New
Products
FT-IR Variable-pathlength gas cell for FT-IR spectroscopy can be adjusted manually or through software from 0.7 to 20.3 m in 1.4-m increments for analyses of gas sam ples at concentrations from percent to part-per-million levels. The Teflon- or nickel-coated cylindrical cell has a sample volume of 4.5 L. It can withstand internal pressures of up to 150 psi and vacuums of up to 10"! torr. A heated version of the cell is also available. S p e c t r a - T e c h • 404
Advanced materials for X R D The X'Pert MPD X-ray diffractometer is a fully automated system that in corporates new materials in the X-ray source and includes two independent goniometers with continuous posi tional monitoring. These features are designed to provide greater flexibility in polycrystalline diffraction mea surements and improved reproduc ibility of beam position on the sam ple. A new X-ray tube constructed with lightweight ceramic insulation is smaller and stronger than conven tional tubes made with glass insula tion. The ceramic insulator is more tolerant of the high tension applied to the tube than conventional glass in sulators are and reduces the chance of tube failure. The new design also improves the spatial stability of the focus and allows the instrument to operate at higher slew speeds. The use history of each X-ray tube can be recorded on a coding region at one end and monitored by the system controller to avoid accidental over loading. Two goniometers sharing a com mon X-ray source are independently
controlled to avoid collisions inside the booth. This arrangement, with up to four detectors, allows two opera tors to work on separate analyses simultaneously. A closed-loop servo system provides direct optical posi tion-sensing control of goniometer axes for continuous monitoring. The servo replaces stepper motor con trols for better movement precision. Computer-controlled optics auto matically align the divergence slit and vary the receiving slit width from 50 μιτι to 3 mm. Other components of the optics system include dedicated monochromators for each wave length and a compact proportional detector with a maximum count rate of 500,000 cps. Philips Electronic Instruments • 401
LITERATURE XRF Brochure describes the EX-3000/3500 and EX-6000/6500 lines of energy-disper sive X-ray fluorescence spectrometers. Instruments, applications, and software are described and illustrated with photo graphs and computer screen shots of XRF spectra. 12 pp. Baird • 405
Particle sizing Literature describes the Mastersizer Micro particle size analysis system. The single-lens instrument uses laser diffrac tion with Mie scattering to characterize particles in the range of 0.3-300 pm. Sam ples are dispersed into a liquid suspension for measurement. Malvern • 406
SFE INSTRUMENTATION
of a PC, a keypad, or an optical encoder. Micro-Now • 402
ESR and EPR The Model 8320A magnetic field control ler, which incorporates a 0.25-in.-thick Hall effect probe field sensor, is designed to control a magnet power supply for fixed or swept fields. The controller operates in the range of 0-12,000 G with typical accu racy of ±10 G; field setting resolution is 0.1 G. The 8320A can store digitized field scan and EPR or ESR resonance data for further analysis with PC-compatible soft ware that includes spectral manipulation, differentiation, and integration functions and calculates spin concentration. The system can be controlled through the use 662 A
AAS The VP90 hydride vapor generator pro vides continuous-flow sampling to reduce matrix effects in AAS determinations of Hg, Se, Sb, Bi, Ge, Sn, and Pb. Samples and reagents are continuously pumped to a reaction vessel, and product gases and vapors are separated in a gas-liquid trap that allows the liquid to drain to waste. The hydride vapor is swept into a heated atom cell with a stream of Ar or N. The reaction vessel is cleaned automatically at the end of each sample run. ATI • 403
Analytical Chemistry, Vol. 66, No. 11, June 1, 1994
Guide provides a list of applications and references in the literature for SFE optimi zation protocols and integration with other analytical methods such as MS. The applications table lists matrix class, sam ple matrix, analyte class, SFE gas, modi fier, temperature and pressure, extraction time, and reference number. S u p e l c o • 407
Training courses Schedule for 1994 includes listings for training courses on operating and trouble shooting GC, LC, GC/MS, ICP-AES, and AA systems. Classes on programming ADL and using StarLIMS software are also offered. Varian • 408
