Tetramethylammonium hydroxide TMAH

The sampling port is controlled by the operation software and can be set to continuously monitor a single one of the three inlets, or multiplexed between two (or all three although it is unlikely that a mission scenario will incorporate all three) of the modes (e.g., BWA in air and CWA in air). Also contained in the SIM is the pyrolyzer assembly, including the tetramethylammonium hydroxide (TMAH) solution delivery subsystem. 

X. Zang, J.C. Brown, J.D.H. van Heemst, A. Palumbo, P.G. Hatcher, Characterization of Amino Acids and Proteinaceous Materials using Online Tetramethylammonium Hydroxide (TMAH) Thermochemolysis and Gas Chromatography Mass Spectrometry Technique, Journal of Analytical and Applied Pyrolysis, 61, 181 193 (2001). 

Characteristic markers of Venice turpentine are larixol and larixyl acetate, but in many cases they may remain undetected, as larixyl acetate hydrolyses and the methylation of hydroxyl groups is not as effective as for carboxylic acids. On-line derivatization with tetramethylammonium hydroxide (TMAH) is, for instance, scarcely effective on hydroxyl groups and involves a number of secondary reactions (isomerization, dehydration and cleavage of hydrolysable bonds) due to the strong alkalinity of the TMAH solution. When the experimental conditions are such that THM of labdanes occurs larixol and larixyl acetate are detected as a single peak since in the derivatization process larixyl acetate is hydrolysed to larixol [29]. 

McKinney D, Bortiatynski J, Carson D, Clifford D, deLeeuw J, Hatcher P (1996) Tetramethylammonium hydroxide (TMAH) thermochemolysis of the aliphatic biopolymer cutan insights into the chemical structure. Org Geochem 24 641-650... 

Tetramethylammonium hydroxide, TMAH, (Fluka Chemicals) was diluted with distilled water from a 25 wt % aqueous solution. In all cases the diazonaphthoquinone dissolution inhibitor used was Fairmont Positive Sensitizer 1009 (Fairmont Chemical Company). The syntheses of the PDMSX oligomers and novolac-PDMSX block copolymers have already been reported (11). The dimethylamine terminated poly(dimethyl siloxane), =510 g/mole (Petrarch), was used as the PDMSX component or to prepare higher molecular weight analogs. 

One of SACHEM s products is tetramethylammonium hydroxide (TMAH), which is sold to semiconductor industries. Suspended particles in TMAH solutions could cause severe mechanical damage to the electronic devices manufactured by their customers. The determination of the particle content in such solutions is therefore critical. It is performed with a laser-equipped particle counter, which provides 70% detection efficiency. The counting must take place in a clean room because tiny airborne particles can land in the solutions and give them a false high reading. A class 1000 environment is required in this case, which means that the count of particles in the air that are greater than or equal to 0.5 jrm in diameter must be less than 1000 per cubic foot. Typically, a customer s specification for TMAH solutions is less than 100 particles per milliliter for particles greater than or equal to 0.5 fim in diameter. 

The analysis of tetramethylammonium hydroxide (TMAH) solutions manufactured by SACHEM Inc. of Cleburne, Texas, includes the determination of trace elements. These elements cause less-than-optimum performance of integrated circuit boards manufactured by SACHEM s customers that use these solutions in their processes. Alkali and alkaline earth metals (e.g., Li, Na, K, Mg, Ca, and Ba) can reduce the oxide breakdown voltage of the devices. In addition, transition and heavy metal elements (e.g., Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ag, Au, and Pb) can produce higher dark current. Doping elements (e.g., B, Al, Si, P, As, and Sn) can alter the operating characteristics of the devices. In SACHEM s quality control laboratory, ICP coupled to mass spectrometry is used to simultaneously analyze multiple trace elements in one sample in just 1 to 4 min. This ICP-MS instrument is a state-of-the-art instrument that can provide high throughput and low detection Emits at the parts per thousand level. Trace elemental determination at the parts per thousand level must be performed in a clean room so that trace elemental contamination from airborne particles can be minimized. 

SACHEM Inc., located in Cleburne, Texas, is a producer of high-purity bulk chemicals for companies that have high-purity requirements in their chemical processing. As stated in Workplace Scene 1.2, one of their products is tetramethylammonium hydroxide (TMAH), which is sold to semiconductor industries. The analysis of TMAH for trace anions such as chloride, nitrate, nitrite, and carbonate is critical for SACHEM s quality control laboratory. If these ions are present on the integrated circuit boards manufactured by one of their semiconductor customers, they may cause corrosion severe enough to affect the functionality and performance of the electronic devices in which the circuit boards are used. In SACHEM s quality control laboratory, ion chromatography procedures have been developed to measure the anion concentrations in TMAH. Because the concentration levels are trace levels, a clean room environment, like that described in Workplace Scene 1.2, is used. A special procedure for carbonate analysis is required so that the absorption of carbon dioxide from the atmosphere can be minimized. 

REAGENT PREPARATION. Phosphate buffer of pH 3.5, a saturated solution of NaH2P04 in distilled water, and tetramethylammonium hydroxide (TMAH) pentahydrate (Sigma) (48by weight in methanol)... 

