In UV visible near-infrared spectroscopy, Raman spectroscopy, fluorescence spectroscopy, and atomic absorption spectroscopy analysis, the materials of the sample cell and optical path window directly affect the signal-to-noise ratio and detection limit. Quartz tubes have become the preferred carrier for spectral testing of gases, liquids, powders, and even high-temperature molten samples due to their extremely high transmittance in the deep ultraviolet region (≥ 185nm), extremely low background fluorescence, excellent chemical inertness, and high temperature and high pressure resistance.

FAQ (Frequently Asked Questions)

Q1: Why is quartz tube used instead of ordinary glass tube in spectral testing?  

A: Ordinary glass (such as borosilicate glass) almost completely cuts off in the ultraviolet region (<350nm), and impurities such as iron and sodium can produce characteristic absorption peaks, interfering with the sample signal. The transmission range of quartz tube can be extended to 185-2500nm, and the background is flat, making it particularly suitable for UV band analysis and trace detection.

Q2: What spectroscopic techniques are quartz tubes suitable for?  

A: Mainly including: ① UV visible spectrophotometry (liquid/gas flow cell); ② Fluorescence spectroscopy (low fluorescence quartz material); ③ Raman spectroscopy (low background quartz reduces quartz peak interference); ④ Atomic absorption spectroscopy (protective tube or sample tube of graphite furnace atomizer); ⑤ Near infrared online detection (long path flow cell).

Q3: What are the special requirements for quartz tubes in different spectral applications?  

A: Yes, it is. For example:

-Synthetic quartz (with low OH content and 185nm transmittance>80%) is required for use in the ultraviolet region;  

-Fluorescence spectroscopy should use "low fluorescence quartz" or "ultra pure quartz" to avoid false peaks in quartz background fluorescence;  

-High temperature spectroscopy (such as molten salt analysis) requires thick walled heat-resistant quartz tubes;  

-It is recommended to use "non luminescent quartz" for Raman spectroscopy to suppress the Raman scattering peak of quartz itself.

Q4: Can we customize quartz tubes with irregular shapes or special optical path structures?  

A: Absolutely possible. We offer customized solutions such as rectangular flow cell tubes, Z-type long path cells, sample tubes with standard fiber optic interfaces, double layered constant temperature tubes, microcapillaries (with inner diameters up to 0.1mm), and flange sealed gas cells.

Q5: Can a detection report be provided for the transmittance of quartz tubes?  

A: Okay. Each batch of materials is accompanied by a transmittance curve (190-2500nm) measured by a UV visible near-infrared spectrophotometer, and specific transmittance values for key wavelengths such as 200nm, 254nm, and 365nm are marked.

User core needs and solutions

-Requirement 1: Obtain sufficient luminous flux in the deep ultraviolet region to avoid sample signals being submerged in noise

We provide synthetic quartz tubes with a transmittance of ≥ 85% at 200nm and ≥ 80% at 185nm, which are much higher than ordinary quartz (about 50% at 200nm).

-Requirement 2: Avoid impurity absorption or fluorescence interference from the quartz tube itself on the sample spectrum

We use high-purity quartz raw material (total metal impurities<5ppm) and perform special annealing treatment on the fluorescent analysis tube, reducing the background fluorescence intensity to less than 1/5 of ordinary quartz.

-Requirement 3: Need to be perfectly matched with the existing spectrometer sample chamber or circulation system

We offer customized sizes within the range of outer diameter 2-100mm and length 10-300mm, and can be matched with PTFE or PEEK joints, O-ring grooves, and standard optical interfaces (SMA, FC, etc.).

-Requirement 4: In situ spectroscopic testing under high temperature or high pressure conditions

We can produce quartz tubes with a pressure resistance of 5MPa and a temperature resistance of up to 1100 ℃, and can integrate gas inlet and outlet branches for high-pressure in-situ catalytic reaction spectral monitoring.

Core values and application advantages of the product

1、 Optical performance advantage - ensuring the authenticity and reproducibility of data

Transmittance range: 185-2500nm (synthetic quartz), covering deep ultraviolet to near-infrared, meeting the requirements of most spectroscopic technologies

UV transmittance: 200nm ≥ 85%, 254nm ≥ 90%, increased sensitivity in the UV region, reducing the power requirement of the light source

Background flatness: Fluctuations within the range of 190-1100nm are less than 3%, with a straight baseline and no need for complex background correction

Fluorescence background: Under excitation at 350nm, the fluorescence intensity at 450nm is less than 0.1% RH, and there are no false peaks in the fluorescence spectrum, making quantification more accurate

Raman background: The intensity of the quartz characteristic peak (about 465cm ⁻⊃1;) is controlled to be the lowest, reducing the obstruction of the sample Raman signal by the quartz peak

2、 Structure and customization capability - adaptable to various spectral instruments and sample forms

