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Analytical chemists are often faced with the task of separating complex chemical mixtures into pure chemical species that can then be precisely identified. To accomplish this task, scientists often use liquid chromatography (LC) or gas chromatography (GC) techniques followed by use of a variety of sophisticated spectroscopic detectors to analyze the purified compounds. At next month's Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, more than 800 companies will unveil a variety of recent innovations in chromatographic equipment (including spectroscopic detectors) as well as products used for processing samples prior to analysis. In addition to browsing through exhibits of the latest tools of the trade, the 30,000 scientists expected to attend will have the option of sitting in on their choice of nearly 1,600 technical papers pertaining to analytical chemistry and spectroscopy. The Atlanta meeting is sponsored by the Pittsburgh Conference, a volunteer-run nonprofit organization that is cosponsored by the Society for Analytical Chemists of Pittsburgh (SACP) and the Spectroscopy Society of Pittsburgh (SSP). An example of recent innovations in spectroscopic analysis of chemical species separated by gas chromatography that scientists can expect to see in Atlanta next month are new element-specific spectroscopic detectors. GC permits rapid and efficient separation of a wide variety of chemical compounds. But in spite of the power of GC as an analytical technique, some compounds that are composed of different elements may be difficult to distinguish. To date, this problem has been addressed by selectively tuning flame photometric detectors or electrolytic conductivity detectors to enhance detection of one element amidst others. A recent breakthrough, however, has been the development of element-specific detectors that circumvent the compromise inherent in previous methods. At the Pittsburgh Conference, Antek Instruments Inc., based in Houston, Tex., will introduce the Model 705 Nitrogen Specific Detector - one of the first products to use element-specific detectors. Designed for use in environmental analysis, herbicide and pesticide analysis, the petroleum industry, and pharmaceutical analysis, the detector effectively eliminates interference from compounds such as hydrocarbons that are normally present in samples, thus simplifying chromatogram interpretation. Chromatograms obtained with conventional detectors present several peaks in addition to those representing nitrogen-containing compounds. In contrast, the new nitrogen detector from Antek Instruments produces peaks only from nitrogen compounds, which may be present in as little as picogram quantities. The Model 705 Detector converts nitrogen-containing compounds to nitric oxide in a pyroreactor and then routes the nitrous oxide to a reaction chamber that contains ozone. Nitric oxide reacts with ozone, thus producing a metastable nitrous oxide that chemiluminesces. The light energy produced is subsequently detected by a photomultiplier tube. A band pass filter (650 to 900 nm) permits the detection of only nitrogen-containing compounds and shows no response to the presence of atmospheric nitrogen. The detector, priced at $11,500, includes the pyroreactor and fittings for attachment to a GC unit. Antek Instruments will display the Model 705 detector and other instruments at booths 2403, 2404, 2503, and 2505 at the Pittsburgh Conference from March 6 through 9. A sampling of other notable products on display follows this article. V. Richard Sheridan is a postdoctoral associate in pharmacology, and Wendy Wilson Sheridan is associate director of foundation and corporate relations, both at Fox Chase Cancer Center, Philadelphia. Circle No. 599 on Reader Service Card Two new type I reagent grade water systems are now available from Barnstead/Thermolyne Corp., headquartered in Dubuque, Iowa. The NANOpure Analytical and Bioresearch Grade water systems feature microprocessor-controlled monitors for ion purity that can be mounted up to 10 feet away from the units. Each system is constructed of noncontaminating polypropylene and is capable of producing up to two liters of water per minute. The systems come complete with a remote dispenser (including a final flow filter) that can produce a spray, steady stream, or drop of pure water. The Bioresearch Grade system uses an additional spiral-wound ultrafilter that produces virtually pyrogen-free type I water. A unique quad arrangement of cartridges in the NANOpure system takes up less wall space than comparable units from other vendors. Removal of ions, organics, bacteria, and pyrogens yields a grade of water suitable for tissue and cell culture, HPLC, and atomic-absorption spectroscopy. When analyzed via sensitive HPLC techniques, Barnstead's NANOpure water exhibits a base variation less than 