Only Online: Flying on Course


Photo courtesy of Rick Butler, CAMI, FAA

FAA’s Forensic Toxicology Lab Enhances Quality and Compliance with
Pipette Calibration System

WITH A SPATE OF HIGH-PROFILE PLANE CRASHES, there has been considerable media attention surrounding aviation safety. However, the behind-the-scenes work of the institutions responsible for the oversight and investigation of the airline industry is often ignored in the headlines. The Federal Aviation Administration (FAA) has a wide range of laboratory capabilities that are applied to everything from plane-crash investigations to researching optimal genetic profiles for pilots.

The Bioaeronautical Sciences Research Laboratory (BSRL), located within the FAA’s Civil Aerospace Medical Institute (CAMI), conducts research and investigations on the bioaeronautical aspects of the safety and security of the nation’s aviation system. Based in Oklahoma City, that lab is the primary national toxicology testing site for aviation accidents investigated by the FAA and the National Transportation Safety Board (NTSB).

The lab’s results are used to make critical determinations regarding the causes of aircraft accidents, making the integrity of its processes critical. To assure the highest level of quality, the BSRL regularly seeks accreditation from the relevant bodies, such as the International Organization for Standardization (ISO), the College of American Pathologists (CAP), and the American Board of Forensic Toxicology (ABFT). A key component to meeting the stringent demands of these accreditation standards is demonstrating that liquid-handling procedures are properly monitored and controlled. With almost 100 pipettes used for assay transfers and other sensitive liquid delivery operations, the lab sought a system that would facilitate the calibration, tracking, and documentation of its entire pipette population.

The BSRL now uses the ARTEL PCS Pipette Calibration System to help meet the stringent regulatory requirements it faces. The results speak for themselves: at the 56th American Academy of Forensic Sciences annual meeting held in February 2009, it was announced that the BSRL met the body’s accreditation standards. Previous inspections by CAP resulted in no deficiencies, which, with this latest accreditation, make BSRL the only laboratory in the nation to be accredited by both ABFT and CAP.

The Challenge of Quality


Photo courtesy of Rick Butler, CAMI, FAA

The BSRL provides forensic support for aviation accidents by performing toxicology analyses for approximately 400 cases a year, the majority of which are fatalities. Typically, the lab searches for traces of alcohol, carbon monoxide, cyanide, or other toxicological agents within the samples it processes. The results, combined with other information from the aircraft scene, are reviewed by an NTSB investigator who makes a determination about the cause of the accident. The concentration of toxicological agents, such as an illicit drug or alcohol, is a critical factor in arriving at this conclusion. For investigators to be secure in their judgments, they must be confident that lab results are based on accurate and precise liquid dispensing.

The forensic-toxicology laboratory has a population of approximately 100 single-channel pipettes of both fixed and adjustable configuration from a range of manufacturers. With such a large number of pipettes, the BSRL needed a system that could perform the measurements necessary for pipette calibration in an effective, convenient manner. The system also needed to track and document calibrations in order to efficiently manage the population and demonstrate compliance during regulatory audits.

Previously, the BSRL had calibrated its pipettes using gravimetry, which weighs liquids on analytical balances. However, this method had several drawbacks. Gravimetric measurement is subject to error caused by environmental conditions such as temperature and humidity. Evaporation, static electricity, and vibration can make obtaining a precise gravimetric measurement difficult. The gravimetric method is used to calculate volume by converting weight to mass and then to volume. Accurate calibration using this method is contingent on knowing the true density of the fluid being pipetted. All of these variables can be addressed using complex calculations and taking steps to remove factors that contribute to error, but this process is painstaking and time consuming.

The ARTEL PCS Pipette Calibration System enabled the BSRL to address many of these challenges. The system is based on a proprietary form of ratiometric photometry, in which the light absorption from two different dye-based solutions is used to calculate liquid volume dispensed by a pipette. Measuring the absorbance values for the two different dye solutions in the same vial and within the same instrument eliminates errors associated with separate readings, such as optical imperfections, pathlength variation, and photometer non-linearity.

The PCS also provides immediate feedback of delivered volume, and can be used on the bench in the same environment as the pipettes. Indeed, a major advantage of the PCS is that it can be used to measure the performance of a pipette in the same environment where the assays are conducted and by the same technologist who actually runs the assay. Differing environmental conditions have no effect on volume measurement, so the system enables the BSRL to verify pipette performance without worrying about potential variability in humidity, temperature, or other environmental factors.

