VialTweeter – Sonoreactor for Trace Mineral Extraction from Soil

For monitoring the health and pollution of soil, pollutants such as trace minerals must be extracted and measured. The VialTweeter facilitates pre-analytical extraction in laboratory workflows significantly. The extraction of trace minerals from soil samples is a great example showing the efficiency and reliability of the VialTweeter for improved extraction results.

Trace Mineral Extraction from Soil Samples

The extraction of trace minerals from soil is a crucial analytical step in environmental monitoring, geochemical studies, and agricultural assessments. Traditional methods, including acid digestion, microextraction and microwave-assisted extraction, are often time-consuming, reagent-intensive, and/or environmentally hazardous.
The VialTweeter, a high-power ultrasonic sonoreactor, is a superior alternative, offering enhanced extraction efficiency, reduced processing time, and minimal reagent consumption. This novel approach significantly improves the recovery of trace elements from soil matrices, ensuring more accurate and reproducible results while adhering to green analytical chemistry principles.

Trace Mineral Extraction from Soil with the Multi-Tube Sonicator VialTweeter

Carretero-Peña et al. (2021) conducted a study demonstrating that the VialTweeter is a highly efficient tool for extracting trace minerals from soil. The key details and findings of their research are outlined below.

Ultrasonic Extraction with the VialTweeter:
4.0–7.5 mg of soil is weighed into 1.5 mL Eppendorf tubes. A specific volume of HNO₃ solution (0.60–1.5 mL) is added, and the tubes are sealed before being placed into a VialTweeter sonoreactor. The samples undergo ultrasonic extraction at room temperature for 450 sec. After sonication, they are centrifuged at 3500 rpm for 10 minutes. A portion of the supernatant is transferred via micropipette into a 10 mL flask, where it is diluted with 5.0% HNO₃. A germanium (Ge IV) internal standard is added to achieve a final concentration of 10 ng/mL before analysis.
Duration with VialTweeter: 450 seconds
 

Acid Digestion of Soil Samples:
50 mg of soil are treated with 2.5 mL of HNO₃ and 5.0 mL of HF in closed Teflon digestion vessels at 90°C for 8 hours. The vessels are then opened, and 2.5 mL of HClO₄ is added before evaporating the mixture to dryness at 200°C on a hot plate. After this, 1.0 mL of HNO₃ is introduced and evaporated again. The final step involves dissolving the residue in 2.5 mL of HNO₃, transferring the solution into a 50 mL volumetric flask, and completing the volume with ultrapure water. Indium (In III) and Yttrium (Y III) internal standards (50 μL of a 10 mg/L solution) are added to ensure accuracy in subsequent elemental analysis.
Duration for Acid Digestion: 8 hours
 

Optimization of Extraction Conditions

The researches tested various extraction conditions to obtain the maximum amount of trace minerals from the soil samples. These conditions maximize trace element recovery while minimizing the use of acids and reducing overall extraction time compared to traditional digestion methods.

Comparison Extraction Efficiency: VialTweeter vs Acid Digestion

The comparative evaluation of mineral extraction yields against reference samples extracted via acid digestion highlights the excellent efficiency and reliability of the multi-tube sonicator VialTweeter.

An extraction efficiency greater than 100% means that the amount of a given element extracted from a sample exceeds the expected or reference value.

With the VialTweeter, efficient high-throughput extraction of substances from samples facilitates the daily workflow in analytical labs.

1. Faster Extraction – Drastically reduces time from hours to minutes.
2. Minimal Sample Contamination – Sealed vial design prevents airborne or cross-contamination.
3. High Reproducibility – Uniform energy distribution across vials eliminates variability.
4. Environmentally Friendly – Reduces acid consumption and hazardous waste.
5. Scalable and High-Throughput – Suitable for rapid environmental monitoring programs.

The VialTweeter Sonoreactor

Ultrasound-Assisted Extraction (UAE) Mechanism

The working principle of the VialTweeter sonoreactor is powerful ultrasonic cavitation, a physical pehnomenon that generates localized high shear forces and pressure differentials within a liquid medium. This phenomenon facilitates the breakdown of soil particles and enhances the leaching efficiency of metal ions into an extraction solvent.

Key advantages of ultrasonic cavitation in soil extraction:

• Improved matrix disruption: Cavitation-induced microjets enhance solvent penetration into soil particles.
• Reduced particle size: The mechanical forces break down aggregates, exposing more surface area for mineral extraction.
• Increased reaction kinetics: Accelerated desorption and dissolution of trace metals into the solution.
• Minimized reagent usage: Reducing acid concentration lowers environmental impact without compromising extraction efficiency.

VialTweeter Configuration and Design

The VialTweeter system consists of a titanium block with 10 vial slots, ensuring uniform ultrasonic energy distribution. It is powered by a 200 watts-powerful ultrasonic generator at a frequency of 26 kHz and transmits equal energy to each sample, ensuring consistent and reproducible extractions across multiple vials simultaneously.

Key Features:

• High-power uniform sonication for batch processing.
• Elimination of cross-contamination due to vial isolation.
• Minimal sample loss in sealed reaction vessels.
• Scalability for high-throughput environmental monitoring.

The VialTweeter is also available as a single-tube sonicator model for the reliable sample preparation of Falcon tubes. Read more about the customized single-tube model for the sterile sonication of Falcon tubes!

Design, Manufacturing and Consulting – Quality Made in Germany

Hielscher ultrasonicators are well-known for their highest quality and design standards. Robustness and easy operation allow the smooth integration of our ultrasonicators into industrial facilities. Rough conditions and demanding environments are easily handled by Hielscher ultrasonicators.

Hielscher Ultrasonics is an ISO certified company and put special emphasis on high-performance ultrasonicators featuring state-of-the-art technology and user-friendliness. Of course, Hielscher ultrasonicators are CE compliant and meet the requirements of UL, CSA and RoHs.

Hielscher Non-Contact Sonicator models UIP400MTP for microplates, VialTweeter and CupHorn: high-speed and high-throughput sample preparation