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In Nigeria, paracetamol is readily available in several retail outlets where the conditions of storage can be poor leading to elevated levels of para-aminophenol (PAP), which is known to be nephrotoxic and hepatotoxic. However, the routine analysis of PAP is mostly by chromatographic separation which requires expensive instrumentation not often available in developing countries. The objective of this research was to develop a sensitive colorimetric method for the quantification of PAP in paracetamol. The method was based on the diazo coupling reaction between diazotised PAP and chromotropic acid. Various reaction parameters critical for optimal detector response were optimized. The validation of the new method was done following the determination of parameters including repeatability, reproducibility and selectivity using current ICH guidelines. The new method was also applied to the assay of PAP in 14 paracetamol tablet samples. The calibration was linear between 0.0297 and 0.2229 µg/mL at 470 nm with limits of detection and quantification of 0.0061 and 0.0185 µg/mL, respectively. The recovery was in the range of 95.96 and 102.21 while intra- and inter-day precisions at three different concentrations did not exceed 4.03%. The new method was successfully applied to quantify PAP in paracetamol with percent content varying from 0.14 to 0.21%w/w. A simple and reliable method for the quantification of PAP has been developed and successfully employed to report, for the first time, the presence of the degradation product at levels beyond the allowable limits in paracetamol dosage forms in Nigeria.

The thiazolylazo compounds and their Co(II), Ni(II) and Cu(II) complexes of barbituric acid, uracil, thiouracil, citrazinic acid, chromotropic acid, gallic acid, pyrogallol and salicylic acid were prepared and characterized by 1H NMR, IR and the effect of pH on the electronic absorption spectra. The mode of ionization, the electronic transitions and the dissociation constants were discussed. The stoichiometries of the complexes were of 1:1, 2:1 and 3:2 (M:L). The copper complexes are of isotropic ESR spectra (except that of gallic acid which showed a complicated one) and are of magnetically diluted behaviour with orbital contribution. Detailed DTA data were obtained and discussed.

A simple, accurate and highly sensitive spectrophotometric method is proposed for the rapid determination of Dipyridamole using p-chlorophenylazo chromotropic acid (p-Cl) and 2-(p-nitrophenylazo)-chromotropic acid (C2B) and Chlorpheniramine maleate using p-chlorophenylazo chromotropic acid (p-Cl), p-iodophenylazo chromotropic acid (p-I), 2-(p-nitrophenylazo)-chromotropic acid (C2B) and 2-(phenylazo)-chromotropic acid (C2R). The method consists of extracting the ion-associates into methylene chloride. The ion-associates exhibit absorption maxima at 544 and 524 nm for p-Cl and C2B with Dipyridamole, and at 540, 524, 536 and 524 nm for p-Cl, p-I, C2B and C2R with Chlorpheniramine maleate, respectively. Dipyridamole can be determined up to 3.50 and 3.78 mg ml−1 using p-Cl and C2B, respectively, while Chlorpheniramine maleate can be determined up to 3.10, 2.36, 1.90 and 1.70 mg ml−1 using p-Cl, p-I, C2B and C2R, respectively. The stoichiometric ratio of the ion-associates was estimated. The molar absorptivity ...

Accurate, rapid and sensitive extraction-colorimetric method for the determination of erythromycin and its esters, depending on the formation of an ion-pairs with chromotropic acid (I), chromotrope 2B (II), chromotrope 2R (III), arsenazo I (IV), arsenazo III (V), benzocaprol red (VI) and acid ethyl blue (VII) is described. The calibration curves resulting from the measurements of absorbance-concentration relations (at the optimum reaction conditions) of the extracted ion-pairs are linear over the concentration range 0.4–56 μg ml−1 with a relative standard deviation (RSD) of 1.3% for 25 μg ml−1 erythromycin. The detection limit, quantification limit, the molar absorptivity and Sandell sensitivity for erythromycin ion-pairs were evaluated. The interference from excipients commonly present in dosage forms and common degradation product was studied. The method is highly specific for the determination of stearate and succinate esters in dosage forms. The method has been compared to the official method and foun...

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.

