Determination Of Free Formaldehyde Research Articles

Study on the Determination of Free Formaldehyde in Carbon-Coated Air Purifying Material by Water Extraction Method

The free formaldehyde in carbon-coated air purifying material was determined by water extraction method. The effects of solid-liquid ratio, extraction time and extraction temperature on the content of free formaldehyde in carbon-coated air purifying material were studied. In this paper, orthogonal tests and single factor tests were designed, and the optimal extraction conditions were 1:40 solid-liquid ratio, 90 min extraction time and 40 °C extraction temperature. Under this extraction condition, the relative standard deviation (n = 8) of the repeated test is 0.80%, and the recovery rate is 90%-100%, which indicates that the analytical method for determining the free formaldehyde in carbon-coated air purifying material by water extraction method is feasible.

Determination of free formaldehyde in cosmetics containing formaldehyde-releasing preservatives by reversed-phase dispersive liquid–liquid microextraction and liquid chromatography with post-column derivatization

An analytical method for the determination of traces of formaldehyde in cosmetic products containing formaldehyde-releasing preservatives has been developed. The method is based on reversed-phase dispersive liquid–liquid microextraction (RP-DLLME), that allows the extraction of highly polar compounds, followed by liquid chromatography–ultraviolet/visible (LC–UV/vis) determination with post-column derivatization. The variables involved in the RP-DLLME process were studied to provide the best enrichment factors. Under the selected conditions, a mixture of 500 μL of acetonitrile (disperser solvent) and 50 μL of water (extraction solvent) was rapidly injected into 5 mL of toluene sample solution. The extracts were injected into the LC–UV/vis system using phosphate buffer 6 mmol L−1 at pH 2 as mobile phase. After chromatographic separation, the eluate merged with a flow stream of pentane-2,4-dione in ammonium acetate solution as derivatizing reagent and passed throughout a post-column reactor at 85 °C in order to derivatize formaldehyde into 3,5-diacetyl-1,4-dihydrolutidine, according to Hantzsch reaction, which was finally measured spectrophotometrically at 407 nm. The method was successfully validated showing good linearity, an enrichment factor of 86 ± 2, limits of detection and quantification of 0.7 and 2.3 ng mL−1, respectively, and good repeatability (RSD < 9.2%). Finally, the proposed analytical method was applied to the determination of formaldehyde in different commercial cosmetic samples containing formaldehyde-releasing preservatives, such as bronopol, diazolidinyl urea, imidazolidinyl urea, and DMDM hydantoin, with good relative recovery values (91–113%) thus showing that matrix effects were negligible. The good analytical features of the proposed method besides of its simplicity and affordability, make it useful to carry out the quality control of cosmetic products containing formaldehyde-releasing preservatives.

A rapid liquid chromatography determination of free formaldehyde in cod

A rapid method for the determination of free formaldehyde in cod is described. It uses a simple water extraction of formaldehyde which is then derivatised with 2,4-dinitrophenylhydrazine (DNPH) to form a sensitive and specific chromophore for high-performance liquid chromatography (HPLC) detection. Although this formaldehyde derivative has been widely used in past tissue analysis, this paper describes an improved derivatisation procedure. The formation of the DNPH formaldehyde derivative has been shortened to 2 min and a stabilising buffer has been added to the derivative to increase its stability. The average recovery of free formaldehyde in spiked cod was 63% with an RSD of 15% over the range of 25–200 mg kg−1 (n = 48). The HPLC procedure described here was also compared to a commercial qualitative procedure – a swab test for the determination of free formaldehyde in fish. Several positive samples were compared by both methods.

Determination of free formaldehyde in vaccines and biological samples using solid-phase microextraction coupled to GC-MS

A headspace solid-phase microextraction method coupled to GC-MS was successfully developed for the trace determination of formaldehyde in veterinary bacterial and human vaccines, and diphtheria-tetanus antigen. The formaldehyde was derivatized by means of the Hantzsch reaction prior to extraction and subsequent determination. Three different types of solid-phase microextraction fibers, polar, and nonpolar poly(dimethylsiloxane) and polyethylene glycol were prepared by using a sol-gel technique. The effects of different parameters such as type of fiber coating, extraction time and temperature, desorption conditions, agitation rate, and salt effect were investigated. Under the optimized conditions, the detection limit of the method was 979 ng/L using the selected ion-monitoring mode. The interday and intraday precisions of the developed method under the optimized conditions were below 13%, and the method shows linearity in the range of 1.75-800 μg/L with a correlation coefficient of 0.9963. The optimized method was applied to the determination of formaldehyde from some biological products. The results were satisfactory compared to the standard method.

