Fluorimetric flow-injection analysis of total amounts of aldehydes in auto exhaust gas and thermal degradation emission gas with cyclohexane-1,3-dione

A simple flow-injection (FI) spectrofluorimetric method for the assay of total volatile aldehydes in auto exhaust gas and emission gas from thermal degradation was developed. Aldehydes, such as formaldehyde, acetaldehyde, propionaldehyde and n-butyraldehyde, reacted with cyclohexane-1,3-dione (CHD) to form more strongly fluorescent compounds. A two-channel flow system was assembled. Distilled water and 0.02% CHD were delivered at 0.75 ml min(-1). The optimum conditions were pH 5 (2.2 M CH(3)COONH(4)-CH(3)COOH buffer solution), reaction temperature 70 degrees C, reaction coil length 0.5 mm i.d. x 7 m, cooling coil length 2 m, sample size 60 microl, excitation and emission wavelengths, 376 nm and 452 nm. Aldehydes in sample gas (10 1) were collected by passing the gas at a flow rate of 0.5 1 min(-1) through two impingers connected in series. 10 ml of methanol was used as an absorbent and diluted sample solution was injected into the carrier stream. The calibration graph was linear in the range 100-1000 ppb. The detection limit was 30 ppb and a sampling frequency of 30 h(-1) was attained. Relative standard deviation for 10 standard formaldehyde solutions (500 ppb) was 1.5%. This rapid and simple FI method was applied to the determination of the total amount of aldehydes, calculated as formaldehyde, in auto exhaust gas and emission gas from the thermal degradation of polymers. The method is useful for monitoring aldehyde emissions and investigating the removal effect of aldehydes from various sources.     

Intermethod comparisons of active sampling procedures and analysis of aldehydes at environmental levels

Within the framework of a European interlaboratory exercise, the Vito facility for the generation of controlled atmospheres was used to test the suitability of four sampling techniques for priority aldehydes namely formaldehyde, acrolein, acetaldehyde, and glutaraldehyde at the ranges of 0.5 to 150 microg x m(-3). The samplers are DNPH-containing impingers, DNPH-impregnated cartridges and filters, and 2-HMP coated XAD-2 tubes. The three first DNPH samplers are to be analyzed by HPLC and the latter by GC-MS for the oxazolidine derivatives. The intermethod comparison comprises two to five sets of experiments depending on the compounds of interest. The aim of the exercise was also to assess the chemical interferences caused by ozone, nitrogen dioxide, and ammonia when using different techniques for sampling and analysis. The active DNPH method (with minor modifications such as shorter sampling time, immediate elution after sampling, and/or eventually wetting of samplers) delivered results within the 30% overall relative uncertainty for formaldehyde, acetaldehyde, and acrolein at the upper microg x m(-3) levels. However, the results suggest that the current DNPH methods for aldehydes do not comply with the 30% minimum performance criteria at the sub microg x m(-3) level. Sampling of aldehydes in the presence of ozone and NO2 interferences by using a "scrubber" cartridge appears to be beneficial to the quality of results.     

Determination of aldehydes in fish by high-performance liquid chromatography

A new analytical method to determine trace volatile aldehydes isolated from the headspace of fish meat at room temperature by high-performance liquid chromatography (HPLC) in the form of 2,4-dinitrophenylhydrazone (DNPHo) derivatives has been developed. Aliquots (50 g) of the fish purée were introduced into a 500-mL glass recipient and were purged with N2 for 40 min through two SEP-PAK C18 cartridges (connected in series) coated with an acid solution of 2,4-dinitrophenylhydrazine. The cartridges were then eluted with acetonitrile (2 mL) and the 2,4-DNPHo formed was quantitated by HPLC-UV analysis using a Zorbax C18 column. The isolated compounds from the dynamic headspace sampling of four kinds of fish species were saturated aldehydes, formaldehyde, acetaldehyde, propanal, butanal, pentanal, and hexanal. Under optimized conditions the detection limits of the HPLC method were in the range of 0.75 nmol/g (formaldehyde) to 2.19 nmol/g (hexanal). The calibration curves were linear in the concentration range from 1.3 nmol/mL to 12.5 nmol/mL. Propanal and acetaldehyde were the major carbonyl compounds identified (ranging from 3.9 nmol/g and 10 nmol/g). This study has revealed the widespread occurrence of formaldehyde, acetaldehyde, propanal, butanal, pentanal, and hexanal in fish meat.     

