[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"$fxLN3MUwXCdr5RPjwZYIDpOj8CHyjOmngWTgoKXPtZbg":3,"$fc2k5e6uANngc6rQ97TNEQMGMfNQJRnI_8RKdfCdiimg":32,"$f3Ft0rKFJHppdzE-vuveecxx1BUcg9iOlMLtyzf_MJDg":188},[4,8,12,16,20,24,28],{"title":5,"slug":6,"path":7},"About Microbeonline.com","about-microbeonline-com","\u002Fabout-microbeonline-com\u002F",{"title":9,"slug":10,"path":11},"About Me","about-me","\u002Fabout-microbeonline-com\u002Fabout-me\u002F",{"title":13,"slug":14,"path":15},"Advertise with Us","advertise-us","\u002Fadvertise-us\u002F",{"title":17,"slug":18,"path":19},"Privacy Policy","privacy-policy","\u002Fprivacy-policy\u002F",{"title":21,"slug":22,"path":23},"Abbreviations","abbreviations","\u002Fabbreviations\u002F",{"title":25,"slug":26,"path":27},"Microbes","microbes","\u002Fmicrobes\u002F",{"title":29,"slug":30,"path":31},"Books","recommended-books","\u002Frecommended-books\u002F",{"type":33,"data":34},"blog",{"slug":35,"title":36,"description":37,"seoTitle":38,"seoDescription":38,"author":39,"createdDate":40,"lastUpdatedDate":41,"draft":42,"category":43,"image":38,"body":44,"faq":45,"tags":61,"related":63},"automated-pipette-liquid-handling-system","Automated Pipette: Liquid Handling System","Automated pipettes use software-controlled robotic arms for precise high-throughput liquid handling. Learn their working principles, parts, benefits, and limitations in microbiology.",null,"Ashma Shrestha","2022-07-10","2026-07-08",false,"lab-equipment","During the early months of the COVID-19 pandemic, reference laboratories across the world faced a problem that had nothing to do with reagent supply or test sensitivity: they could not pipette fast enough. A trained technician performing manual RNA extraction can process 48–96 samples in a working day. A single robotic liquid handling system running a validated automated extraction protocol can process 384 or more samples in the same period — with lower error rates and without fatigue-related drift in the final hours of a shift.\n\nFor most clinical microbiology laboratories — a district hospital lab in Nepal, a regional diagnostic centre in Nigeria, a teaching hospital laboratory in the Philippines — an automated liquid handling system remains out of reach financially. But understanding how these systems work, where they are being deployed, and what problems they solve is increasingly important. Automation is not a distant future for laboratory medicine. It is already the standard in reference laboratories, blood banks, and genomics facilities that students will encounter during training and careers.\n\nA pipette is [equipment](\u002Fequipment-essential-for-microbiology-laboratory\u002F) that helps measure and dispense liquid materials of desired measurements in any laboratory. Since almost all science laboratories require precise and accurate liquid measurement for their experiments, the pipette is used widely.\n\n![Automated Pipette - Solo Liquid Handlerby Hudson Robotics](https:\u002F\u002Fassets.microbeonline.com\u002Fblogs\u002FNew_SOLO-1-1024x955-1.jpg)Figure: Solo Liquid Handlerby Hudson Robotics\n\n**An automated pipette or automated liquid handling system is a pipette operated by software that commands a pipette\u002Frobotic liquid handling tool to aspirate the desired amount of sample and dispense it into the required container. Although these pipettes provide automated aspiration and dispensation, changing pipette tips, and placing and holding trays can be either automatic or manual. Commonly, automated pipettes are called liquid handling robots.**\n\n## Why Automated Pipetting Matters\n\nManual pipetting is accurate and reliable for small sample numbers. But it has three inherent limitations that become critical at scale:\n\n**Fatigue-related error:** A technician pipetting 200 samples over six hours applies slightly different plunger pressure, tip immersion depth, and aspiration angle as the session progresses. These variations are small per sample but systematic across the batch — the last 50 samples of the run are pipetted differently from the first 50.\n\n**Throughput ceiling:** One technician with one micropipette processes one sample at a time. In a high-burden laboratory during an outbreak, this becomes the rate-limiting step for diagnosis.\n\n**Contamination risk from repeated human contact:** Every manual tip change, every plate movement, every tube uncapping is a contamination opportunity. Automation eliminates most of these touchpoints.\n\nAutomated liquid handling systems address all three. In genomics laboratories, automated RNA extraction has been shown to reduce processing time per sample by up to 75% while improving inter-sample reproducibility. In blood banking, automated pipetting for grouping and crossmatching eliminates transcription errors that occur when technicians manually record results from individual tubes.\n\nFor microbiology students: even if you never operate a liquid handling robot in your career, you will encounter reports and quality documents generated by these systems. Understanding the principle is essential for interpreting what those systems do and what their error modes are.