural formaldehyde was present in the fish. Soaking in 3% formaldehyde solution for 30 minutes significantly increased fish formaldehyde content from 1.4-1.7 to 154-157 ppm, and decreased to 42.3-58.1 after 24 and 12h salting which then dropped to 25.0-35.9 ppm after drying, respectively. Those of control showed a slight decrease after salting and increase after drying, i.e. 2.7-3.4% in the final products. This results indicate that salting could not disguise the illegal use of formaldehyde to preserve raw materials, however small amount of formaldehyde in dried salted fish could be regarded natural formaldehyde of the fish.

Identifying the Site-Dependent Photoactivity of Anatase TiO2(001)-(1×4) Surface

We here report our investigation on the photocatalytic reactions of methanol on the anatase TiO2(001)-(1×4) surface using scanning tunneling microscopy and temperature-programmed desorption. Our results show that in the reduced surface the Ti-pair defect sites are photoinactive, but in the reoxidized surface the partially oxidized defect sites are photoactive to dissociate methanol and methoxy to formaldehyde. The perfect (1×4) lattice sites are photoactive, even though they are inactive in thermally driven reaction. The photocatalytic reaction of methanol (CD3OH) at the perfect lattice sites is evidenced by the conversion of CD3OH to various other deuterated methanol (CD3OD and CD2HOH) and a small amount of formaldehyde (CD2O) after ultraviolet light irradiation, in contrast with no such conversion reaction in the nonirradiated sample. The production of CD3OD and CD2HOH can be attributed to the reverse reaction between the produced CD2O and the H or D adatoms during or after ultraviolet light irradiation...

Decomposition of Methanol on Mixed CuO-CuWO4 Surfaces.

Mixed CuO(2 × 1)-CuWO4 layers on a Cu(110) surface have been prepared by the on-surface reaction of the CuO(2 × 1) surface oxide with adsorbed (WO3)3 clusters. The adsorption and decomposition of methanol on these well-defined CuO-CuWO4 surfaces has been followed by high-resolution X-ray photoelectron spectroscopy (XPS), high-resolution electron energy loss spectroscopy (HREELS), and temperature-programmed desorption (TPD) to assess the molecular surface species and their concentration, while the state of the surface oxide phases before and after methanol decomposition has been characterized by scanning tunneling microscopy (STM), low energy electron diffraction (LEED), and XPS. Surface methoxy species form the primary methanol decomposition products, which desorb partly by recombination as methanol at 200-300 K or decompose into CHx and possibly CO. The most reactive surfaces are mixed CuO-CuWO4 phase, with CuWO4 coverages 0.5-0.8 monolayer, thus pointing at the importance of oxide phase boundary sites. In a minority reaction channel, a small amount of formaldehyde is detected on the CuWO4 surface. The CuWO4 oxide phase becomes modified as a result of reduction and a morphology transition triggered by the methanol decomposition, but the pristine surface state can be recovered by a postoxidation treatment with oxygen.

The effect of the small amount of formaldehyde in the SurePath liquid when establishing protocols for immunocytochemistry.

Background:SurePath® is an ethanol-based liquid fixative. In addition to ethanol, it also contains a small amount of formaldehyde (<0.2%). The aim of this study was to investigate the immunoreactivity of cells stored for different lengths of time in the SurePath liquid.Materials and Methods:Rest material from one malignant and three benign effusions were fixed in SurePath for 1–12 days. Cytospins were incubated with cytokeratin 7 antibody (AB) to evaluate the staining intensity of carcinoma cells and benign, reactive mesothelial cells. Protocols varied as to pretreatment and AB incubation time.Results:Reduced immunostaining intensity was seen within 5 days of storage in the SurePath liquid. It was restored when the pretreatment time was prolonged.Conclusions:The small amount of formaldehyde in the SurePath liquid seems to affect the immunoreactivity. Local immunocytochemistry protocols in the cytology laboratories should consider this when optimizing their procedures. Postfixation with formalin should be omitted.

