Formaldehyde release measurement

Researchers had noted the release of formaldehyde by chemically treated fabric under prolonged hot, humid conditions (85,86). The American Association of Textile Chemists and Colorists (AATCC) Test Method 112 (87), or the sealed-jar test, developed in the United States and used extensively for 25 years, measures the formaldehyde release as a vapor from fabric stored over water in a sealed jar for 20 hours at 49°C. The method can also be carried out for 4 hours at 65°C. Results from this test have been used to eliminate less stable finishes. 

Control of Formaldehyde Release. Once the sealed-jar test became a factor in measuring the formaldehyde release of fabrics suppHed to garment cutters, limitations were placed on the allowable limits acceptable to the garment producers. These limits brought to the fore two classes of reagents those based on DMDHEU, and those based on the /V, /V- dim ethyl o1 ca rh am a tes (4) (88). 

The effect of panel age on formaldehyde release was investigated in the first study summarized in Table I, and this variable was evidently very important with respect to the formaldehyde levels measured. As noted in the Remarks column in the table, formaldehyde levels ranged from 0.1 - 0.3 ppm for freshly manufactured specimens, while levels in the range of only 0.05 - 0.1 ppm were associated with matched specimens that had been aired out for 90 days at 23 C and 44% relative humidity. This aging effect is consistent with the theoretical considerations discussed earlier and with test results to be presented later in this report. 

Roffael (15) measured formaldehyde emissions from a phenolic particleboard using the WKI-Method which involves suspending small samples over 50 cm of distilled water in tightly closed polyethylene bottles and measuring formaldehyde levels in the water after varying times. Temperatures were maintained at 42 C. This work indicated that formaldehyde release from the phenolic particleboards ceased after a relatively short reaction period (approximately 96 hours). This finding is consistent with the resin stability considerations discussed previously under theoretical considerations. 

In these studies, formaldehyde release rate coefficients were measured for different consumer products using two methods. 

Each of these products was conditioned at room temperature, and 100% relative humidity (RH) (31 to 67 days). Formaldehyde release was measured as described H, 8, 15). A modified JIS desiccator procedure was used, and formaldehyde was quantitated using a pararosaniline procedure (15, 16). Formaldehyde release rate coefficients were calculated (15). An average coefficient of variation of 16% was obtained for this measurement (15). Samples displaced less than 12% of the chamber air (15). 

MD purchased these samples. Formaldehyde release was measured in a dynamic (ventilated) chamber system with one air change per hour as described (17). Air temperature and humidity were controlled. Formaldehyde was trapped using a midget impinger train (H). Samples displaced less than 12% of the chamber air (n). Aqueous formaldehyde and total extracted formaldehyde were measured as described (1, 8, 15-18). 

After testing each of the four individual products, three pairs of products were tested. Formaldehyde release when multiple products were in the same chamber was measured as above. The three pairs tested were particle board/plywood, particle board/insulation, and particle board/carpet. 

Unwashed new clothing samples (Table IIC), fiberglass insulation products with formaldehyde resins (Table IID), paper products (Table HE), fabrics (cotton, nylon, olefin, and blended) (Table HF), and carpets (Table HG), had substantially 3 to > 100 fold) lower formaldehyde release rate coefficients, as measured by this method, than did pressed wood products or urea formaldehyde foams (1, 15). 

Formaldehyde release rates were measured using multiple consumer products in a dynamic chamber. Particle board and plywood had high formaldehyde specific release rate coefficients. Combined plywood and particle board had a release rate 68% of the sum of the two products and 91% of the particle board release (Table V). When particle board was combined with insulation, the combined release rate was 71% of the sum of the separate release rates and 73% of the particle board release. Particle board and carpet combinations gave similar results. 

Pressed wood products and urea formaldehyde foam products had much higher release rates than those from most of the other products tested. Similar release rates have been observed by others (19). More than half of the products tested had very low release rate coefficients, and this included individual samples from six of seven of the types of products. Products equilibrated at 100% RH prior to the measurement were used to measure formaldehyde release. This equilibration may have removed a variable amount of formaldehyde (8, 14-17). 

Formaldehyde release rate coefficients measured in desiccators were similar to those determined in the dynamic chamber at similar loadings. Initial formaldehyde release rate coefficients for one sample each of particle board and plywood measured at 11.4 and 8.6 m /m in these chambers at one volume change per hour were 2-fold higher than those measured in desiccators at higher loadings (8, 15, 17). However, when the release rate coefficients were adjusted for differences in loading, the calculated release rate coefficients were similar to those measured in desiccators (8, 15, 17). 

Two sensitive fluorometric enzymatic methods for the determination of formaldehyde release from wood products were described. These methods were developed using the enzyme formaldehyde dehydrogenase to catalyze the oxidation of formaldehyde to form formic acid and NADH in the presenc of oxidized nicotinamide adenine dinucleotide (NAD ). The increase in NADH, which is directly proportional to the concentration of formaldehyde, is measured fluorometrically at em ... 

The measurements of formaldehyde release from wood products usually involves two steps sampling and analysis. For sampling,... 