The widespread falsification and/or adulteration of commercially available pharmaceutical preparations call for reliable methods of drug identification, preferably through selective and rapid sorting color tests that could be undertaken with minimum equipment remote from laboratory facilities. The present work deals with a convenient adaptation and refinement of a spot test devised by Feigl (1966) for urotropine, based on the hydrolytic cleavage of that substance in the presence of sulfuric acid, splitting out fomaldehyde which is identified by its color reaction with chromotropic acid. A simple emergency kit was developed for the quick, efficient, inexpensive and easy performance of urotropine tests by semiskilled personnel even in the drugstore laboratory (or office) as well as in a mobile screening operation. It is shown that when the reagents are added according to the recommended sequence a self-heating system is generated, increasing substantially the reactions' rates and the test sensitivi...

With comparable molar quantities, chromotropic acid reacts with compounds containing aldehyde groups -CHO e.g. with formadehyde or glyoxylic acid to form cyclic compounds with rings containing four chromotropic acid fragments — cyclotetrachromotropylene derivatives. The cyclic compounds, due to the presence of a cavity in the molecule, can play the part of host and complex smaller molecules, which has been confirmed on the basis of triethylamine by the 1H-NMR measurements. Using spectrophotometric method the stability constant of 1:1 complex formed between Ti(IV) and cyclic compound chromotropic acid with formaldehyde has been determined - K = (9,0 ± 0,1) 104.

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.

For dusty environments consideration is being given to estimating an exposure from formaldehyde leached from particulate matter once it enters the respiratory tract. Approaches developed for determination of formaldehyde which may be released from formaldehyde resin-containing dusts involve leaching in water at physiological temperature for 4 to 6 hours and measuring the leached formaldehyde by the 2, 4-dinitrophenylhydrazine (2, 4-DNPH), chromotropic acid (CTA), or acetylacetone (ACE) (Hantzsch Reaction) analysis procedures. A previous study of wood and paper product dusts showed that CTA indicated ten times higher levels of formaldehyde than those measured by ACE. A lack of information exists on releasable formaldehyde measured by 2, 4-DNPH versus ACE and CTA on similar samples. This study presents a comparison of the amounts of releasable formaldehyde measured by these three procedures applied to water extracts of formaldehyde resin-containing wood and paper product dusts and expands the numbe...

A new heteronuclear complex, rare earth (III)-copper (II)-m-trifluomethyl chlorophosphonazo (CPA-mCF3) system for determining trace rare earth ions is presented. In a medium of 0.02mol/L NH4Cl,1. 0×10−3mol/L Cu(II),1.0×10−5 mol/L CPA-mCF3, a very sensitive polarographic adsorptive wave is observed by using a single sweep oscillopolarograph at about –0.83V (vs. Ag/AgCl). The linear relationship between the peak current and the concentration of rare earth exists from 6. 0×10−9 to 1. 0×10−6 mol/L. The detection limit of rare earth is down to 2. 0×10−9 mol/L for Tm3+. This method has been applied to determine trace RE in several samples of Chinese tea. The results are satisfactory. The composition of the complex is detected as RE (II): Cu (II): CPA-mCF3 = 1: 1: 2.

Acid dissociation constants of the title multidentate ligand (PACA) consisting of both chlorophenolylazo and chromotropic acid fragments were elucidated as pKa1 = 7.27 (from HO- at the 1-position of the chromotropic acid moiety) and pKa2 = 10.54 (from HO- in the chlorophenol moiety), by a comparison with an analogous ligand, 2-[(3-chlorophenyl)azo]-1,8-dihydroxynaphthalene-3,6-disulfonic acid(BACA). Coordination modes of VO(IV), Ni(II), and Cd(II) with PACA, BACA, and 2-[(3-chlorophenyl)azo]-1-hydroxynaphthalene-3,6-disulfonic acid(BARGA) were studied by means of spectroscopy and polarography in aqueous solution. Stability constants of the PACA complexes [M(HL)] with VO(IV), Ni(II), and Cd(II) are governed by HSAB properties.

