Pipettes Resource Guide 2018 Pipettes Resource Guide

PIPETTES RESOURCE GUIDE 2018 PIPETTES RESOURCE GUIDE INTRODUCTION LESSON IN LIQUID HANDLING by Trevor Henderson, PhD by Erica Tennenhouse, PhD QUESTIONS TO ASK WHEN FOCUS ON PIPETTE TIP DESIGN BUYING A PIPETTE by Angelo DePalma, PhD by Lab Manager INSIGHTS INTO... PURCHASING TIPS • Personalized Pipettes by Angelo DePalma, PhD • Low-Volume Pipetting by Mike May, PhD and Angelo MAINTENANCE MATTERS DePalma, PhD by Rachel Muenz Lab Manager 2017 1 LabManager.com Introduction by Trevor Henderson, PhD Pipetting is part of nearly every laboratory’s workflow. The goal of pipetting is to ensure maximum accuracy and repeatability when transferring fluids. Research and development labs in the chemicals, foods, materials, and paints industries use pipettes routinely. However, it is in the life sciences that the greatest number of pipettes and related supplies are found. This established technology continues to undergo improvements, most related to usability and consistency. If you’re looking to buy one, there are many different features to take into consideration before making your purchase, including ergonomics, low force, fitting, ease of use, reliability, accuracy, and precision. Lab Manager 2017 2 LabManager.com PIPETTES RESOURCE GUIDE Questions to Ask When Buying a Bath or Chiller by Lab Manager How does my sample volume influence which pipette is the best fit? Pipettes come in a variety of different sizes to suit whichever volume needs are required. If you know you will always be pipetting the same volume of liquid, then a fixed volume pipette will be best. If the amount to be pipetted is changing from sample to sample, then a variable pipette will be ideal. How does sample viscosity impact my selection of a pipette? The viscosity of the sample will have a direct influence on which pipette is required. For aqueous samples which are low viscosity, an air displacement pipette is ideal. These pipettes are driven by a piston in an airtight sleeve which generates a vacuum. For more viscous or heavy liquids, a positive displacement pipette should be used. These pipettes are driven by a disposable piston which comes into direct contact with the sample. What pipette should I use for PCR, ELISA, or other immunoassay applications? PCR, ELISA, and many other immunoassay methods utilize microwell plates. Microplates come in many configurations: 6, 24, 96, 384, and 1536 well plates arranged in a 2x3 matrix are typically used. In order to accommodate faster throughput with such methods, many pipette manufacturers offer multichannel pipettes. These allow for faster pipetting of multiple samples: instead of having to fill 96 wells individually, an 8 channel pipette can be used, reducing the number of aspirations and dispenses to 12. Lab Manager 2017 3 LabManager.com PIPETTES RESOURCE GUIDE Purchasing Tips by Angelo DePalma, PhD • Find a comfortable, ergonomic fit to prevent poor pipetting technique, which affects accuracy and precision. • Look for pipettes and tips that were designed together. • Don’t skimp on consumables: consistency in pipette tips reduces fit variability and benefits overall performance. • Be sure to select a vendor with robust global manufacturing capabilities to ensure uninterrupted pipette tip supply. • Lab managers typically believe that if manual pipettes are not enough, they have to splurge on a robotic system. That’s untrue. They should consider options in between, which may be more economical and, for many workflows, more efficient. Lab Manager 2017 4 LabManager.com PIPETTES RESOURCE GUIDE Maintenance Matters by Rachel Muenz 3 THINGS TO CONSIDER BEFORE SIGNING UP FOR A PIPETTE MAINTENANCE AGREEMENT 1. Ask what a calibration involves. Some companies will simply check if the pipette is calibrated, whereas others will provide a more in-depth check and pipette cleaning. 2. If you’re using a third-party company, find out if they are familiar with your brand of pipette. 3. Check whether they offer in-lab calibration/maintenance or if you need to send the pipette away. Pipette abuse; unfortunately, it’s as common in labs There are many common errors people make when as the instruments themselves. However, a few simple maintaining or calibrating their pipettes, though the main maintenance tasks, along with proper calibration are all you one is simply not doing maintenance at all. Errors most need to keep your pipettes at their best. often happen in pipette storage, handling, overall usage, and pipetting technique as there is a lot of variability from user Educating users on proper technique is essential to avoiding to user. pipette neglect. The key to a really good pipette calibration program is being proactive. A good calibration program will Overly-aggressive tolerance limits, people calibrating their be able to