-Liquid samples: Flow cell tube (Z-type, straight through type), colorimetric dish tube (10mm standard optical path), temperature control jacket tube

-Gas samples: Long path gas cell tube (optical path 0.5-2m), micro gas tube (inner diameter 1-3mm)

-Solid/Powder: Rotating Sample Tube, Capillary Tube (Used for X-ray Diffraction/Raman Combination)

-High temperature samples: a combination structure of heat-resistant tubes with open ends (which can be used with tube furnaces) and embedded tubes with sample boats

-Pressure system: pressure resistant quartz tube with threaded or flanged interface (working pressure ≤ 5MPa)

3、 Typical Spectral Application Scenarios and Customization Suggestions

UV Vis spectrophotometry: Biochemical reagents, drug solutions, rectangular flow cell tube, 10mm optical path, double ended SMA connector - achieves continuous flow detection and saves sample volume

Fluorescence spectroscopy: Rare earth complexes, quantum dots, low fluorescence quartz four sided transparent tube with constant temperature jacket - eliminates quartz background, improves signal-to-noise ratio by more than 3 times

Raman spectroscopy: Polymer, mineral, battery materials, non luminescent quartz capillary (inner diameter 0.5-1mm) - reduces quartz peak interference to obtain pure sample Raman spectra

Atomic Absorption Spectroscopy: Analysis of Heavy Metal Elements, Graphite Furnace Outer Protective Tube+Sample Injection Tube - High Temperature Resistant, Easy to Clean, No Memory Effect

In situ catalytic reaction spectroscopy: catalyst powder+reaction gas, high-temperature and high-pressure flow cell tube (with gas inlet and outlet and quartz window) - real-time monitoring of reaction intermediates, more dynamic data

Near infrared online detection: oil, alcohol, dairy products, long path (50-200mm) straight tube, pressure and corrosion resistance - long path improves the sensitivity of weak absorption sample detection

What practical application problems can be solved?

Problem 1: Ordinary glass tubes absorb heavily in the ultraviolet region, resulting in the inability to detect low concentration samples

-Root cause: Transition metal ions and intrinsic absorption sidebands in glass are located near 350nm.

-Solution: The synthetic quartz tube extends the available wavelength band to 185nm, and the absorbance of the ultraviolet sample can be accurately measured, reducing the detection limit by one order of magnitude.

Problem 2: The fluorescence peak of the quartz tube overlaps with that of the sample, resulting in false positives

-Root cause: Ordinary quartz contains impurity defect centers, which produce broad-spectrum fluorescence under UV excitation.

-Solution: Low fluorescence quartz is used and treated with a high-temperature hydrogen atmosphere, resulting in a background fluorescence intensity of only 15% or less than that of ordinary quartz, ensuring accurate detection of weak fluorescence samples.

Problem 3: In flow injection analysis, there is leakage or misalignment of the pipeline interface or optical path

-Root cause: Standard quartz tubes do not have matching connectors, and users may easily deviate when transferring them themselves.

-Solution: We can integrate or precision process the interface drawings provided by the user (such as 1/4-28 UNF threads, SMA 905 fiber sockets, etc.) to ensure an optical coupling efficiency of ≥ 95%.

Question 4: During high-temperature in-situ spectroscopy testing, bubbles or explosions may occur in the quartz tube

-Root cause: High hydroxyl (OH) content in the material leads to bubble nucleation at high temperatures; Uneven wall thickness may cause thermal stress.

-Solution: We provide low OH quartz (OH ≤ 10ppm) and use precision thickness control tube drawing technology, with a wall thickness tolerance of ± 0.1mm and a safe temperature resistance of up to 1100 ℃.

Why choose us?

1. Material grade transparent optional

We offer three grades: ① High purity quartz (cost-effective type); ② Synthetic quartz (optical grade, highest UV transmittance); ③ Low fluorescence ultra pure quartz (fluorescence/Raman specific). Each type is accompanied by a measured transmittance curve.

2. Processing capability for irregular optical path structures

We have a complete set of processes including CNC irregular cutting, hydrogen oxygen flame precision welding, and optical grade end face polishing (roughness Ra ≤ 0.02 μ m), which can produce Z-shaped pools, W-shaped folded optical tubes, integrated bubble or lens structures.

3. Cleanliness meets spectral level requirements

18 step precision cleaning (acid washing+ultra pure water rinsing+infrared drying), fat free and dust-free, can be directly used for trace analysis without the need for users to clean again.

4. Strong batch consistency

For multi-channel spectrometers or production process quality control (such as online testing in pharmaceutical factories), we ensure that the optical path difference of quartz tubes in the same batch is ≤ ± 0.05mm and the transmittance deviation is ≤ 2%.