The iodide-iodate test for the detection of volatile organic acids and the chromo tropic acid test for the detection of formaldehyde have been evaluated for use in the selection of materials for the storage and display of antiquities. At present the “Oddy test” with lead is used to identify those materials that have the potential to corrode lead. Since the volatile organic acids and formaldehyde that corrode lead can also affect other materials, the test is also used as an indicator of the evolution of these gases. A comparison with the Oddy test with lead has shown that the chromotropic acid test is more sensitive than the Oddy test and may detect formaldehyde at a level that is unlikely to cause corrosion. The iodide-iodate test and chromotropic acid test take approximately 2 hours to perform compared with 28 days for the Oddy test. The combined use of the iodide-iodate test and the chromo tropic acid test has been shown to be a good indicator of the suitability of a material for use in the stor...

The objective of this work was to identify suitable methods for personal sampling of formaldehyde in ambient air at sub-ppm levels. Experiments were conducted to survey several of the commercially available monitors and to compare them to the more established “active” methods, which are based on a variety of different chemistries: chromotropic acid, 2-(hy-droxymethyl)piperidine, and 2,4-dinitrophenylhydrazine. Experiments were conducted in a laboratory plexiglas exposure chamber. Stable formaldehyde concentrations were generated by heating alpha-polyoxymethylene in a refillable, high-permeation rate diffusion tube. The experiments were designed to determine the suitability of the monitors for short-term and time weighted average (TWA) monitoring for formaldehyde. Short-term sampling was performed at nominal concentrations of 0.3 and 2 ppm. TWA sampling was performed at nominal concentrations of 0.3, 0.5, and 1 ppm. A total of 6 passive and 5 active methods were evaluated. Several devices were capable of m...

Epidemiology studies have suggested that exposures to formaldehyde in combination with dust particles in workplace atmospheres may be linked to increased risk of some cancers. Information on the amounts of formaldehyde associated with different sized particles is lacking as well as appropriate methodology for assessing the possible significance of this mode of exposure. This prompted studies to evaluate methods for estimating amounts of formaldehyde that may be released from inhaled particles of paper and wood product dust containing formaldehyde-based resins. The relationship between quantities of released formaldehyde and particle soaking conditions were assessed. The chromotropic acid, MBTH, and acetylacetone analysis procedures were examined for their appropriateness in measuring released formaldehyde. Use of the chromotropic acid procedure for this purpose indicated formaldehyde levels for wood product dusts that were approximately 10 to 14 times higher than those determined by the MBTH and acetylace...

A method for the estimation of formaldehyde dose from inhalable dust/fibers using a commercially available inhalable sampler was developed. Filters containing sampled dust/fibers were placed in 10 ml of distilled water and incubated at 37°C for 4 hours to liberate the formaldehyde from the dust/fibers. After incubation, the filter extracts were passed with a 0.45 μm filter to remove particles left in the extracts. Two analytical procedures were used for the analysis of the filter extracts. Either a 4-ml aliquot was analyzed using the chromotropic acid procedure, as outlined in NIOSH Method 3500, or a 1-ml aliquot was treated with 2,4-dinitrophenylhydrazine and a catalytic amount of perchloric acid and analyzed by high-performance liquid chromatography for the resulting 2,4-dinitrophenylhydrazone. The limits of detection for the chromotropic acid procedure and the 2,4-dinitrophenylhydrazine procedure were 0.44 and 0.08 μg per filter sample, respectively. Relative standard deviations of replicate d...

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.

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.

Two methods for measuring formaldehyde at ppb levels--the modified pararosaniline (PRA) and the modified chromotropic acid (CTA)--were evaluated in a laboratory study. A dynamic double dilution system was used to generate controlled test atmospheres of formaldehyde by the catalytic depolymerization of trioxane. Impinger samples were collected from the sampling manifold and analyzed accordingly. Both methods demonstrated good precision (3.5% for the PRA and 3.4% for the CTA) but differed in accuracy and collection efficiency. Accuracy was 87.7 +/- 7.5% for the PRA and 92.5 +/- 4.2% for the CTA, while collection efficiency was 91.9 +/- 6.9% and 98.7 +/- 4.7% respectively. These differences were mainly due to the use of 1% NaHSO3 as the absorbing solution in the CTA method. Additionally, the NaHSO3 solution has the advantage of long sample preservation, making the modified CTA the method of choice in most non-industrial indoor air sampling situations.

