Adaptive tracking notch filter system Patent

Adaptive notch filter, using modulation techniques for reversed phase noise signa

Fast liquid chromatography/electrochemistry/mass spectrometry of ferrocenecarboxylic acid esters

Rapid liquid chromatographic separations of ferrocenecarboxylic esters of various alcohols and phenols have been achieved on reversed-phase columns of 20 mm length. After separation, the ferrocene derivatives are oxidized electrochemically under formation of the charged ferrocinium species, which are easily detected by mass spectrometry using an atmospheric pressure chemical ionization source operated in the heated nebulizer mode. While a series of nine phenol derivatives was separated within less than 1.5 min, six alcohol derivatives eluted within 1 min. Limits of detection using a single quadrupole mass analyzer ranged from 60 to 190 nmol/l. Additional work was directed on the use of a graphite in-line filter instead of a silica-based reversed-phase column to achieve the separation

MS-DIAL: data-independent MS/MS deconvolution for comprehensive metabolome analysis.

Data-independent acquisition (DIA) in liquid chromatography (LC) coupled to tandem mass spectrometry (MS/MS) provides comprehensive untargeted acquisition of molecular data. We provide an open-source software pipeline, which we call MS-DIAL, for DIA-based identification and quantification of small molecules by mass spectral deconvolution. For a reversed-phase LC-MS/MS analysis of nine algal strains, MS-DIAL using an enriched LipidBlast library identified 1,023 lipid compounds, highlighting the chemotaxonomic relationships between the algal strains

Amplified reflection, phase conjugation, and oscillation in degenerate four-wave mixing

A number of new optical effects that result from degenerate four-wave mixing in transparent optical media are proposed and analyzed. The applications are relevant to time-reversed (phase-conjugated) propagation as well as to a new mode of parametric oscillation

Separation of Nucleic Acids by Ion Pair Reversed Phase High Performance Liquid Chromatography (IP RP HPLC)

Ion-pair reversed-phase high performance liquid chromatography (IP RP HPLC) is shown to be an effective method to reliably analyze DNA. IP RP HPLC is a much faster and safer alternative to conventional methods of DNA separation and quantification. The method described here utilized a two-buffer effluent system consisting of triethylammonium acetate (TEAA) and acetonitrile (ACN). The method reliably separated and quantified DNA samples of 54 and 58 nt. This method will be used and optimized to separate similarly sized RNA samples. The ultimate goal is to separate mixtures of nucleotides generated from in-vitro transcription reactions

Determination of the urinary aglycone metabolites of vitamin K by HPLC with redox-mode electrochemical detection

We describe a method for the determination of the two major urinary metabolites of vitamin K as the methyl esters of their agyclone structures, 2-methyl-3-(3-3-carboxymethylpropyl)-1,4-naphthoquinone (5C-side-chain metabolite) and 2-methyl-3-(5-carboxy-3-methyl-2-pentenyl)-1,4-naphthoquinone (7C-side-chain metabolite), by HPLC with electrochemical detection (ECD) in the redox mode. Urinary salts were removed by reversed-phase (C18) solid phase extraction (SPE) and the predominately conjugated vitamin K metabolites hydrolysed with methanolic HCl. The resultant carboxylic acid aglycones were quantitatively methylated with diazomethane and fractionated by normal-phase (silica) SPE. Final analysis was by reversed-phase (C18) HPLC with a methanol-aqueous mobile phase. Metabolites were detected by amperometric, oxidative ECD of their quinol forms, which were generated by post-column coulometric reduction at an upstream electrode. The assay gave excellent linearity (r2 typically = 0.999) and high sensitivity with an on-column detection limit of <3.5 fmol (<1pg). The inter-assay precision was typically 10%. Metabolite recovery was compared to that of an internal standard (2-methyl-3-(7'-carboxy-heptyl)-1,4-naphthoquinone), added to urine samples just before analysis. Using this methodology we confirmed that the 5C- and 7C-metabolite were major catabolites of both phylloquinone (vitamin K1) and menaquinones (vitamin K2) in humans. We propose that the measurement of urinary vitamin K metabolite excretion is a candidate non-invasive marker of total vitamin K status