Managing Drilling Wastes: Detoxification of Two Formaldehyde-Releasing Biocides

Summary An increased awareness of the environmental impact and operational costs associated with freshwater usage and wastewater disposal in energy production has shifted industry interest toward replacing freshwater sources with lower-quality or recycled water in oilfield applications, and has highlighted the importance of addressing toxicity as part of a successful waste-management plan. Poor-quality and recycled waters often contain high concentrations of bacterial assemblages, which can cause operational challenges such as corrosion, slime formation, and souring. Microbial-control agents, such as biocides, are subsequently necessary to manage bacteriological problems. However, these chemicals are highly reactive and can react indiscriminately with biological targets, making their toxicity both a performance metric and an ecological, human-health, and disposal concern. The luminescent-bacteria toxicity test presented in this work, for instance, is a key regulatory parameter in the pumpoff and landspray disposal of drilling fluids in Alberta, Canada. Considering the necessary toxicity of biocides, controlled detoxification following use is a pertinent factor in responsible hazard management. Formaldehyde-releasing agents are the most widely used category of microbial-control additives that slowly and continuously release small amounts of formaldehyde, a toxic environmental pollutant and known human carcinogen. This research evaluated the acute (short-term) aquatic toxicity of two liquid formaldehyde-releasing biocides, identified necessary parameters for their detoxification, measured the resulting change in their toxicity over time, and used regulatory requirements for toxicity testing set by the Alberta Energy Regulator (AER) for drilling-waste management to evaluate the practical relevance of this detoxification to waste-management practices. The additives investigated were a tetrakis(hydroxymethyl)phosphonium sulfate (THPS)-based product, and a 1,3-dimethylol-5,5-dimethylhydantoin (DMDMH)-based product. Laboratory results suggest that the THPS-based additive was more toxic than the DMDMH-based additive on a percent volume basis, and pH was an important factor in THPS toxicity. Aeration alone decreased the toxicity of DMDMH over the course of the experiment, while a combination of aeration and pH increase were necessary to decrease the toxicity of THPS over the same time period. This work presents a proof of concept for a relatively simple and cost-effective detoxification of the evaluated additives, highlights the key parameters for this process, and uses toxicity-threshold levels referenced by the AER drilling-waste-management directive to evaluate their application in waste-assessment practices.

Formulation approach for the development of a stable, lyophilized formaldehyde-containing vaccine

Formaldehyde has been used in the inactivation of a number of viral and bacterial toxins used in vaccines. In some cases, a small amount of formaldehyde may be necessary in order to prevent reversion back to the toxic state during storage. When a lyophilized preparation is required, care must be taken to ensure that formaldehyde is not lost during the process in order to ensure safety of the product. A design of experiments (DOEs) approach was taken to devise a stable, lyophilized, vaccine formulation. A formaldehyde-inactivated bacterial toxin was used as a model antigen. Entrapment of formaldehyde in an amorphous matrix and/or interactions with amorphous components was found to be required for complete recovery of formaldehyde during lyophilization. In formulations consisting of sucrose and citrate, formaldehyde could be recovered across a wide range of excipient concentrations. Stability of the antigen was dependent on formaldehyde concentration, with antigen stability decreasing with increasing formaldehyde concentration. This is in contrast to the risk of reversion which increases with decreasing concentrations of formaldehyde. Finally, variations in temperatures during annealing, primary drying, and secondary drying had no impact on formaldehyde recovery.

Formaldehyde emissions in large rotating electrical machines – root cause analysis, background and prevention

Odours have been generated during commissioning and first time operation of large rotating electrical machines. These emissions were observed in machines from several manufacturers. Subsequent investigations indicated that formaldehyde was present. The main source of the emissions was located in the insulation varnish of the sheets of the stator core. In core sheet varnishes, formaldehyde containing precursors are often used as crosslinking agents. Energy input during the curing process, determines the extent of reversibly bonded formaldehyde after the cure. Weakly bonded formaldehyde is released when the coated sheets are heated during the early operation of the generator. The influence of the curing conditions on the formaldehyde emissions of stator core sheets was investigated in laboratory experiments. Experiments showed a decrease in formaldehyde emissions by increasing the energy input during the curing process. Even if the energy input was high enough to achieve the required mechanical (e.g. cross cut test), chemical (e.g. rubbing alcohol test) and electrical properties (e.g. surface resistivity), the formaldehyde release could still be reduced by further increase of the energy input. Appropriate material properties do not correlate with the amount of releasable formaldehyde in the varnish. This gives an opportunity to modify the curing to reduce or eliminate the emissions without negatively impacting the insulating properties. The influence of the chemistry of the varnishes on the formaldehyde release was also studied. Varnishes based on phenolic and melamine resins give the highest emissions, while the polyester-based varnishes showed no emissions. The temperature dependence and the kinetics of the formaldehyde release of stator core sheets are investigated in model tests. The laboratory experiments on the kinetics of the emissions showed, that at a certain temperature the majority of formaldehyde is emitted over a short time. Later emissions approach zero with continued thermal exposure. Temperature tests on stator core sheets in the range of 30–100°C showed, that at 30°C small amounts of formaldehyde are released. Interestingly, the formaldehyde emission does not increase linearly with increasing temperature, it shows a first maximum at about 60°C and a second maximum at about 100°C. This implies chemical reactions associated with definite activation energies that are required for splitting off the formaldehyde. Measures can be taken, during lamination processing, to avoid improper formaldehyde emission in large rotating electrical machines (safety measures and venting in existing machines, optimization of the curing process, development of formaldehyde free coatings for stator core laminations).

