A scientifically operated charge-coupled device detector combined with fluorescence quenching high-performance thin-layer chromatographic plates was employed for the detection of organic compounds, The plates were excited with 254 nm light from a mercury lamp, and quantitative information was obtained from organic compounds that absorbed the optimum conditions for detection. The linear dynamic range, sensitivity, and reproducibility of the system were evaluated by quantitative analysis of famotidine, acetaminophen, caffeine, and acetylsalicylic acid. The detection limits of the system were found to be in the nanogram range.

Recent developments in technology have suggested a promising ATOMIC EMISSION DETECTORS future for plasma spectroscopy. New optical technologies, suchResearch in spectroscopic detectors continues to improve as volume phase technology and unconventional optical measurements in plasma spectroscopy. Current 'state of the systems, when coupled with new generations of optical art' detection is performed using charge transfer devices detectors promise to provide powerful tools for plasma (CTDs). When run in the scientific mode, these devices achieve diagnostics or spectrochemical analysis. Next generation very low read noise and almost non-existent dark current.1-3 charge injection devices will provide both complete random When CTDs are coupled with e ´chelle spectrometers, a powerful access of individual detector sites and 'collective readout,' a system for measuring atomic emission is created, as illustrated new readout mode. Collective readout will promise faster in Table 1. This system has many desirable properties such as readout and improved signal to noise ratios. A new generation high resolution, high sensitivity and a wide dynamic range. of pre-amp per pixel array detectors with proper addressing Furthermore, CTDs achieve simultaneous multichannel detecarchitecture will allow random pixel readout and extreme tion of signal and background. Improvements in the near resistance to blooming. These technological advances will yield future should occur through the modification of current array new capabilities for not only current and future plasma detector technology and readout and in the development of sources, but also vintage sources such as the microwavenovel detector arrays. induced plasma, the direct current plasma, direct current arc Unfortunately, improvements in conventional CCD technoland the direct current spark. Developments in software data ogy are required to accommodate the wide range of intensities processing techniques including neural networks and other found in atomic spectroscopy. When the full well potential of chemometric techniques will allow present and future a pixel is reached, charge can spill over into nearby pixels in spectroscopists to extract useful diagnostic and chemical a process called blooming. In atomic emission, where strong information from the almost overwhelming abundance of and weak lines occur in close spatial proximity, blooming from analytical data generated by the present and future generations strong analyte or background (Ar) lines will typically cause of array detectors.interference and decrease the sensitivity and dynamic range of the device. While the CCD can be made antiblooming, quanti-Keywords: Spectroscopic instrumentation; plasma fication of the collected charge is not possible for strong lines spectroscopy; volume phase technology; charge injection in which the full well has been surpassed.4,5 Hence, during a devices; array detectors; charge transfer devices multicomponent analysis, multiple measurements can be required at a variety of different integration ti...

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A high-performance thin-layer chromatography (HPTLC) method using a scientifically operated charge-coupled device detector is described for the assay of tetracycline pharmaceutical products. Quantitative information can be obtained for all samples on a TLC plate within a few seconds. The separation efficiency and detection limits were determined on both normal phase and reverse phase TLC plates. Fluorescence detection mode offers higher sensitivity than fluorescence quenching mode. The dynamic range, sensitivity, accuracy and precision of the system were evaluated. Detection limits of the impurities are in the range of 0.1 to 0.5 ng or 0.3 to 1% of tetracycline, depending on the compound, with a recovery percentage over 85%. The existing impurities in tetracycline capsules were determined using both HPLC and HPTLC techniques. All of the impurities were below the regulation level.

The SSC dipole magnets must be very accura_ly the extreme purity of the magnetic field and the fact that the aligned for the accelerator to work correcdy. To align the moles have an averagecoil radius of 12 mm while the magnet magnets one must accurately know the center of the magnetic bore radius is 25 mm. field. However, locating the center is difficult because of the extremeuniformityof thedipolefield. A technique hasbeen Analternate technique hasbeendeveloped whichallowsthe developed to determine the magnetic centerof the SSCdipole useof directmagneticcentering whileavoidingthe problems magnetunder ambient test conditions. This technique associated with usingfceddown on a dipole magnet. This involves flowing currentin the upperhalf of the coilsin the techniqueinvolvesflowing currentin the upperhalf of the directionoppositeto the currentin the lower half. This is coilsin thedirectionopposite to thecurrentin the lowerhalf. doneusinga temporary leadconnected to the splice joiningthe The resultingfield is predominandyskew quadrupole,as two coil halves and two matchedpower supplies. The shownin Figure 1,andhashighfield gradientswhichallow resultingfield isprimarilyskewquadrupole andhashighfield thecenterto beaccm'awly locatedusinga moleandfeeddown gradients whichallow thecentertobeaccurately located.The analysis,lt shouldbe notedthat thisis nota truequadrupole, viability of this methodhasbeen verified by analysisusing sincesymmetryabout45°and135°axesis notsatisfied,and Taylor seriesexpansionof the resulting magnetic field, substantial amountsof higherordertermsarepresent.We Analysis hasalsoverified that off-the-shelfpowersupplies shall,however, referto thistechnique asthe "skewquadrupole havelowenough mismatchto be usedin thistechnique.The centering technique". analytacal resultshave been verified through the test of a short dipole magnet at the Brookhaven National Laboratory.Reversing the current direction in the lower half of the magnet is done using a temporary lead connected to the splice