Salicylates analysis

Jarvie DR, Heyworth R, Simpson D. Plasma salicylate analysis A comparison of colorimetric, HPLC and enzymatic techniques. Ann Clin Biochem 1987 24 364-73. 

Wagner s solution (phosphate rock analysis) dissolve 25 g citric acid and 1 g salicylic acid in water, and make up to 1 liter. Twenty-five to fifty milliliters of this reagent prevents precipitation of iron and aluminum. 

Many pharmaceutical compounds contain chromophores that make them suitable for analysis by UV/Vis absorption. Products that have been analyzed in this fashion include antibiotics, hormones, vitamins, and analgesics. One example of the use of UV absorption is in determining the purity of aspirin tablets, for which the active ingredient is acetylsalicylic acid. Salicylic acid, which is produced by the hydrolysis of acetylsalicylic acid, is an undesirable impurity in aspirin tablets, and should not be present at more than 0.01% w/w. Samples can be screened for unacceptable levels of salicylic acid by monitoring the absorbance at a wavelength of... 

Examples of the application of HPLC to the analysis of (a) acetaminophen, salicylic acid, and caffeine (b) chlorinated pesticides (c) tricyclic antidepressants and (d) peptides. (Chromatograms courtesy of Alltech Associates, Inc. Deerfield, IL). 

This experiment describes the quantitative analysis of the asthma medication Quadrinal for the active ingredients theophylline, salicylic acid, phenobarbital, ephedrine HGl, and potassium iodide. Separations are carried out using a Gi8 column with a mobile phase of 19% v/v acetonitrile, 80% v/v water, and 1% acetic acid. A small amount of triethylamine (0.03% v/v) is included to ensure the elution of ephedrine HGl. A UV detector set to 254 nm is used to record the chromatogram. 

Sodium Salicylate.—When an aldehyde is shaken with a saturated solution of sodium salicylate, there seems to be evidence of the formation of a weak molecular compound, and with cinnamic aldehyde well-defined crystals have been obtained which give on analysis —... 

Scheme 43 Structure and retrosynthetic analysis of the salicylate macrolides salicylihalamide A (215a) and B (215b) by various groups [103]...

Merola reported the preparation of hydrido(carboxylato)iridium(lll) complexes, mer-[lrCl(0C(0)R)(H)(PMe3)3] (90) (R = Ph, Me), by oxidative addition of acetic acid or benzoic acid to [Ir(cod)(PMe3)3]Cl (67) [46]. The structure of 90 (R = Ph) in which the carboxylato ligand coordinates as an T -ligand, was confirmed by X-ray analysis. The reaction of 67 with salicylic acid yielded the product 91, which resulted from activation of the O-H bond of the carboxylato but not of the hydroxo group (Scheme 6-13). 

R.Tauler and E. Casassas, Application of principal component analysis to the study of multiple equilibria systems — Study of Copper(ll) salicylate monoethanolamine, diethanolamine and triethanolamine systems. Anal. Chim. Acta, 223 (1989) 257-268. 

As the majority of stabilisers has the structure of aromatics, which are UV-active and show a distinct UV spectrum, UV spectrophotometry is a very efficient analytical method for qualitative and quantitative analysis of stabilisers and similar substances in polymers. For UV absorbers, UV detection (before and after chromatographic separation) is an appropriate analytical tool. Haslam et al. [30] have used UV spectroscopy for the quantitative determination of UVAs (methyl salicylate, phenyl salicylate, DHB, stilbene and resorcinol monobenzoate) and plasticisers (DBP) in PMMA and methyl methacrylate-ethyl acrylate copolymers. From the intensity ratio... 

Metal salicylates are occasionally incorporated into mixtures of unknowns for qualitative inorganic analysis. During the conventional group separation, organic radicals are removed by evaporation with nitric acid. When salicylates are present, this can lead to formation of trinitrophenol through nitration and decarboxylation. This may react with any heavy metal ions present to form unstable or explosive picrates, if the evaporation is taken to dryness. The MAQA alternative scheme of analysis obviates this danger. 

Sodium bicarbonate administration for cardiac arrest is controversial because there are few clinical data supporting its use, and it may have some detrimental effects. Sodium bicarbonate can be used in special circumstances (i.e., underlying metabolic acidosis, hyperkalemia, salicylate overdose, or tricyclic antidepressant overdose). The dosage should be guided by laboratory analysis if possible. 

