One of the most widely used, and widely needed, laboratory tools would have to be the pH meter. Regardless of the chemistry being practiced, this tool has forged a place for itself in almost every laboratory. Some probes find constant use and enjoy prominence on the bench, whereas some get shoved aside until needed due to the footprint of some models. The people at IQ Scientific Instruments (www.phmeters.com) now offer an accurate, yet pocket-sized, solution that can keep the pH probe handy as well as hand-sized and out of the chemist’s way.
The Model IQ125 Minilab Pocket pH Meter is 142 x 28 x 15 mm and weighs only 48 g. It takes two 3V lithium batteries (included) and the kit includes an extra reference probe tip. The batteries will run for 150 hours continuously and the unit is equipped with an automatic shut off as well as a 10-hour warning indicator. The probe is very easy to use and comes with its own set of pH standards in the typical 4, 7 and 10 solutions. One of the nice things about the probe is that it is quickly calibrated. Just one single drop onto the meter interface (it must be a large enough drop to cover the reference probe as well) will start the process, since the tip and the included solvent dropper are both held simultaneously, one needs steady hands. An easy to read LCD interface will indicate when each reading is complete. A quick rinse and wipe of the tip prepares the probe before proceeding onto the next standard or sample. The shape of the unit may be limiting. It can sit in a beaker of solution as long as the opening is large enough to accommodate the probe’s width (28 x 15-mm) so test tubes and other small containers generally cannot be probed as a whole unless the volume allows the tip to be submerged. Likewise, bigger containers or large enough volumes may cause the probe to be partially submerged.
The probe’s pH range is from 2.0-12.0 and the temperature limits are 5-40C. There is only one decimal point, so the probe will not be the best choice in cases where higher accuracy is required. Since the silicon probe isn’t protected, care must be made not to scratch the tip or otherwise mar or impede the probe surface. Thus, the probe has its limitations, but as a rugged, hard working reference for buffered samples, this product is a good investment. The button design is workable, but they are small, inset soft buttons that could be problematic for gloved hands, however IQ Scientific Instruments has overcome such problems by including an ingenious button-pushing tip along with the probe-cap (although some caution should be recommended in pushing too hard in order to avoid damage). Overall, the IQ Minilab Professional Pocket pH Meter is a rather good investment and, therefore, is recommended as a handy addition to any laboratory toolbox.
Ronald A. Miller
Research Biochemist
Department of Alzheimer's Disease Research
Merck Research Laboratories