程序升温汽化大体积进样气相色谱法同时测定空气中的甲醛及其他10种羰基污染物（英文）

Long-term indoor-air limit for formaldehyde stipulated by the European Commission is 1 μg/m3,while the World Health Organization has set a threshold of 100 μg/m3 that should not be exceeded for more than 30 min. To date,however,only a few analytical techniques have been developed that can be used to detect formaldehyde at these very restrictive limits. Thus,there is a need to develop for comprehensive methods for analyzing airborne formaldehyde and other carbonyl pollutants in the ambient environment. The aim of this study is to develop a highly sensitive online automated preconcentration gas chromatographic method using large-volume injection with a programmed temperature vaporization injector for the analysis of airborne formaldehyde and ten other carbonyl compounds. The influence of several parameters,such as the maximum volume injected,programmed temperature vaporization transfer time and temperature,carrier gas flow rate,and type of packing material was investigated. After optimization,highly satisfactory results in terms of the absolute and methodological detection limits were achieved,i. e. as low as the μg/m3 level for all the carbonyl pollutants studied. A commercially available sampler,originally designed for active sampling,was evaluated as a passive sampling device;this optimized technique was applied to monitor the concentrations of carbonyl pollutants in the indoor air of ten public buildings in Florence. The strength of this methodology lies both in the low detection limits reached in the simultaneous analysis of a wide group of 2,4-dinitrophenylhydrazine derivatives,and the potential adaptability of this method to other gas chromatographic applications to achieve lower sensitivity.     

Analysis of low molecular weight aldehydes in air samples by capillary electrophoresis after derivatization with 4-hydrazinobenzoic acid

This work reports the analysis of selected aldehydes in air samples using capillary electrophoresis (CE). The method is based on the reaction of aldehydes with 4-hydrazinobenzoic acid (HBA) to give the corresponding hydrazones with maximum absorbance at 290 nm. Under optimized CE conditions, the HBA derivatives of four carbonyls (formaldehyde, acetaldehyde, propionaldehyde, and acrolein) were completely separated from one another, in less than 6 min, using a pH 9.3 tetraborate buffer at 0.040 mol L(-1) concentration as background electrolyte. A few method validation parameters were determined revealing good migration time repeatability (< 1.5% CV) and area repeatability (< 2% CV), excellent linearity (50-300 microg/L, r > 0.996) and adequate sensitivity for environmental applications. The limits of detection with respect to each single aldehyde were in the range of 2.7-8.8 ng L(-1). The methodology was applied to the determination of aldehydes indoors. Samples were collected in HBA impregnated octadecylsilica cartridges, at different times during the day. The most abundant carbonyls in the samples were acetaldehyde followed by formaldehyde, with estimated peak concentrations of 4.3 and 2.9 ppbv, respectively.     

Development and validation of a sensitive thermal desorption–gas chromatography–mass spectrometry (TD-GC-MS) method for the determination of phosgene in air samples

A new rapid, sensitive and reliable method was developed for the determination of phosgene in air samples using thermal desorption (TD) followed by gas chromatography–mass spectrometry (GC-MS). The method is based on a fast (10 min) active sampling of only 1 L of air onto a Tenax® GR tube doped with 0.5 mL of derivatizing mixture containing dimercaptotoluene and triethylamine in hexane solution. Validation of the TD-GC-MS method showed a low limit of detection (40 ppbv), acceptable repeatability, intermediate fidelity (relative standard deviation within 12 %) and excellent accuracy (>95 %). Linearity was demonstrated for two concentration ranges (0.04 to 2.5 ppmv and 2.5 to 10 ppmv) owing to variation of derivatization recovery between low and high concentration levels. Due to its simple on-site implementation and its close similarity with recommended operating procedure (ROP) for chemical warfare agents vapour sampling, the method is particularly useful in the process of verification of the Chemical Weapons Convention.

1,3,5,7-四甲基-8-丙酰肼-二氟化硼-二吡咯甲烷柱前衍生高效液相色谱测定白酒中的脂肪醛

以合成的1,3,5,7-四甲基-8-丙酰肼-二氟化硼-二吡咯甲烷(BODIPY-丙酰肼)作为柱前荧光衍生试剂,用于高效液相色谱分离荧光法检测甲醛、乙醛、丙醛、丁醛、戊醛、己醛、庚醛、辛醛、壬醛、癸醛、十一醛、十二醛等12种脂肪醛.通过对衍生条件和分离条件进行优化,建立了测定脂肪醛的HPLC/FD新方法.衍生反应以H3P...     

