Investigation of Electron Transfer by Biofilms by using an Electrochemical Quartz Crystal Microbalance.

Both the short- and long-term electron-transfer processes of electrode-respiring biofilms are demonstrated by using an electrochemical quartz crystal microbalance (QCM). The QCM monitors the frequency shift from the initial resonant frequency (background) in real time, while the current increases, because of biofilm growth. In the short term, the frequency shift is linear with respect to current for the biofilm.

Ferrocenated au nanoparticle monolayer adsorption on self-assembled monolayer-coated electrodes.

The robust, irreversible adsorption of omega-ferrocene hexanethiolate-protected gold nanoparticles (composition ca. {Au(225)(SC6Fc)(43)}) on electrodes provides an opportunity to investigate their submonolayer and monolayer films in nanoparticle-free solutions. Observations of nanoparticle adsorption on unmodified electrodes are extended here to Au electrodes having more explicitly controlled surfaces, namely self-assembled monolayers (SAMs) of alkanethiolates with omega-sulfonate, carboxylate, and methyl termini, and in different Bu(4)N(+)X(-) electrolyte (X(-) = C(7)H(7)SO(3)(-), ClO(4)(-), CF(3)SO(3)(-), PF(6)(-), NO(3)(-)) solutions in CH(2)Cl(2).

Interfacial ion transfers between a monolayer phase of cationic Au nanoparticles and contacting organic solvent.

The highly cationic nanoparticle [Au(225)(TEA-thiolate(+))(22)(SC6Fc)(9)] adsorbs so strongly on Pt electrodes from CH(3)CN/Bu(4)NClO(4) electrolyte solutions that films comprised of 1-2 monolayers of nanoparticles can be transferred to nanoparticle-free electrolyte solutions without desorption and ferrocene voltammetry stably observed. (TEA-thiolate(+) = -S(CH(2))(11)N(CH(2)CH(3))(3)(+); SC6Fc = S(CH(2))(6)-ferrocene; Fc = ferrocene). The Fc(+/0) redox couple's voltammetry is used to detect the adsorption.

Electrospray ionization mass spectrometry of intrinsically cationized nanoparticles, [Au(144/146)(SC(11)H(22)N(CH(2)CH(3))(3)(+))(x)(S(CH(2))(5)CH(3))(y)](x+).

Electrospray ionization triple-quadrupole mass spectrometry of ca. 1.6 nm diameter thiolate-protected gold nanoparticles has been achieved at higher resolution than in previous reports.

Voltammetry and redox charge storage capacity of ferrocene-functionalized silica nanoparticles.

We describe the electrochemistry of 15 nm diameter silica nanoparticles densely functionalized with ferrocene (FcSiO(2)) through siloxane couplings. Each nanoparticle bears approximately 600 Fc sites, as measured by potentiometric titration (590 Fc) and diffusion-controlled voltammetry (585 Fc) and estimated by XPS (630 Fc). The nanoparticle ferrocene coverage amounts to ca.

Identification of impurities in ivermectin bulk material by mass spectrometry and NMR.

The identification and characterization of four process impurities in bulk ivermectin and four process impurities in bulk avermectin, using a combination of MS and NMR, are discussed herein. These process impurities were shown to be 24-demethyl H2B1a, 3'-demethyl H2B1a, 3''-demethyl H2B1a and 24a-hydroxy B2a isomer. The impurities were shown to be process impurities and are present in avermectin bulk also.

Development and validation of a stability indicating HPLC method for determination of lisinopril, lisinopril degradation product and parabens in the lisinopril extemporaneous formulation.

The purpose of the research described herein was to develop and validate a stability-indicating HPLC method for lisinopril, lisinopril degradation product (DKP), methyl paraben and propyl paraben in a lisinopril extemporaneous formulation. The method developed in this report is selective for the components listed above, in the presence of the complex and chromatographically rich matrix presented by the Bicitra and Ora-Sweet SF formulation diluents. The method was also shown to have adequate sensitivity with a detection limit of 0.

Characterization of an extemporaneous liquid formulation of lisinopril.

The stability of lisinopril in an extemporaneously prepared suspension stored at or below 25 degrees C for 28 days under ambient light exposure was studied. A formulation of 1-mg/mL oral suspension was prepared from commercially available 20-mg lisinopril tablets, using Bicitra and Ora-Sweet SF as the compounding vehicles to make a final volume of 200 mL. Individual samples, stored in 8-oz amber polyethylene terephthalate bottles, were used for each test performed.