0.0005 absorbance units. The two systems, which can be bench- or wall-mounted, range in price from $2,200 for the NANOpure Analytical System, to $2,700 for the NANOpure Bioresearch System. Barnstead/Thermolyne, Booths 2440-2443 Circle No. 600 on Reader Service Card Using a new Metal-Free Column System, bioscientists can improve recovery of valuable proteins and other biopolymers that previously adsorbed to metal columns. The system can be used with all types of buffers, thus eliminating the risk of corrosion of the column. The column body is made of polyether ester ketone (PEEK), a polymer that is inert to all HPLC solvents and buffers and can withstand pressures up to 5000 psi. The cartridges use a biocompatible alumina-ceramic frit that is not only more rigid than the commonly used teflon frit but also demonstrates a reduced chance of media impregnation. Metal-free holders, metal-free pumps, and other accessories are also available, providing a complete metal-free sample path in chromatography. Columns are available in a standard 4.6 mm ID in five different lengths (30, 50, 100, 150, and 250 mm) and range in price from $36 to $66. Alltech Associates, Booths 1002-1005, 1103, 1105 Circle No. 601 on Reader Service Card El Dorado Hills, Calif.-based Guided Wave Inc. says it has achieved an advance in fiber-optic design that is incorporated in the company's Model 300 Mainframe spectrophotometer. Rather than using a conventional fiber-optic bundle, a single 500 m m core fiber provides increased signal-to-noise ratio, baseline stability, and photometric range in comparison to that offered in spectrophotometers currently on the market. These sensitive NIR-VIS monitors can be multiplexed, thus permitting one analyzer to monitor up to 16 different points at distances up to 300 meters. The spectrophotometer is computer-controlled with easily addressable software packages available, permitting complete diagnostic control of parameters such as temperature and wavelength. Average system price is $70,000. Guided Wave, Booths 1141, 1143 Circle No. 602 on Reader Service Card A variety of products purified via liquid chromatography (LC) are most suitably monitored using refractive index detectors. Although many detectors currently on the market perform well for small-scale analytical LC operation, their performance is severely compromised with preparative-scale LC processes due to optical disturbances created by high product concentration and high flow rate. Anspec Company Inc., Ann Arbor, Mich., now offers a refractive index detector suitable for preparative LC. The Model ERC-7562 features precise temperature control and highly corrected optics that permit accurate, on-line measurements at flow rates up to two liters per minute. The detector, priced at $6,700, is specifically designed for preparative LC, thereby offering applications in food, beverage, pharmaceutical, and petrochemical industries. Anspec Company, Booths 2746-2749 Circle No. 603 on Reader Service Card Analytical chemists in the petroleum, chemical, and environmental monitoring industries are familiar with the difficulty of separating complex hydrocarbon mixtures into components. Gas chromatography (GC) is a technique of choice in these types of analyses; however, selection of the appropriate column can be problematic. Supelco Inc., based in Bellefonte, Pa., has now developed a GC column designed for high-resolution analysis of hydrocarbon mixtures. The Petrocol DH capillary column is 100 meters long, with a 0.25 mm internal diameter and 0.5 mm film coating. The internal diameter prevents overloading of highly concentrated sample components; thus mixtures with widely different component concentrations can be analyzed. The column is priced at $695. Supelco, Booths 1928, 1930 Circle No. 604 on Reader Service Card Scanning electron microscopes (SEM) in conjunction with energy dispersive X-ray (EDX) analysis permit the compositional analysis of samples with extremely high resolution. Spectrographs obtained from X-rays emitted from a sample following electron bombardment can accurately determine the chemical makeup of the sample. Traditional EDX analysis is performed separately from this microscope itself. Nissel Sangyo America Ltd., a division of Hitachi that is based in Mountain View, Calif., claims to have achieved a breakthrough in analytical SEM by combining the successful S-2500 SEM with a Kevex Delta class EDX analysis system. Essentially, the EDX analysis system directs the microscope's operation, dictating such parameters as accelerating voltage, magnification, focus, astigmatism, and contrast. A 60° conical lens permits high-tilt angles on large specimens to maintain short working distances required for high-resolution work. System prices start at $120,000. Nissel Sangyo America, Booth 3112 Circle No. 605 on Reader Service Card

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