Determination of low-aliphatic aldehydes indoors by micellar electrokinetic chromatography using sample dissolution manipulation for signal enhancement

This work describes a novel approach for the analysis of selected aldehydes (formaldehyde, acetaldehyde, propionaldehyde, and acrolein) and acetone in environmental samples using micellar electrokinetic chromatography (MEKC). The method is based on the reaction of carbonyl compounds with 3-methyl-2-benzothiazoline hydrazone (MBTH) that gives an azine intermediate with maximum absorbance at 216 nm. A systematic evaluation of sample dissolution medium was conducted as a means to enhancing sensitivity. In the best condition, samples were dissolved in 0.030 mol.L(-1) tetraborate solution. This condition presented enhancement factors in the range of 35-54 for the aldehydes under investigation, computed as the improvement of the concentration limits of detection (LODs) with reference to the sample dissolved in pure water. The running buffer was 0.020 mol.L(-1) tetraborate, pH 9.3, containing 0.050 mol.L(-1) sodium dodecyly sulfate (SDS). The overall methodology presented several advantages over established methods for aldehydes. Worthy mentioning that MBTH is available in high purity degree, dispensing laborious reagent purification procedures. A few method validation parameters were determined revealing good migration time repeatability (< 2.5% coefficient of variation, CV) and area repeatability (< 4% CV), excellent linearity (20-120 micro g/L, r > 0.995) and adequate sensitivity for environmental applications. The LODs with respect to each single aldehyde were in the range of 0.54-4.0 micro g.L(-1) and 11 micro g.L(-1) for acetone. The methodology was applied to the determination of aldehydes indoors. Samples were collected in an impinger flask containing 0.05% MBTH solution, at a flow rate of 0.80 L.min(-1), during 2.5 h, at different times during the day. The most abundant carbonyls in the samples were acetone, followed by formaldehyde and acetaldehyde, with estimate peak concentrations of 452, 5.2 and 2.2 ppbv, respectively.     

Direct organocatalytic asymmetric α-hydroxymethylation of ketones and aldehydes

Direct organocatalytic asymmetric α-hydroxymethylation of ketones and aldehydes with formaldehyde has been developed, which furnished the corresponding α-hydroxymethylated adducts with high chemo- and enantioselectivity. The reaction is catalyzed by proline derivatives and is a simple method for the enantioselective synthesis of α-hydroxymethylated ketones and aldehydes, and C-2 symmetric diols.     

Polarographische Bestimmung von Spuren von Carbonylverbindungen in organischen Lösungsmitteln

Traces of formaldehyde, acetaldehyde and acetone in organic solvents are determined polarographically as semicarbazones. Solvents miscible with water are measured directly in aqueous buffer solution of semicarbazide, while from those nonmiscible with water the carbonyl compounds are first extracted with a solution of semicarbazide. The polarography of semicarbazones as an analytical method is considerably more sensitive than the direct polarography of aldehydes in a neutral or alkaline medium: in 1 ml samples of solvents, formaldehyde, acetaldehyde and acetone can be determined in concentrations of about 10^?4%. The method also permits the determination of formaldehyde, acetaldehyde and acetone simultaneously.     

Evaluation of a passive sampler for airborne formaldehyde

Summary A diffusive sampler for the large scale routine determination of airborne formaldehyde was developed. Formaldehyde is sampled in a badge-type passive sampler containing a 2,4-dinitrophenylhydrazine-coated filter paper as sampling layer. Formaldehyde is immediately converted to the corresponding hydrazone, which, after desorption with acetonitrile, is separated and quantified by gradient HPLC using UV detection at 345 nm. Calibration was done via an active sampling method and showed an excellent, time- and concentration-independent linear performance of the diffusive samplers. A detection limit of about 0.05 ml/m³·h (ppm·h) and a relative standard deviation of about 10% ensured a good analytical reliability. By testing the influence of air movements at the sampler surface, a minimum air velocity of 10 cm/s was found necessary to ensure representative sampling.     

Iodine as a mild and versatile reagent for the synthesis of 1,3-dioxane derivatives via the Prins reaction

Iodine is found to be an effective reagent for the cross-coupling of olefins with aldehydes under mild conditions to produce 4-substituted 1,3-dioxane derivatives in excellent yields and in short reaction times with high selectivity. The use of iodine makes this procedure simple, convenient, cost-effective and practical. This method works not only with formaldehyde but also with acetaldehyde, propionaldehyde and cyclohexanecarboxaldehyde.     

