omation mbers - Society for Laboratory Automation and Screening

TP068
Kirby Reed
Gilson, Inc.
Applications
3000 West Beltline Highway
Middleton, Wisconsin 53562
kreed@gilson.com
Evaluating and Determining Precision and Accuracy for Automated Liquid Handlers
Dispensing Nanoliter Volumes of Viscous Solutions
The thrust in today’s research is to smaller and smaller scale in order to complete a greater number of assays in
a given amount of time leading to higher throughput and hopefully drugs to market. Micro scale research is not
trivial, especially in regards to the dispensing of nanoliter volumes of viscous solutions and reagents with accuracy
and precision. This application will demonstrate an evaluation procedure that will determine precision and accuracy
for a series of viscous solutions dispensed in the nanoliters range via an automated liquid handler that employs
non-contact solenoids for liquid aspiration and dispensing. The study is based on spectrophotometric analysis and
will compare the results to the more commonly chosen weighing technique.
TP069
Laurent Rieux
University of Groningen
Pharmaceutical Analysis
A. Deusinglaan 1
Groningen9713 AV Netherlands
l.rieux@farm.rug.nl
NanoLC-MS analysis of TNFα in Microdialysates
180
Co-Author(s)
Patty Mulder, Harm Niederlaender,
Elisabeth Verpoorte, Rainer Bischoff
TNFα is a small (17.4kDa) protein with pleiotropic activities related to cytotoxicity and inflammation. In order to
study the role of TNFα in disease models in living animals, it is sampled locally by implanting a microdialysis probe.
Due to the low concentrations expected (pg/mL) and the minute volumes of microdialysate, enhanced analytical
sensitivity is required. We are therefore developing an analytical platform based on nanoLC-ESI-MS, which will
be coupled with microdialysis for real-time, on-line analysis of TNFα in rats To this end, a nanoESI interface was
built in-house. Electrical contact was made through a liquid junction by applying a high voltage on a stainlesssteel
zero-dead-volume connection. The nanointerface was mounted on an xyz-micropositioner that allowed
some rotational positioning. The performance of the nanointerface (spray stability, signal-to-noise ratio (SNR)) was
studied with respect to positioning of the spray needle and eluent composition. Positioning the interface in front of
and close to the MS inlet gave the highest signal intensity, whereas SNRs were optimal at longer distance. The use
of distally coated needles gave the most consistent SNRs and it was easier to obtain a stable spray. At the same
time, these needles required lower spray voltages and were robust. Better SNR and higher signal intensities were
obtained with bare-silica needles, but they required more careful tuning. Therefore, distally coated needles were
chosen for further work, which consisted of setting up a nanoLC system with a 75-µm-id analytical column. Work
to analyze microdialysates spiked with TNFα to evaluate system sensitivity is underway.