A new sampling method for monitoring personal exposure to formaldehyde is described. The method consists of drawing air through a solid sorbent tube containing silica gel impregnated with 20 percent sodium bisulfite. The formaldehyde collected reacts to form the sodium formaldehyde bisulfite addition product. This salt may then be desorbed with water and the resulting solution analyzed for formaldehyde using the chromotropic acid colorimetric method. The collection and desorption efficiency of the method were tested using an atmosphere generator capable of producing calibrated, dynamic atmospheres of formaldehyde. The new solid sorbent sampler gave results equivalent to a bubbler/H2O collection method and to the formaldehyde concentration calculated for the atmosphere generator. The overall method was very simple, and the desorbed solutions did not require filtration prior to analysis. The capacity of this sorbent material for retaining formaldehyde before breakthrough occurred was much higher th...

An improved method for the spectrophotometric determination of titanium using chromotropic acid is described. The optical density of Ti-chromotropic acid complex at 470 nm has been found to be independent of pH from 3 to 6. Acetic acid sensitises the optical density of the complex. The interfering effect of Fe(III) up to 200 μg/ml has been overcome by adding 5 mg Fe(III) to both the standard and the test solutions followed by reduction with a mixture of ascorbic and acetic acids at pH 3–4. The photosensitivity of chromotropic acid has been eliminated by preparing the reagent solution in 0.3N H2SO4. The development of Ti-chromotropic acid colour is instantaneous and the optical density does not change for a period of at least 12 hrs. The method has been successfully applied to the determination of traces of TiO2 in various ceramic materials such as feldspar, silica bricks, burnt magnesite, chromite and glass.

A practical and correct methodology for evaluating CH2O in air without sampling artifact formation is presented. Formaldehyde is collected on an annular denuder coated with bisulfite-triethanolamine. The sorbent layer is extracted with water and the solution analyzed by the chromotropic acid (CTA) procedure. Sorption efficiency and loading capacity have been investigated along with storage stability. Results of laboratory validation studies have indicated that a small annular denuder was able to sample about 300 μg CH2O without an appreciable decrease in the initial collection efficiency (99% at 2.5 1 min−1). Tests on storage stability before and after exposure have also demonstrated that both oxidation of bisulfite and release of CH2O did not occur for time periods as long as 1 month.

The usefulness of test results in assessing the health hazard potential of residential formaldehyde exposures depends in great measure on the accuracy and reliability of sampling/analysis methods employed, the protocol used in collecting samples, sampling objectives, and an understanding of residential formaldehyde dynamics and their relationship to environmental variables. Active sampling and analysis methods including detector tubes, the impinger/chromotropic acid method, the impinger/pararosaniline method, and the CEA continuous monitor are reviewed as to advantages and limitations for residential sampling. Passive dosimeter methods including the Dupont Pro-Tec Badge, 3M Monitor, Air Quality Research, Inc. Passive Formaldehyde Kit, and Envirotech, Inc. Dosimeter are also reviewed. Sampling considerations for one-time formaldehyde sampling using the impinger/chromotropic acid method are discussed in detail, including pre-sampling closure of residences, maintenance of a standard indoor temperature both before and during sampling, the undesirability of sampling during cold, dry winter weather, sample number, sampling location, height and duration, environmental measurements during sampling, source identification and sample storage. A model formaldehyde sampling protocol based on the impinger/chromotropic acid method is described.