Using 2,4 DNPH-PVC membrane sensors for indirect determination of formaldehyde in urea glue and wastewater

Three simple, rapid, and sensitive ion-selective electrodes for indirect determination of free formaldehyde in urea glue and wastewater have been developed. The methods are based on the formation of the membrane sensors 2,4-dinitrophenylhydrazine-phosphtungestic acid (DNPH-PTA), 2,4-dinitrophenylhydrazine-phosphomolybdic acid (DNPH-PMA), and 2,4-dinitrophenylhydrazine-tetraphenylborate (DNPH-TPB) as neutral carriers. The sensors are stable and show fast potential responses of 30 s, and near-Nernstian cationic slopes of 56.2 ± 0.5, 54.3 ± 0.5, and 53.8 ± 0.4 mV per decade of activity between pH 0.5 and 3.5 over a wide range of 2,4-dinitrophenylhydrazine concentrations (1 × 10−5 to 1 × 10−2 M). These sensors were used for indirect determination of formaldehyde over concentration range (1 × 10−4 to 1 × 10−1 M). The selectivity coefficients of the developed sensors indicate excellent selectivity for 2,4 DNPH over a large number of organic and inorganic species. The mediator o-nitrophenyloctyl ether has a significant affect on the lifetime of the fabricated sensors. The analytical applications of the proposed sensors showed good results for indirect determination of formaldehyde in formaldehyde solutions, wastewater solutions, and free formaldehyde in urea-formaldehyde liquid and powder glues. The results were compared favourably with that obtained by ASTM, colorimetric, and British Standard methods.

Evaluation of analytical methods for the determination of free formaldehyde on textile substrate

Release of formaldehyde from durable press-treated fabrics is a problem for human health and safety because formaldehyde is suspected to be carcinogenic. The accuracy of the standard test method for the free formaldehyde determination, Japan Law 112, depends on the formaldehyde content of the sample. The detection of low formaldehyde contents is particularly important in fields, like children clothing, so the application of high-performance liquid chromatography was evaluated. The results obtained by the standard test method, Japan Law 112, where UV/Vis spectrometer was used, were compared with the results obtained by HPLC method in which separation was performed on an RP C18 column with water–methanol as a mobile phase. It was shown that the detection limit and limit of quantification were improved using the HPLC method.

Determination of free formaldehyde in foundry resins as its 2,4-dinitrophenylhydrazone by liquid chromatography

Formaldehyde is a toxic component that is present in foundry resins. Its quantification is important to the characterisation of the resin (kind and degradation) as well as for the evaluation of free contaminants present in wastes generated by the foundry industry. The complexity of the matrices considered suggests the need for separative techniques. The method developed for the identification and quantification of formaldehyde in foundry resins is based on the determination of free carbonyl compounds by derivatization with 2,4-dinitrophenylhydrazine (DNPH), being adapted to the considered matrices using liquid chromatography (LC) with UV detection. Formaldehyde determinations in several foundry resins gave precise results. Mean recovery and R.S.D. were, respectively, >95 and 5%. Analyses by the hydroxylamine reference method gave comparable results. Results showed that hydroxylamine reference method is applicable just for a specific kind of resin, while the developed method has good performance for all studied resins.

Determination of free formaldehyde in nail preparations by differential pulse voltammetry

AbstractFree formaldehyde in nail preparations, extracted with dichloromethane and 0.002 M hydrochloric acid (1:2v./v.), was determined by differential pulse voltammetry(DPV) using a thin‐film mercury electrode (TFME) in a basic solution. The various factors such as deposition time, concentration of mercury (II) and of coexisting organic and inorganic interferences on the precision of the analysis have been explored. Under optimum conditions the peak potential of formaldehyde was −1.652V [vs. the saturated calomel electrode(SCE)], and a linear current vs. concentration relationship was over 2.0–80.0 mg L−1. The results obtained were in good agreement with those of the official European Economic Community(EEC) acetylacetone method.

Determination of free formaldehyde in nonwovens in the presence of glyoxalic acid and aldehydes

A method for the determination of free formaldehyde in nonwovens in the presence of interfering components is described. After RP-HPLC separation the water extracted formaldehyde reacts with acetylacetone in a knitted open tube reactor to form a lutidine derivative which is measured, even at low concentrations, by the UV detector. The minimum detectable concentration is 25 μg/kg.