Analytical pyrolysis with field ionization mass spectrometry (online Py-FIMS) or in combination with GC/MS (Curie point Py-GC/MS) led to a significant increased number of identified subunits (e.g., Bracewell et al., 1989 Schulten et al., 2002). In addition, the application of tetramethylammonium hydroxide (TMAH) methylation, followed by GC/MS, was successfully applied. The most abundant pyrolysis products identified are benzene, phenol and furan derivatives, aliphatic and carboxylic compounds, and indene derivatives (Schulten et al.,2002). New approaches have been used for the quantification of n-alkyl fatty acids of DOM and isolated fractions in the form of individual compounds after solvent extraction followed by derivatiza-tion with TMAH. 

Chefetz, B., Chen, Y., Clapp, C. E., and Hatcher, P. G. (2000). Characterisiation of organic matter in soils by thermochemolysis using tetramethylammonium hydroxide (TMAH). Soil Sci. Soc. Amer. /. 64, 583-589. 

Clifford, D.J., Carson, D.M., McKinney, D.E., Bortiatynski, J.M., and Hatcher, P.G. (1995) A new rapid technique for the characterization of lignin in vascular plants thermochemolysis with tetramethylammonium hydroxide (TMAH). Org. Geochem. 23, 169-175. 

Filley, T.R., Minard, R.D., and Hatcher, P.G. (1999) Tetramethylammonium hydroxide (TMAH) thermochemolysis proposed mechanisms based upon the application pf 13C-labeled TMAH to a synthetic model lignin dimer. Org. Geochem. 30, 607-621. 

Liver and kidney homogenate samples were prepared for F-AAS quantisation by digestion with an appropriate concentration of aqueous tetramethylammonium hydroxide TMAH [1]. The tissue levels of Cu, Cd, Pb, and Zn, the reproducibility of the analyses, and the recovery of added element standards compare favorably with the results obtained by standard wet ashing procedures using concentrated HN03 or HNO3DHCIQ. 

H. Matusiewicz, B. Golik, Determination of major and trace elements in biological materials by microwave induced plasma optical emission spectrometry (MIP-OES) following tetramethylammonium hydroxide (TMAH) solubilization, Microchem. J., 76 (2004), 23 D29. 

Dissolution and Extraction in General For the dissolution of fish tissues different procedures are reported. Acid or alkaline digestion or solvent extraction is usually used for the separation of Hg species from biological matrices [45, 46]. For the quantitative extraction of Hg, four methods were examined HC1 leaching, alkaline-methanol extraction with tetramethylammonium hydroxide (TMAH) and... 

Lithographic Characterization. Electron-beam exposures were conducted on an EBES system operating at 20 kV, with a beam address and spot size both equal to 0.25 ym. Electron response parameters were evaluated using linewidth control patterns. P(SI-CMS) was spray developed after exposure using an APT Model 915 resist processor in toluene-methanol (1 1) for 30 sec followed by a methanol rinse for 45 sec. Aqueous solutions of tetramethylammonium hydroxide (TMAH, 25% in water, Fluka Inc.) were used for the novolac resist development. Exposed films were dip-developed for 20 sec. in TMAH-water (1 2.5) solutions. 

In a few cases the original experiments described in this book were performed at an equilibrium temperature Te, of 850° C. This was done for the case of polymers that are more heat resistant. For these experiments, all the other conditions were maintained the same. When different conditions were used for the experiment (e.g. the use of tetramethylammonium hydroxide, TMAH, for in situ derivatization of pyrolysate, or off line silylation) these modifications as well as any changes in the separation conditions are described with these particular experiments. 

Table 6.7.3. Compounds identified in the pyrogram of polyfacrylic acid) Mw = 1,000,000 in the presence of tetramethylammonium hydroxide (TMAH) as shown in Figure 6.7.4.

Pyrolysis in the presence of tetramethylammonium hydroxide (TMAH) at a lower temperature of 300° C was studied for both PES and PSF [11]. In this study, the main component for the thermally assisted hydrolysis and methylation of PES was dimethyl derivative of bis(4-hydroxyphenyl)sulfone. This compound was formed through selective cleavages of ether linkages maintaining intact the sulfone structures. For PSF thermally assisted hydrolysis and methylation at 300° C, the main constituents were dimethyl derivative of bis(4-hydroxyphenyl)isopropylidene (bisphenol A) and also dimethyl derivative of bis(4-hydroxyphenyl)sulfone. A partial decomposition of the sulfone groups in PSF during the THM reaction also was noted. The findings also were confirmed by matrix assisted laser desorption mass spectrometric measurements. 

McKinney D.E., Hatcher P.G. (1996) Characterization of peatified and coalified wood by tetramethylammonium hydroxide (TMAH) thermochemolysis.Iret.J. Coal Geol. 32, 217-28. 

Ammonium, tetramethyl-, hydroxide EINECS 200-882-9 Hydroxyde de tetramethylammonium Methanaminium, N,N,N-trimethyl-, hydroxide NMD 3 NMW-W Tetramethylammonium hydroxide TMAH UN1835. Usually marketed as a 10% aqueous solution. d 4 = 1.00. [Pentahydrate] crystals mp = 53 . Ruka Janssen Chimica Sigma-Aldrich Fine Chem. 

Derivatization of the sample renders many of these polar pyrolysis products sufficiently volatile for gas chromatographic separation. Thus it is possible to separate and detect many more strucmrally significant products than observed by conventional pyrolysis techniques.The most common of the derivatization processes is a methylation reaction where organic matter is mixed with tetramethylammonium hydroxide (TMAH) prior to pyrolysis. Throughout the literature, several different terms have been employed to describe derivatization reaction and in this chapter the term thermochemolysis will be used. 

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