\n\n## Liquid Handling System\n\n![Liquid Handling system - Liquid handling systemImage source:https:\u002F\u002Fonline-shop.eppendorf.co.in\u002FIN-en\u002FAutomated-Pipetting-44509.html#goto-Automated-Pipetting-WebPMain-44509](https:\u002F\u002Fassets.microbeonline.com\u002Fblogs\u002FLiquid-handling-system.png)Figure: Liquid handling system\\\nImage source:https:\u002F\u002Fonline-shop.eppendorf.co.in\u002FIN-en\u002FAutomated-Pipetting-44509.html#goto-Automated-Pipetting-WebPMain-44509\n\nThere are various systems for handling liquids. Pipettes are one of the liquid handling systems. These can be manual, semi-automatic, or automatic.\n\nThe **manual pipetting** requires calibrating the pipettes, entering the desired volume in the pipette, and aspirating and dispensing the liquid by laboratory workers. It works best for laboratories dealing with small sample volumes because only a sample is processed at a time.\n\nThe **semi-automatic pipettes** require user intervention during moving the plates\u002Ftube in-between steps or exchanging the tips but not during aspiration and dispensation. It provides handling of 10-100 samples at a time depending on the types. The pipettes can have a single channel or multiple channels for liquid handling.\n\nThe **automatic pipettes or robotic liquid handlers** have robotic arms for moving the plates\u002Ftubes and exchanging tips during experiments. Only the step of entering the desired volume in the software requires the intervention of humans, and it provides a walk-away facility. It also helps in handling more than 100 samples at a time.\n\n## Working Mechanism of Pipette\n\nPipettes usually work based on two mechanisms; air displacement and positive displacement. The basic principle of pipetting is to displace\u002Fdispense (pushing out) a sample volume after aspiration (pulling in). The plunger and piston control these actions. The difference in piston and displacement methods determines the types of pipettes. These methods use plastic tips for displacement.\n\nBesides these, other methods that do not use tips are also available. The technique like acoustic droplet ejection method is one of the non-tip-based pipetting methods.\n\n### Air Displacement Method\n\nAs the name suggests, the air displacement method for aspirating a certain amount of liquid dispenses almost the exact amount of air. The air displacement method has a piston-cylinder system that helps in measurement. The piston is connected to a plunger that pushes out the air volume equal to the liquid to be aspirated. The aspiration creates an air cushion that separates the aspirated sample (liquid) in a plastic tip from the pipette piston.\n\nWith the expansion of the air in the cushion, the 2-8% extra liquid is drawn. In order to overcome the problem, proper calibration of the pipette is necessary. In addition, temperature, humidity, and air pressure of the liquid also determine the amount of air trapped which might create inaccuracy during aspiration.\n\n### Positive Displacement Method\n\nThe air displacement method is not applicable when handling liquid that has more density, higher viscosity, and high air pressure. Since the air displacement method lacks precision while handling such samples due to the air-cushioning, positive displacement overcomes these problems. The method’s accuracy depends on the disposable plastic tips used because these tips have integrated pistons. The piston is coupled to the piston rod of the dispensing devices. The method requires specially designed tips instead of tips from any other system.\n\nThe aspiration of liquid in positive displacement occurs by pulling the piston up rather than pushing down, preventing the formation of an air cushion. The pulling up creates a vacuum which draws the liquid into the tips.\n\n### Acoustic Droplet Ejection (ADE) Method\n\nADE method is an entirely contactless method of dispensing liquids. Here, placing the source of acoustics (sound energy) near the surface helps eject a small droplet of samples into the plate. The frequency of the sound determines the sample volume.\n\n## Parts of Automated Pipette\n\nThe automated pipette has the following parts.\n\n- **Control system:** These control the movement of robotic arms.\n- **Washing area:** It is the place where cleaning or dispensing heads and plates occurs.\n- **Sensors:** These feed information to the control systems and help maintain accuracy.\n- **Dispensing heads:** These control the liquid flow in the vessels.\n\n## Benefits of Automated Pipette\n\nThe benefits of the automated pipette or liquid handling system are as follows:\n\n- **Thorough output**\n\nThe pipetting obtained by using automation is thorough or accurate. Unlike manual pipetting, there is a decrease in human errors because the machines carry out all the manual work.\n\n- **Enhanced reproducibility**\n\nThe automated pipetting provides increased reproducibility in the laboratory. That means the technique helps obtain consistent results.\n\n- **Walk away facility**\n\nThe machines carry out all the work, and the contamination decreases. Once the information is fed in, they can perform other laboratory duties by running the pipetting process in the background.\n\n- **Decreased contamination**\n\nSince the machine carries out almost labor work susceptible to contamination, the risk of contamination due to human contact decreases. Likewise, continuous cleaning and maintenance also decrease the contamination.\n\n## When to Switch to an Automated Pipette?