ISO-9001

FS34680

A Responsible Care*
Company 

Quantification of Odorants in a Scented Product Environmental Sampling of Workplace Exposures Tracking a Haze Formation in a Headlamp Assembly Casting Defect Analysis Identification of an Unknown Material Thermal Analysis of Failed Products Volatile Organic Compound Emissions in Fertilizer and Pesticides

1. Quantification of Odorants in a Scented Product
A customer who produces a scented product had to prove that the advertised amount of odorant was present in their products. Using headspace GC/MSD, a procedure was developed that met this customer's needs. Statistical data were generated to define the procedure's accuracy and precision.

2. Environmental Sampling of Workplace Exposures
A large factory was experiencing periodic "sick building" episodes. AS&T's mobile lab, equipped with a GC/MSD, was sent to their facility. The data gathered during that visit offered clues but did not pinpoint the problem. At the customer's request, the common irritants (for example, formaldehyde, acetaldehyde, carbon monoxide, and paint solvents) were eliminated as root causes. One limiting factor in solving this problem was that it occurred only sporadically. Although identifying the problem required at least five visits over a three-month period, the final report was a relief to the customer and its workers who had been struggling with the problem for a considerable length of time.

3. Tracking a Haze Formation in a Headlamp Assembly
A client was having problems with a new headlamp assembly that was being designed for a major automotive company. The assembly was made out of composite materials. During trials, a haze was forming over the reflective surface and reducing the lamp intensity to an unacceptable level. If the problem wasn't solved, the client was going to lose the contract. We evaluated the haze using ¹H NMR and FT-IR spectroscopic methods. The haze appeared to be mostly a hydrocarbon oil. No such oil was used in any part of the composite formulation according to the client. A technique was developed which allowed heating various parts of the assembly to temperatures near the temperature of the lamp and collecting any volatiles, which were then analyzed by NMR. It was found that a rubber vent tubing supplied by the automotive company released a significant amount of volatiles, and the NMR data indicated that the volatiles were identical to that found inside of the headlamp assembly. We actually went to the automotive company for the client and presented the data. The client retained the contract and the problem was fixed by specifying a different type of tubing.

4. Casting Defect Analysis
A foundry had been experiencing casting defects due to burn-in of the sand engine molds. Scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS) identified the sand inclusions as well as a glassy phase that was rich in sodium, magnesium, aluminum, silicon, and calcium. An examination of a sand additive used at the foundry found it to have a similar composition. Differential scanning calorimetry (DSC) found that the additive had melting behavior that was quite different from their previous additive. The results suggested that the customer would be better off using a different sand additive.

5. Identification of an Unknown Material
An unknown material was submitted for identification. The material was thought to be a corrosion inhibitor similar to benzotriazole or tolyltriazole.

Fourier transform infrared spectroscopy (FT-IR) was initially used to examine the material and to classify the major functional groups present. We found significant levels of aliphatic and NH functionalities, possibly suggesting an azole structure. However, there was only a small amount of aromatic functionality, which implies that the major component is not benzotriazole or tolyltriazole.

Energy dispersive x-ray spectroscopy (EDS) was used to perform an elemental analysis on the material. We found only carbon, oxygen, and nitrogen present. No inorganic salts were detected. This shows that the compound is organic in nature.

Nuclear magnetic resonance spectroscopy (NMR) was used to probe the hydrogen atoms (¹H) and carbon atoms (¹³C) in the sample. Initial results indicated mostly aliphatic species and lesser amounts of aromatic species, in agreement with the FT-IR results. More advanced NMR experiments such as DEPT (Distortionless Enhancement By Polarization Transfer) showed evidence of branching. Other advanced 2-dimensional NMR experiments such as COSY (COrrelation SpectroscopY) and HETCOR (HETeronuclear CORrelation) were of limited use because there was substantial overlap in the ¹H NMR spectrum. However, there was sufficient evidence from these experiments to show that there were at least two different CH-CH₃ species present, and the integrations suggested that the sample was actually a mixture of at least two very similar compounds.

Gas chromatography with a mass selective detector (GC/MSD) was used to separate the mixture. There was evidence of three major components in the chromatograph. The mass spectrum for each peak in the chromatograph was obtained. However, none of the spectra matched any of the library spectra.

Fourier transform mass spectroscopy (FT-MS) was used to obtain an accurate mass analysis of the components in the sample. Once an accurate mass was obtained, the exact molecular formula was determined. We found that the major component had a molecular formula of C₇H₁₁N₃.

A 2-dimensional NMR experiment called INADEQUATE (Incredible Natural Abundance DoublE QUAntum Transfer Experiment) was then used to map out all of the carbon-carbon connectivities in the sample. This experiment is not typically run because the sensitivity is very poor and requires a long experiment time. However, the results enable an unambiguous assignment of the carbon spectrum.

Using information from all of the techniques used, the sample was determined to be a mixture of the hydrogenation products of tolyltriazole. The hydrogenation products are 3,4,5,6-tetrahydro-6-methylbenzotriazole and 3,4,5,6-tetrahydro-5-benzotraizole. There was also evidence for unreacted starting materials (tolyltriazoles).

Using an internal standard, the levels of each species were quantitated. Along with a Karl-Fischer titration for the water level present, we could account for all of the components present in the sample.

6. Thermal Analysis of Failed Products
Manufacturing processes are usually beset by a large variety of variables that need to be controlled to produce the desired product. When a product fails in the field, it can be a difficult task to identify the root cause of the problem, e.g., out-of-control molding variable. We have consistently helped manufacturers having cracking, blistering, peeling and other modes of failure by characterizing the thermal properties of these products. Thermal characterization has proven to be a valuable tool that provides information leading to cause and solution for difficult manufacturing problems.

7. Volatile Organic Compound Emissions in Fertilizer and Pesticides
Many products made today in the fertilizer and pesticide industries have the potential for emission of volatile organic compounds. Consequently, these manufacturers must file "Estimation of Volatile Emission Potential" requirements with the California EPA to sell their products in that state. The data must be obtained using a specified method as outlined in the "Estimation of Volatile Emission Potential of Liquid and Solid Pesticides by Thermogravimetry" to meet state regulations. The Materials Characterization Group was a pilot participant in the California EPA Interlaboratory Trials (ILT) that established this laboratory procedure involving 115°C and 55°C regimens. Since implementation of this regulation, we have provided this testing to a large number of clients allowing them to comply with these EPA requirements.