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Before ending this guide it is worthwhile mentioning two aspects of particle sizing that, so for, have been ignored - sampling and sample preparation. It is fair to say that the majority of variation in particle sizing measurements is ultimately traceable to either incorrect sampling or sample preparation. Particle size analysis results are only applicable when the samples drawn are representative and the dispersion techniques appropriate.
Sampling and sample preparation are precursors to particle sizing. As such they are often not directly addressed by manufacturers of particle sizing instrumentation. Yet they are probably the most important sources of error.
Problem areas to consider: unrepresentative samples; large and/or dense particles trapped, or segregated, before they reach the sensing zone; and inadequately dispersed samples in the submicron range.
When deciding which instrument to purchase it is common to send samples to several manufacturers. The biggest problem in comparing results obtained this way lies in the assumption that all the samples were prepared in the same manner. It is a common failing to assume the first measurement reported is correct. (This is also true when comparing any new particle size result to the historical database.) A better approach is this: Prepare equally representative samples; determine the best method for dispersing the sample; and then advise each manufacturer to disperse the sample in the same way.
BIBLIOGRAPHY 1.Terry Allen, Particle Size Measurement, 4th edition, Chapman and Hall, 1991.
2. Brian Kaye, Direct Characterisation of Fine Particles, Wiley-lnterscience, 1981. 3. Modem Methods of Particle Size Analysis, H.G. Barth editor, Wiley-lnterscience, 1984. 4. Particle Size Distribution: Assessment and Characterisation, T. Provder editor, American Chemical Society Symposium Series 332, Washington D.C, 1987. 5. Particle Size Analysis 1988, P.J. Lloyd editor, Wiley-lnterscience, 1988.
6. Particle Size Analysis, J.D. Stockham and E.G. Fochtman editors, Ann Arbor Science Publishers Inc, Ann Arbor, Michigan, 1977. First Published in Labmate UK & Ireland, September 2011 The Latest Platform for AFM and Optics
JPK Instruments continue to expand its family of high performance research systems with the announcement of the availability of the NanoWizard®
3 NanoOptics AFM system. Over the past decade, optical phenomena on the nanoscale
have developed into an exciting area of research. To study light on the nanoscale and especially its interaction with matter, researchers look for methods with nanometer spatial resolution. The combination of Light Microscopy-derived techniques and Scanning Probe Microscopy is a powerful solution. This so-called Near-field Optical Microscopy delivers optical information from sample surfaces with sub-wavelength resolution.
JPK first coupled their NanoWizard AFM to a Raman spectrometer in 2003 starting a new chapter for SPM and optics. Building strong relationships with the nano-optics community, collaborating with home-builders and users worldwide has enabled JPK to develop more powerful and flexible systems. JPK strongly believes in combining techniques, in particular AFM with optics. This has opened up a field of new applications including TERS/SERS, tip-enhanced fluorescence, nanomanipulation with light, chemical surface analysis and compound detection, metamaterials, developments of optically active components such as dyes, markers, light sources and switches. A large number of user publications underscore the success of this technology approach. Now, JPK introduces their latest platform for AFM and optics - the NanoWizard3 NanoOptics system.
The NanoWizard NanoOptics head comes with excellent physical and optical access to the sample from top and bottom as well as from front and side, even when the head and condenser are in place. Additionally, it has an integrated port for fibre SNOM applications. The new system is ready for a broad range of applications from nanoscale optical imaging by aperture and scattering-type SNOM to experiments involving interactions of light with the sample such as absorption, excitation, nonlinear effects and quenching. These include aperture fibre SNOM experiments where an integrated fibre SNOM port in the NanoOptics head and the tuning fork module allows hassle-free integration of techniques. The NanoWizard3 NanoOptics AFM can be used in a large number of configurations. The AFM system can be used for many more applications. It is also possible to interface and run different heads such as the ForceRobot®
300 and the CellHesion® 200 or to use the TopViewOptics™. Circle no. 438
Making Scientific Discovery More Accessible
Microscale glassware kits promote safety, economy and convenience for small-scale organic chemistry experiments. Performing chemical experiments in microscale is easier with specialised kits from Kimble Chase, the largest manufacturer of laboratory glassware products in the world. Williamson microscale kits offer a selection of specially tooled laboratory glassware with patented thermoplastic connectors to allow quick, easy and secure connections. Other available kits feature components with GCI threads or 14/10 standard taper joints.
Chemists are supplied with everything they need to perform fractional distillations, chromatography, filtration, sublimation, oxygenation and Dean Stark reactions using significantly reduced quantities of chemicals. Kimble Chase offers numerous kits, including the Williamson Microscale and Macroscale Kits with all the glassware needed to follow experiments cited in the authoritative textbook, Macroscale and Microscale Organic Experiments (Williamson, K.L., 2007).
Microscale kits from Kimble Chase include the components necessary for many of the common organic chemistry lab procedures, including separatory funnels, flasks, tubing adapters, centrifuge tubes, thermometer adapters and stopcocks. In addition, Kimble Chase offers a selection of accessories, which include thermometers, aluminum heating blocks and condensers. The kits are packed in rugged polyethylene storage cases with die cut foam inserts, and are available with custom printing. Corrugated EKONO-CASES offer a low cost alternative to plastic cases, and both are sized to be easily stored in bench drawers.
Kimble Chase Microscale Kits are available worldwide from multiple manufacturing facilities located in the US, Europe and Asia. Circle no. 439
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