\n\n- **Conversion into a molecular laboratory**\n\nAn automated pipette helps in many molecular techniques like sequencing and [blotting](\u002Fsouthern-blotting-principle-steps-and-applications\u002F) because it provides precision while handling liquid samples. Also, it helps in processing multiple samples at a time.\n\n- **One-time investment**\n\nThe cost of automated pipettes is high compared to manual and semi-automatic pipettes, but it is sustainable in the laboratory that is opting for decreasing manual labor.\n\n- **Automation**\n\nSince many laboratories are switching to automation, an automated pipetting system is another good addition to the automation of the laboratory.\n\n- **Processing a larger sample size**\n\nThe processing of the liquid samples in your laboratory is increasing, leading to an increase in pipetting tasks. An automated pipette can pipette more than 100 samples in an hour, which helps complete the work faster with accuracy.\n\n## Limitation of Automated Pipette\n\nThe limitation of automated pipettes are as follows:\n\n- **High installation cost**\n\nThe cost of robotic liquid handlers ranges from approximately **$10,000 for entry-level systems to $150,000 or more for fully integrated high-throughput platforms**. This makes them inaccessible to most smaller diagnostic laboratories, particularly in resource-limited settings.\n\n- **High maintenance cost**\n\nThe maintenance of an automated pipette needs to be carried out regularly, and the maintenance cost is also high. In addition, trained maintenance workers are scarce.\n\n## How to Remember\n\n**Manual → Semi-automatic → Automatic: increasing throughput, decreasing human touchpoints.** Think of it as a spectrum of human involvement:\n\n- Manual: human does everything (aspirate, dispense, move plates, change tips)\n- Semi-automatic: machine aspirates and dispenses; human moves plates and changes tips\n- Automatic (robotic): human enters the program; machine does everything else\n\nEach step up the spectrum increases throughput and reproducibility, and increases cost and maintenance complexity.\n\n**Air displacement = cushion between piston and liquid. Positive displacement = no cushion.** Air displacement is the standard for aqueous samples — the air cushion is reliable, and temperature\u002Fviscosity effects are manageable with calibration. Positive displacement removes the air cushion entirely — the piston contacts the liquid directly — making it essential for viscous, volatile, or high-density samples where an air cushion would compress or expand and produce volume errors.\n\n**ADE = sound ejects droplets, no tip needed.** Acoustic droplet ejection uses sound energy to eject precise nanoliter-to-microliter droplets from the source well directly into the target well — no tip, no contact, no contamination risk. It is the most precise and contamination-free method, but also the most expensive and least common. If asked about contactless pipetting in an exam — ADE is the answer.\n\n**The walk-away principle:** An automated system runs unsupervised once programmed. This is the single most important practical advantage in a high-throughput laboratory — the technician can perform other tasks while the system processes samples.\n\n## Key exam facts in one table\n\n| Topic | Key fact |\n| --- | --- |\n| Definition | Software-controlled pipetting system; robotic arms aspirate and dispense without continuous human intervention |\n| Also called | Liquid handling robot; automated liquid handling system |\n| Manual pipetting | Human-controlled; one sample at a time; best for small volumes and small batches |\n| Semi-automatic | Machine aspirates\u002Fdispenses; human moves plates and changes tips; 10–100 samples at a time |\n| Fully automatic (robotic) | Walk-away facility; >100 samples\u002Fhour; human intervention only for programming |\n| Air displacement principle | Piston displaces air equal to target volume; air cushion separates piston from liquid; affected by temperature and viscosity |\n| Positive displacement principle | No air cushion; piston contacts liquid directly; accurate for viscous, volatile, high-density samples; requires specialised tips |\n| Acoustic droplet ejection (ADE) | Contactless; sound energy ejects droplets; no tip required; highest precision and contamination control; most expensive |\n| Key benefits | Throughput (>100 samples\u002Fhour), reproducibility, reduced human error, walk-away operation, reduced contamination |\n| Key limitations | High installation cost ($10,000–$150,000+), high maintenance cost, trained operators required, not feasible for most LMIC diagnostic labs |\n| Clinical microbiology applications | COVID-19 nucleic acid extraction, blood bank automation, high-throughput ELISA, genomic sequencing setup |\n| CV of automated systems | Typically <1% coefficient of variation — superior to manual pipetting at high volumes |\n\n**References**\n\n1. Tegally, H., San, J. E., Giandhari, J., et al. (2020). Unlocking the efficiency of genomics laboratories with robotic liquid-handling. *BMC Genomics*, 21, 729. \u003Chttps:\u002F\u002Fdoi.org\u002F10.1186\u002Fs12864-020-07137-1>\n2. Clinical and Laboratory Standards Institute (CLSI). (2016). *Clinical Microbiology Procedures Handbook* (4th ed.). American Society of Microbiology. \u003Chttps:\u002F\u002Fdoi.org\u002F10.1128\u002F9781555818814>\n3. ISO 8655-1:2022. *Piston-operated volumetric apparatus — Part 1: Terminology, general requirements and user recommendations*. International Organization for Standardization.