title: Direct gradient reversed-phase high-performance liquid chromatographic determination of salicylic acid, with the corresponding glycine and glucuronide conjugates in human plasma and urine.
abstract: A gradient reversed-phase HPLC analysis for the direct measurement of salicylic acid (SA) with the corresponding glycine and glucuronide conjugates in plasma and urine of humans was developed. The glucuronides were isolated by preparative HPLC from human urine samples. The concentration of the glucuronides in the isolated fraction were determined after enzymatic hydrolysis. Salicylic acid acyl glucuronide (SAAG) was not present in plasma. No isoglucuronides were present in acidic and alkaline urine of the volunteer. The limits of quantitation in plasma are: SA 0.2 microgram/ml, salicyluric acid (SU) 0.1 microgram/ml, salicylic acid phenolic glucuronide (SAPG) 0.4 microgram/ml and salicyluric acid phenolic glucuronide (SUPG) 0.2 microgram/ml. The limit of quantitation in urine is for all compounds 5 micrograms/ml. Salicylic acid acyl glucuronide is stable in phosphate buffer pH 4.9 during 8 h at 37 degrees C; thereafter it declines to 80% after 24 h. The subject's urine was therefore acidified by the oral intake of 4 x 1.2 g of ammonium chloride/day. With acidic urine, hardly any salicylic acid is excreted unchanged (0.6%). It is predominantly excreted as salicyluric acid (68.7%).
authors.affiliation: Department of Clinical Pharmacy, Academic Hospital Nijmegen Sint Radboud, Netherlands.
authors.forename: T B
authors.initials: TB
authors.lastname: Vree
authors.forename: E W
authors.initials: EW
authors.lastname: van Ewijk-Beneken Kolmer
authors.forename: C P
authors.initials: CP
authors.lastname: Verwey-van Wissen
authors.forename: Y A
authors.initials: YA
authors.lastname: Hekster
mesh_terms: D000215:Acylation; D002851:Chromatography, High Pressure Liquid / Q000379:methods* / Q000706:statistics & numerical data; D004355:Drug Stability; D005965:Glucuronates / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D005998:Glycine / Q000031:analogs & derivatives* / Q000097:blood / Q000652:urine; D006626:Hippurates / Q000097:blood / Q000652:urine; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D008297:Male; D010636:Phenols / Q000097:blood / Q000652:urine; D012459:Salicylates / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D020156:Salicylic Acid; D012680:Sensitivity and Specificity
chemical_list: D005965:Glucuronates; D006626:Hippurates; D010636:Phenols; D012459:Salicylates; C000693:salicylurate; D020156:Salicylic Acid; D005998:Glycine