Highly sensitive and selective catalytic determination of formaldehyde and acetaldehyde

A highly sensitive, simple and selective kinetic method was developed for the determination of ultra-trace levels of formaldehyde and acetaldehyde based on their catalytic effect on the oxidation of N,N-diethyl-p-phenylenediamine (DPD) with hydrogen peroxide. The reaction was monitored spectrophotometrically by tracing the formation of the red-colored oxidized product of DPD at 510nm, within 30s of mixing the reagents. The optimum reaction conditions were: 20mmolL(-1) DPD, 250mmolL(-1) H(2)O(2), 150mmolL(-1) phosphate, 150mmolL(-1) citrate and pH 6.60+/-0.05 at 25 degrees C. Following the recommended procedure, formaldehyde and acetaldehyde could be determined with linear calibration graphs up to 0.50 and 1.4microg mL(-1) and detection limits, based on the 3S(b)-criterion, of 0.015 and 0.035microg mL(-1), respectively. In addition, analytical data for other 10 aldehydes were also presented. The high sensitivity and selectivity of the proposed method allowed its successful application to rain water, mainstream smoke (MSS) and disposed tips of smoked cigarettes (DTSC). A sample aliquot was directly analyzed for its total water-soluble aldehyde content. A second sample aliquot was heated at 80 degrees C for 10min to expel acetaldehyde and the aliquot was analyzed for its content of other water-soluble aldehydes (expressed as formaldehyde equivalent), and acetaldehyde was determined by difference. The analytical results were in excellent agreements with those obtained following the standard HPLC method based on pre-column derivatization with 2,4-dinitrophenylhydrazine. Moreover, published catalytic-spectrophotometric methods for the determination of aldehydes were reviewed.     

Polymer-mediated extraction of the fluorescent compounds derived by Hantzsch reaction with dimedone for the sensitive determination of aliphatic aldehydes in air

An extraction method based on the thermo-responsive precipitation of a water-soluble polymer, poly(N-isopropylacrylamide) [PNIPAAm], was applied to the concentration of dimedone (5,5-dimethylcycrohexane-1,3-dion) derivatives for the highly sensitive determination of aldehydes in air. Aliphatic aldehydes including formaldehyde, acetaldehyde, propanal, 1-butanal, 1-heptanal, and 1-hexanal in air were well solubilized into the aqueous solution of dimedone and ammonium acetate by mixing the solution and air sample in a polyvinyl fluoride bag. Fluorescent derivatives of aldehydes that had formed by the Hantzsch reaction with dimedone were concentrated by polymer-mediated extraction. The recoveries of the fluorescent compounds increased with increasing the carbon number of aldehyde and were more than 80% for the derivatives from aldehydes having more than three carbon atoms under the optimal conditions. Microgram per m3 (sub-ppb) levels of the aliphatic aldehydes, propanal, 1-butanal, 1-heptanal, and 1-hexanal, in ambient air were successfully determined by HPLC separation with fluorometric detection. The sampling volume and time required were only 1l and 20 s, respectively.     

A diffusive sampling device for simultaneous determination of ozone and carbonyls

A new diffusive sampling method for the simultaneous determination of ozone and carbonyls in air has been developed. In this method, silica gel impregnated with a mixture of trans-1,2-bis(2-pyridyl)ethylene (2BPE) and 2,4-dinitrophenylhydrazine (DNPH) is used as the absorbent; further, a porous sintered polyethylene tube (PSP-diffusion filter), which acts as a diffusive membrane, and a small polypropylene syringe (PP-reservoir) for elution of the analytes from the absorbent are used. The carbonyls present in air react with DNPH in the absorbent to form hydrazone derivatives. Concurrently, ozone in the air reacts with 2BPE to form pyridine-2-aldehyde, which immediately reacts with DNPH to form a pyridine-2-aldehyde hydrazone derivative. All the hydrazones derived from airborne carbonyls, including pyridine-2-aldehyde (formed from ozone), are completely separated and analyzed by high-performance liquid chromatography. The sampling rates of ozone (44.6 mL min(-1)) and formaldehyde (72.0 mL min(-1)) are determined by comparison with the rates obtained in an active sampling method. The sampling rates of other carbonyl compounds are calculated from the respective molecular weights according to a rule based on Graham's law. The calculated sampling rates agree with the experimental values. The DSD-BPE/DNPH method is advantageous because it is simple and allows for the simultaneous analysis of ozone and carbonyls.     

