Data integrity in forensic laboratories is not to be taken lightly. Considered by juries making life-altering decisions (such as whether to convict an accused drunk driver or acquit a murder suspect), forensic test results must be validated and verified prior to presentation to the court. To ensure accurate and precise results, laboratories need an integrated quality assurance program.
Quality systems support is a key focus area for the National Forensic Science Technology Center (NFSTC), which provides technical assistance, training, and community outreach support to the American forensic science and justice communities. In one initiative to help its members have complete confidence in the results they provide to the justice community, the organization offers rigorous training programs for new technicians. In the past four years, nearly 35 newly hired forensic laboratory analysts have been sent by their employers to attend training at the NFSTC headquarters in Largo, Florida. Because these training programs may be among the first forensic laboratory experiences for many enrollees, one of the core philosophies of the program is to simulate a real-world laboratory environment.
“We have put in place all of the quality assurance and quality control resources that a trainee should find in his/her own laboratory,” notes David Epstein, Chief Scientist at the NFSTC.
Liquid Handling Quality Assurance (LHQA) is an important segment of the NFSTC’s technician training program due to the importance of liquid delivery in forensic laboratory testing procedures, the limited availability of sample material and the minute volumes typically tested, where even small discrepancies in delivered volumes can impact the integrity of evidentiary results. The organization emphasizes pipette training, not only to teach students technologies for verifying liquid delivery devices and pipetting correctly, but also to educate them about their significance.
“Many new trainees do not understand that pipettes can fail in a silent manner, and that they cannot just look at the instruments to confirm that they are working. We try to instill in the students that pipette function cannot be taken for granted,” notes Epstein. In addition, many new technicians have not received proper pipetting skills instruction; they do not realize that operator technique is a major source of error.
To effectively educate its trainees about the importance of liquid delivery for accurate test results and the need to verify instrumentation performance, the NFSTC uses the Artel PCS® Pipette Calibration System. The PCS is based on ratiometric photometry, a proprietary technology that provides immediate verification of delivered volume, and can be used on the bench for effective pipette calibration and operator pipetting technique training.
The NFSTC selected the PCS because it provides a tool for minimizing the risk of both sources of pipetting error – the pipette and the operator. The PCS provides on the spot measurement of liquid delivery device instrumentation, allowing for frequent checking and hands-on training.
“With the PCS, we are able to quickly test each individual before training and then post-training to show the improvement,” notes Epstein. “It is one of the only technologies that provide the ability to check the precision and accuracy of a person using a pipette.”
“By using the PCS and related technologies, laboratories have a streamlined way to assure the quality of their liquid delivery processes,” states Epstein.
The PCS provides automated, NIST-traceable results, eliminating one quality assurance burden from the shoulders of forensic laboratory managers. It also includes pipette management software that provides automatic scheduling of pipette calibrations and complete electronic record keeping. Transcription errors are eliminated, regulatory compliance is enhanced, and technicians are freed from time consuming and error-prone manual record keeping.
Data from the pipetting skills portion of one particular training session, generated with the PCS, can be found in Figure 1. In this example, 11 criminalists pipetted 10 µL used a fully functioning, recently calibrated pipette. Ten data points were obtained from each student and the data analyzed by the PCS for precision and accuracy. It is clear that these laboratory professionals exhibited significant variability in pipetting competency.
The students were retested after training on proper pipetting technique and a marked improvement in the accuracy and precision of their pipetting was evident, as seen in Figure 2.
“The PCS was very easy to work with,” recalls Kyle Mueller, a recent NFSTC training program graduate and currently a forensic scientist at the Phoenix Police Department. “The NFSTC training program instructors made it clear that it’s important to have accurate and precise volume measurements in testing and provided a very useful introduction to the forensic laboratory.”