Recently Soltanpour and Schwab3developed an NH4HCO3 ‐DTPA (AB‐DTPA) soil test to simultaneously extract NO3, P, K, Zn, Fe, Mn, and Cu. In this test carbon black was used to clear the extract for the chromotropic acid method of nitrate determination. However, use of carbon black was inconvenient due to its staining and sometimes contaminative properties. The purpose of the study reported here was to determine the effect of the elimination of carbon black from the AB‐DTPA test on the extractable levels of P, K, Zn, Fe, Mn, and Cu. The results indicated that carbon black adsorbed Fe‐, Mn‐, and Cu‐DTPA, but did not affect the levels of P, K, and Zn in the AB‐DTPA extracts. Regressions of the modified AB‐DTPA test (no carbon black) on the DTPA test for Zn, Fe, Mn and Cu were run. These regressions showed that the levels of AB‐DTPA‐extractable Zn, Fe, Mn, and Cu are highly correlated to the levels of these nutrients determined by the DTPA test. It was concluded that carbon black should be eliminated fr...

Phenol is a significant interference in the commonly used chromotropic acid test for formaldehyde. This interference can be considerably reduced or eliminated by adsorption with XAD-7® polymeric absorbent before analysis. The efficiency of phenol removal ranges from 95% to greater than 99.5% at concentrations ranging up to 100 micrograms/mL without affecting the formaldehyde concentration.

The modified pararosaniline method for formaldehyde which uses no poisonous mercury reagent is not affected by phenol/formaldehyde ratios ranging from 1 to 100, whereas such ratios caused almost total inhibition of the chromotropic acid method, even if water, 1% sodium bisulfite or 0.01 N H2SO4 were used to simulate different collection media. No influence of phenol also occurred even for 11 days of storage at room temperature before analysis.

The equilibria between gallium(III) ion and selected hydroxyaromatic and dihydroxyaromatic ligands at 25°C, μ=0.100 M (KNO3) have been determined. Potentiometric measurements on 1:1, 2:1, and 3:1 molar ratios of ligand to Ga(III) have been made as a function of degree of neutralization over the entire accessible −log [H+] scale. Calculations were carried out so as to take account of competing hydrolytic reactions, and formation constants of gallium(III) with chromotropic acid, 8-hydroxyquinoline-5-sulfonic acid, 5-sulfosalicylic acid, and 1,2-dihydroxy-benzene-3,5-disulfonic acid were obtained. Stable hydroxo chelates do not form under the reaction conditions employed. The protonation constants of the ligands and the formation constants of the gallium chelates are discussed and compared with previously published work on these gallium chelates and on chelates of “analogous” metal ions such as those of Fe(III) and A1(III).

This report describes the automation of colorimetric and fluorometric methods for the determination of low levels of formaldehyde and related compounds in drinking water, natural water and industrial effluents. The colorimetric method utilizes chromotropic acid and the fluorometric method is based on the reaction of formaldehyde with 2, 4 - pentanedione and ammonia to form a fluorescent product. The fluorometric method was found to be much more specific than the colorimetric procedure and both methods are capable of determining formaldehyde down to 10 ug/litre at a rate of 10–20 samples per hour. The results of a preliminary survey concerning the occurrance of formaldehyde and related compounds in a wide variety of samples, ranging from drinking waters to industrial effluents, are also reported. The results indicate that considerable quantities of these compounds are present in some waters receiving industrial wastes and these results also show that those samples which contain formaldehyde also i...

The chromotropic acid method is used extensively for the measurement of low levels of formaldehyde in occupational and community environments. However, this procedure is not accepted universally as a standard method, and needs to be evaluated more thoroughly. Due to the deficiencies in knowledge regarding sample stability, a preliminary stability comparision of standard formaldehyde solutions in aqueous media was performed. Possible storage options of ambient, refrigeration and freezing conditions were investigated. In an attempt to detect any similarities or differences in stability between laboratory-prepared solution standards and field samples of formaldehyde, a side-by-side study was conducted. It was observed that both water-impinged solutions and laboratory-prepared aqueous formaldehyde solutions degraded rapidly upon ambient and refrigerated storage. One percent sodium bisulfite solution as the collection medium for formaldehyde provided good solution stability for ambient and refrigerated samples...