As the following pages of this section will show, there is hardly a new method of analysis which is not immediately tried for the determination of aspirin as such, or in formulations and biological fluids. The analysis of aspirin is intricately interwoven with that of salicylic acid, its precursor and degradation product. From the very first, residual salicylic acid was determined by the convenient reaction with ferric salts — typical for phenols — which give a violet complex with salicylic acid. 

In a more comprehensive study, 46 constituents were identified in the interdigital secretion of the white-tailed deer, 0. virginianus [129]. Only relatively volatile compounds up to methyl salicylate were identified in the secretion, because samples for GC-MS analysis were enriched from the headspace gas of the secretion collected on cotton swabs. Some variations in the relative concentrations of the compounds between the secretions from dominant and subordinate animals were observed, but it was not possible to conclude definitely whether these differences were related to age or dominance. 

An indication has been obtained that the opening of the salicylate hydrogen bond may become partially rate limiting in proton transfer (33) from substituted salicylate ions to hydroxide ions and buffer species in 50% (v/v) MejSO-HjO (Hibbert and Spiers, 1989a). Temperature-jump measurements of the equilibration between the salicylate ion and its dissociated species lead to curved plots of against buffer concentration and against hydroxide-ion concentration. Analysis of the results in terms of the mechanism in (33) gave the approximate values ki = 5x 10 s" and A, = 3 X 10 s ... 

The second method is when TLC is used to compare an unknown substance with the pure substance. For example, an aspirin sample prepared in the laboratory could be compared with a pure sample of aspirin. Three spots are made on the baseline of the TLC plate one of the laboratory-prepared aspirin, a second of a sample of pure acetyl salicylic acid, and a third of a sample of both the laboratory and the pure samples (a co-spot). Once the plate has been developed, analysis is carried out by comparison. If the co-spot shows only one spot, it can be concluded that the laboratory-synthesised sample is exactly the same compound as the pure substance. 

Mercado-Bianco J, van der Drift KMGM, Olsson PE, Thomas-Oates JE, van Loon LC, Bakker PAHM (2001) Analysis of the pmsCEAB Gene Cluster Involved in Biosynthesis of Salicylic Acid and the Siderophore Pseudomonine in the Biocontrol Strain Pseudomonas fluorescens WCS374. J Bacteriol 183 1909... 

Determination of various analgesic and antipyretic pharmaceuticals on reversed phase has included not only the analysis of serum levels of aspirin, salicylic acid and salicyluric acid using acidified acetonitrile (557), or methanol (338), but also suUinpyrazone under isocratic conditions (339), and 6-chloro-a-methylcarbazole-2-acetic acid (340). The polar thiol metabolites of acetaminophen were analyzed by RPC and the method was found to be superior to other chromatographic techniques used in this analysis (341). 

Methods for analysis of analgesics including salicylic acid and acetylsal-icylic acid (567) in combination with a variety of other active ingredients have been reported 068). Antipyrine and benzocaine in eir drops have been determined by RPC and the method was found to be four to. six times imiic lapul Ilian llic licsl allei native (569). Salicylic acid and benzoic acid haVe also been assayed in ointments (576). 

The United States Pharmacopoeia 23 [11] and Indonesian Pharmacopoeia IV [9] describe the assay of benzoic acid and salicylic acid in ointments. Two chromatographic columns (20 x 2.5 cm) are used to effect the separation. One transfers a mixture of 1 g siliceous earth and 0.5 mL diluted phosphoric acid (3 in 10) to the first column (A), then packs above this a mixture of 4 g siliceous earth and ferric chloride-urea reagent. A mixture of 4 g siliceous earth and 2mL of sodium bicarbonate solution (1 in 12) is packed into the second column (B). For analysis, column A is mounted directly above column B. The sample solution is inserted onto column A, allowed to pass into the column, and then washed with 2-40 mL of chloroform. Benzoic acid can be eluted from column B by using a 3 in 100 solution of glacial acetic acid in chloroform. The benzoic acid content then can be determined by a spectrophotometric method such as that described earlier (section 4.5). 

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