A.KRÜSS Optronic Tips correct cleaning refractometer
PDF · Manufacturer document
A refractometer prism is in direct contact with the sample. Films, dried deposits or cleaning liquid left by a previous measurement can change the conditions of the next measurement. A surface that looks clean is not necessarily ready for the next sample.
This article draws on the A.KRÜSS Optronic cleaning guide to explain prism cleaning and checks during sample changes. The cleaning medium, quantity and procedure must still follow the model instructions, sample properties and laboratory safety requirements.
Why clean promptly after measurement
The manufacturer recommends cleaning the prism immediately after each measurement to prevent samples drying or hardening on it. Delayed cleaning can make viscous residues harder to remove. Acidic, alkaline or otherwise aggressive samples particularly require prompt cleaning and a check of the prism condition.[1]
For sequential measurements, cleaning aims to remove visible contamination and reduce carryover into the next sample. Include cleaning checks when changing between aqueous and oily samples, or between samples with substantially different compositions.
Choose the cleaning medium for the sample
The guide lists water for several aqueous sample types, including sugar solutions, salt solutions and honey, and suggests isopropanol for mineral oils. These examples show why wiping with water is not a universal cleaning method.[1]
The sample table is not a cross-model solvent recipe. Before using an organic solvent, check compatibility with the prism, seals and other wetted materials and consult its safety data sheet (SDS). Do not substitute a solvent merely because it seems stronger, or mix cleaning agents.
Connect cleaning with a reference check
- Remove the sample. Absorb it with soft, absorbent, lint-free material, then wipe as instructed using material moistened with an appropriate cleaning medium. Do not scrape deposits with a hard object.
- Inspect the contact area. Check the prism and sample well for visible residues or abnormal conditions; do not wait for the sample to dry on the surface.
- Check a reference when needed. Between substantially different samples, the manufacturer recommends water or another suitable reference. Set reference conditions and acceptance criteria for the model and laboratory procedure.
- Add the next sample. Use a pipette or micropipette to dispense it smoothly and avoid bubbles.
A reference check assesses the current measurement state; it does not mean the instrument must be readjusted each time. If a reference result is abnormal, first check the reference material, cleanliness and measurement conditions. Do not adjust the instrument while residues remain.
Checks when readings are inconsistent
- Has the sample dried on the prism or left a subtle oil film?
- Is the cleaning medium suitable for both the sample and wetted instrument materials?
- Are there bubbles, and is sample contact with the prism adequate?
- Was an appropriate reference checked after the sample change, under consistent conditions?
The manufacturer warns that bubbles affect results. Cleanliness and sample loading therefore need separate checks; not every fluctuation is a matter of instrument accuracy.[1]
Key points
Use a sequence of sample removal, appropriate cleaning, confirmation of cleanliness and smooth sample loading. A consistent cleaning and check procedure for the sample type makes troubleshooting easier than frequently changing solvents or repeatedly adjusting the instrument.
References
- [1] A.KRÜSS Optronic Tips correct cleaning refractometer, PDF page(s) 1–2 (file page order). View reference resource