With a chemical such as a polyol, which has multiple uses and must be accurately characterized to ensure functionality; exact acidity or alkalinity must be specified before inclusion in a final product mix. Finding a single method to determine either value, which are often low-range and require tiny titrant amounts, cut a client's lab sampling time in half using METTLER TOLEDO Titration Excellence.
The exact specifications of a polyol are dictated by its end use, which can include everything from food products to insulation. Characterization must be very accurate to achieve desired performance. Of paramount importance is the polyols acidity or alkalinity. Not only are these values more difficult to define in a non-aqueous solution than in an aqueous one; one test is used to determine either acidity or alkalinity, but not both. Because these values are typically very minute with polyols, an operator may perform one test only to determine the other is needed. Additionally, this particular analysis typically has required small amounts of environmentally unstable titrants, which is not an ideal situation for lab operators or for exact results.
Building on Past Experience
Teaming with polyol expert Ross Koile, PhD, of Koile and Associates proved fruitful in meeting a client's challenge of determining either acidity or alkalinity with a single-step analysis. First, a solvent suitable for dissolution and electrode response was required. Then, to make the analysis usable and repeatable, it had to be easy to perform so that it could be used by lab operators of a variety of skill levels. The solution was not obvious, but was ultimately found to be robust and highly accurate. The key was redefining titration to 'neutral' using experience gleaned from past titration techniques.
A New Chemical Analysis
The new analysis used a set amount of bicarbonate that would be titrated as a blank using a stable acid in a mixture of alcohols and salt to optimize solubility and electrode response. A volume comparison with the blank allowed the test operator to determine whether a sample was basic or acidic with a single test. By using any of the METTLER TOLEDO Titration Excellence Line with this new method, acidity or alkalinity was determined with just One Click using an extra dosing unit for the accurate and consistent preparation of both samples and blanks.
Using the blank value with METTER TOLEDO's DV1005 5 mL burette, the titration volume was always optimized so that even low acidity or alkalinity levels required a significant amount of titrant, increasing accuracy. The titrator also stored a prepared blank average for later use in sample calculations. By ensuring only one test would be required, sample preparation time was effectively halved for significant time-savings. The DGi116-SC Solvent pH electrode's large glass membrane, electrostatically shielded reference and high-flow, movable sleeve junction proved ideal for fast and resolute measurement Adding the Rondo20 autosampler enhanced throughput by offering automated cleaning/electrode conditioning with no sample crossover thanks to METTLER TOLEDO's unique PowerShower.
To learn more about how METTLER TOLEDO Titration Excellence can help master even the most complex titration challenges, visit http://us.mt.com/us/en/home/supportive_content/specific_overviews/Polyo_Analysis_OneClick.html?crel=ePR_PP_EN