Chromotropic Acid Method Research Articles

Formaldehyde may be found in cosmetic products even when unlabelled.

Concomitant contact allergy to formaldehyde and formaldehyde-releasers remains common among patients with allergic contact dermatitis. Concentration of free formaldehyde in cosmetic products within allowed limits have been shown to induce dermatitis from short-term use on normal skin.The aim of this study was to investigate the formaldehyde content of cosmetic products made in Lithuania. 42 samples were analysed with the chromotropic acid (CA) method for semi-quantitative formaldehyde determination. These included 24 leave-on (e.g., creams, lotions) and 18 rinse-off (e.g., shampoos, soaps) products. Formaldehyde releasers were declared on the labels of 10 products. No formaldehyde releaser was declared on the label of the only face cream investigated, but levels of free formaldehyde with the CA method was >40 mg/ml and when analysed with a high-performance liquid chromatographic method – 532 ppm. According to the EU Cosmetic directive, if the concentration of formaldehyde is above 0.05% a cosmetic product must be labelled “contains formaldehyde“. It could be difficult for patients allergic to formaldehyde to avoid contact with products containing it as its presence cannot be determined from the ingredient labelling with certainty. The CA method is a simple and reliable method for detecting formaldehyde presence in cosmetic products.

Preservatives in cosmetics in the Israeli market conform well to the EU legislation.

Preservatives are important and frequent skin sensitizers, found in a wide range of products for personal and occupational use. According to the European legislation, some cosmetic ingredients are restricted in terms of quantity and a detailed list of ingredients must be present on the product or packaging. To examine the use of preservatives in common cosmetics on the Israeli market. Sixty different Israeli brand cosmetics, including shampoos, liquid soaps, body creams and hand creams were randomly selected. Ingredient labels were examined. The products were investigated by the chromotropic acid method for release of formaldehyde and by high performance liquid chromatography for the presence of formaldehyde, DMDM hydantoin and methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) and MI content. All products but one contained a detailed list of ingredients printed on the package. According to labelling, the most prevalent preservatives in Israeli shampoos and liquid soaps were DMDM hydantoin and MCI/MI. Hand creams and body creams contained mainly parabens but also iodopropynyl butylcarbamate, phenoxyethanol and DMDM hydantoin. Formaldehyde in doses from 4 to 429 ppm, and DMDM hydantoin were detected in 38 and 16 (63% and 27%) of the products, respectively. MCI/MI was detected in 11 (18%) of the products, with highest prevalence in rinse- off products (55%). Excluding one hand cream which measured 106 ppm MI, the amount of formaldehyde, DMDM hydantoin, MCI/MI and MI was within the allowed concentrations by the European directive in all cases. In Israel, adaptation of the European directive prevails, as shown by the measurements we performed on randomly selected products.

Concentrations of formaldehyde in rain waters harvested at the Nigerian Institute for Oil Palm Research

Formaldehyde has been recognized as one of the most important pollutants and a carcinogen that is present in the air, water, foods, soils, fabrics, cosmetics, cigarette smoke and treated wood. Related health effects and hazards are linked to formaldehyde, depending on mode of exposure which includes: weakness, blindness, vomiting et cetera. Additionally, occupational exposure through vapours, results in a temporary reversible decrease in lung function. Ocular exposure to formaldehyde could result in permanent alterations to vision or blindness. At concentrations below maternal toxicity, formaldehyde is considered not to be a reproductive or developmental toxicant. Sufficient evidence is now available for the carcinogenicity of formaldehyde in both humans and animals. The International Agency for Research on Cancer has classed formaldehyde as a group 1carcinogen. Rain water is harvested and used for domestic and industrial purposes in Nigeria. Scarce information is available in the developing countries like Nigeria, relating to the sources of exposure to formaldehyde and other toxic substances. It was against the above background that samples of rain water were collected between April and October, 2008, 2009 and 2010 at the meteorological research unit of the Nigerian Institute for Oil Palm Research (NIFOR) in order to monitor the concentrations of formaldehyde, which were subsequently consumed by ingestion an d thus generate data on same for the populace of the area of study. The chromotropic acid method described by the National Institute for Occupational Safety and Health (NIOSH) was adopted for the determination of formaldehyde in the rain waters. Results indicated that the concentration range of the formaldehyde in the rain waters varied from month to month throughout the six months duration of analysis. The values detected were below the toxicity level recommended by the World Health Organization (WHO) and other world bodies for drinking water. In conclusion, the results of the rain waters collected for the period of assay suggests that the values did not cause any toxicity effects and thus were fit for human consumption based on the low formaldehyde concentrations.

