A sampler, often known as a micropipette, is a crucial piece of equipment in medical, biological, and chemical laboratories. It’s used for precise and controlled aspiration of specific liquid volumes. This tool enables researchers and lab technicians to perform highly accurate and contamination-free sampling.
Samplers come in various types, such as fixed volume and variable volume, with capacities ranging from a few microliters to several milliliters. They’re used in diagnostic tests, DNA and RNA extraction, solution preparation, and many other sensitive laboratory procedures.
Proper use of samplers not only ensures accurate results but also prevents sample waste and human error. Therefore, selecting a high-quality sampler and regularly calibrating it are among the most important factors for success in laboratory work. This article from Arya Mabna Tashkhis will explain samplers and how to use these laboratory tools.
Sampler Components and Functions
Here’s a breakdown of the different parts of a sampler and their roles:
| Component Name (Farsi) | English Name | Position on Sampler | Function / Technical Explanation |
| پیستون | Plunger | Top of sampler | When pressed, it displaces air inside the sampler, causing precise aspiration or dispensing of liquid from the tip. |
| خارجکننده سرسمپلر | Tip Ejector | Side or back of body | Used to detach disposable tips without direct hand contact, reducing contamination and increasing safety when working with samples. |
| تنظیمکننده حجم | Volume Adjustment | Top of body, near plunger | Used to set the desired liquid volume in variable volume samplers, usually by rotating a dial or pressing buttons. |
| نمایشگر حجم | Volume Display | On body, below adjustment | Displays the set volume digitally or mechanically, aiding in accurate and reproducible sample collection. |
| بدنه پیپت | Pipette Body | Main, middle part of sampler | Holds all components; has an ergonomic design to prevent hand fatigue during prolonged use. |
| انتهای میکروپیپت / سرسمپلر | Pipette Head / Tip Cone | Lowest part of sampler | The attachment point for disposable tips; plays a key role in accurate liquid transfer and preventing leaks or volume errors. |
Types of Samplers and Their Applications
1. Fixed Volume Pipette
A fixed volume pipette aspirates liquid in only one specific, unchangeable volume (e.g., 100 or 1000 microliters). This type of sampler is very useful for repetitive tests with identical volumes and ensures high accuracy.
It’s used in clinical or biological laboratories for preparing solutions or transferring samples to specific containers. Using these samplers is straightforward as there’s no need to adjust the volume. The user simply presses the plunger to the first stop to aspirate the liquid and presses it again to dispense it. Due to its simple and precise design, the chance of error is reduced. This tool is mainly used in situations where high repetition and accuracy are essential.
2. Variable Volume Pipette
A variable volume pipette allows the user to set the desired volume for liquid aspiration within a specific range (e.g., 10 to 100 microliters). This feature provides high flexibility for various experiments and is used in many research and diagnostic sectors. Volume changes are made by rotating a volume dial or button, and a digital or mechanical display shows the exact amount.
Before use, the desired volume must be set. Then, with a tip attached, the liquid is slowly aspirated. Dispensing the liquid is done by pressing the plunger to the second stop. Proper use of this type of sampler requires precision and practice. Regular calibration is also essential to maintain accuracy.
3. Single Channel Pipette
A single channel pipette has one liquid aspiration channel and is used for transferring liquids individually from one tube or container to another. This type of sampler is very common in routine experiments, biological and chemical analyses, and working with enzymes or sensitive materials. Users can use this tool for accurate and reproducible aspiration of small volumes.
This sampler is typically used in conjunction with microtubes, test tubes, or single-well plates. Its use involves attaching a tip, aspirating by pressing the plunger to the first stop, and dispensing into the target container. Its ergonomic design reduces fatigue during long-term use. For more accurate results, appropriate and high-quality tips should be used.
4. Multi Channel Pipette
A multi channel pipette includes several outputs (usually 8 or 12 channels) in parallel, allowing simultaneous aspiration and transfer of multiple samples. This type of sampler is very useful in laboratories that work with microplates or ELISA and significantly reduces experiment time.
