Fibre-Optic UV Dip Probe Dissolution System

What is the Fibre-Optic UV Dip Probe Dissolution System?

A fibre-optic UV dip probe system measures drug concentration in situ by immersing probes in each dissolution vessel and reading absorbance through a spectrometer. It needs no sample withdrawal, so no volume loss or filter delay occurs. It is best for fast-dissolving products.

Overview

Each vessel holds a quartz or sapphire immersion probe with a fixed optical path length of 1, 2 or 10 mm, connected by optical fibres to a multiplexed diode-array UV spectrometer. A light source, typically a pulsed xenon or deuterium lamp, is switched between probes, and absorbance is recorded every few seconds with second-derivative or multi-wavelength corrections for turbidity. Because measurement occurs in the medium, time resolution is excellent, which suits fast-dissolving products, and there is no sampling delay or volume change. Undissolved particles can, however, scatter light, so baseline correction and probe placement are important, and the probe must be positioned so that it does not perturb flow. Probes need regular cleaning to avoid film formation. The technique relies on UV-active analytes with minimal excipient interference and requires calibration curves in each medium.

How does it work?

A sampling system places a filtered probe in the compendial sampling zone of each vessel and moves a defined volume of medium by syringe pump, peristaltic pump or vacuum to the destination. Valves select the channel, timers trigger sampling at preset times, and flush steps clear the lines. Probes are fitted with filters, typically 10 µm full-flow or 0.45 µm, which stop dissolution by removing undissolved particles. In-situ fibre-optic probes skip withdrawal entirely and measure absorbance in the vessel. Data such as time, volume and vial position are logged. Performance depends on timing accuracy, volume accuracy, dead volume, adsorption to tubing and filters, and the effect of the probe on hydrodynamics. Replacement of sampled volume with fresh medium can keep vessel volume constant.

What are the key features?

• In situ absorbance reading with no sample withdrawal
• Quartz or sapphire probes with 1, 2 or 10 mm path
• Multiplexed diode-array spectrometer for all vessels
• Turbidity correction using second-derivative or dual-wavelength methods
• Reading intervals down to a few seconds
• Calibration curve storage for each medium and probe

What are the technical specifications?

A typical fibre-optic uv dip probe dissolution system configuration offers number of probes of 6–8, wavelength range of 200–400 nm, path length of 1, 2, 10 mm, probe material of quartz or sapphire, 316 stainless steel, light source of pulsed xenon and reading interval of 5–10 s per probe. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Fibre-Optic UV Dip Probe Dissolution System is used in fast-dissolving tablets, real-time dissolution profiles, method development and content uniformity of release. Across the wider Sampling Systems class, laboratories also deploy it for dissolution profile automation, regulated QC testing and extended-release studies.

Which standards and certifications apply?

Relevant standards and methods include USP <711>, USP <1092>, Ph. Eur. 2.9.3, JP 6.10, ChP 0931, ASTM E2503 and 21 CFR Part 11. Certification candidates for this model are CE and ISO 9001 manufacturing; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Validate automated sampling against manual pulls during OQ and method transfer, checking timing, volume accuracy and carry-over. Clean and inspect probes and cannulas regularly, since blockage and film build-up affect recovery. Replace pump tubing and filters per schedule, and evaluate drug adsorption on tubing and filters. Keep cannula position within the compendial zone and avoid contact with paddles or baskets. Ensure software provides audit trail, user access control and time-stamped records. Include samplers in preventive maintenance and calibration programs alongside the dissolution tester.

How do I select the right Fibre-Optic UV Dip Probe Dissolution System?

Select in situ probes when time resolution matters, when sample volume loss must be avoided, or when filters absorb drug. Specify path lengths, number of probes, wavelength range and baseline correction needs. Turbid, coloured or multi-component formulations should use a sampling system with HPLC analysis instead.

How does it compare with other Sampling Systems variants?

Match the system to the number of time points, unattended operation needs and analytical method. Syringe-pump samplers give accurate aliquots and suit vial-based HPLC analysis. Peristaltic online systems suit continuous UV profiles and fraction collection. Fibre-optic probes give the fastest time resolution without withdrawal but need UV-active, non-interfering analytes. Media replacement is worth having when withdrawn volume exceeds a few percent of vessel volume. Manual kits suit single-point QC and backup. Key specifications are timing accuracy, volume accuracy, channel count, filter options, carry-over, compatibility with the existing tester and software data integrity. Validate against manual sampling before replacing it in a regulated method.