Trichloroacetic acid application

The transformation of carboxylic acids with CDI into imidazolides has a wide range of applicability. CDI reacts with aliphatic, aromatic, and heterocyclic carboxylic acids under very mild conditions, and these reactions are not affected by the presence of functional groups unless the latter are strongly nucleophilic and themselves react with CDI in such cases a reversible protection of the functional groups is necessary. The reaction of CDI also works in such specific cases as trifluoro- and trichloroacetic acids, leading to the very reactive Af-trifluoro- and N-trichloroacetylimidazoles. 1 111... 

There is a great deal of interest in the determination of lead, particularly micromethods applicable to the analysis blood lead in children. Consequently, reports continue to appear on the atomic absorption determination of lead in blood and urine. Ninety percent of blood lead is found in the erythrocytes and, therefore, whole blood is analyzed rather than serum or plasma. Berman etal. 134) have described a procedure for determining normal lead levels in which only 250 fd of blood are taken. The blood is deproteinized with 1 ml of 10 % trichloroacetic acid and then the lead is extracted with APDC into 1 ml of MIBK, at pH 3.5. 

The furosemide extraction procedure was later examined for potential application in the analysis of thiazide diuretics in milk. Since this procedure could not provide sufficiently clean extracts for thiazides, additional acidic and basic extraction procedures were evaluated (557). Thus, milk was deproteinized with trichloroacetic acid, phosphoric acid, or potassium dihydrogen phosphate and centrifuged. The supernatants were extracted with ethyl acetate, evaporated to dryness, reconstituted in mobile phase, and analyzed by liquid chromatography. The recoveries in most cases were low and widely variable. Basic extraction, on the other hand, with sodium bicarbonate/potassium carbonate mixture or potassium monohydrogen phosphate followed by extraction with ethyl acetate also gave poor recoveries in most cases. It appears that a significant degradation of chlorothiazide occurred under the basic conditions. 

The introduction of the phenoxy compounds - 2,4-D and 2,4,5-T - in the mid 40 s, provided much more effective arboricldes than had heretofore been available (2,6,8). Control of many brushy species for site preparation in reforestation was now available. Perhaps one of the early applications of this was made by Fred Furst in the Siuslaw National Forest where approximately 10,000 acres of conifer, overstoried by alder, were released by treatment with 2,4-D. Other chemicals used in this era included trichloroacetic acid (TCA), used in girdling treatment of trees, and for control of grass prior to reforestation. Aminotriazole, also introduced during this period, found some use for control of Rhus species and grass in forest nurseries. 

The Frank and Demint [200] method is directly applicable to water samples. After addition of sodium chloride (340g IT1) and aqueous hydrochloric acid (1 1) to bring the pH to 1, the sample was extracted with ethyl ether and the organic layer was then extracted with 0.1M sodium bicarbonate (saturated with sodium chloride and adjusted with sodium hydroxide to pH8). The aqueous solution adjusted to pHl with hydrochloric acid was extracted with ether and after evaporation of the ether to a small volume, Dalapon was esterified at room temperature by addition of diazomethane (0.5% solution in ether) and then applied to a stainless steel column (1.5m/3mm) packed with Chromosorb P (60-80 mesh) pretreated with hexamethyldisilazane and then coated with 10% FFAP. The column was operated at 140°C, with nitrogen carrier gas (30mL muT1) and electron capture detection. The recovery of Dalapon ranged from 91 to 100% the limit of detection was O.lng. Herbicides of the phenoxyacetic acid type did not interfere trichloroacetic acid could be determined simultaneously with Dalapon. 

Application and Principle This procedure is used to determine the proteolytic activity of papain, ficin, and bromelain. The assay is based on a 60-min proteolytic hydrolysis of a casein substrate at pH 6.0 and 40°. Unhydrolyzed substrate is precipitated with trichloroacetic acid and removed by filtration solubilized casein is then measured spectrophotometri-cally. 

Lin, H., Huang, E. Y., Chang, H. Y., and ChangChien, C. C. (2005), Therapeutic effect of topical applications of trichloroacetic acid for vaginal intraepithelial neoplasia after hysterectomy, Jpn. J. Clin. Oncol, 35, 651-654. 

Upon addition of an acid, such as trichloroacetic acid, the absorption maximum showed the hypsochromic shift and the cycloreversion quantum yield increased as much as 10 -fold. Protonation to the dimethylamino group decreased the electron-donating ability of the substituent and resulted in the change in reactivity. This acid-gated reactivity is potentially applicable to nondestructive readout in a polymer memory medium. 

BelF found that glyatl cleavage by lead lelrHueetnte is markedly calalyzed by trichloroacetic acid the add catalysis is accounted for by the transition state III. A practical application ucid-cutulyzed glycol cleavage is reported by Oroh."" The diaxial IV could nol ba cleaved xutUfaulotily under ordinary conditions to 1,6-... 

Trichloroacetic acid in simple aqueous solution (TCA-SAS) involves pre-peel preparation, application of the TCA-SAS solution to the required depth (usually the papillary dermis), flaking, natural skin regeneration and post-peel care. 

Resorcinol solutions have been used in combination with glycolic acid, trichloroacetic acid (TCA) and 5-fluorouracil (5-FU). Many modified versions of Jessner s solution have been presented, containing kojic acid, hydroquinone, etc. The effectiveness of these resorcinol solutions depends on skin preparation, skin sensitivity and thickness, the type of applicator and the force of application, the number of coats applied, the type of solution used, the quality of the solution s preparation, etc. Moreover, products with a tyrosinase-inhibiting action (kojic acid, hydroquinone, etc.) only produce their effect in the long term. Single application of these products cannot treat melasma in any way. Only repeated applications, allowing the gradual absorption of products that inhibit melanocyte metabolism, can be considered as an effective treatment. 

This statement too may cause raised eyebrows but an objective assessment of errors and costs can support it. Thus, De Courcy s trichloroacetic acid reagent (D2) is capable of convenient application to the detection of pregnanetriol in the nonketonic fraction from one-sixteenth of a 24-hour collection from men (100-150 ml) on simple LLC paper chromatograms (a TLC method could no doubt also be devised for this). As she pointed out, the same quantity can be obtained from one-thousandth of a 24-hour collection (1.5-2 ml) of urine from some patients with adrenal hyperplasia. Quantitative estimation by the same reaction after elution from the paper or TLC chromatogram could also be used either by one of the many variations of the micro-17-ketogenic steroid methods or by the same fluorescence reaction (e.g., W7). Further confirmation of identity could be obtained by using a small fraction of the latter after the periodate oxidation for a paper LLC, or TLC, chromatogram and application of the Zimmerman reaction to demonstrate the formation of etiocholanolone (B32). 

The micellar solvent system used in this assay has several advantages, in addition to rapid separation SDS is an effective-denaturing agent and, as such, can be used to stop reactions without the need for protein precipitation with trichloroacetic acid or heating. Since SDS also has a unique solubilizing power, it can be used for direct injection of concentrated protein solutions into the RPLC system, without time-consuming steps to remove protein precipitates or extraction of folate analogues. Therefore, the assay is simple, rapid, inexpensive, and applicable to crude hydrolase preparations. 

Strong acids, such as HCl and HBr (dilute or concentrated), H2SO4 (satisfactory for special applications at room temperature below 10%), HF, HCIO4, H3PO4, and formic, oxalic, and trichloroacetic acids. 

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