Introduction

In modern scientific research and experimental analysis, the sample collection room is the first step to ensure the reliability of data. And in this process, sample collection vials, as the key carrier for sample storage and transportation, its selection and use are directly related to the integrity and stability of the sample and the accuracy of the subsequent analysis.

Sample collection vials are widely used in many fields. Different types of vials are carefully differentiated in terms of material, structure, additives and closure for different samples with different physicochemical properties, analytical needs and storage conditions.

Basic Classification of Sample Collection Vials

Different types of samples have different requirements for sample collection vials during collection and storage.Therefore, understanding the basic classification of sample collection vials will help experimenters to make the most appropriate choice according to actual needs. Overall, sample tubes can be categorized in terms of material, sealing method and dimensions such as solvent and structural morphology.

1. Classification by material: glass vs. Plastic

• Glass Sample Tubes: Usually made of high borosilicate glass with good chemical inertness and thermal stability, suitable for most organic solvents and high temperature processing scenarios. Especially in high-precision analysis or the collection of easily adsorbed compounds, glass vials can effectively avoid sample degradation or contamination.
• Plastic sample collection vials: common materials include polypropylene, polyethylene, polycarbonate, etc. They are more impact resistant and lightweight, and are suitable for cryogenic freezing, biological sample collection, and routine clinical testing. Some of the high-end plastic vials are also resistant to a certain degree of chemical corrosion.

2. Classification by sealing method: screw, bayonet, gland type

• Screw-in type: the most common type, easy to open and seal, suitable for most general laboratory needs. Screw-port caps are usually paired with PTFE/silicone gaskets to ensure sealing and chemical compatibility.
• Bayonet type: Quickly closed by a snap, suitable for fast operation or occasions requiring frequent opening, mostly used in automated platforms or certain standardized testing processes.
• Gland type: Sealed by metal cap and gland, the most airtight, commonly used in gas chromatography and other experiments that require high volatility control. Suitable for long term storage and transportation, especially widely used in environmental sample testing.

3. Classification by volume and shape: standard, miniature, conical bottom, etc.

• Standard vials: common volumes are 1.5 ml, 2 ml and 5 ml, which are suitable for the collection and analysis of most liquid samples. The shape is mostly cylindrical, which is easy to be grasped by automated equipment.
• Micro vials: with a volume of 0.2ml-0.5ml, commonly used for very small sample sizes or high throughput experimental designs. Suitable for micro sampling system.
• Cone-bottomed vials: The bottom of the vial is designed in the shape of a cone, which is convenient for sample concentration, centrifugal operation and residue-free aspiration, commonly used in protein/nucleic acid extraction experiments.
• Flat bottom/round bottom vials: Flat bottoms are suitable for autosampling equipment, while round bottoms are more suitable for manual operation or vortex mixing scenarios.

Applications in Biological Samples (blood samples as an example)

As one of the most common and basic biological samples, blood is widely used in a variety of fields, including clinical diagnosis, genetic testing, and proteomics research. Due to its complex composition and strong biological activity, the requirements for collection containers are particularly strict. The sample collection vials used for different applications are different in terms of additives, materials and structural design, which directly affect the quality of the samples and the accuracy of the subsequent analysis.

1. Environment and purpose of use

• Clinical medical testing: for routine blood, biochemistry, electrolytes, hormone level testing, etc., need to be fast, efficient, avoid hemolysis and contamination.
• Molecular biology research: such as RNA-seq, whole genome sequencing (WGS), qPCR, etc., which requires higher requirements for nucleic acid integrity and sample preservation conditions.
• Protein and metabolomics analysis: concerned about protease activity inhibition, solvent compatibility, stability after repeated freezing and thawing.

2. Common sample collection vials types and configurations

• Containing anticoagulant vials: EDTA tubes are widely used in hematology testing and nucleic acid extraction, which can effectively inhibit the coagulation process and protect the cellular morphology; Heparin tubes are suitable for plasma analysis, suitable for certain chemical tests (e.g., blood gas analysis), but interfere with certain PCR reactions; and Sodium citrate tubes are mostly used for coagulation function testing.
• Additive-free pure blood collection tubes: used for serum testing, such as catching up on work, renal function, immunology tests, etc. After the blood is naturally coagulated, the serum is separated by centrifugation to avoid chemical additives interfering with the experimental reaction.
• Specialized vials for cryopreservation: made of high-strength PP material, able to withstand ultra-low temperature (-80℃ to liquid nitrogen environment). Commonly used for long time preservation of plasma, serum, cellular components, etc., widely used in biological sample banks and long-term follow-up studies.

