A Tip on Tips: Small is the Next Big Thing in Automated Forensic Separations

 A Tip on Tips: Small is the Next Big Thing in Automated Forensic Separations

Shrinking budgets. Competing priorities. If you’ve ever thought about becoming a detective, try this test of your sleuthing skills: find ways to cut costs from a forensic lab budget without compromising quality and efficiency.

It’s just as difficult as it sounds.

With budgets already stretched thin, every bit of savings adds up. However, here are two tips to save money that can actually strengthen quality and efficiency at the same time.

The first money-saving tip is to incorporate automation, which should come as no surprise. In addition to increasing sample throughput, hands-free automation takes over tedious, low-value labor like pipetting so that analysts are free to apply their time and expertise to data interpretation and report writing. As labor is generally the largest single expense in the overall forensic lab budget, this reallocation of time towards high value tasks enables the lab as a whole to get more done in less time. Automated systems also eliminate human-derived variability and errors so that less time and materials are spent on quality incidents and retesting.

forensic pipette tipsThe second tip to save your lab’s money is to use your automated liquid handler to perform as much of your assay as possible on the deck of your instrument. “How do I do that?”, you say. Use your tips – your pipette tips that is – to miniaturize your assay! That’s right; we’re talking about a technology shrunk down so much that the reaction takes place within a single disposable pipette tip.

This technology is known as dispersive solid phase extraction (dSPE) or dispersive pipette extraction (DPX), and it is specially designed for automated workflows using one of two formats.

The first format is an “in-tip” configuration; a specialized pipette tip that contains a freely moving resin sorbent with high sensitivity and specificity contained between a lower frit barrier and an upper porous barrier. Samples are mixed with a solvent and aspirated into this tip. The tip’s internal baffle system and air purposely drawn into the tip work to promote thorough, turbulent mixing as the liquid contacts the sorbent. During this mixing, any analyte(s) of interest in the sample are captured on the sorbent through ionic exchange or hydrophobic interactions, depending on the resin type. The resin is washed to remove any potential interfering compounds, and the purified analyte is then eluted and ready for downstream analysis such as GC-MS or LC-MS/MS. This is the perfect solution for the forensic toxicologist who can now use microliter instead of milliliter quantities of a biological fluid to analyze tens of drugs of abuse within just a couple of quick pipetting steps.

forensic pipette tipsThe savings start to add up. Without interferents in the sample, sensitive analytical instruments downstream in your workflow are protected from fouling, thus reducing the time-consuming and costly frequency of maintenance and repair. In the automated tip-based workflow, the lab realizes labor efficiencies through reallocated time and fewer quality issues. As the reaction is so small, fewer reagents and consumables are used.

“That’s some mighty good sleuthin’ for savings,” a toxicologist may declare. While on the other hand, a DNA analyst may counter with, “Not so fast there; what’s in it from my perspective?”

Not to worry bio-buds, I’ve got enough tips for everyone…

The second format, a tip-on-tip configuration, employs the same principle as the in-tip format, but applied to sample lysis. It uses a resin filled tip that is attached to a larger wide bore tip. A sample of evidence is first aspirated into the wide bore tip. Then this tip is used to pick up the smaller tip containing the resin mix. The two tips are pressure-fit together and then the sample is dispensed from tip to tip, mixed with the resin, and then finally dispensed in its purified form into a microplate well or tube.

forensic pipette tipsAt the leading edge of tip-based technologies is DNA extraction. Tip-on-tip methods of separating different cell types in cases of sexual assault are currently being explored with great promise. Here, instead of the resin having affinity for a drug analytes, it targets particular cell specific protein complexes. This new method can be used to isolate male DNA from all sperm heads including those that are not intact, and degraded or of low quantity biological material. The time- and money-saving benefits that we just covered still apply in this automated tip-based workflow.

Although tip-based biological workflows are still being perfected, keep an eye out for their upcoming commercial debut. The future is closer (and smaller) than you think.

As long as forensic markets continue to realize big savings from automated miniaturized assays, this trend will grow into new application areas. I’m interested to hear your ideas on how automated miniaturization can aid your applications. Until then, the next time your management asks you to look into cost-saving measures that promote quality and efficiency, you can confidently respond, “Have I got a tip for you!”

“Dr. Miller's Unfiltered Tips" is authored by Dr. Kevin Miller, Senior Market Segment Leader, Scientific Content Manager at Hamilton Company in Reno, NV. After earning a Ph.D. in Molecular Anthropology from the University of Cambridge, Dr. Miller actively engaged in promoting, researching, and furthering forensic science advances, and remains committed to this endeavor today. In his words, "I am a forensic geneticist who, like most forensic folks my age, fell into the field from somewhere else (I was digging up Viking remains in the Northern Isles of Scotland, but that is a completely different story) and stayed … at least until I brought automated liquid handling to my laboratory. Now I work with automation engineers, and try to make sense their world for the people in mine. I’ve picked up a lot of tips, and given away a few. Sometimes useful. Always unfiltered."


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