\n4. Eppendorf AG. (2019). *The Lab Pipetting Guide*. Eppendorf. \u003Chttps:\u002F\u002Fwww.eppendorf.com\u002Fpipetting-guide>\n5. Mahon, C. R., Lehman, D. C., & Manuselis, G. (2018). *Textbook of Diagnostic Microbiology* (6th ed.). Elsevier.",[46,49,52,55,58],{"question":47,"answer":48},"What is an automated pipette and how does it differ from a manual micropipette?","An automated pipette (also called a liquid handling robot or automated liquid handling system) is a software-controlled instrument where robotic arms aspirate and dispense defined volumes without continuous human intervention. A manual micropipette requires the operator to perform every aspiration, dispensation, tip change, and plate movement individually. Automated systems process more than 100 samples per hour with coefficient of variation values typically below 1%, eliminating fatigue-related error and throughput limitations of manual pipetting.",{"question":50,"answer":51},"What is the difference between semi-automatic and fully automatic pipetting systems?","Semi-automatic pipetting systems handle aspiration and dispensation mechanically but require human intervention for moving plates or tubes between steps and for changing tips. They process 10–100 samples at a time. Fully automatic (robotic) systems use robotic arms to move plates, change tips, and manage all physical steps — the only human input required is programming the run parameters at the start. Fully automatic systems provide a walk-away facility, allowing the technician to perform other tasks while the system processes samples.",{"question":53,"answer":54},"What is acoustic droplet ejection (ADE) and how is it different from standard pipetting?","Acoustic droplet ejection (ADE) is a contactless pipetting method that uses focused sound energy (acoustic waves) to eject precise droplets of liquid from a source well directly into a target well — no tip, no physical contact, no contamination risk from tip-to-liquid contact. The volume of each droplet is controlled by the frequency of the acoustic pulse. ADE achieves the highest precision and lowest contamination risk of any liquid transfer method but is also the most expensive and is used primarily in high-throughput drug discovery and genomics applications.",{"question":56,"answer":57},"What are the main advantages of automated liquid handling in clinical microbiology?","The main advantages are: higher throughput (>100 samples per hour versus 48–96 by a manual technician), improved reproducibility (identical volume and timing across all samples), reduced fatigue-related error (no drift in technique over long processing sessions), reduced contamination risk (fewer human touchpoints during the run), and walk-away operation (technician time is freed for other tasks). These advantages were demonstrated clearly during the COVID-19 pandemic, when reference laboratories used robotic extraction systems to process hundreds of PCR samples per day.",{"question":59,"answer":60},"Why are automated pipetting systems not commonly used in district-level laboratories in low- and middle-income countries?","The primary barriers are cost and maintenance. Entry-level automated liquid handling systems cost from approximately $10,000; fully integrated high-throughput platforms cost $150,000 or more. Ongoing maintenance requires trained service engineers, regular calibration, and replacement parts — all of which are difficult to access and expensive in resource-limited settings. Most district-level diagnostic laboratories in Nepal, Nigeria, the Philippines, and similar settings rely on manual micropipettes and glass pipettes for routine work, with automation limited to national reference laboratories or large urban hospital laboratories.",[62],"pipette",[64,88,111,136,161],{"slug":65,"title":66,"description":67,"seoTitle":68,"seoDescription":69,"author":39,"createdDate":70,"lastUpdatedDate":41,"draft":42,"category":43,"image":38,"faq":71,"tags":87},"glass-pipettes-types-handling-and-uses","Glass Pipettes: Types, Handling, and Uses","Glass pipettes transfer mL-scale volumes in microbiology labs. Learn the types (Mohr's, serological, volumetric, Pasteur), how to read the meniscus correctly, and the drain-out vs. blow-out distinction students most often confuse.","Glass Pipettes: Types, Meniscus Reading, Blow-Out Rules, and Uses","Compare Mohr, serological, volumetric, and Pasteur pipettes, read the meniscus correctly, and apply drain-out and blow-out rules for accurate transfers.","2022-07-29",[72,75,78,81,84],{"question":73,"answer":74},"What is the difference between a Mohr's pipette and a serological pipette?","A Mohr's pipette is a drain-out type: the graduation marks stop above the tip, and the liquid in the ungraduated section below the last mark is not delivered. Never blow out a Mohr's pipette. A serological pipette is a blow-out type: the graduation marks extend to the tip, and the last drop must be expelled by pressing the bulb at the end of dispensing. Serological pipettes are identified by a blow-out ring near the suction end at the top. Confusing the two introduces a systematic delivery error — blowing out a Mohr's