As temperature increases over the 30- 40°C range, the polymer collapses and the particles aggregate. Wavelength scans at diff erent temperatures, and thermal gradient scans are used to partially characterise these processes, along with measurements over a range of pH, salt concentrations and gold particle concentrations. T e product’s temperature ramping function allows quick scanning of the eff ect of temperature on particle scattering at a given wavelength.

Previously, there was no other way to do that than to manually take data points at diff erent temperatures from

wavelength spectra. T e heating/cooling rates and rapid equilibration over all eight cell holders means that

more experiments (over diff erent concentrations, pH) can be achieved. T e accurate results for high-absorbing samples eliminates dilutions and reduced errors.

IMPROVING THROUGHPUT AND DATA ACCURACY To understand how this speed improves sample throughput and data quality, let’s consider the following scenario. A common lab experiment is to create a calibration curve by sequentially measuring several

The Cary 3500 can be confi gured in three diff erent ways, allowing simultaneous measurements of at diff erent experimental temperatures

standards then measuring a series of unknown samples to determine the relative concentrations of the analytes they contain. Duplicate analyses of the standards or unknowns might also be included. Most UV-Vis systems require that one solution (standard, “unknown” or duplicate) is measured at a time even when using a mechanical multicell accessory. It would take approximately 10 minutes to collect data across the wavelength range 350- 800nm from seven standards and unknown samples. T e Cary 3500 UV-Vis will collect the data from standards and unknowns, automatically generate the calibration curve and determine sample concentration data in a single measurement that takes less than fi ve seconds. T is not only saves time, it also helps improve data quality by

eliminating errors or variability that can be introduced during the measurement process. T is variability can be caused by human error, changing environmental factors or changes in the samples themselves – all detrimentally impact data quality and daily operational effi ciency.

CASE STUDY In another real-world example, Dr Mohammad Al Kobaisi from the School of Chemistry and Biotechnology, Swinburne University of Technology has experienced controlled stirring and wide range temperature control options with the Cary 3500, using UV-Vis to monitor processes in situ. T e stability of the signal allows for long-term kinetic processes too, opening up a range of experiments that were previously unable to do due to drift. T e intuitive software and data management prevents the loss of results and ensures well organised projects and archives and expands the fl exibility to control more parameters while conducting research experiments. In conclusion, the experimental possibilities with new UV-Vis instruments are endless. T ey create new possibilities for quantitative and qualitative analysis. Simultaneous system design with integrated non-moving multicell holder provides productivity and reproducibility required in pharmaceutical and biopharmaceutical industries.

Simultaneously create a calibration curve and determine sample concentrations in a single measurement. In this example a calibration curve was created using fi ve standards, while data from two unknown samples, and replicates of both, were collected in less than fi ve seconds

Dr Ursula Tems & Dr Matt Quinn are with Agilent. 39

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