Comparison of green enhanced fluidity reversed phase liquid chromatography with HPLC

The growing interest in high throughput assays is the result of the increasing numbers and complexity of samples being produced by modern combinatorial synthetic procedures. The low viscosities and high diffusivities of enhanced fluid mixtures allow highly efficient separations to be achieved with analysis time gain as compared to High-performance liquid chromatography (HPLC). In this study, possibilities and limitations of HPLC mobile phases ethanol/water, acetonitrile/water, and methanol/water at higher proportion aqueous content and acetone/ acetonitrile as non-aqueous mobile phases were evaluated to compare liquid chromatography with green enhanced fluidity liquid chromatography (EFLC) separations by adding different concentrations of carbon dioxide as ternary mobile phase. The techniques were evaluated via van Deemter plots on reversed phase columns. EFLC allows reduce analysis time reduction and to obtain improved column efficiencies by effectively increasing the permeability of the system and by ensuing faster diffusion kinetics and further better selectivity. Similarly the impact on retention and separation in reversed phase using C18 and Naphtylethyl (Pi NAP) stationary phases were explored. A mixture of 16 priority PAH pollutants were used to investigate these effects. Next to interesting changes in selectivity improvements in analysis time and shifting Van Deemter curves could be measured in this way demonstrating the potential of this new green variant of HPLC

Simultaneous quantification of 12 different nucleotides and nucleosides released from renal epithelium and in human urine samples using ion-pair reversed-phase HPLC

Nucleotides and nucleosides are not only involved in cellular metabolism but also act extracellularly via P1 and P2 receptors, to elicit a wide variety of physiological and pathophysiological responses through paracrine and autocrine signalling pathways. For the first time, we have used an ion-pair reversed-phase high-performance liquid chromatography ultraviolet (UV)-coupled method to rapidly and simultaneously quantify 12 different nucleotides and nucleosides (adenosine triphosphate, adenosine diphosphate, adenosine monophosphate, adenosine, uridine triphosphate, uridine diphosphate, uridine monophosphate, uridine, guanosine triphosphate, guanosine diphosphate, guanosine monophosphate, guanosine): (1) released from a mouse renal cell line (M1 cortical collecting duct) and (2) in human biological samples (i.e., urine). To facilitate analysis of urine samples, a solid-phase extraction step was incorporated (overall recovery rate ? 98 %). All samples were analyzed following injection (100 ?l) into a Synergi Polar-RP 80 Å (250 × 4.6 mm) reversed-phase column with a particle size of 10 ?m, protected with a guard column. A gradient elution profile was run with a mobile phase (phosphate buffer plus ion-pairing agent tetrabutylammonium hydrogen sulfate; pH 6) in 2-30 % acetonitrile (v/v) for 35 min (including equilibration time) at 1 ml min(-1) flow rate. Eluted compounds were detected by UV absorbance at 254 nm and quantified using standard curves for nucleotide and nucleoside mixtures of known concentration. Following validation (specificity, linearity, limits of detection and quantitation, system precision, accuracy, and intermediate precision parameters), this protocol was successfully and reproducibly used to quantify picomolar to nanomolar concentrations of nucleosides and nucleotides in isotonic and hypotonic cell buffers that transiently bathed M1 cells, and urine samples from normal subjects and overactive bladder patients

Analysis of iodinated quorum sensing peptides by LC-UV/ESI ion trap mass spectrometry

Five different quorum sensing peptides (QSP) were iodinated using different iodination techniques. These iodinated peptides were analyzed using a C-18 reversed phase HPLC system, applying a linear gradient of water and acetonitrile containing 0.1% (m/v) formic acid as mobile phase. Electrospray ionization (ESI) ion trap mass spectrometry was used for the identification of the modified peptides, while semi-quantification was performed using total ion current (TIC) spectra. Non-iodinated peptides and mono- and di-iodinated peptides (NIP, MIP and DIP respectively) were well separated and eluted in that order. Depending on the used iodination method, iodination yields varied from low (2%) to high (57%)