Determination of trace perchlorate in river water by ion chromatography with online matrix removal and sample concentration.

This paper proposes a simple ion chromatographic approach to determine trace amounts of perchlorate in river water samples. Determination of the trace perchlorate by ion chromatography typically faces two challenges: interference by matrix ions such as chloride, nitrate, and sulfate in the samples and insufficient detection sensitivity. In the present study, online pretreatment of the samples with an OnGuard II Ba/Ag/H disposable sample pretreatment cartridge prevented the sulfate peak tailing from overlapping with the perchlorate peak on the chromatogram.

Desirable pharmacokinetic properties of (13)C-uracil as a breath test probe of gastric emptying in comparison with (13)C-acetate and (13)C-octanoate in rats.

Objective: To investigate the possible use of a (13)C-uracil breath test for gastric emptying by evaluating the pharmacokinetic properties of (13)C-uracil in a breath test in rats, in comparison with (13)C-acetate and (13)C-octanoate, traditional (13)C-probes for gastric emptying.

Material And Methods: Absorption of the (13)C-probes from different parts of the gastrointestinal tract was evaluated in fasted rats. (13)C-Uracil breath tests for gastric emptying were carried out in conditions where delayed gastric emptying was induced by clonidine, quinpirole, and propantheline, and in a postoperative ileus model.

Determination of the beta-blocker carteolol in human plasma by a sensitive gas chromatographic-negative-ion chemical ionization high-resolution mass spectrometric method.

A specific and sensitive gas chromatographic-high-resolution mass spectrometric method for the determination of 5-(3-tert.-butylamino-2-hydroxy)propoxy-3,4-dihydrocarbostyril (carteolol), which is a beta-blocker giving depression of intraocular pressure, was developed to elucidate the pharmacokinetics of its ophthalmic application. Carteolol has been determined by high-performance liquid chromatography but with less satisfactory sensitivity.

New norepinephrine potentiators: synthesis and structure-activity relationships of a series of 4-phenyl-1,2,3,4-tetrahydroisoquinolin-4-ols.

A variety of 1,2,3,4-tetrahydroisoquinolin-4-ols (1-6) were prepared as part of our search for new norepinephrine (NE) potentiators and to clarify the structure-activity relationships. These compounds and some previously prepared compounds were compared with 2-methyl-4-phenyl-1,2,3,4-tetrahydroisoquinolin-4-ol (PI-OH) (1a) for ability to potentiate NE. The potency, for 2-substitution, was found to be in the order: Me > Et > iso-Pr > H.

Resolution, absolute stereochemistry, and enantioselectivity of 2-methyl-4-phenyl-1,2,3,4-tetrahydroisoquinolin-4-ol.

Racemic 2-methyl-4-phenyl-1,2,3,4-tetrahydroisoquinolin-4-ol (PI-OH) (1) was found to be an effective potentiator of the contractile response of norepinephrine (NE) on rat anococcygeus muscle. This paper describes the resolution of racemic PI-OH by an HPLC method to give the optically pure enantiomers (+)-1 and (-)-1. The absolute configuration of (+)-1 was R as determined by CD analysis and by single-crystal X-ray diffractometric analysis of the methiodide 6 derived from (+)-1.