For determining formaldehyde, the Intersociety Committee of the American Public Health Association recommends a method using chromotropic acid (CA), and for determining total aliphatic aldehydes a method using 3-methyl-2-benzothiazolone hydrazone (MBTH). In field studies, the use of these separate methods involves performing many tasks in parallel and in duplicate. Inspection of the chemistry underlying the MBTH method suggested that the CA method might be successfully applied to MBTH-containing samples, provided that MBTH did not act as an interferent. We applied the recommended CA method to water and 0.05% MBTH impinger solutions from parallel sampling trains at six field sites, and found the mean formaldehyde levels to differ on the average by 5%. Having established that a single MBTH sample can yield both the formaldehyde and total aliphatic aldehyde contents of a sampled atmosphere we devised a combined method with improved techniques that streamlined laboratory analysis by maximizing procedural overlap.

Seven funeral homes were surveyed in 1980 to determine the magnitude of embalmers' exposure to formaldehyde, other chemical vapors, and total and respirable particulates. Air was monitored for formaldehyde by personal and area samples, and assayed using the chromotropic acid method. Personal sampling revealed time-weighted average formaldehyde concentrations which ranged from 0.1 to 0.4 ppm (mean 0.3 ppm) and 0.5 to 1.2 ppm (mean 0.9 ppm) during the embalming of intact and autopsied bodies, respectively. Concentrations of other airborne chemicals and of particulates were negligible. In preparing autopsied bodies, embalming technique and condition of the body itself appeared to be major determinants of formaldehyde exposure.

A method is described for the analysis of three permanent finishes based on formaldehyde. The finish is hydrolysed by 12N sulphuric acid, without heating, and the yield of formaldehyde is assessed colorimetrically by means of the reaction with chromotropic acid. The method is critically examined, and its applications are illustrated by practical results from finishes on viscose rayon and cotton.

The development of a rapid and precise method for analyzing formaldehyde is described. By using an experiment design technique known as simplex optimization, the sensitivity for this procedure was maximized. The analysis requires under 2 minutes of the analyst's time per sample and gives an average coefficient of variation of 1.3 percent. The average sensitivity is 0.294 A/μg/ml and as little as 0.018 μg/ml can be detected with 90 percent confidence if triplicate analyses are performed.

Procedures for monitoring formaldehyde concentration in air ultimately require a standard solution with which to calibrate the response of the analytical method. Although formaldehyde solutions of nominal concentration may be prepared from a variety of sources, the solutions must be standardized. The sulfite-pH/ titration method was tested and found to give erratic results. This paper presents evidence to indicate that the sulfite-pH/titration procedure requires modification. This modified procedure was used to standardize solutions of free formaldehyde. One of these standardized solutions was used to calibrate the chromotropic acid colorimetric procedure for formaldehyde. The calibrated colorimetric method accurately quantitated the concentration of a solution prepared from dry sodium formaldehyde bisulfite, previously calibrated using the direct-iodine/titration method. This correlation indicates that the modified sulfite-pH/titration standardization procedure is an accurate means of standardiz...

This study examined formaldehyde vapor exposures that occurred in the gross anatomy laboratories of a major medical school during a 12-week study period. Formaldehyde samples were collected using personal sampling pumps to draw air through midget impingers containing a 0.1% solution of sodium bisulfite dissolved in deionized water as the absorbing medium. Breathing zone and ambient air samples were collected and analyzed from 8 laboratories on a rotating basis. Analysis was via the chromotropic acid method recommended by the National Institute for Occupational Safety and Health. It was found that 44% of all breathing zone samples were greater than the 1.0 ppm ceiling value for occupational exposure recently recommended by the American Conference of Governmental Industrial Hygienists. Only 11% of ambient air samples were in excess of 1.0 ppm.

An analytical technique is described for determining microgram quantities of airborne vapors of diethanolamine and 2-methylaminoethanol. The amine is collected in distilled water. The hydroxy ethyl radical of the amine is oxidized to formaldehyde with periodic acid, and the formaldehyde is subsequently determined by the chromotropic acid method.

A simple modification of the chromotrophic acid method that will give accurate air monitoring data for formaldehyde in the presence of a two-fold concentration of phenol is presented. This simple modification of a widely-used method sufficiently reduces the interference due to phenol within the limitations specified, so that formaldehyde monitoring data of acceptable accuracy can be obtained when the phenol to formaldehyde ratio is as high as 2:1.