Determination of Free Formaldehyde in Durable Press Fabric: Comparison of Cold Sulfite Method with Headspace Gas Chromatography

Comparison of free formaldehyde contents obtained by the cold sulfite and headspace gas chromatography methods at 25°C indicates surprisingly good agreement at low formaldehyde concentrations (&lt;500 μg/g fabric). At higher concentrations, the agreement is less satisfactory, the cold sulfite method giving considerably lower values than headspace gas chromatography and the actual amount present. The agreement extends to durable press fabrics with considerable N-methylol content, suggesting that the low temperature and the short reaction time of the cold sulfite method eliminate contributions from N-methylol hydrolysis.

Determination of free formaldehyde in nail varnish by HPLC

Free formaldehyde in cosmetic samples can be determined by HPLC and post-column derivatisation as a lutidine derivative. Applying this method to nail varnishes results in poor reproducibility. It is demonstrated that most of the formaldehyde determined is generated by hydrolysis of the resin in aqueous solution during sample clean-up, extraction and determination procedures. The hydrolysis is slowest in acidic solution at low temperature. The formaldehyde concentration is thus a function of the method of determination. Kinetic evaluation of its formation by hydrolysis shows that the initial concentration of free formaldehyde in the resin is below 100 ppm.

Determination of free formaldehyde in the presence of donators in cosmetics by HPLC and post-column derivation

The determination of free formaldehyde in the presence of its donators in cosmetic samples by a combination of reversed phase chromatography and post column reaction detection is described. The free formaldehyde is separated on a RP column with water as eluent from interfering formaldehyde-containing compounds and consecutively determined by the lutidine method in a reaction detector with knitted open tubes. With detection in the visible (420nm) the minimum detectable quantity is 40 ppb, with fluorimetric detection 15 ppb. The sample clean-up procedure for cosmetic products ranging from mascara to shampoo is by extracting the formaldehyde with water of pH 3, where the decomposition rate of the donators is minimal. Smaller amounts of free formaldehyde are always found compared to the standard lutidine method.

Determination of Free Formaldehyde on Cloth at Low Concentrations'

When the AATCC Test Method 112-1978 is used to determine free formaldehyde on cloth, the accuracy and precision become progressively poorer as the level of free formaldehyde drops below 200 μg/g (ppm). Because of the introduction of new cellulose reactants, which yield ultra-low levels of formaldehyde on cloth, a modified analytical procedure has been developed that gives accurate and reproducible results with formaldehyde content on cloth in the range of 15 to 175 μg/g. This paper provides details of the colorimetric procedure, which is based on use of 3-methyl-2-benzothiazolinone hydrazone in lieu of the Nash reagent. No additional equipment is necessary.

Determination of Free Formaldehyde On Emulsion Treated Substrates

Determination of Free Formaldehyde On Emulsion Treated Substrates

Determination of free formaldehyde in underwears

Determination of free formaldehyde in underwears

Hygienic Study on Packaging and Vessel Made of Synthetic Resin (III)

The soluble components transferect from urea resin tablewares used for long period, were discussed in the previous paper.In this paper, the methods of separation and determination of free formaldehyde were studied by liquid chromatography with thermal detector, for a basic study on the toxicity of formaldehyde.The thermal detector was unsatisfactory for determination of formaldehyde in low concentration, because of poor sensitivity. Therefore, the determination were made on the combined use to liquid chromatography and colorimetry with acetylacetone.The chromatographic conditions used were as follows:Apparatus JLC A Type (Nihon Denshi)Fixed phase Dowex 50W-X8Eluent 0.1N HClFlow rate of eluent 0.6ml/minColumn: for separation 0.8×50cm (room temp.)for detection 0.8×8cm (35°C)Sensitivity ±1/100°C or 3/1000°C cfsChart speed 60mm/hrMain results of experiments are summarized as follows:(1) The recovery of free formaldehyde (Cf) was 90-100% in the case of addition of formaldehyde.(2) Total formaldehyde (Ct) was determined after steam distillation and combined form formaldehyde (Cc) was calculated from the following formula.Combined HCHO(Cc)ppm=Total HCHO(Ct)-Free HCHO(Cf)(3) Free formaldehyde was determined about 1-87ppm on 12 samples of urea and melamine resin tablewares, and combined formaldehyde was about 0-31ppm.