trend a particular pipette’s performance over time. pipette in a different environment from the one the pipette Another thing that’s very useful is being able to establish is actually used in or with different tips than the ones action limits because the key to being proactive is to be normally used on the pipette, are other key mistakes. Some able to know how your pipettes are performing before they users clean their pipettes with bleach or other corrosive actually have a failure. agents but don’t give the pipette a final rinse with deionized water. That means salts crystallize and disrupt the movement Though when to calibrate depends on what the pipette of the pistons. Another error is users wiping off all the is being used for and how often, guidelines for pipette grease on the pipettes’ pistons when cleaning them but not calibration are also set by the American Society for Testing re-greasing the pistons afterward. and Materials. Those recommend quarterly control checks of ten data points, and monthly verification checks of four To avoid such mistakes, the user’s manual, manufacturer’s data points. customer service department and literature, as well as third- party calibration companies, and companies that provide Labs should use the guidelines of whatever body they are training, education, and calibration systems are all good accredited by for pipette calibration/ maintenance and resources to consult. recommends users should check their pipettes at least every year to make sure they’re in calibration. As for general maintenance, that all depends on what the lab is doing. For example, in some cell culture or PCR applications, pipettes may need to be cleaned after each use or experiment. Lab Manager 2017 5 LabManager.com PIPETTES RESOURCE GUIDE Focus on Pipette Tip Design by Angelo DePalma, PhD dispense volumes in the microliter range, molding quality, physical integrity, and uniformity become critical for accurate, reproducible liquid movement within the pipette tip. For pipette tips, fit dictates function. Tip height is critical, particularly in multichannel pipettes and devices where 96 or 384 tips are expected to draw and deliver precisely the same volume. Tips seated too high on a pipette tip fitting may not reach fluid level and thereby aspirate air. Failing to make contact when touching off during dispensing causes liquid to remain within the tip. Affected wells become dead points. These problems are magnified with today’s ultra- low volume pipetting. The volumetric margin of error Pipette tips appear to be technically simple, almost shrinks when dispensing 0.2 microliters compared with 500 commoditized, yet their design and manufacture require microliters. significant thought and engineering. Some liquid handling applications demand purpose-driven pipette tips with Contamination and cross-contamination are perennial features like low retention or binding, used for high-viscosity issues in pipetting. Pipetting creates aerosols of the pipetted liquids containing sugars or glycerin or highly concentrated sample that are suspended in the air space inside the pipette salts. tip between the drawn liquid and the pipette nose cone. Absent some sort of barrier, aerosols enter the pipette, Exquisite engineering notwithstanding, no pipetting system remain inside, and carry over to subsequent samples. Cross- performs reliably if the tip discharges contaminants during contamination occurs as previously aspirated air is dispensed operation. Slip agents, which are chemicals employed along with the sample. during the manufacture of injection-molded plastic parts to enhance manufacturability, are one potential contamination Filtered pipette tips prevent aerosols from reaching the source. Tips not manufactured under pristine conditions and innards of the pipette and carrying over to the next liquid thoroughly inspected may harbor adventitious biological or transfer. Several filter and barrier designs are available, chemical contaminants as well. constructed from different materials and each with specific effectiveness related to contamination control. For plastics, of which tips are made, leachables and extractables may affect data fidelity and experimental results Filter tips prevent contamination of the pipette and sample- in insidious ways. Buffers, salts, acids, bases, and organic to-sample cross-contamination. DNA/RNA applications chemical constituents may initiate leaching of residual often employ these tips to mitigate the activity of DNases monomers, polymerization agents, or even metals. and RNases, enzymes that hydrolyze nucleic acids. Filter tips are also appropriate for manipulation of radioisotopes, Minimum compositional requirements should therefore which many labs still use due to legacy methods or the

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