Samples tetramethylammonium hydroxide

Monobasic acids are determined by gas chromatographic analysis of the free acids dibasic acids usually are derivatized by one of several methods prior to chromatographing (176,177). Methyl esters are prepared by treatment of the sample with BF.—methanol, H2SO4—methanol, or tetramethylammonium hydroxide. Gas chromatographic analysis of silylation products also has been used extensively. Liquid chromatographic analysis of free acids or of derivatives also has been used (178). More sophisticated hplc methods have been developed recentiy to meet the needs for trace analyses ia the environment, ia biological fluids, and other sources (179,180). Mass spectral identification of both dibasic and monobasic acids usually is done on gas chromatographicaHy resolved derivatives. 

Modern analytical pyrolysis has conventionally been canied out only by thermal energy to break some covalent bonds in the sample molecules at elevated temperatures to produce smaller and/or volatile fragments (pyrolyzates). On the other hand, the reactive pyrolysis in the presence of organic alkaline, such as tetramethylammonium hydroxide [(CH / NOH] (TMAH) has recently received much attention especially in the field of chai acterizing condensation polymers. 

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. 

Pyrolysis in the presence of tetramethylammonium hydroxide (THM)-GC/MS allowed the identification of high- and low-molecular weight components in manila Copal and sandarac fresh and artificially aged samples. The pyrograms showed signals due to the polymer fraction and to free diterpenoids [43]. THM-GC/MS has also been used to determine the molecular composition of Pinaceae resins, allowing the study of fresh, naturally and artificially aged samples [16, 44 46]. 

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. 

New synthetic procedures used to crystallize VPI-5 are described. Mixtures of amines and quaternary ions are utilized to crystalize pure VPI-5. A low cost, high yield preparation involves the use of triisopropanol amine and tetramethylammonium hydroxide. Some samples of VPI-5 can be transformed into AIPO4-8 upon certain calcination conditions. Extensive washings of the aforementioned, as-synthesized VPI-5 yields a product which does not transform into AIPO4-8. 

The recoveries of SMZ and its five metabolites from swine liver and kidney were increased (72-97% with RSD 2-24%) when employing the ion-pair agent tetramethylammonium hydroxide (TM AH) in situ with SFE. The homogenized tissue sample was mixed with Hydromatrix and placed into the extraction vessel. A TMAH methanolic solution was added directly to the cell. The vessel content was extracted with supercritical MeOH-modified COz at 400 bar/60°C, and the extract was poured through two vials containing MeOH. Lipidic endogenous material was partitioned with chloroform. An in situ addition of TMAH enhanced the extractability of the polar metabolites the greatest improvement was observed for sulphate metabolite—from 0% to 72% (170). 

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. 

C. Y. Zhou, M. K. Wong, L. L. Koh, Y. C. Wee, Microwave digestion of biological samples with tetramethylammonium hydroxide and ethylenediaminetetraacetic acid for element determination, Talanta, 43 (1996), 1061D1068. 

C. Brunori, M. B. de la Calle, M. Angelone, R. Morabito, Determination of total selenium in mussel and wheat samples after tetramethylammonium hydroxide digestion, Ann. Chim., 89 (1999), 873D880. 

P. Martins, D. Pozebon, V. L. Dressier, G. A. Kemieciki, Determination of trace elements in biological materials using tetramethylammonium hydroxide for sample preparation, Anal. Chim. Acta, 470 (2002), 195D204. 

J. B. B. da Silva, D. L. G. Borges, M. A. M. S. da Veiga, A. J. Curtius, B. Welz, Determination of cadmium in biological samples solubilized with tetramethylammonium hydroxide by electrothermal atomic absorption spectrometry, using ruthenium as permanent modiPer, Talanta, 60 (2003), 977 D 982. 

T. Uchida, H. Isoyama, K. Yamada, K. Oguchi, G. Nakagawa, H. Sugie, C. Iida, Determination of twelve elements in botanical samples with inductively coupled plasma atomic emission spectrometry after leaching with tetramethylammonium hydroxide and ethylenediaminetetraacetic acid, Anal. Chim. Acta, 256 (1992), 277 D284. 

A. S. Ribeiro, A. L. Moretto, M. A. Z. Arruda, S. Cadore, Analysis of powdered coffee and milk by ICP-OES after sample treatment with tetramethylammonium hydroxide,... 