Improving continuous chemiluminescence determination method of formaldehyde in the atmosphere: reducing interference of acetaldehyde and others by using iodoform reaction

ABSTRACT

The continuous and selective determination method of formaldehyde (HCHO) in ambient air using chemiluminescence method has been developed. The counter current flow tube was used to collect gaseous formaldehyde. The major interferences of HCHO determination from acetaldehyde, ethanol, and ferrous ion were removed by applying iodoform reaction. Effect of acetaldehyde on chemiluminescence signal of formaldehyde at the same concentration was reduced from 19 to 0.3% by applying iodoform reaction. Subsequently, HCHO was online detected by measuring chemiluminescence produced from the reaction of HCHO, gallic acid, H₂O_2, and KOH. The limit of detection (S/N = 3) was 4.5 ppbv in air. The calibration graph was linear up to 6.25 ppmv. HCHO concentration measured by the present method showed good agreement with that obtained by the 2–4 DNPH-HPLC method.     

A New Method for the Measurement of Airborne Formaldehyde Using Derivatization with 3,5-Bis(Trifluoromethyl) Phenylhydrazine and Analysis by GC-ECD and GC-MS/SIM

Abstract

A new method was developed and described for the measurement of airborne formaldehyde using derivatization with 3,5-bis(trifluoromethyl)phenylhydrazine (TFMPH) coated onto silica solid phase extraction cartridges. Analysis by GC-ECD provides a detection limit of 74 ng formaldehyde per sample. A field study was conducted to compare the use of TFMPH to 2,4-dinitrophenylhydrazine (DNPH) and NIOSH method 3500 (chromotropic acid, CTA). Samples were collected from indoor and outdoor environments known or suspected to contain formaldehyde. Use of TFMPH with GC-ECD analysis correlates well with both methods (R²=0.93, slope=1.07 vs. DNPH; R²=0.99, slope=1.06 vs. CTA). Spiked samples were shown to be stable at least 7 days when stored at –20 °C. Analysis of samples by GC-MS with selected ion monitoring (GC-MS/SIM) also proved feasible. Laboratory and field results show the use of TFMPH to be viable for quantifying airborne formaldehyde in occupational and environmental samples.     

Quantitative Determination of Formaldehyde In Air Using the Acetylacetone Method

Abstract

The quantitative determination of formaldehyde in air using the fluorimetric acetylacetone method is described. Known concentrations of formaldehyde were generated and collected in water using abosorbers. The sampling rate was 0.5 1/min, and the sampling volumes varied from 2 to 20 1, depending on the concentration level. Under these conditions the entire sampling and the analytical method were evaluated over a range of 0.2–1.7 mg formaldehyde per m³ of air.

The precision of the method expressed as a mean value of the relative standard deviation of 7 independent measurements (6 single determinations each) was (3.4 ± 1.6) % (SD). The accuracy was (101 ± 5) % (SD). The detection limit of the method was estimated to be 0.040 mg formaldehyde per m³ of air (5 liter air sample).     

Fluoral-P,a member of a selective family of reagents for aldehydes

The compound 4-amino-3-penten-2-one is introduced as a member of a selective family of reagents for aldehydes. The stability, selectivity and reactivity of the reagent are described and its utility in automatic determinations of formaldehyde is demonstrated. It is shown that the condensation reaction between 4-amino-3-penten-2-one (called Fluoral-P) and formaldehyde gives a product detectable by fluorescence. The flow injection system utilizing this reagent can be used to determine formaldehyde in the lower. nanomole range.     

4-Carbomethoxybenzaldehyde as a highly sensitive pre-column fluorescence derivatization reagent for 9,10-phenanthrenequinone

9,10-Phenanthrenequinone (PQ) is harmful environmental pollutant that is detected in airborne particulates. The measurement of PQ in the air should be necessary to evaluate the potential adverse effects of PQ on human health. We have recently developed a determination method for PQ based on the fluorescence derivatization of PQ using benzaldehyde and ammonium acetate as a reagent. In this study, in order to obtain more sensitive and selective fluorescence derivatization reaction, we measured the fluorescence of the reaction mixture of PQ with 21 kinds of aromatic aldehydes in the presence of ammonium acetate. Among the tested aldehydes, 4-carbomethoxybenzaldehyde was found to be the best reagent in regard to fluorescence intensity and emission wavelength maximum. Based on the fluorescence derivatization with 4-carbomethoxybenzaldehyde, a highly sensitive chromatographic method was developed for the determination of PQ with the detection limit (S/N=3) of 1.2 fmol/injection.