over-delivers; not blowing out a serological under-delivers.",{"question":76,"answer":77},"How do you read the meniscus correctly in a glass pipette?","For colourless and light-coloured liquids, read from the bottom of the concave meniscus curve, with your eye exactly level with the graduation mark. Reading from the top of the curve over-reads the volume. For coloured or opaque liquids that form a convex meniscus, read from the top of the curve. Parallax error — caused by positioning your eye above or below the graduation mark — produces false high or false low readings and is eliminated by always levelling your eye with the mark before reading.",{"question":79,"answer":80},"What is a volumetric pipette and when is it used?","A volumetric pipette (also called a bulb pipette or transfer pipette) is a non-graduated pipette designed to deliver one specific fixed volume with the highest accuracy of any glass pipette type. It has a single volume mark on the bulb section and no graduation marks along the stem. It is used when one exact volume is needed repeatedly — for example, in titrations, standard solution preparation, or media preparation steps requiring a precise defined volume. It is not suitable when partial volumes or flexible delivery amounts are needed.",{"question":82,"answer":83},"Why is mouth pipetting prohibited in the laboratory?","Mouth pipetting creates a direct route for laboratory liquids — including infectious specimens, toxic chemicals, and corrosive reagents — to enter the mouth, be inhaled, or be swallowed. It has caused laboratory-acquired infections, chemical poisonings, and deaths. All aspirating in the laboratory must be done with a pipette bulb, three-valve filler, or mechanical pipetting aid. Mouth pipetting is prohibited by laboratory safety regulations in all clinical and research settings globally.",{"question":85,"answer":86},"What are the different accuracy classes of glass pipettes?","Graduated glass pipettes are classified as Class A, Class As, and Class B based on accuracy. Class A and Class As pipettes have tightly specified error tolerances and are suitable for analytical and clinical work requiring high accuracy. Class B pipettes have double the error limits of Class A and are used for general laboratory work where a lower level of precision is acceptable. For any work where volume accuracy affects clinical results — serological titrations, media preparation to precise concentrations — Class A pipettes should be used.",[62],{"slug":89,"title":90,"description":91,"seoTitle":38,"seoDescription":38,"author":39,"createdDate":92,"lastUpdatedDate":93,"draft":42,"category":43,"image":38,"faq":94,"tags":110},"multichannel-pipettes-parts-and-calibration","Multichannel Pipettes: Parts and Calibration","Multichannel pipettes aspirate and dispense into multiple wells simultaneously. Learn their parts, forward and backward pipetting technique, calibration procedure, and when to use them in ELISA and MIC testing.","2022-07-23","2026-07-19",[95,98,101,104,107],{"question":96,"answer":97},"What is a multichannel pipette used for in clinical microbiology?","Multichannel pipettes are used for any procedure that uses a microtiter plate format — 96-well or 384-well. The most common clinical microbiology applications are ELISA (loading patient samples and reagents across the plate), broth microdilution MIC testing (preparing serial antibiotic dilutions across a row of wells), and serological titrations. The multichannel pipette delivers identical volumes into multiple wells simultaneously, improving reproducibility compared to repetitive single-channel pipetting.",{"question":99,"answer":100},"What is the difference between an 8-channel and a 12-channel multichannel pipette?","A standard 96-well microtiter plate has 8 rows (labelled A to H) and 12 columns (labelled 1 to 12). An 8-channel pipette fills one entire column at a time, requiring 12 pipetting steps to fill a full plate. A 12-channel pipette fills one entire row at a time, requiring 8 pipetting steps to fill a full plate. The choice between them depends on whether the procedure is organised by column or by row — for example, if each row contains one patient's serial dilutions, a 12-channel pipette processes one patient per step.",{"question":102,"answer":103},"What is the difference between forward and backward pipetting with a multichannel pipette?","Forward pipetting (also called exact pipetting) is the standard method: press the plunger to stop 1 before aspiration, release to fill, then press to stop 1 to dispense and stop 2 to blow out. It is used for standard aqueous liquids. Backward pipetting (overfilling technique) presses the plunger to stop 2 before aspiration, aspirating more than the target volume, then dispenses only to stop 1 — the excess remains in the tip and is discarded. Backward pipetting is used for foamy or viscous liquids where forward technique causes inconsistent fill across channels.",{"question":105,"answer":106},"Why must a trough (reagent reservoir) be used with a multichannel pipette?","A multichannel pipette has 8 or more tip cones spread across a fixed distance that matches the spacing of a microtiter plate. Individual test tubes are too narrow and spaced too far apart for all channels to reach the liquid simultaneously. A reagent trough provides a wide, shallow source of