Each channel functions like an independent sampler, allowing the user to fill or empty several wells of a plate in one movement. Its advanced design increases efficiency and reduces operator fatigue. These samplers are typically used in high-volume and repetitive experiments.
Comparison of Sampler Types in Laboratories
| Features / Sampler Type | Fixed Volume Sampler | Variable Volume Sampler | Single Channel Sampler |
| Adjustable Volume | ❌ Fixed (e.g., only 100μl) | ✅ Adjustable (e.g., 10–100μl) | ✅ Depending on type (fixed or variable) |
| Number of Channels | 1 Channel | 1 Channel | 1 Channel |
| Main Application | Repetitive tests with same volume | Various experiments with different volume needs | Aspirating individual and precise samples |
| Main Advantage | High accuracy and easy to use | Flexibility in volume adjustment | High control and precision for single sampling |
| Manual Adjustment Needed | ❌ No | ✅ Yes | Depending on type |
| User Error Probability | Very low | Moderate (requires precision in volume setting) | Low |
| Suitable For | Repetitive tests, training | Research, variable experiments | General laboratory applications |
Sampler Use Techniques
Forward Pipetting Technique
In this common method, you press the plunger to the first stop, then immerse the tip into the solution and gently release the button to allow the set volume of liquid to enter the tip. To dispense the liquid, you press the plunger again to the first stop and then all the way down to the second stop. This technique is suitable for most aqueous, biological, and low-viscosity solutions. This method offers high accuracy and a lower chance of volume error. It is the standard for everyday laboratory use.
Reverse Pipetting Technique
In this method, the plunger is first pressed all the way down to the second stop. Then, when aspirating, the button is slowly released back to the initial position, which causes a larger volume of liquid to be drawn up than the set amount. When dispensing, only press to the first stop, leaving the excess amount in the tip. This method is very useful for viscous, foaming, volatile, or temperature-sensitive solutions. The reverse technique provides high accuracy for sampling specific liquids and prevents bubble formation and volume fluctuations.
Laboratory Sampler Care
1. Regular Cleaning of the Body and Shaft
To prevent cross-contamination between samples, clean the outer body and shaft of the sampler with 70% alcohol or mild disinfectant solutions. Avoid getting liquid inside the pipette. This should be done daily or after working with biological samples. Using a lint-free cloth is recommended.
2. Periodic Sampler Calibration
To maintain the accuracy and correctness of sampled volumes, the sampler should be calibrated every 6 to 12 months. This should be done by trained personnel or specialized companies. Failure to calibrate will lead to errors in experiments and inaccurate results. In sensitive environments, the calibration interval should be shorter.
3. Vertical Storage on a Special Stand
The sampler should be stored on vertical stands or special holders. This prevents liquid from entering the internal parts of the device and prevents damage to sensitive components. Never leave it on a bench or lay it on its side. Improper storage is a common cause of plunger and spring damage.
4. Using Appropriate and Disposable Tips
Always use standard, clean tips that are compatible with the brand and volume of the device. Using inappropriate tips can lead to liquid leakage, reduced accuracy, or damage to the tip cone. Tips contaminated with corrosive materials also reduce the device’s lifespan. For working with sensitive materials, use filtered tips.
5. Avoiding Sudden Aspiration or Rough Use
Suddenly pressing the plunger or releasing it with force can damage the spring or plunger. During operation, movements should be slow, controlled, and continuous. Improper use, in addition to reducing accuracy, will lead to the need for premature sampler repair. Proper user training in this area is very important.
Important Tips for Choosing and Buying the Right Sampler
To choose and buy the right sampler, first determine your specific laboratory application; for example, use a multichannel sampler for high-volume tasks and a single-channel type for high accuracy. Specify your required volume and select a sampler with the appropriate volume range (e.g., 10–100 microliters).
Accuracy, reproducibility, and a calibration certificate are key features of a standard sampler. The ergonomic design of the body is very important to prevent hand fatigue and injury during prolonged use. Compatibility with various standard and readily available tips should also be checked. Furthermore, reputable brands and good after-sales service should be prioritized when making your selection.
