Reliable Analysis of the Interaction between Specific Ligands and Immobilized Beta-2-Adrenoceptor by Adsorption Energy Distribution.

Although a comparatively robust method, immobilized protein-based techniques have displayed limited precision and inconsistent results due to a lack of strategy for the accurate selection of drug adsorption models on the protein surface. We generated the adsorption data of three drugs on immobilized beta-2-adrenoceptor (β-AR) by frontal affinity chromatography-mass spectrometry (FAC-MS) and site-specific competitive FAC-MS. Using adsorption energy distribution (AED) calculations, we achieved the best adsorption models for the binding of salbutamol, terbutaline, and pseudoephedrine to immobilized β-AR.

Interlaboratory study of free cyanide methods compared to total cyanide measurements and the effect of preservation with sodium hydroxide for secondary- and tertiary-treated waste water samples.

Several methods exist for the measurement of cyanide levels in treated wastewater,typically requiring preservation of the sample with sodium hydroxide to minimize loss of hydrogen cyanide gas (HCN). Recent reports have shown that cyanide levels may increase with chlorination or preservation. In this study, three flow injection analysis methods involving colorimetric and amperometric detection were compared within one laboratory, as well as across separate laboratories and equipment.

Thermodynamic characterization of separations on alkaline-stable silica-based C18 columns: why basic solutes may have better capacity and peak performance at higher pH.

A systematic study was made to explain the large improvements in separation performance and capacity of basic compounds at alkaline conditions. The adsorption of three probe components was investigated on four alkaline-stable silica-based C18 columns at three different pH-levels: 3, 7 and 11. The probes were 3-phenyl-1-propanol (neutral), 2-phenylbutyric acid (acidic) and metoprolol (basic).

Postnatal manganese exposure attenuates cocaine-induced locomotor activity and reduces dopamine transporters in adult male rats.

In the present study, we examined whether exposing rats to manganese (Mn) during the preweanling period would affect basal or cocaine-induced locomotor activity in adulthood and reduce the number of striatal dopamine transporter binding sites. On postnatal day (PD) 1-21, rats were given oral supplements of vehicle or Mn chloride (250 or 750 microg/day). Striatal Mn and iron (Fe) accumulation as well as serum Fe levels were measured on PD 14, PD 21, and PD 90.

Heterogeneous adsorption of 1-indanol on cellulose tribenzoate and adsorption energy distribution of the two enantiomers.

The distributions of the adsorption energies (AED) of two enantiomers, (R)-1- indanol and (S)-1-indanol, on a chiral stationary phase were measured and the results are discussed. The chiral phase used is made of cellulose tribenzoate coated on porous silica. The AEDs were determined using the expectation maximization method, a numerical method that uses directly the raw experimental isotherm data, inverts this set of data into an AED, and introduces no arbitrary information in the calculation.

Analysis of active sites and heterogeneity in commercial reversed-phase octadecylsilanated silica with numerically calculated sorption distributions.

Sorption isotherms spanning six orders of magnitude of pyridine concentration in a 60:40 methanol:water mobile phase adjusted to pH 5 were obtained with the frontal analysis method on three ODS stationary phases: Zorbax Pro-10/150, Vydac 218TPB10, and YMC 120AS10. The data was fit to a heterogeneous Langmuir model in which the association constant, K, is continuously distributed over a finite range of values. The results indicate a small degree of secondary adsorption for all three phases as a separate peak in K-space at higher values of K than the primary hydrophobic partitioning, and additional adsorption at even higher K values for the Zorbax and to a much smaller degree the YMC phase.

Determination of single component isotherms and affinity energy distribution by chromatography.

Adsorption isotherm data were acquired by frontal analysis (FA) and large sample-size band profiles were recorded for phenol and caffeine. For both compounds, the isotherm data fit well to the Langmuir, Toth, and Bi-Langmuir models of adsorption. The Langmuir model must be dismissed because it does not predict accurately the overloaded band profiles.