Thiamine deficiency (TD) in rats produces lesions similar to those found in humans suffering from Wernicke's encephalopathy, an organic mental disorder associated with alcoholism. Male Sprague-Dawley rats (n = 29) were deprived of thiamine via a regimen of thiamine-deficient chow and daily intraperitoneal injections of the thiamine antagonist pyrithiamine hydrobromide. Spectra were obtained by using the STEAM sequence. No significant change occurred in the ratio of Cr/NAA, while the ratio of Cho/NAA declined significantly (60 +/- 11%) on Day 14. Eleven rats received intraperitoneal injections of thiamine hydrochloride at the end of 12 days, and dose-dependent recovery in Cho/NAA was observed.
A method is described for the production of a gradient elution solvent delivery system for ion chromatography. The system uses elther a two pump or a three pump configuration wlth a pressure of less than 400 psi. A 100-mm separator column and a fiber suppressor column are used along with both etectrochemical and conductometrlc detectlon. The Initial eluent is a 0.003 M NaHCO, to which a strong eluent (elther 0.004 M Na,CO, or 0.002 M Na,CO, + 0.002 M NaOH) is added. With the component arrangement described, F-, Ci-, and NO2-elute under essentlaily isocratic conditions. I-, SCN-, Cr2072-, and S20: -ail elute within 22 min. Retention times of less than 22 min are given for 18 different anions. The preparatlon and chemical composltlon of the gradients are discussed and gradlent proflles are presented. Ion chromatography as developed by Small et al.(1) has significantly altered the determination of inorganic and organic ions (2). One of the limitations to ion chromatography that restricts its use is that the relative retention times for species of interest can vary widely reducing the number of species amenable to analysis in any one given sample injection. A prominent example of this variation is in the analysis of the halide ions. The conditions necessary for the analysis of Fand Cl-ions result in an unacceptably long retention time and peak shape for the I-ion. Conversely, the conditions necessary for the efficient analysis of I-results in little or no separation between the F-and C1-peaks (3).Three common approaches, when confronted with samples containing species with widely varying retention times, are to use multiple injections under different analytical conditions (4,5), stronger eluents (6), or traditional eluents with a shorter separator column (7). These methods result in either extended analysis time or significant changes in the early portion of the chromatogram including loss of peaks. Silica-coated polyamide crown resins have been employed (8) but the resolution of common ions suffers to some extent. A method developed by Wang et al. (3) used a sequential electrochemical and conductometric detection scheme to analyze for F-, C1-, Br-, and I-in one sample injection. The analysis time reported by Wang et al. was approximately 30 min, but the method did require that the operator switch a valve a t a critical time in the analysis to redirect the fluid flow and thus minimize the analysis time.The concept of gradient elution chromatography has been widely and successfully employed in high-performance liquid chromatography for the analysis of species with widely varying retention times (9). Gradient elution has been applied to the analysis of SOS2-, Sod2-, and Sz02-containing solutions by Sunden et al. (10) but no attention was given to the early eluting species such as F-or C1-.
A Na fusion-ion chromatographic (IC) method for determination of F, Cl, Br, and I Is described. Seventeen organic halo compounds and eleven mixtures were decomposed by Na fumes at 280-290 c'C for 1 h or longer. These products were absorbed by 250 mL of standard eluent and the ab-
The retention times and detection limits of a selected group of six transition metal cations and four inorganic anions determined using a simultaneous separation and detection system are presented. The over-all analysis time is usually less than 20 min and detection limits are at or near the 1 p.p.m. level. Two different systems are described, the first for the repetitive analysis of similar solutions and the second for samples of widely varying composition.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.