How Measuring Sample Volume and Detecting Precipitates Works

Significant time and effort is expended in screening chemical and biological sample libraries. However, no matter how advanced the screening system, the end results are only as good as the quality of the sample in the microplate wells.

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Problem: Significant time and effort is expended in screening chemical and biological sample libraries. However, no matter how advanced the screening system, the end results are only as good as the quality of the sample in the microplate wells.

Compound managers responsible for delivering samples in plate format to screening groups need to have confidence in the quality of their delivered product. Unfortunately, survey data suggests that up to 5 percent of microplate wells may be empty, and 3 to 5 percent of wells may have samples at the wrong concentration.

Empty plate wells—or wells with samples at the wrong concentration—can have a significant impact on the end results. In particular, precipitates in compound solutions not only lead to poor quality screening results, but also result in significant cost wastage. Knowing the sample volume in the source microtube, and whether there is any precipitate, prior to plating, is thus key to improving the quality of screening output.

Scientists need to know:

• If there is any sample in the source microtube
• How much volume of sample is in the tube
• If any of the sample has precipitated out of solution

Existing approaches using gravimetric, ultrasonic and other liquid level sensing methods have their disadvantages and cannot determine if sample has precipitated out of solution. A visual check can help spot precipitates, but this is a tedious task if conducted regularly for all samples, especially in a large library.


RTS Tube Auditor

Solution: To improve the quality of delivered plates to screening groups and to reduce the cost of wasted screening (time, effort, reagents, missed hits, etc.), vision technology can be used to audit both volume and precipitate in racks of up to 96 tubes (without requiring de-capping).

RTS Tube Auditor™, a high-speed, high-resolution vision system, images multiple sample tubes simultaneously. The images are analyzed and the liquid meniscus detected for each tube audited. Once the position of the meniscus has been determined, the volume of liquid is calculated, taking into account tube and liquid types. Further algorithms are used to detect the presence of a cap and any precipitate in the base of the tube.

Benefits of this approach include:

• Speed: Less than 2 minutes to audit a 96 tube rack
• Accuracy: Volume measurement better than +/-10μl
• Precipitate and cap detection
• No need for tare-weighing
• Non-contact and operates with capped tubes

Suitable applications:

• Multiple applications within the CM/HTS process
• Biobanking
• Sample quality control and empty tube detection
• Sample dissolution and solubility quality checks
• Cap detection (to avoid liquid handling tip damage)

In addition to CM/HTS applications, this technology exhibits good performance when auditing DNA (in buffer) and other biological fluids, requiring significantly less time than conventional methods. Vision technology has made it possible to provide compound managers with a high-speed, high-accuracy instrument for auditing sample volumes and detecting precipitates.

Tedious manual visual checks or slow automated processes can be eliminated by the Tube Auditor™ with regular monitoring of sample tubes, increasing confidence in the quality of the sample being stored, thereby reducing the impact of variable quality on downstream processes such as screening.

For more information, visit www.rtslifescience.com.

Categories: How it Works

Published In

Q is for Quality Magazine Issue Cover
Q is for Quality

Published: May 1, 2010

Cover Story

Q is for Quality

Despite the vigilance of federal, state and local regulators and of accreditation organizations that evaluate and certify laboratories, the development and maintenance of quality in laboratories are constant concerns.