Role of Lattice Oxygen and Lewis Acid on Ethanol Oxidation over OMS-2 Catalyst

Ethanol-gasoline fuel vehicles result in a statistically significant increase in emissions of ethanol, although they are environmentally friendly due to their lower levels of carbon oxide and hydrocarbon emissions. This work focused on catalytic oxidation of ethanol on octahedral molecular sieve (OMS-2) catalyst, which was synthesized using refluxing method. The catalyst demonstrated great reactivity with acetaldehyde as the major intermediate. Small amounts of formaldehyde were detected while little acetic acid was observed in the presence of oxygen. Results suggested that ethanol adsorption occurred through the breakage of O−H bond forming ethoxide species on Lewis acid sites of the catalyst and OMS-2 could partially oxidize adsorbed ethanol to acetaldehyde and formaldehyde from the consumption of catalyst lattice oxygen in the absence of oxygen flow. Acetaldehyde and formaldehyde formed were directly oxidized to carbon dioxide in the presence of an oxygen flow. The major path of ethanol complete oxidation on OMS-2 catalyst appeared to be the direct oxidation of acetaldehyde to carbon dioxide.

06/02095 Technologies for direct production of flexible H 2/CO synthesis gas : Song, X. and Guo, Z. Energy Conversion and Management, 2006, 47, (5), 560–569.

The CO/H2 reaction over a series of lanthanide-oxide (Ln2O3, Ln = La, Sm, Yb, Lu) modified Rh/Al2O3 catalysts is employed as a test reaction to show the capabilities of the DRIFTS technique in the identification of reaction sites. Methane, heavier hydrocarbons, methanol, ethanol and small amounts of formaldehyde are obtained in this process. Heavy hydrocarbons and methanol present a maximum in activity around 270°C while the maximum is located around 210°C for ethanol and HCOH. The addition of lanthanide oxides produces a decrease in the total activity of the Rh/Al2O3 catalyst. However, the selectivity towards heavy hydrocarbons and oxygenated products is increased. The DRIFTS spectra under reaction conditions have shown a relationship between the presence of a (CO) stretching band at 2030 cm−1 and the activity towards methanol. Ethanol production is however correlated with another band at 2010 cm−1. Rh+ ions on large metallic clusters are proposed as the active centres for methanol production. However, rhodium sites interacting with Ln3+ ions at the metal/support interface and in the vicinity of a partially hydrogenated carbon residue are suggested as the centres for the synthesis of ethanol.

Photo-oxidation mechanism of l-alanine in TiO 2 photocatalytic systems as studied by proton NMR spectroscopy

Photocatalytic decomposition of alanine as a representative amino acid was investigated in detail for nine different kinds of TiO 2 powders by proton NMR spectroscopy. Acetic acid was detected as a stable major intermediate via a fragile intermediate of acetaldehyde. Pyruvic acid was formed on rutile surface, while acetamide was detected on anatase surface. Pyruvic acid was formed directly from alanine, whereas acetamide was produced likely from acetaldehyde and ammonia, which are the decomposition components of alanine. In addition, small amount of formaldehyde and formic acid was formed and decomposing to CO 2.

