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I like the Fisher AB15 meter. Large LCD display for presbyopic eyes, and it will do multipoint calibrations. Most laboratory grade pH meters will do multipoint calibration, however. We typically do a 3 point pH calibration at 4, 7, 10, but you can do more if you like. I pair this with a refillable accuTuph combination pH electrode that has a built-in Ag/AgCl reference electrode. These electrodes have thicker glass membranes than the usual pH electrodes, and are a little more student-resistant. The refillable electrode solution allows you to maintain and use this electrode for many, many years. It is possible to get 5-10 years service out of these electrodes. If you will be calibrating concentrated Tris buffers on a regular basis, consider spending a little extra on a double junction electrode rather than the single junction electrode. Double junction electrodes are more resistant to clogging in general and "Tris effect" in particular. (Tris binds Ag+ in the reference electrode, and can make your pH electrode go "wonky" for a while after exposure.) Gel combination electrodes are worthless, and I would not consider using one in the research laboratory. They have very limited shelf and useful life, and cannot be refurbished when they go bad. And they don't recover gracefully from exposure to Tris. I haven't tried FET pH electrodes, but they seem needlessly expensive considering the glass membrane technology works very well and gives years of service. Cheers, _______________________________________ Roger S. Rowlett Gordon & Dorothy Kline Professor Department of Chemistry Colgate University 13 Oak Drive Hamilton, NY 13346 tel: (315)-228-7245 ofc: (315)-228-7395 fax: (315)-228-7935 email: [log in to unmask] On 7/18/2012 2:21 AM, Anirban Banerjee wrote: > Dear all, > > May I ask for recommendations for pH meters that work reliably over the range of buffers and components that constitute common crystallization screens ? > > Thanks very much in advance. > > Anirban