liquid where all channels can immerse to equal depth at the same time, ensuring each channel aspirates the same volume. Unequal immersion depth is one of the most common causes of inconsistent volume delivery across channels.",{"question":108,"answer":109},"How is a multichannel pipette calibrated?","Multichannel pipettes are calibrated using the gravimetric method: dispensed distilled water is weighed on an analytical balance, and volume is calculated using the formula V = w × Z, where w is the average weight of water dispensed and Z is a conversion factor based on water density at the measured temperature. Each channel must be calibrated individually, which makes multichannel calibration more time-consuming than single-channel calibration. Target accuracy is 99–101% of nominal volume. Because of the complexity, many laboratories use specialist calibration service providers for multichannel pipettes.",[62],{"slug":112,"title":113,"description":114,"seoTitle":38,"seoDescription":38,"author":39,"createdDate":115,"lastUpdatedDate":93,"draft":42,"category":43,"image":38,"faq":116,"tags":135},"micropipette-parts-types-and-uses","Micropipette: Parts, Types, and Uses","Learn the parts, types, and uses of micropipettes — including air vs. positive displacement, pre-wetting technique, reverse pipetting for viscous samples, and common errors that affect diagnostic accuracy.","2022-07-19",[117,120,123,126,129,132],{"question":118,"answer":119},"What is the difference between air displacement and positive displacement micropipettes?","In air displacement micropipettes, a cushion of air separates the piston from the liquid inside the tip. The piston displaces air, which draws liquid into the tip. This method is accurate for standard aqueous samples but is affected by temperature, viscosity, and altitude. In positive displacement micropipettes, the piston contacts the liquid directly inside a specialised tip — there is no air cushion. This makes positive displacement pipettes accurate for viscous, volatile, and high-density samples that would compress or expand an air cushion and produce volume errors.",{"question":121,"answer":122},"How do I select the correct micropipette size for my volume?","Always select the smallest micropipette whose range covers the target volume. For example, to transfer 5 µL, use a P20 (range 2–20 µL) rather than a P200 or P1000. Using a pipette at the extreme low end of its range introduces proportionally large errors — a P1000 set to 5 µL operates at 0.5% of its working range, where small variations in technique produce large percentage errors in actual volume delivered.",{"question":124,"answer":125},"What is pre-wetting a micropipette tip and why is it necessary?","Pre-wetting involves aspirating the target liquid into a new tip and dispensing it back into the source container, repeating 2–3 times before the actual transfer. A dry tip surface absorbs a small amount of liquid on first contact, causing the first aspiration to deliver slightly less than the set volume. Pre-wetting saturates the tip surface, eliminating this short-delivery error. It is especially important for critical measurements in PCR setup, serial dilutions, and ELISA.",{"question":127,"answer":128},"When should reverse pipetting be used instead of forward pipetting?","Reverse pipetting is used for viscous samples (glycerol, serum, concentrated protein solutions) and volatile liquids (ethanol, chloroform). In forward pipetting, the air cushion compresses under the resistance of viscous flow, causing under-delivery. Reverse pipetting overcomes this by aspirating more than the target volume (press to stop 2), then dispensing only to stop 1 — the excess in the tip acts as a buffer that compensates for the resistance of viscous flow. Never press to the second stop when dispensing in reverse pipetting.",{"question":130,"answer":131},"What are the most common micropipette errors in the laboratory?","The most common errors are: using too large a pipette for the target volume (e.g., P1000 for 5 µL work); not pre-wetting the tip before critical first aspirations; pipetting at an angle greater than 20° during aspiration; immersing the tip too deeply into the liquid; and using standard tips for PCR work where filter tips are mandatory. Each error produces a different type of volume inaccuracy or contamination event.",{"question":133,"answer":134},"How often should micropipettes be calibrated?","Micropipettes should be calibrated every 3–6 months under normal laboratory use, or more frequently if used heavily or after being dropped or repaired. Calibration uses the gravimetric method — weighing dispensed distilled water at a known temperature and converting weight to volume using a density conversion factor. Accuracy should fall between 99% and 101% of the nominal volume. ISO 8655 is the governing standard for piston-operated volumetric apparatus.",[62],{"slug":137,"title":138,"description":139,"seoTitle":38,"seoDescription":38,"author":39,"createdDate":140,"lastUpdatedDate":41,"draft":42,"category":43,"image":38,"faq":141,"tags":160},"pipette-tips-types-uses-and-criteria-to-choose-it","Pipette Tips: Types, Uses, and Criteria to Choose It","Pipette tips are the aseptic barrier between specimen and pipette. Learn tip types — filter, low-retention, wide-bore — and when each is clinically mandatory