Thermal Chemistry of Iodomethane on Ni(110). 2. Effect of Coadsorbed Oxygen

The effect of coadsorbed oxygen on the thermal chemistry of iodomethane on Ni(110) single-crystal surfaces was studied by temperature-programmed desorption and X-ray photoelectron spectroscopy. It was found that extensive molecular desorption occurs at temperatures approximately 60 K higher than those seen for the desorption of multilayer CH3I on the clean surface, and that the activation of the C−I bond in the adsorbed iodomethane is deferred but not fully eliminated by the coadsorbed oxygen. The selectivity for the conversion of the surface methyl intermediates produced by the C−I bond scission is also affected by the oxygen precoverage. In broad terms, a decrease in methane production is accompanied by the formation of heavier hydrocarbons, mainly ethane and ethylene but also some propene and butene. Most of these hydrocarbons are presumably produced via a mechanism centered on a methylene insertion step, but additional low-temperature (∼190 K) ethylene and ethane are also made by direct coupling of methylene and methyl groups, respectively. Small amounts of formaldehyde, the only oxygenated hydrocarbon observed, and propenyl and butenyl radicals are seen as well.

Combustion characteristics of candles made from hydrogenated soybean oil

AbstractHydrogenated soybean oil, referred to as soywax by candle makers, is a renewable and biodegradable alternative to paraffin wax in candle manufacturing. Soywax was investigated for its tendency to produce soot as well as potentially harmful organic volatiles (acrolein, formaldehyde, and acetaldehyde) during combustion. Beeswax and paraffin candles were used as references. A considerable amount of soot was produced from the combustion of paraffin candles, but little or none was observed from soywax candles. Compared to paraffin candles, soywax candles burned at a significantly slower rate and required less air. Small amounts of formaldehyde were detected and quantified in the fumes of burning paraffin candles. However, formaldehyde, peaks found in the chromatograms of soy‐ and beeswax candles were similar to or slightly higher than that of the blank. Since soywax candles exhibited burning properties similar to those of beeswax candles, soywax shows promise in candle applications.

UV Direct Photolysis of N-Nitrosodimethylamine (NDMA): Kinetic and Product Study

The ultraviolet (UV) direct photolysis of N-nitrosodimethylamine (NDMA) in aqueous solutions at pH 3 and 7 leads to dimethylamine, and nitrite and nitrate ions as the major degradation products. In addition, small amounts of formaldehyde, formic acid, and methylamine are formed. When the initial concentration of NDMA was 1 mM, only a 13% decrease in the total organic carbon (TOC) was measured at pH 7, whereas no significant change in the TOC was observed at pH 3. In the concentration range 0.01–1 mM NDMA, zero-order kinetics is obeyed, whereas first-order kinetics is followed at concentrations below 0.01 mM. The photolysis occurs much faster at pH 3 than at pH 7, which is explained by the difference in the quantum yields of the process at these two pH values. UV Direct photolysis is an efficient process for the removal of NDMA from contaminated waters, and electrical energy per order (EEO) values as low as 0.3–0.5 kWh/order/m3 were calculated for treatment of low concentrations of NDMA (0.001 mM).

(2-26) Chemical Species Histories up to Ignition in Premixed-Compression-Ignition Natural-Gas Engine((NCS-3)Novel Combustion Systems 3-Homogeneous Charge, Premixed Charge Compression Ignition Engines)

It has been respected to realize large-scale natural-gas engines. Low flame-propagation speed and poor spatial in-cylinder penetration of gaseous fuels impede the large-scale natural-gas practical. Premixed compression-ignition (homogeneous-charge compression-ignition, HCCI) engines have not such kind of problems, because natural-gas and air are supplied as mixtures, and burn out through speedy knocking-like combustion. However, a very narrow operating range could be established due to a lack of autoignition-timing control procedures. A formaldehyde-assisted premixed-compression-ignition natural-gas engine concept has been proposed previously by the authors to realize large scale natural-gas engines having ignition-timing control procedures. Generation/consumption histories of chemical species during the preflame induction period approaching to the final hot-flame ignition were investigated concerning the formaldehyde-assisted compression-ignition natural-gas engine. Small amount of formaldehyde is supplied as an additive into the premixed intake charge of natural gas and air. The formaldehyde addition has a strong promoting effect for lean mixture ignition of natural gas. When suitable amount of formaldehyde, even a hundreds ppm order of magnitude, is added into the intake fuel/air mixture the piston-compression ignition will occur adequately near the top dead center. This procedure enabled us to obtain ignition or hot-flame explosion even of the fuel/air mixtures nonflammable through a simple piston compression. The formaldehyde acts efficaciously as the ignition-promoting additive for the methane-based gaseous fuels which are weak in cool-flame generation during the preflame induction periods. Natural gas is a typical one of this kind. The in-cylinder gas composition histories were obtained by gas sampling / analyzing processes with a magnetic operating valve and gas chromatographs, concerning mainly to the methane, carbon monoxide, carbon dioxide and formaldehyde. Experiment was carried out using a single cylinder engine and a commercial natural gas 13A. The formaldehyde concentration shows a slight rise followed by prompt decrease at the final stage of the ignition delay period ; so-called blue-flame period, but seemingly stable during almost the whole induction period up to the ignition. A piston compression of a simple charge of natural gas and air with no intake formaldehyde addition showed a gradual formaldehyde generation during the preflame period and sometimes slight consumption at the final stage before the hot-flame occurrence. When the intake air is mixed with formaldehyde only, i. e., no fuel is included, the formaldehyde is consumed briskly near the top dead center, and shows a small but recognizable pressure rise due to a heat release. The effect of formaldehyde added into the fuel/air mixture leading to the ignition would not be an event antecedent to the natural gas preflame reaction but a promoting event of the preflame reaction of the main natural gas fuel. It is demonstrated that during the induction period preflame reaction of main natural gas fuel is under way the effect of formaldehyde addition become extremely efficacious at the final stage just before the heat release of hot flame occurrence.

