32. Increased Throughput of Vitamin D Analysis using a Multiple Parallel LC-MS system
Poster: Tue 6:30-7:30PM
Robert Ellis
MDS Analytical Technologies
Adrian M. Taylor, Affiliation 1
David M. Cox 1, Affiliation 1
Min Yang 1, Affiliation 1
Robert Ellis, Affiliation 1
Tania Sasaki, Affiliation 2

1. MDS Analytical Technologies, 71 Four Valley Drive, Concord, Ontario, Canada L4K 4V8
2. Life Technologies, 850 Lincoln Centre Dr., Foster City, CA, 94404
With the growing demand on clinical laboratories to analyze increasing numbers of samples but maintain the same turn around times, a system is required that will significantly increase the throughput of a routine analysis. Multiplexing LC systems, and synchronizing to a single MS, can generate the high throughput needed by maximizing the efficiency of the MS. An integrated multiplex system has been specifically designed to synchronize two LC systems and a mass spectrometer, allowing injection of samples into two LC streams in parallel. The overlapping LC runs and efficient use of MS detection is shown to result in an overall higher throughput system for common routine clinical analyses.
The two-stream integrated multiplex LC-MS system consisted of a mass spectrometer, two autosamplers, two gradient LC pump systems, a shared column loading pump, a column oven, and switching valves for stream selection. All devices were controlled via the mass spectrometer software and a prototype device driver. The switching valves were controlled with precise timing to control the flow path of each LC stream to perform injection loop loading, and LC gradient elution. Targeted MS data acquisition was enabled by selecting a retention time window around the peaks of interest.

The developed multiplex LC-MS system was applied to two commonly performed clinical applications; Vitamin D and amino acid analysis. The multiplex workflow was applied to an already developed and robust amino acid analyzer kit for accurate quantification of amino acids from protein hydrolysate samples. The amino acid method requires a long column equilibration time, limiting the sample throughput of this method using a traditional system. By staggering the operation of the LC systems, the MS is acquired from the LC stream that is eluting analytes while the second stream is equilibrating the column and loading the next sample. All amino acids were monitored with equivalent fidelity using the multiplexed method.

Using the Multiplex LC-MS system in the Vitamin D analysis cuts out the time around the peaks of interest allowing this time to be spent washing the syringe and preloading the next sample, maximizing the analysis throughput.

For both of these clinically relevant application, the runtime was essentially cut in half, doubling the overall sample throughput.
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