The PCS can be used with the ARTEL Pipette Tracker pipette management software, which automates data collection during calibrations, facilitates calibration scheduling, and generates data reports for regulatory compliance. The Pipette Tracker software helps to remove steps associated with manual data entry (which are necessary when using gravimetry) and virtually eliminates the risk of transcription errors because results are automatically logged in a database.

Getting Started

When the BSRL first implemented the PCS in 2006, each user was entered into the pipette tracking database with a separate login and each pipette was entered individually with the requisite tracking identification data. The lab also set a standardized tolerance for all pipettes (+/- 3% relative inaccuracy and +/- 5% coefficient of variation) and created standard operating procedures for using the system. Regular calibrations were mandated twice a year in addition to as-needed interim verification checks between scheduled calibrations or before critical assays in order to provide stronger confidence in results.

The benefits conferred by the PCS have been significant, minimizing staff time devoted to the difficult and meticulous process of gravimetric calibration. “In the long run, we’ve saved so much time by implementing Artel’s system,” said Sabra Botch, a member of the Biochemistry Team at the BSRL. “Once every user and pipette is entered into the system, it’s just a matter of following the proper procedures.”

Furthermore, the Pipette Tracker software provides all the necessary documentation in an automated manner so that lab technologists do not need to spend valuable lab time on cumbersome paperwork. The system also creates labels that can be applied to pipettes and scanned with a barcode reader during calibration to facilitate more convenient record keeping.

Flying on Course

Documenting the calibration function has been critical in enabling the BSRL to meet its regulatory requirements. To meet relevant ISO standards, ISO 9000 and ISO 14001, and the CAP and ABFT standards, it is necessary to trace and document all calibration activities. The PCS provides traceable measurement results based on National Institute of Standards and Technology (NIST) requirements so every calibration is founded in metrological standards. The Pipette Tracker software can also be used to record a complete audit trail for every calibration with comprehensive data tracking.

“For every question the auditors had, the Pipette Tracker provided the necessary answer,” said Botch. She also noted that calibration frequency, target volumes, and the precision and accuracy results of ten data points are all recorded for individual calibrations to the satisfaction of regulatory authorities.

A Useful Tool for Monitoring Operator Competency

A crucial benefit of the PCS is that it provides near-instant feedback to users when calibrating a pipette. A ten-point data set can be created within three minutes, which allows for interim verification checks above and beyond scheduled calibrations if a user suspects a pipette may be out of tolerance. This feature prevents malfunctioning pipettes from being used in critical assays.

Additionally, the PCS’s ability to generate immediate results allows operators to monitor their own pipetting skills and to “calibrate themselves.” Improper operator technique can be a significant source of error and even minimal changes in pipetting technique has a considerable impact on data. By providing immediate feedback on the accuracy and precision of a set of pipetted aliquots, the PCS serves as a useful tool to aid lab technologists in enhancing and monitoring their own pipette skills.

One way that the BSRL has addressed the issue of proper pipetting technique is through participation in Artel’s nationwide Pipetting Olympics program held during National Medical Laboratory Professionals Week. During the event, labs across the country participate by competing against their colleagues and against other labs to demonstrate pipetting skill. Medals are awarded for the participants with the best precision, noted by the lowest coefficient of variation, in their liquid dispensing performance.

The competitive nature of this event serves as a tremendous motivator for lab technologists to focus on their pipetting skills. “We have participated for the last three years, and our results have improved consistently each time we have competed,” said Botch. She also noted that the mere process of participating in the event and making pipette users responsible for their own calibration has raised awareness within the lab about the importance of accurate and precise liquid delivery. “Just by having the PCS on the bench has really drawn attention to how critical pipetting is to our success.”

Over the Horizon

With the Artel pipette calibration system, the BSRL was able to meet the stringent accreditation requirements it faced. Given the importance of its mission, regulatory compliance is a critical way to demonstrate the organization’s commitment to quality. Air crash investigations can determine civil liability and criminal judgments, and there can be no question about lab results when they support the interpretation of evidence. In forensic toxicology, assay volumes are crucial in determining the presence of a toxicological agent that may be a key piece of evidence. With the PCS in their lab, the BSRL can trust its results for years to come.

For more information about Artel, go to: www.artel-usa.com

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