Integrated flow analysis platform for the direct detection of nitrate in water using a simplified chromotropic acid method

This work describes the first use of a direct nitrate analyser using chromotropic acid. A simplified chromotropic acid method eliminating several steps previously associated with this method is employed in the platform. In a sulphuric acid medium, chromotropic acid reacts with nitrate ions and produces a characteristic yellow colour associated with an absorbance band in the visible region (λmax = 430 nm). The modified method allows for nitrate determination over the linear range 0.9–80 mg L−1 nitrate with a limit of detection of 0.73 μg L−1 nitrate. Validation was achieved by analysing water samples from various sources including groundwater, trade effluent and drinking water by the modified method and by ion chromatography. The method was implemented on a flow analysis platform incorporating a paired emitter–detector diode (PEDD) as the optical detector. An excellent correlation coefficient of 0.993 was obtained between the modified method and ion chromatography. The modified chromotropic acid method represents a rapid, simple, low cost technique for the direct determination of nitrate in water.

Spectrophotometric Estimation of Sulfadoxine in Pharmaceutical Preparations

Four simple, sensitive, accurate and rapid visible spectrophotometric methods (A, B, C and D) have been developed for the estimation of sulfadoxine in pharmaceutical preparations. They are based on the diazotization of sulfadoxine with sodium nitrite and hydrochloric acid followed by coupling with N‐(1‐naphthyl) ethylenediamine dihydrochloride (Method A) to form pink coloured chromogen, diphenylamine (Method B) to form light pink coloured chromogen, chromotropic acid (in alkaline medium) (Method C) to form orange coloured chromogen, Resorcinol (in alkaline medium) (Method D) to form light orange coloured chromogen and exhibiting absorption maxima (λmax) at 536 nm, 524 nm, 520 nm and 496 nm respectively. The coloured chromogens formed are stable for more than 2 h. Beer’s law was obeyed in the concentration range of 1.0 ‐ 5.0 μg/mL in Method A , 5.0 ‐ 25.0 μg/mL in Method B, 5.0 ‐ 25.0 μg/mL in Method C and 4.0 ‐ 8.0 μg/mL in Method D respectively. The results of the three analysis have been validated statistically and by recovery studies. The results obtained in the proposed methods are in good agreements with labeled amounts, when marketed pharmaceutical preparations are analyzed.

Formaldehyde in reusable protective gloves

Due to the clinical findings in a single patient's case, formaldehyde was suspected to be present in clinically relevant levels in reusable protective gloves. Therefore, 9 types of gloves were investigated with the semi-quantitative chromotropic acid method. It was found that 6/9 gloves emitted some formaldehyde and that 4/9 gloves emitted > or =40 microg of formaldehyde. Most of the formaldehyde was found on the inside of the gloves. To get an indication of the clinical relevance, a comparison with a protective cream declared to contain the formaldehyde-releasing agent diazolidinyl urea was performed by comparing areas of gloves with areas of cream layers with thickness 1-2 mg/cm(2). It was found that the amounts of formaldehyde emitted from the gloves might be in the same range as emitted from a layer of cream.

Presence of formaldehyde in topical corticosteroid preparations available on the Swedish market.

The aim of this study was to investigate the formaldehyde content of topical corticosteroid preparations available on the Swedish market. 73 samples were analysed with the chromotropic acid (CA) method for semi-quantitative formaldehyde determination and 30 samples with a high-performance liquid chromatographic method. These included 24 ointments, 28 creams, 1 lotion, 6 liniments, 2 gels, 9 solutions, 2 mousses and 1 oral paste. Formaldehyde was found in 5 creams and 1 ointment. Sources of formaldehyde in these preparations were discussed. Isopropanol was identified as a probable source of yellow discoloration, leading to false-negative results with the CA method.

