January 20th 2025
A recent study highlights the potential of dissolved organic matter (DOM) as a key indicator for water quality management in Lake Baiyangdian.
November 27th 2024
Theoretical and Experimental Investigation of the Electronic Spectra of Antitumor Compounds
May 1st 2005Time-dependent density functional theory and ZINDO/S methods have been used to compute and analyze the electronic spectra of benzazoles, 2-phenylbenzazoles, and 2-(4-aminophenyl)benzazoles. The observed spectra of the studied antitumor drugs are diffuse and highly solvent-dependent. Spectral analysis of the charge density distributions and relative polarities of the ground and excited states have enabled understanding of the observed solvent effects.
Photonic Bandgap Fibers in Gas Detection
April 1st 2005Photonic crystal fibers are novel optical waveguides that offer promising alternatives for various sensing applications. This article describes an experiment in which the absorption spectrum of acetylene was measured to demonstrate the effectiveness of photonic bandgap fibers for high sensitivity gas detection. Methane also was studied to determine the same capability in weakly absorbing gases.
Characterization of Archaeological Findings by FT-IR Spectroscopy
April 1st 2005The authors describe their work characterizing archaelogical ceramics by means of Fourier-transform infrared (FT-IR) absorption. Semiquantitative analyses using the technique can identify the main components and trace elements constituting the ceramics. An accurate knowledge of the chemical composition of the samples gives useful information for their classification.
Tech Note: Diffractive MEMS in Spectroscopy
April 1st 2005MEMS are small, microfabricated devices that are finding application in a variety of industries in both analytical and manufacturing settings. This paper reviews the properties of diffractive MEMS devices and examines their application in chemical spectroscopy.
Economic Prosperity Drives Spectroscopy Prospects in 2005
March 1st 2005Overall, 2004 was a good year for the laboratory analytical and life science instrument industry. A rebound in industrial demand, steady increases in life science spending, and strong growth in Asia and North America drove instrument systems and aftermarket sales. Similar to last year, 2005 should bring healthy sales growth as many of the end-market and regional drivers of last year continue to fuel demand.
Tech Note - Design Criteria for ICP Spectrometry Using Advanced Optical and CCD Technology (PDF)
The authors describe an ICP detection technology that combines photo-current conversion and a solid-state multichannel detector.
IMS for Cleaning Verification (PDF)
January 2nd 2005The need to verify cleaning between manufacturing runs presents a special challenge to the analytical chemist. In this article, the principles of ion mobility spectrometry are described, its performance is compared to HPLC for the analysis of cleaning validation samples, and findings are presented from a study to establish the feasibility of using IMS in validating a cleaning verification method.
Post-Tableting NIR Analysis: A Look at PAT Applicability to the Output of Solid Dosage Forms (PDF)
January 2nd 2005A majority of current discussion about NIR's applicability to pharmaceutical manufacturing is focused on preparative processes such as granulation, drying, and blending. The author examines different considerations for NIR for the output of the manufacturing line - finished tablet analysis.
PAT, NeSSI, and Sample Conditioning Systems: State of the Technologies and Future Directions (PDF)
January 2nd 2005This article reviews the development of FDA's PAT Initiative along with CPAC's ANSI/ISA-76.00.02 (2002) (NeSSI) development. The intent is to show how the NeSSI components could contribute to the PAT philosophy and physical requirements.
Chemometrics and PAT: What Does It All Mean? (PDF)
January 2nd 2005A paradigm shift is required for chemists and engineers to best utilize chemometrics in their processes. This change demands that one not be too fixated upon ideal textbook thermodynamic models but instead continually check these models using real-time data input and chemometric analysis. The author discusses implementation strategies and the benefits that chemometrics can bring to the process environment.
Considerations for Primary Vacuum Pumping in Mass Spectrometry Systems (PDF)
Mass spectrometry systems have specific vacuum requirements. New developments in oil-free, or dry, primary vacuum pumps have been introduced recently and are discussed in this article with respect to capacity, throughput, and specific pumping requirements for process gases.