Customer Application Case (Anonymous)

Case 1: A well-known analytical instrument company (equipped with a UV visible spectrophotometer flow cell)

Background: The customer has developed a high-end dual beam UV Vis spectrophotometer, which requires a micro flow cell (optical path 10mm, inner diameter 2mm, sample volume<50 μ L). The original supplier provided quartz tubes with a transmittance of only 65% below 220nm, and the inter batch optical path deviation reached ± 0.2mm, resulting in poor reproducibility of the molar absorptivity measured by the user.  

Solution: We provide synthetic quartz Z-shaped flow cell tubes with optical polishing on the end face, 200nm transmittance of 88%, and optical path tolerance of ± 0.05mm.

Result:

-The energy in the ultraviolet region of the instrument has been increased by 30%, and the signal-to-noise ratio has reached the industry-leading level.  

-The absorbance reproducibility (RSD) of the customer's instrument decreased from 2.1% to 0.4%.  

-This circulation pool has become a standard configuration for this model of instrument for customers, with a cumulative supply of over 5000 pieces.  

-Customer feedback: "You have resolved our long-standing issue with UV transmittance batches

Case 2: A catalytic research team in Europe

Background: To study the surface intermediates of catalysts in methane dry reforming reactions, an in-situ Raman spectroscopy cell with high temperature (800 ℃), normal pressure, and accessible reaction gas is required. The core difficulty lies in the strong Raman background peak (about 465cm ⁻⊃1;) generated by quartz tubes at high temperatures, which precisely covers the Raman shift of key Ni-O bonds in the catalyst (about 500-550cm ⁻⊃1;).  

Solution: We customize a non luminescent quartz capillary tube (outer diameter 6mm, inner diameter 4mm, length 150mm) and perform special annealing treatment to suppress the intrinsic Raman peak of quartz. Simultaneously integrate two gas inlet and outlet branches and a pair of quartz windows.  

Result:

-The peak intensity of the quartz tube at 465cm ⁻⊃1; decreased to 30% of that of ordinary quartz, and the characteristic peak of Ni-O was clearly distinguishable.    

Case 3: An environmental monitoring station (using atomic absorption spectroscopy to measure lead in water)

Background: Use graphite furnace atomic absorption spectrometer to detect trace lead in drinking water (detection limit requirement<1 μ g/L). The imported quartz protective tube was originally used, but after 30 uses, white sediment appeared on the inner wall, causing a memory effect and leading to an increase in blank values. The cost of replacing imported pipes is high (about 2000 yuan per piece), and the delivery time is up to 8 weeks.  

Solution: We customize outer protective tubes (outer diameter 18mm, inner diameter 14mm, length 120mm) and sample injection tubes (outer diameter 3mm, inner diameter 2mm) that match the instrument, using high-purity quartz and performing inner wall passivation treatment.  

Result:

-The blank absorbance decreased from 0.045 to 0.008, and the detection limit of the method was optimized from 0.9 μ g/L to 0.3 μ g/L.  

-Solved the customer's dilemma of downtime and waiting for materials.  

Case 4: A pharmaceutical company (near-infrared online monitoring of fluidized bed drying process)

Background: Real time monitoring of moisture content is required during the drying process of pharmaceutical granules. The stainless steel probe was originally used in conjunction with the optical fiber, but the particles were prone to adhere to the light window, causing signal drift. I hope to use a long path quartz flow tube (200mm path length) as a bypass flow cell to allow particles to flow through the tube for continuous NIR detection.  

Solution: Customize a straight through quartz tube with an inner diameter of 20mm, an outer diameter of 24mm, and a length of 220mm. Both ends are equipped with sanitary grade chuck joints, and the tube body is sandblasted to prevent signal saturation caused by total reflection of light on the inner wall of the tube.  

Result:

-The frosted treatment makes the NIR diffuse reflection signal more stable, and reduces the RMSEP (Root Mean Square Error of Prediction) of the moisture prediction model by 32%.  

-The particles do not adhere and can run continuously for 3 months without dismantling or washing.  

-We have helped customers achieve real-time control of the drying process, reducing the drying time for a single batch by 15% and saving approximately 400000 yuan in energy consumption annually.  

-Process engineer evaluation: "Although this quartz tube is not an original accessory of the instrument, it understands our process difficulties better than the original factory solution

Whether you are a spectral instrument R&D engineer, laboratory researcher, or online detection system integrator - we can customize the most suitable spectral grade quartz tube based on your wavelength range, sample morphology, interface standards, and budget.  

Provide your optical path diagram or photos of existing sample tubes immediately, and receive customized solutions and quotations within 24 hours to make your spectral data purer, more reliable, and more reproducible.

Luverre Quartz is a manufacturer specializing in quartz tubes and other quartz items.We have over 18 years experience with the production of quartz tubes, we will be your reliable partner on quartz tubes and other quartz items.

Luverre Quartz can manufacture customized quartz tubes in various shapes, such as spiral, square, round, with processing including cutting, bending, welding, etc., and available in different colors, such as transparent quartz tubes, opaque quartz tubes, milky white quartz tubes, red quartz tubes, and so on.