Detection and Estimation of Part-per-Billion Levels of Formaldehyde Using a Portable High-Throughput Liquid Absorption Air Sampler

In view of the known adverse health effects of formaldehyde and its suspected carcinogenicity, a convenient and simple apparatus for its rapid detection is highly desirable. A portable high-throughput liquid absorption air sampler (PHTLAAS) was therefore evaluated for the rapid and ultrasensitive detection of formaldehyde. Controlled concentrations of formaldehyde in air were generated with a constant-drive syringe pump and mixing chamber apparatus and were either sampled by the PHTLAAS, at a rate of about 200 L/min, or fed to two series-connected liquid impingers. In either case, the formaldehyde was absorbed in a small volume of aqueous sodium bisulfite and measured by the chromotropic acid method. The reddish-purple color of the chromogen formed with chromotropic acid provides a sensitive test for the screening of low levels of formaldehyde in ambient air. Comparison of samples collected from the test sampler with those from the impingers before and after each test yielded PHTLAAS collection efficienci...

Quantitation of taurolidine decomposition in polymer solutions by chromotropic acid formaldehyde assay method

A sensitive, selective, and specific assay was needed to study the degradation kinetics of taurolidine and its stabilization by polyvinylpyrrolidone (PVP). The purpose of the present study was to evaluate the usefulness of the chromotropic acid method and other formaldehyde or amine derivatization methods. The methods evaluated included formaldehyde derivatization with chromotropic acid, acetylacetone, 4-amino-5-hydrazino-3-mercapto-1,2,4-triazole, semicarbazide hydrochloride, or 2,4-dinitrophenylhydrazine and taurolidine decomposition product derivatization with dansylchloride or 7-chloro-4-nitrobenz-2-oxa-1,3-diazole chloride. Results indicated that the chromotropic acid method provided sufficient selectivity, reproducibility and sensitivity. It was able to quench taurultam decomposition and avoided PVP interference. The method was optimized by performance based selection of reagent lots, appropriate reagent storage and preparation, and controlled derivatization conditions. In conclusion, the optimized chromotropic method was the most appropriate method for quantitating taurolidine decomposition.

Field precision of formaldehyde sampling and analysis using NIOSH method 3500.

This study examined the field precision of National Institute for Occupational Safety and Health (NIOSH) Method 3500, also known as chromotropic acid method, in the range of exposure limit covers the Occupational Safety and Health Administration (OSHA) permissible exposure limit of 0.75 ppm and the OSHA action level of 0.5 ppm airborne formaldehyde. Using this method, 78 area samples (25 sets of replicate samples) were collected in a workplace and analyzed. The concentrations of formaldehyde ranged from 0.05 to 1.72 ppm with a mean +/- standard deviation of 0.95 +/- 0.31 ppm. The precision (coefficient of variation, CV) of 25 sets of replicated samples ranged from 0.03 to 0.24 with an overall (pooled) precision of 0.09, which is in agreement with that stated in NIOSH Method 3500. In 68% of replicate samples the precision was equal to or less than 0.09. The relative accuracy of the sampling and analytical procedure used in this study was evaluated by collecting 12 sets of side-by-side replicate samples using both NIOSH Method 3500 and OSHA Method 5.2 Method 53 was used to determine whether the concentrations of formaldehyde were within the desired range. The overall mean concentrations were 0.98 +/- 0.42 for Method 3500 and 0.78 +/- 0.28 ppm for Method 5.2. These were no statistically different. The pooled CVs were 0.114 and 0.076 for Method 3500 and Method 52, respectively.

Field Precision of Formaldehyde Sampling and Analysis Using NIOSH Method 3500

This study examined the field precision of National Institute for Occupational Safety and Health (NIOSH) Method 3500, also known as chromotropic acid method, in the range of exposures that covers the Occupational Safety and Health Administration (OSHA) permissible exposure limit of 0.75 ppm and the OSHA action level of 0.5 ppm airborne formaldehyde. Using this method, 78 area samples (25 sets of replicate samples) were collected in a workplace and analyzed. The concentrations of formaldehyde ranged from 0.05 to 1.72 ppm with a mean ± standard deviation of 0.95 ± 0.31 ppm. The precision (coefficient of variation, CV) of 25 sets of replicate samples ranged from 0.03 to 0.24 with an overall (pooled) precision of 0.09, which is in agreement with that stated in NIOSH Method 3500. In 68% of replicate samples the precision was equal to or less than 0.09. The relative accuracy of the sampling and analytical procedure used in this study was evaluated by collecting 12 sets of side-by-side replicate samples using both NIOSH Method 3500 and OSHA Method 52. Method 52 was used to determine whether the concentrations of formaldehyde were within the desired range. The overall mean concentrations were 0.98 ± 0.42 for Method 3500 and 0.78 ± 0.28 ppm for Method 52. These were not statistically different. The pooled CVs were 0.114 and 0.076 for Method 3500 and Method 52, respectively.