vs. optional.","2022-07-15",[142,145,148,151,154,157],{"question":143,"answer":144},"Why are filter tips mandatory for PCR work?","During pipetting, aerosols are generated — fine droplets that can travel upward through the tip and into the pipette barrel. In PCR, even nanogram quantities of contaminating DNA or PCR product entering the barrel are enough to cause false-positive results in subsequent runs. Filter tips contain a hydrophobic polyethylene filter inside the tip shaft that physically blocks aerosols and liquid from travelling beyond the tip. Filter tips are mandatory for all PCR setup, RT-PCR, sequencing, and RNA handling. Standard non-sterile tips are not acceptable substitutes for this work.",{"question":146,"answer":147},"What is the difference between low-retention tips and standard tips?","Standard polypropylene tips allow a thin film of liquid to adhere to the inner tip surface, which is not significant for most aqueous samples. Low-retention tips have a modified hydrophobic inner surface that minimises this adhesion, resulting in more complete liquid delivery and better volume accuracy. They are used for viscous samples, concentrated protein solutions, expensive or scarce reagents, and any situation where even a small residual volume left in the tip represents a meaningful loss or accuracy problem.",{"question":149,"answer":150},"When should wide-bore pipette tips be used?","Wide-bore tips have an enlarged orifice compared to standard tips. They are used when the sample contains intact cells, blood, dense cell suspensions, or any particulate material that would be sheared or clogged by the narrow opening of a standard tip. Shearing cells through a narrow tip orifice damages cell membranes, affects cell viability, and produces inaccurate counts in haemocytometer or flow cytometry applications. Wide-bore tips allow these samples to pass through without mechanical damage.",{"question":152,"answer":153},"Can non-sterile autoclavable tips be used for RNA work?","No. Autoclaving kills microorganisms but does not reliably eliminate RNase activity. RNases are extremely heat-stable enzymes that can survive autoclaving and degrade RNA samples on contact. For RNA extraction, RT-PCR, and any procedure involving RNA, only certified RNase-free pre-sterile tips should be used — these are manufactured and packaged under conditions that confirm absence of RNase, DNase, ATP, and endotoxins, and come with a sterilization certificate.",{"question":155,"answer":156},"What does tip colour indicate?","Tip colour is a size indicator, not a sterility indicator. Yellow tips typically correspond to the 200 µL volume range; blue tips to the 1000 µL range; white or clear tips to the 10 µL range. Colour coding is largely standardised across major manufacturers but can vary — always confirm the volume range on the packaging label. Sterility status is stated on the packaging, not indicated by colour.",{"question":158,"answer":159},"Why should tips never be touched by hand before use?","Human skin carries RNases, DNases, and microorganisms that transfer to the tip on contact. For molecular work, skin RNases degrade RNA samples; for microbiology culture work, skin commensals introduced on a tip can appear as contaminants in culture results. Tips should always be attached using the pipette's tip ejector mechanism pressing into the tip rack, and removed using the tip ejector button — hands should never contact the tip body or orifice.",[62],{"slug":162,"title":163,"description":164,"seoTitle":165,"seoDescription":166,"author":167,"createdDate":168,"lastUpdatedDate":169,"draft":42,"category":43,"image":170,"faq":171,"tags":187},"types-of-pipettes-used-in-the-microbiology-laboratory","Types of Pipettes Used in the Microbiology Laboratory","Learn the types of pipettes used in microbiology — glass, micropipette, multichannel, automated, and calibrated — with a guide on choosing the right pipette for your procedure.","Laboratory Pipettes: Choose the Right Type and Avoid Volume Errors","Choose among glass, micropipette, multichannel, and automated pipettes by volume and task, with calibration, handling, and error-prevention guidance.","Acharya Tankeshwar","2026-06-28","2026-07-10","https:\u002F\u002Fassets.microbeonline.com\u002Fblogs\u002Fcolorful-pipette-for-microbeonline.png",[172,175,178,181,184],{"question":173,"answer":174},"What are the main types of pipettes used in a microbiology laboratory?","Five main types are used: glass pipettes (graduated, volumetric, and Pasteur) for mL-scale transfers; micropipettes for µL-scale precision work; multichannel pipettes for simultaneous transfer into multiple wells of a microtiter plate; automated liquid handling systems for high-throughput processing; and pipette tips, the disposable consumables that serve as the aseptic barrier in all micropipette-based work.",{"question":176,"answer":177},"What is the difference between a pipette and a micropipette?","A glass pipette measures and transfers volumes in the milliliter range (0.1 mL to 25 mL) and requires a pipette bulb or filler for aspiration. A micropipette measures and transfers volumes in the microliter range (0.2 µL to 10,000 µL) using an air displacement mechanism — liquid enters only the disposable tip and never contacts the pipette barrel. The key distinction is scale: glass pipettes work in