Salicylic acid concentrate

Aspirin Aspirin is rapidly hydrolyzed in plasma to salicylic acid with a half-life of 20 minutes. Plasma levels of aspirin are essentially undetectable 2 to 2.5 hours after dosing, and peak salicylic acid concentration occurs 1 hour (range, 0.5 to 2 hours) after aspirin administration. Salicylic acid is primarily conjugated in the liver to form a number of minor metabolites. Salicylate metabolism is saturable and the total body clearance decreases at higher serum concentrations. 

Blacklock C.J., J.R. Lawrence, D. Wiles, E.A. Malcolm, I.H. Gibson, C.J. Kelly, and J.R. Paterson (2001). Salicylic acid in the serum of subjects not taking aspirin. Comparison of salicylic acid concentrations in the serum of vegetarians, non-vegetarians, and patients taking low dose aspirin. Journal of Clinical Pathology 54 553-555. 

Tinnitus may be the first indication that the serum salicylic acid concentration is reaching or exceeding the upper therapeutic range. 

The deficiency of tlie LH equation was demonstrated also for pentachlorophenol [25] and by Cunningham [26-28]. The quantum yields for photodegradation of salicylate and other strongly sorbing substituted benzenes were less than those measured for nonsorbing chlorophenols. For salicylic acid, which chemisorbs, the photo-oxidation rates in air-saturated solutions are independent of the salicylic acid concentration, although the surface excess increases with the concentration [29]. 

Fig. 9.3 COD/CODin vs. treatment time, with a low initial salicylic acid and sulfuric or perchloric acid. Salicylic acid concentration 3.6 mmol dm-3, sulfuric acid or perchloric acid concentration 1 mol dm-3, temperature 70°C, applied current density 15.8 mA cm-2...

Fig. 9.7 COD vs. oxidation time, at 70, 80, and 90°C pH 13.0 persulfate concentration 56 mmol dm-3 and salicylic acid concentration 3 mmol dm-3...

After a single oral dose of 900 mg given to 5 subjects, peak plasma-aspirin concentrations of 16 to 50 ig/ml (mean 37) were attained in about 14 minutes, and peak plasma-salicylic acid concentrations of 47 to 113 pg/ ml (mean 78) were reported at 0.5 to 1 hour (B. E. Cham et al., Ther. Drug Monit., 1980, 2, 365-372). 

Following daily oral doses of 3.9 g to 8 subjects for 8 days, steady-state plasma-salicylic acid concentrations of 105 to 227 pg/ml (mean 173) were reported by the 36th day of treatment the steady-state plasma concentrations had declined to 45 to 208 pg/ml (mean 129) (R. H. Rumble etal., Br. J. din. Pharmac., 1980, 9, 41-45). 

In a fatality due to the ingestion of about 120 ml of methyl salicylate, postmortem salicylic acid concentrations were, blood 615 pg/ml and liver 455 ig/g (J. Ryall, Bull. int. Ass.forens. Toxicol., 1974,10 ), 10). 

Following a single oral dose of 1 g of salsalate to 12 subjects, a mean peak plasma concentration of 21 pg/ml of salsalate was attained in 1.5 hours and peak plasma-salicylic acid concentrations of 38 to 77 ig/ml (mean 54) were reported at 2 to 4 hours (L. I. Harrison et al., J. din. Pharmac., 1981,27,401-404). 

Paterson has proposed that natural salicylates contribute to the recognized benefits of a healthy frait and vegetable diet. Salicylic acid is responsible for the anti-inflammatory action of aspirin, and it may cause the reduced risk of colorectal cancer observed in those who take aspirin. Salicylic acid and other salicylates occur naturally in fruits and plants, and diets rich in these are beheved to reduce the risk of colorectal cancer. Serum salicylic acid concentrations are greater in vegetarians than nonvegetarians, and there is overlap between concentrations in vegetarians and those taking low-dose aspirin However, Janssen et al. concluded that the content of (acetyl)salicyhc acid in diets may be too low to affect disease risk. Additional work is needed to confirm this concept. 

The catalytic efficiency of the Ti02/montmorillonite was tested on the photooxidation of salicylic acid. A photocatalyst suspension (0.1 wt/vol%) was prepared in 0.15 mM salicylic acid solution. Irradiations for 1 h were performed and samples were withdrawn after 5, 10, 20, 30,40, 50 and 60 min irradiation. Aliquots of the samples irradiated for various durations were centrifuged and particles interfering with photometry were removed by filtration through a sieve with 0.2 ptm pore size. Changes in salicylic acid concentration taking place as the reaction progressed were monitored by spectrophotometry at 297 nm (Fig. 3). The initial equilibrium concentration of salicylic acid was lowered by the adsorption of molecules on the oxide surface before irradiation [see the difference... 

The study had three objectives first, changes in NIR spectra were correlated to the time aspirin tablets spent in the hydrator (the calibration had a correlation coefficient of 0.95 and SEE of 18.8 h) second, a calibration was developed for the prediction of tablet salicylic acid content (the researchers ensured that prediction of salicylic acid was based on changes in salicylic acid concentration, and not some related process, such as absorption of moisture, by evaluation of loadings spectra from principal component analysis of the data. The HPLC-determined salicylic acid levels ranged from 0.36 to 1.66 mg, and the NIR method allowed prediction of the degradant with a standard error of 144 mg) and third, the mass of water absorbed by the tablets was determined by NIR spectroscopy. 

The concentration of salicylic acid in the aqueous phase of a 1.0% w/v polysorbate 20 solution at pH 1.0 can be calculated if the total salicylic acid concentration is known [62] using the equation,... 

RELATIONSHIP BETWEEN SALICYLIC ACID CONCENTRATION AND EXTINCTION COEFFICIENT AT 530... 

Monovalent cations such as Na" and form weak complexes with the mono- and difunctional organic acid anions. Stability constants are typically in the range of log K = —1.1 to —1.5 (for the dissociation reaction Martell and Smith 1977). In any aqueous speciation model a small percentage (less than about 10%) of the available organic acid anion will form monovalent cation complexes. These complexes should be included in chemical models for completeness. A small error will result if the complexes are ignored and this may or may not be of concern depending on the application. Kharaka et al. (1986) report that the Na and K salicylate complexes are more stable, however, and inclusion of these species will be necessary in waters having substantial salicylic acid concentrations. 

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