Importance of Small but Essential Details in Proper Laboratory Practice

Elena Yehezkel, Global R&D, Teva Pharmaceutical Industries, Ltd, Netanya, Israel
Dorit Shaked, Global R&d, Teva Pharmaceutical Industries, Ltd, Netanya, Israel
Elena Polonsky, Global R&d, Teva Pharmaceutical Industries, Ltd, Netanya, Israel
Zina Rodin, Global R&d, Teva Pharmaceutical Industries, Ltd, Netanya, Israel
Meirav Amar, Global R&d, Teva Pharmaceutical Industries, Ltd, Netanya, Israel
Vladimir Ioffe, Global R&d, Teva Pharmaceutical Industries, Ltd, Netanya, Israel

In our days, most of the work in modern analytical methods is performed by sophisticated instruments (spectrophotometers, HPLC, GC, Mass-spectrometers, etc.). However, one should not neglect the importance of "manipulations" which should be performed properly by the staff of analytical laboratories. This "hand-made" work is a key to success of analysis and reliability of analytical result.

Most critical cases depending on manual operations are usually in the field of interlaboratory activities, such as "Cross-Testing", "Intermediate Precision" chapters in validation of analytical methods or "Tech. Transfer" of analytical methods from laboratory to another, from site to site and from one company to another. Difference in work habits of "originating" and "adopting" laboratories may sometimes be a root cause for failures of interlaboratory operations and compliance issues with respect to preset specifications limits and acceptance criteria.

The real examples of such cases are presented, including the follows:

• Proper volumetric adjustments using volumetric flasks, especially, when formation of foam may take place
  
• Accurate weighing of liquid standards and samples
• Proper performance of mechanical operations, such as stirring, mixing, shaking, sonicating, etc., to ensure reliable sample extraction (recovery) from solid or viscous matrix
• Habits of using low volume volumetric pipettes for dilution
  
• Difference between chromatographic equipment in different laboratories: "seemingly similar" requiring serious method adjustment, especially for gradient HPLC methods
  
• Use of polymer labware instead of glassware

Only face-to-face meetings between the originating and adopting laboratories staff, inspection of differences in analytical equipment and examination of work habits can solve the problems of interlaboratory work and avoid failures.
Conclusions: Every questionable case should be treated individually; all the definitions of manual operations should be provided in details in analytical methods and protocols to ensure that in all laboratories involved in an interlaboratory study, all the operations will be performed in identical manner.