Measurement of urinary oxalic acid: A comparison of five methods

Objective: Five methods for oxalate analysis in urine are compared with respect to reliability, accuracy, and practicability. Results: Suppressed and unsuppressed ionchromatography, as well as the enzymatic Sigma-Kit, achieve low coefficients of variation for the within-batch imprecision (1.1–8.0%) and between-day imprecision (1.6–7.2%). The results of these methods are comparable and the mean recovery rate ranges between 99.7% and 100.9%. The enzymatic Boehringer-Kit gives higher CV (3.1–9.5%) and the results are lower than those obtained by the methods mentioned above; the recovery rate is sufficient (92.4%). Conclusion: The handling of the chromatographic methods is very easy, whereas the enzymatic methods require more manual work. In relation to sample throughput, changes for the enzymatic methods are about twice as high as for the chromatographic methods. In respect to reliability and accuracy, the chromotropic acid method cannot be recommended (recovery rate 68%).

A Rapid Formaldehyde Assay Using Purpald Reagent: Application under Periodation Conditions

Measurement of formaldehyde is encountered in a broad range of applications including the wine and alcohol industry and environmental pollution surveillance. In carbohydrate structural chemistry, frequent use is made of formaldehyde by periodate oxidation of terminal vicinal diols. Popular methods for the detection of formaldehyde use reagents such as chromotropic acid (4,5-dihydroxynaphthalene-2,7-disulfonic acid) or acetylacetone. The chromotropic acid method requires heating of the sample under strongly acidic conditions, which is undesirable in many applications. The acetylacetone method yields a yellow color product, and is less specific and sensitive (Mimuraet al., J. Hyg. Chem.22, 39–41, 1976). The reaction of formaldehyde with Purpald (4-amino-3-hydrazino-5-mercapto-1,2,4-triazole) works under alkaline conditions at room temperature, and the sensitivity is superior to other methods. The color development by this reagent, however, requires oxidation of the adduct with hydrogen peroxide, air oxygen, or dilute periodate. We found that low levels of periodate, commonly used to oxidize specifically terminal vicinal diols to yield formaldehyde, are compatible with color development with the Purpald reagent. We have investigated the conditions required for use of the Purpald reagent, especially in conjunction with periodate oxidation reactions. We have used the assay either in test tubes or with microplates, attaining sensitivity of as little as 1 nmol formaldehyde.

Selective Monitoring of Formaldehyde in Air by Use of the Stopped-Flow Technique

Abstract Two kinetic methods based on the stopped-flow technique are proposed for the determination of formaldehyde in air by reaction with 3-methyl-2-benzothiazolone hydrazone (MBTH), followed by photometric detection at 620 nm, and with acetylacetone, followed by fluorimetric detection at δcx = 410 nm and δcm = 510 nm. Kinetic methodology considerably shortens the formaldehyde analysis time (measurements can be obtained within a few seconds) relative to existing methods based on these reactions and equilibrium measurements (ca. 30 and 60 min are needed for equilibrium to be reached in the photometric and fluorimetric method, respectively). One additional advantage of the kinetic methodology is its high selectivity, which was checked by studying the effect of various organic and inorganic species. Calibration graphs were linear over the ranges 20–600 and 20–1000 ng ml−1 formaldehyde for the photometric and fluorimetric methods, respectively. Both methods were applied to the determination of formaldehyde in air from urban- areas; the accuracy of the results was confirmed by comparing them with those provided by the standard chromotropic acid method. The poposed kinetic methods were found to be more sensitive, rapid, reproducible and easier to use than the widely accepted standard method.

Formaldehyde instead of dimethylamine determination as a measure of total formaldehyde formed in frozen Argentine hake (Merluccius hubbsi)

SummaryThe relationship between dimethylamine (DMA) and formaldehyde (FA) contents of fillet and minced flesh of hake (Merluccius hubbsi) during frozen storage was analysed. the relation is clearly linear and independent of the type of product and storage temperature. As the intercept was nearly zero, a constant relation between FA and DMA was established, with both similar as keeping time predictors. Measuring FA content by the chromotropic acid method was equivalent to, but easier than measuring DMA content.