Jackson et al. [29] reported a simple method for dissolving tissue samples using a 25% alcoholic solution of tetramethylammonium hydroxide which contained 2% m/v APDC. Clear homogeneous solutions were obtained when 100—300 mg weights of liver, brain, or muscle tissues were heated at 60°C with 1—3 ml of the base/APDC solution, and the cooled solutions were diluted with toluene. The solutions were then analysed for Zn, Cu, Fe and Mn. This procedure has also been applied successfully to the analysis of Cu in brain [30] and Pb in human placental tissue and animal liver [31]. The addition of APDC ensured the stability of solutions of exogenous metal ions added for calibration as well as those of endogenous metals from the tissues for at least 24 h after dilution with toluene. Gross and Parkinson [32] ommitted APDC from their solution of the quaternary ammonium hydroxide and used water rather than toluene for the final dilution. They were able to dissolve successfully 28 different types of human tissue, and measured Cu, Pb, Zn, Cd and Mn in liver by ETA—AAS with RSD s of 0.04—0.06. Quantitative recovery, 94—104%, was observed for all metals... 

Some applioations require the use of a basic medium for ultrasonio digestion. Most such involve biologioal samples the matrix of which is decomposed by hydrolysis — which is more effeotive in a basio medium than in an acidic medium. One example is the digestion of tissues, where sells are disrupted in a basic medium such as that provided by tetramethylammonium hydroxide, sodium hydroxide, potassium hydroxide or sodium methoxide. 

Least et al. reduced the sample size to 20 pi serum, plasma, or saliva, in a microscale procedure. The extraction was carried out with a chloroform-isopropanol solution of the internal standard, 3-isobutyl-l-methylxanthine. After alkylation with tetramethylammonium hydroxide and pentyl iodide, gas chromatography was carried out on a packed 3 OV-17 on Gas Chrom Q column, by temperature programming from 180°C to 260°C, and using a nitrogen sensitive detector. With the sample volume used, the background interference is equivalent to about 0.1 mg/litre, and 0.5 mg theophylline per litre can easily be measured. Between-run... 

Pranskevich et al. preferred a packed column of 3 SP 2250 DB as stationary phase because the butyl derivative, which is a weak base, gas chromatographs markedly better on this phase than on the same percentage loadings of other brands of OV-17. After an initial chloroform extraction of 1.0 ml serum sample, a toluene wash and back extraction into 0.5 M ammonium hydroxide, derivatization was accomplished by the addition of 15 yl of an 8 1 mixture of N,N-dimethylacetamide (400 yl) and 2.4 tetramethylammonium hydroxide in methanol (50 yl) to the dried extract. Butyliodide (15 yl) was then added and the gas chromatographic assay... 

Bupivacaine (49a) and its phenolic metabolites (49b-c) were detected in urine after the samples underwent hydrolysis, LLE with ether, concentration by evaporation and derivatization with diazomethane, to obtain the methyl ethers (49d). End analysis was by GC-MS in the SIM mode". Another methylation reaction with this reagent was mentioned in Section III.A.2 . On-site methylation with tetramethylammonium hydroxide was proposed for the analysis of phenolic additives in polymeric materials, by the pyrolysis-GC method" . Pressurized LLE using phenytrimethylammonium hydroxide (50) or trimethylsulfonium hydroxide (51) for simultaneous methylation was applied to the... 

After LLE of phenols and carboxylic acids in water, on-line methylation with 51 was applied together with large volume injection (100 xL). The solvent was removed before the analytes were transferred into the GC column with MS detection in full scan mode. Volatile fatty acids, dicarboxylic acids, benzoic acids and phenols in water, at concentrations of 0.4 to 0.1 p.M, could be determined in 5 mL samples. Lactic, pyruvic and malonic acids required higher concentrations due to their higher water solubility and lower methylation rates" . Samples of particulate matter were subjected to LLE with THE, and hydrolysis/methylation of the extract with tetramethylammonium hydroxide. 

Dissolution Rate Measurements Sample films were spun onto silicon wafers from isoamyl acetate solutions of sample resins or sample resin and PMPS. The films were immersed in an aqueous solution of tetramethylammonium hydroxide. Dissolution rates were obtained from a plot of the measured residual film thickness against the immersion time. The film thickness was measured with an interferometer. 

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