Solubility, tensile, and color properties of modified soy protein isolate films.

Protein solubility (PS) values of different soy protein isolate (SPI) films were determined in water, 0.01 N HCl, 0.01 N NaOH, 4 M urea, and 0.2 M 2-mercaptoethanol. Tensile and color (L, a, and b values) properties of films also were determined. Control films were cast from heated (70 degrees C for 20 min), alkaline (pH 10) aqueous solutions of SPI (5 g/100 mL of water) and glycerin (50% w/w of SPI). Additional films were cast after incorporation of dialdehyde starch (DAS) at 10% w/w of SPI or small amounts of formaldehyde in the film-forming solutions. Also, control film samples were subjected to heat curing (90 degrees C for 24 h), UV radiation (51.8 J/m(2)), or adsorption of formaldehyde vapors. PS of control films was highest (P < 0.05) in 2-mercaptoethanol, confirming the importance of disulfide bonds in SPI film formation. All treatments were effective in reducing (P < 0.05) film PS in all solvents. Both DAS and adsorbed formaldehyde rendered the protein in films practically insoluble in all solvents. Adsorption of formaldehyde vapors and heat curing also substantially increased (P < 0.05) film tensile strength from 8.2 to 15.8 or 14.7 MPa, respectively. However, heat curing decreased (P < 0.05) film elongation at break from 30 to 6%. Most treatments had small but significant (P < 0.05) effects on b color values, with DAS-containing films having the greatest (P < 0. 05) mean b value (most yellowish). Also, DAS-containing, heat-cured, and UV-irradiated films were darker, as evidenced by their lower (P < 0.05) L values, than control films. It was demonstrated that PS of SPI films can be notably modified through chemical or physical treatments prior to or after casting.

A new fluorescent probe for sensitive detection of carbonyl compounds: sensitivity improvement and application to environmental water samples

The use of 2-aminooxy- N-[3-(5-dimethylamino-naphtalene-1-sulfonylamino)-propyl]-acetamide (dansylacetamidooxyamine, DNSAOA, 2) as a new molecular probe for trace measurement of carbonyl compounds (i.e. aldehydes and ketones) in water samples is reported. 2 can be considered as an evolution of the parent N-(5-dimethylamino-1-naphtalenesulphonamido)-3-oxopentane-1,5-dioxyamine (dansyloxyamine, DNSOA, 1) molecule that was initially proposed in a recent paper. An updated procedure for the synthesis of 2 leading to higher purity of such oxyamino probes and a subsequent better sensitivity of the method was described. The reactivity behaviour of 2 with solutions containing small amounts of formaldehyde, acetaldehyde, propionaldehyde and acetone is also described: even for concentrations less than 1 μM, C1–C3 aldehydes can be fully derivatized within 10 h and only one calibration curve is needed. Longer reaction times are nevertheless required for accurate measurements of the less reactive acetone. Very low limits of detection (LODs), mainly depending on the initial purity of the probe, have been obtained: 10 nM of formaldehyde and 5 nM of the other carbonyls can be detected. The limit of quantification (LOQ) of the method is close to 25 fmol. 2 was used in measuring the carbonyl content of snow, ice and cloud-water samples. The first data concerning acetaldehyde in alpine and polar snow, and a first estimation of acetone in cloud-water droplets are reported here.