A comparative study of formaldehyde detection using chromotropic acid, acetylacetone and HPLC in cosmetics and household cleaning products

Chromotropic acid and acetylacetone methods for qualitative determination of formaldehyde were tested in parallel on 48 commercial samples, with high-performance liquid chromotography (HPLC) implemented for quantitative measure. In addition, interference with the detection of formaldehyde was investigated by analyzing 12 other aldehydes and ketones, 7 essential oils and 3 polysorbates. Throughout this comparative study, the disadvantages of the chromotropic acid method, of which 2 variants were used, were delineated and we found that the acetylacetone test proved to be a more efficient screening method for formaldehyde detection in a clinical laboratory.

Spectrophotometric determination of hexamethylenetetramine

A spectrophotometric method has been developed for the quantitative determination of aqueous hexamethylenetetramine (HMT) alone, in the presence of large amounts of formaldehyde, and in the presence of urine. The method is based on the perchloric acid hydrolysis of HMT to formaldehyde, oxidation of formaldehyde by hydrous silver(I) oxide, and oxidation of silver(O) with iron(III) in the presence of FerroZine. Optimum conditions were developed and HMT was determined over the range from 3 × 10–7 to 3.3 × 10–6 mol dm–3. The method developed is approximately 7.5 times more sensitive than the chromotropic acid method.

Comparison of the Chromotropic Acid and Pararosaniline Methods for Measuring Formaldehyde Concentrations of Pressed-Wood Product Emissions

Formaldehyde concentrations of particleboard emissions in special measuring chambers were determined by both the chromotropic acid and pararosaniline methods, and the results were compared. Airborne and formalin-based calibration methods were compared also. An additional experiment was done to consider the possibility that aspects of the measuring system other than the calibration could bias results obtained from either analytical method. Synthetic formaldehyde atmospheres were substituted for pressed-wood products in the measuring chambers, and the concentrations were measured by both the chromotropic acid and pararosaniline methods. Formaldehyde concentrations determined by the chromotropic and pararosaniline methods agreed both on synthetic formaldehyde atmospheres and on emissions from five lots of particleboard from four different manufacturers.

An Evaluation of the Effect of Source and Concentration on Three Methods for the Measurement of Formaldehyde in Indoor Air

Three methods for measuring formaldehyde (HCHO) in indoor air were evaluated under field and laboratory conditions using different sources and concentrations of formaldehyde in air. Two impinger methods (the chromotropic acid method and modified pararosaniline method) and the Draeger short-term detector tube method (with and without activation tubes) were compared when sampling for formaldehyde from a particle board box, formalin solution, and a conventional home. Concentrations of formaldehyde ranged from 0.05-0.5 ppm in air. All samples were collected independently using personal sampling pumps and a Draeger bellows pump. The results indicate that the Draeger tube method using an activation tube gives lower results than either of the impinger methods. Without using an activation tube (concentrations greater than 0.5 ppm), the Draeger tube method was comparable to the two impinger methods. In addition, there are indications that the chromotropic acid method gives different results than the modified pararosaniline method, depending on the source of formaldehyde. The modified pararosaniline method indicated higher results than the chromotropic acid method when sampling from a particle board++ box but not from a formalin source. Overall analytical precision for each method of analysis was good.

An Evaluation of the Effect of Source and Concentration on Three Methods for the Measurement of Formaldehyde in Indoor Air

Three methods for measuring formaldehyde (HCHO) in indoor air were evaluated under field and laboratory conditions using different sources and concentrations of formaldehyde in air. Two impinger methods (the chromotropic acid method and modified pararosaniline method) and the Draeger short-term detector tube method (with and without activation tubes) were compared when sampling for formaldehyde from a particleboard box, formalin solution, and a conventional home. Concentrations of formaldehyde ranged from 0.05–0.5 ppm in air. All samples were collected independently using personal sampling pumps and a Draeger bellows pump. The results indicate that the Draeger tube method using an activation tube gives lower results than either of the impinger methods. Without using an activation tube (concentrations >0.5 ppm), the Draeger tube method was comparable to the tow impinger methods. In addition, there are indications that the chromotropic acid method gives different results than the modified pararosaniline method, depending on the source of formaldehyde. The modified pararosaniline method indicated higher results than the chromotropic acid method when sampling from a particleboard box but not from a formalin source. Overall analytical precision for each method of analysis was good.