Ensure measurement accuracy and consistency with Hanna Instruments HI731335 replacement cuvette caps. These precision-engineered caps feature a locking index tab and light-blocking design, essential for accurate photometric measurements with HI96 series portable photometers.
Precision Features:
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Locking index tab: Ensures cuvette is inserted in the same position every time for consistent path length
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Light-blocking design: Prevents stray light from entering the optical system and interfering with measurements
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Secure threaded fit: Screws tightly onto HI731331 glass cuvettes for leak-proof sealing
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Sample protection: Prevents contamination, evaporation, and spillage during handling and storage
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Value 4-pack: Includes four replacement caps for multiple cuvettes
Why Proper Alignment Matters:
Accurate photometric analysis requires consistent cuvette positioning. According to the Beer-Lambert Law, absorbance depends on the optical path length (distance light travels through the sample). The HI731335's locking index tab ensures the cuvette is inserted in the same orientation for both blank measurements (zero) and sample readings, maintaining consistent path length and accurate results.
The Beer-Lambert Law:
The quantity of radiation absorbed is given by: A = log I₀/I
Absorbance is also expressed as: A = ε • C • l
Where:
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A = Absorbance (dimensionless)
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ε = Molar extinction coefficient [L/(mol•cm)]
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C = Concentration of the substance (mol/L)
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l = Optical path length through sample (cm)
Consistent cuvette positioning ensures the path length (l) remains constant, critical for accurate concentration measurements.
Optical System Protection:

Professional Applications:
Essential for laboratories, water treatment facilities, aquaculture operations, pool service professionals, and environmental testing applications where measurement accuracy and repeatability are critical. The HI731335 caps are the same high-quality components supplied with new HI96 series photometers.
Technical Specifications:
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Model: HI731335
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Quantity: 4 caps per pack
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Compatibility: HI96 series portable photometers with HI731331 glass cuvettes
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Features: Locking index tab, light-blocking design
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Weight: 4 oz
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Country of Origin: Romania
Professional-Grade Quality:
Manufactured by Hanna Instruments to exacting standards. Replace worn or missing caps to maintain measurement accuracy and protect your samples from contamination.
Use with HI731331 glass cuvettes (sold separately). Keep spare caps on hand to ensure uninterrupted testing and maintain measurement integrity.