3. Caveat

• Influence of materials on sample stability: Plastic vials may adsorb proteins or nucleic acids, requiring the use of low adsorption materials or surface treatment. Glass vials are stable but are not suitable for all freezing conditions Lab technicians need to make a judgment based on the nature of the sample and the needs of the experiment.
• Importance of labeling and traceability system: During the experiment, samples are easily confused due to labeling, incomplete information and other problems, which seriously affects the reliability of data. It is recommended to use laser-printed labels, frozen storage durable stickers or electronic tracking system (such as RFID, barcode) for the whole process of sample management.

The preservation and handling of blood samples play a decisive role in the results of experiments, and the appropriate sample collection vials not only maximize the preservation of sample activity and integrity, but are also a prerequisite for high-quality research. With the development of precision medicine and high throughput technology, the demand for biological sample collection vials is becoming increasingly liquefied and refined.

Chemical Analysis and Laboratory Samples

In analytical chemistry, drug discovery, food safety testing and other laboratory work, sample collection vials are not only storage containers, but also highly synergistic components of the analytical process with the instrument. Especially in liquid chromatography, gas chromatography and other high-precision testing techniques, the selection of vials is directly related to the reproducibility and accuracy of the analysis and the stable operation of the instrument.

1. Application of vials in liquid chromatography and gas chromatography analysis

• HPLC vials: excellent chemical stability is required to prevent the sample solution from reacting or adsorbing to the wall of the vial. Typically 2 ml screw-top glass vials with PTFE/silicone gasket caps are used, which are resistant to organic solvents and maintain a tight seal. For photosensitive samples, brown bottles are available.
• GC vials: since GC analysis is highly dependent on sample volatility, the vials need to be tightly sealed and are often made of glass vials with pressure caps; in addition, to prevent the loss of volatile components, pre-punched gaskets are often used to seal with aluminum caps.
• Applications with small sample volumes: For high throughput screening and trace component detection, 0.3 ml-0.5 ml microvials can be used with cannulae to minimize sample loss.

2. Autosampling system size and compatibility requirements

Modern laboratories commonly use autosamplers to improve detection efficiency and consistency, and uniform standards are proposed for vial specifications and shapes:

• Common specifications: 2ml standard caliber (OD 12mm * Height 32mm) is the main circulation model, widely compatible with multi-brand autosampling system.
• Vial appearance requirements: the bottle mouth needs to be flat, the bottle body needs to be resistant to mechanical friction, to ensure that the mechanical arm clamping stability.
• Specialized Tray Adaptation: Some brands of systems require a specific bottom structure (flat bottom, rounded bottom, or with grooves) to adapt to the vial tray.

3. Special materials and functional design

In order to guarantee the analytical accuracy of complex samples, laboratories often use specially designed vials:

• Inert borosilicate glass: It is the preferred vial material for HPLC/GC because of its high chemical resistance and cleanliness, avoiding reaction or adsorption with trace components in the sample.
• PTFE gasket cap: high solvent corrosion resistance, repeatable puncture, suitable for autosampling needle operation, avoiding sample contamination and leakage.
• Silanization treatment bottle: the surface is treated with a special coating to reduce the adsorption of polar molecules, commonly used in trace analysis.

By choosing the right materials, construction and specifications, vials in chemical analysis not only improve detection efficiency and instrument compatibility, but also contribute to the consistency and reliability of sample data. Especially in trace analysis and automated processes, the proper configuration of vial systems has become one of the core details to guarantee the quality of the test.

Selection of Vials in Environmental Sample Collection

Environmental sample collection covers a wide range of media, such as water, soil, and atmosphere, and the samples have complex compositions and may be under extreme conditions (e.g., highly corrosive, highly volatile, trace contaminants, etc.). In order to ensure the reliability of the collected data and to comply with regulatory requirements, it is crucial to select the appropriate vials for sample collection.

1. Application scenarios

• Water samples: Baokou surface water, groundwater, industrial wastewater, etc., commonly used to detect heavy metals, organic pollutants. Nutrient salts, etc.
• Soil extract: liquid samples obtained by chemical extraction, containing pesticide residues, heavy metals or organic compounds.
• Airborne particulate collection liquid: particulate samples used to elute from filter membranes or bubble absorbing liquids.