The measurement of formaldehyde release from wood products Involves the collection of formaldehyde vapor in the test chamber using a suitable absorbing solution and then analyzing the formaldehyde collected. For many years, formaldehyde emission measurements were carried out using the desiccator test sampling method due to... 

In cooperation with DSM, MCN developed a method of measurement for the determination of the formaldehyde release from particle board, based on a theorie for mass transfer, implying that under steady state conditions the emission of formaldehyde of a given particle board can and should be defined by two parameters of the particular board. These two parameters are (1) Ce defined as the equilibrium formaldehyde concentration (with ventilation rate 0") and (2) kgg defined as the overall mass transfer coefficient of the board. In (ideal mixed) climate rooms the stationary formaldehyde... 

Out of the results of the intersection should follow an equilibrium concentration of 0.35 mg/m, which is not in accordance with the determined equilibrium value. So this experimental set up is a case of a situation which is not well defined and therefore not suitable for measurement of the relevant formaldehyde release parameters of the particleboard. 

Predicting Real-Life Formaldehyde Release by Measurement in the Laboratory... 

The purpose of this study was to evaluate laboratory formaldehyde release test methods for predicting real-life formaldehyde air concentrations human exposure levels, and health risk. Three test methods were investigated the European perforator test, the gas analysis method at 60 C and 3% RH, and the gas analysis method at 23 C and 55% RH. Different types of particleboard bonded with urea-formaldehyde and urea-melamine-formaldehyde resins were tested. The results were used to rank boards as a function of test method, conditioning, short-term humidity, and temperature variations during storage. Additional experiments were conducted in small experimental houses at a Dutch research institute. Our conclusions are that relative ranking of products is influenced by the test method and by change in relative humidity. The relationship between test method and release in real-life situations is not clear. In fact, it seems impossible to use laboratory measurements to predict real-life product performance of board if the board is not fully in equilibrium with the atmosphere. 

HIS BOOK SUMMARIZES OUR CURRENT UNDERSTANDING of many problems related to measuring, abating, and understanding formaldehyde emission from wood products bonded with formaldehyde-based adhesive resins. It contains expanded and updated versions of selected papers presented at an ACS symposium, Formaldehyde Release from Cellulose in Wood Products and Textiles. In addition, three chapters from participants who could not attend the meeting were added. 

A similar analytical scheme for following the transformation of 3,4,6-tri-O-methyl-D-fructose gave somewhat better results. In these experiments, the disappearance of 3,4,6-tri-O-methyl-n-fructose was determined by measuring the formaldehyde released on periodate oxidation. The periodate consumption by these mixtures served as a check on the formation of products other than 3,4,6-tri-0-methyl-n-glucose and 3,4,6-tri-O-methyl-D-mannose, since each of the 3,4,6-tri-O-methylhexoses consumes 1 mole of periodate per mole. Actually, the periodate titers increased approximately 20% during the time-period that the apparent concentration of 3,4,6-tri-O-methyl-D-fructose diminished to about 60% of the initial concentration (when the reaction was carried out in sodium hydroxide solution). The change in periodate consumed was attributed to occurrence of demethylation. When the transformation was carried out in either calcium hydroxide or barium hydroxide solutions, the periodate consumption increased markedly. Hence, calcium and barium ions appear to catalyze this side reaction. ... 

When UF foam is formed, formaldehyde is released. It is important to make sure that the proper ratio of components is employed and suitable construction measures are taken, as otherwise the problems of formaldehyde release from foam over short term or long term may be encountered. With present day technologies, it is possible to satisfy strict conditions that a formaldehyde level of 0.1 ppm should not be exceeded in the air of a room used continuously for dwelling purposes. 

Trioses and tetroses have been separated as their trimethylsilylated oximes by g.l.c. mass-spectral data for these derivatives were also recorded. Mixtures of xylitol, arabinitol, mannitol, glucitol, and maltitol have been separated efficiently by h.p.l.c. of the corresponding 4-nitrobenzoates. Alditols have been determined in the presence of neutral sugars by oxidation with acidified sodium periodate and colorimetric measurement of the formaldehyde released. G.l.c. retention data have been reported for the TMS derivatives of a large number of aldonic acids and their lactones and aldaric acids. ... 

In practice, the most critical raw material might be the water, espeeially if dwell water is used or water purification units are not well maintained. Polymer dispersions should be observed while stored in tanks. Overlay by an approx. 1 to 2% preservative solution containing a formaldehyde releaser to protect condense water via the gas phase is a very efficient measurement to keep the polymer dispersions and the tank in good condition. The same procedure helps to keep fresh finished goods, while stored in tanks. A lot of good ideas can be transfered from other industries producing water based materials, like e.g. cosmetics, food, adhesives (Wallhaeusser, 1995). 

This release of formaldehyde can also be quantified by using formaldehyde dehydrogenase, as described above. An alternative way to determine demethylase activity by measuring the amounts of released formaldehyde is the use of the Nash reaction [68, 69]. This method is based on the formation of the colored 3,5-diacetyl-1,4-dihydropyridine by condensation of formaldehyde and acetylacetone in the... 

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