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Polarization spectroscopy
A single-reflection diamond attenuated to tal reflectance accessory is designed for spectroscopic analysis of hard samples. The diamond is brazed into a tungsten carbide block with a 2-mm2 clear sam pling area. A clamping device with a sap phire anvil crushes hard samples without rotation to avoid sample movement or heat generation. Graseby Specac • 415
AutoProbe M5 scanning probe micro scope offers atomic-scale resolution and accommodates samples up to 16 in. χ 16 in. χ 1 in. The microscope can be operated in multiple modes, including contact, noncontact, and intermittent-contact AFM; STM; lateral force microscopy; and mag netic force microscopy using a single scan ning sensor. It features prealigned canti levers and on-axis viewing of the canti lever and sample and is controlled through Windows-based software. Park Scientific Instruments B417
Series II/ZS50 is a ZnSe photoelastic mod ulator for use in vibrational circular dichroism and Raman spectroscopies. It can be used to measure circular and linear dichroism, birefringence, and optical rotation by varying the polarization state of light at a fixed frequency. Hinds • 419
Extended range for particle size distribution Model LA-910 particle size distribution analyzer, an upgrade of the LA-900 analyzers, contains improved optics to extend the lower particle size limit, an automated sampling and analysis system for unattended operation, and a dry feeder that can disperse submicrometer cohesive fine powders. The fixed analyzer optics perform Fraunhofer diffraction, Mie scattering, and backscattering to determine size distribution for particles from 20 nm to > 1 mm in diameter. A shorter wave length light source and wider angle sili con detector expand the Mie scatter ing range for sizing of particles down to 20 nm as opposed to the 40-nm lower size limit for the LA-900 analyzers. Pre viously, particles in the 20-nm range could be measured only by photon cor relation spectroscopy, which has a much narrower sizing range than dif fraction/light-scattering methods. The automated system handles up to 24 samples and can be programmed to use up to 3 different user-supplied dispersion media within a run. The computer-controlled Powderjet dry feeder disperses cohesive fine pow ders as submicrometer particles using a high applied pressure and a jet noz zle, and it allows switching between wet and dry measurements in < 5 min. The pressure and shear rate of the jet stream can be set to lower values for delicate friable powders or to retain the agglomerated form of a powder sample. Horiba 1 4 1 6
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Voltammetry CV-50W voltammetric analyzer is de signed for demonstrating electrochem ical principles in teaching laboratories and for routine analyses. Operated using a Windows-based interface and mouse commands, it performs 14 controlled-potential voltammetry techniques such as cyclic voltammetry, differential pulse voltammetry, and Osteryoung square-wave voltammetry in addition to bulk electrolysis, chronoamperometry, and chronocoulometry. BAS E'chem B418
Porosimetry ASAP 2405 accelerated surface area and porosimetry analyzer can be operated in two modes. The standard system uses ni trogen as the adsorbate for surface area measurements and performs full adsorp tion and desorption isotherms for up to six samples. A low surface area option adds krypton as an adsorbate for surface areas < 5 m2 for up to 5 samples in sequence. The krypton option includes a molecular drag pump and a 1333-Pa pressure trans ducer with resolution of 0.067 Pa. Micromeritics • 420
Mercury monitoring The MC3000 mercury concentrator acces sory for cold vapor methods in AAS con tains a gold amalgam absorbent and an in ductive heating system to improve the
Next-generation GC HP 6890 Series GC system incorpo rates a sensor feedback-based modular electronic pneumatics system that controls and monitors all gas pres sures and flows. The electronic pneu matics control system, which is more extensive than that of the HP 5890 Series, automatically compensates for changes in ambient temperature and barometric pressure for greater in strument stability. All run parameters can be set from the keyboard and can be documented for a method. The pneumatics are divided into modules for more leak-free perfor mance. Capabilities for injection in clude forward pressure control in splitless injection mode to reduce the risk of sample loss, mass flow control cou pled with backpressure control in split mode, and electronic adjustment of split ratios. Split and splitless injection are optimized individually. Detectors have also been upgraded in the 6890 Series. The nitrogenphosphorus FPD has been redesigned for a longer bead lifetime and better signal stability. The FID has improved signal processing speed and can be ig-
Analytical Chemistry, Vol. 67, No. 3, February 1, 1995
nited automatically from within a pro grammed method. The full-range ther mal conductivity detector no longer requires gain switching for low- and high-sensitivity detection modes. Multiple sample streams can be se lected automatically and analyzed by different methods. Automated features include clock-time programming to load and run a method in unattended operation, pre- and postrun functions, storage of all GC setpoints for up to five methods, and a run-time log that records all changes in setpoints for a run. Keyboard functions have been up graded to provide information and guidance on setpoint parameters and ranges during methods setup. Hewlett Packard • 421