2. Key requirements for sampling vials

• Strong sealing: Avoid sample volatilization, leakage or moisture absorption during transportation or storage, especially important for VOC detection.
• Good corrosion resistance: samples may contain strong acids, alkalis or organic solvents, which require the use of high borosilicate glass or bottles made of special plastics.
• Inert design: The inner wall of the vial needs to avoid adsorbing contaminants or reacting with sample components, and some analyses require the use of bottles that have been silanized or pre-washed.
• Compliance with sampling regulations: All types of environmental monitoring programs are usually guided by national or international standards, such as the U.S. EPA, China’s Environmental Quality Standards for Surface Water, etc., and vials must be selected to meet their sampling requirements.

Improperly selected vials may cause problems such as degradation of target substances, adsorption of pollutants, and biased blanks, which may affect the accuracy of the test results or even lead to data nullification. Therefore, the scientific and reasonable selection of sample vials in environmental monitoring is not only related to the quality of analysis, but also related to the compliance and scientific environmental decision-making.

Vial Selection Guide: How to Choose Based on Sample Type and Analytical Needs

Facing a great variety of sample collection vials, how to make an efficient and scientific choice in practical work is a common problem for experimentalists.

1. Sample properties determine the structural choice of the preliminary material

• Properties of the sample itself: If the sample is highly volatile, a glass bottle with an excellent sealing cap and a PTFE gasket is preferred to maximize the loss of components. In the face of strong corrosive samples, you should use chemical-resistant borosilicate glass bottles, or use high-density polyethylene, fluorinated plastics and other special materials known as the bottle. In addition, for biologically active samples rich in nucleic acids, proteins or microorganisms, enzyme-free, aseptically treated vials need to be used, and low adsorption or inert materials are preferred to avoid sample degradation or non-specific adsorption.
• Type and compatibility of analytical equipment: The autosampling system used, need to ensure that the size of the vial used, the accuracy of the bottle mouth, the thickness of the gasket, etc. are in line with the standard specifications of the instrument manufacturer. Usually, a standardized screw-top 2 ml glass bottle is used to ensure that the injection needle is steadily extracted and to avoid needle blockage or leakage. For manual sampling or dispensing, a more flexible vial type is preferred.
• Sample storage conditions: The storage conditions of the sample directly affect the choice of material and closure structure of the vial. Most glass or polypropylene vials are adequate for samples that are generally refrigerated for short periods of time. If the samples need to be stored at low temperature (-20℃ or -80℃), special freezing tubes should be used, which are made of low-temperature-resistant PP and equipped with anti-leakage O-ring sealing structure. If the samples are stored in liquid nitrogen for a long period of time, special liquid nitrogen grade vials must be used, and internal threaded caps or caps to be strengthened for sealing should be used to prevent freezing and bursting of the vials. In addition, for photosensitive materials, brown or opaque vials should also be used or equipped with light-proof storage devices.
• Balance of cost and experiment size: For high-throughput experiments or teaching laboratories, affordable plastic vials can be chosen to reduce consumption costs. For precision analyses or high-value sample handling, the focus should be on bottle cleanliness, material inertness, and sealing performance, which can help ensure data accuracy even at a slightly higher cost. In addition, when building sample libraries or managing long-term projects, it is important to prioritize high-standard vials that are barcoded, freezer-resistant, and contamination-resistant in order to improve sample tracking and data management efficiency.

Taken together, the sample vial, though small, is an important link between experimental design, sample quality and analytical results. Through the systematic consideration of sample characteristics, experimental equipment, storage methods and budget size, the experimental heat source can more scientifically select the most appropriate sample collection vial, laying a solid foundation for the entire research process.

Future Trends and Innovative Directions

With the development of scientific research automation and green experiment concept, sample collection vials are evolving in the direction of keeping up with the funny and environmental protection.

On the one hand, high throughput laboratories have increasing requirements for sample processing speed and density, prompting vials to gradually move towards miniaturization and modularization. Micro-size vials are becoming mainstream, and when used with automated systems, they not only save space and reagents, but also enhance operational efficiency, adapting to the modern experiments’ demand for speed and precision.

On the other hand, the research and development of environmentally friendly materials has also become the focus of the industry. In order to reduce the environmental burden caused by disposable plastics, more and more vials are adopting biodegradable or bio-based materials. At the same time, the packaging and production process tends to be simplified and green, in line with the trend of sustainable laboratory construction.

In the future, vials will not only be consumables, but also a key part of the intelligent and sustainable development of laboratories.