mL, micropipettes work in µL.",{"question":179,"answer":180},"How do I choose the right pipette for a procedure?","Three questions guide selection. First, what volume do you need? If the volume is in mL, use a glass pipette; if in µL, use a micropipette — and select the smallest micropipette model whose range covers your target volume. Second, how many simultaneous transfers are needed? If filling a microtiter plate, use a multichannel pipette. Third, what is the contamination risk? For PCR, RNA work, or infectious specimens, use filter tips with any micropipette.",{"question":182,"answer":183},"When is a multichannel pipette used instead of a single-channel micropipette?","A multichannel pipette is used whenever the target container is a microtiter plate — 96-well or 384-well format. Clinical applications include ELISA, broth microdilution MIC testing, and serological titrations. The multichannel pipette delivers identical volumes into multiple wells simultaneously from a single plunger depression, improving reproducibility compared to repetitive single-channel pipetting.",{"question":185,"answer":186},"What is a calibrated loop and how does it differ from a pipette?","A calibrated inoculating loop delivers a defined volume (1 µL or 10 µL) of specimen onto a culture plate — functioning as a volume measurement device without needing a pipette or tip. It is used specifically for semi-quantitative urine culture in microbiology. A pipette, by contrast, aspirates and dispenses liquid between containers using a mechanical aspiration mechanism. The calibrated loop is a low-cost, practical alternative to pipettes for a specific clinical purpose in resource-limited settings.",[62],[189,195,201,206,210,214,219,224,228,232],{"slug":190,"name":167,"description":191,"image":192,"body":193,"postCount":194},"acharya-tankeshwar","Editor-in-chief","https:\u002F\u002Fassets.microbeonline.com\u002Fauthors\u002Ftankeshwar-acharya-author-microbeonline.jpg","***Tankeshwar Acharya, MSc (Medical Microbiology)***\n\n*Tankeshwar Acharya is an Assistant Professor in the Department of Microbiology at Patan Academy of Health Sciences (PAHS), Nepal, where he has been teaching and practicing clinical microbiology for over 14 years. He is the founder of Microbe Online, one of the leading free microbiology education resources on the web, covering bacteriology, mycology, parasitology, immunology, and clinical laboratory diagnostics written from direct experience in both the classroom and the diagnostic laboratory.*",433,{"slug":196,"name":39,"description":197,"image":198,"body":199,"postCount":200},"ashma-shrestha","SEO Copywriter and Science Communicator\nKathmandu, Nepal","https:\u002F\u002Fassets.microbeonline.com\u002Fauthors\u002Fashma-shrestha.png","Ashma Shrestha holds a Master of Science in Medical Microbiology from the Institute of Science and Technology (IOST), Tribhuvan University, Nepal, where she developed a strong foundation in virology, molecular biology, and diagnostic microbiology.\n\nShe now works as an SEO Copywriter at Resolution Digital, where she combines her scientific training with research-driven content strategy. She is certified in Google Analytics and Google Business Profile (GBP), and brings a data-informed approach to science communication writing content that is not only accurate but structured to reach and serve the students who need it most.\n\nAt microbeonline, Ashma contributes articles primarily in virology and molecular biology, areas she finds most compelling for their mechanistic depth and their growing clinical relevance. Her writing reflects the same standard the site is built on: factual rigor, clear explanation of the *why* behind microbiology concepts, and content that helps students move from memorization to genuine understanding.\n\nShe is passionate about making complex microbiological concepts accessible without sacrificing accuracy; a skill that sits at the intersection of her scientific training and her professional work in content and SEO.",81,{"slug":202,"name":203,"description":204,"image":38,"body":38,"postCount":205},"sushmita-baniya","Sushmita Baniya","Author \u002F Contributor",32,{"slug":207,"name":208,"description":204,"image":38,"body":38,"postCount":209},"samikshya-acharya","Samikshya Acharya",20,{"slug":211,"name":212,"description":204,"image":38,"body":38,"postCount":213},"alisha-tripathi","Alisha Tripathi",6,{"slug":215,"name":216,"description":217,"image":38,"body":38,"postCount":218},"aastha-shrestha","Aastha Shrestha"," Author \u002F Contributor",9,{"slug":220,"name":221,"description":222,"image":38,"body":38,"postCount":223},"guest-author","Guest Author","Guest Author \u002F Contributor",2,{"slug":225,"name":226,"description":204,"image":38,"body":38,"postCount":227},"srijana-khanal","Srijana Khanal",18,{"slug":229,"name":230,"description":222,"image":38,"body":38,"postCount":231},"dr-poonam-acharya","Dr. Poonam Acharya",1,{"slug":233,"name":234,"description":204,"image":38,"body":235,"postCount":236},"nisha-rijal","Nisha Rijal","**Nisha Rijal** is a microbiologist and quality assurance specialist. She served for nearly 12 years as a microbiologist at the National Public Health Laboratory (NPHL), Nepal's national reference laboratory, and continues to work as a consultant microbiologist in international public health organization. ",51]