Automated dissolution testing in this case means sampling, measuring, and result calculation are automated. The user adds the samples when prompted to do so by the system and takes care of filling and cleaning of the vessels. The online ADS-L systems are so called „closed loop“ dissolution systems. The basic building blocks for an ADS-L automated online dissolution systems are a dissolution testing instrument type PTWS 120, PTWS 820, PTWS 620, PTWS 1220 or PTWS D620, a TIDAS L diode array UV/VIS spectrophotometer with multi cell changer, a peristaltic pump for sample transfer and the powerful control software package WinDiss ARGUS.
Unlike the off-line systems where samples are removed from the dissolution vessels and stored either for transfer to a measurement system or for further preparation (e.g. dilution), the samples here are circulated in a closed loop. This means there is no sample volume loss over the time of the dissolution test. At programmed time points the sample circulation is stopped and either a single point absorbance reading or a full UV spectrum of each vessel is collected.
The dissolution testing instrument can be equipped with a movable EPE auto sampling system, an ITM individual media temperature monitoring system, a manual or automated tablet drop magazine and 6 to 12 stirred testing stations. There is no need for a staggered start option here as all samples are simultaneously delivered into the flow-cells of the connected UV/VIS spectrophotometer and measured at equal time points, complying with the USP requirement of the 2% time limit for sampling from all vessels. Attached to the tip of the sampling probes are exchangeable filter tips. A rinsing time has to be taken into account to allow enough time to fill up all tubing with a representative sample. This may take between 15 to 45 seconds prior to the actual measurement. The reading time will be approximately 5 to 10 seconds for 8 vessels. In this case all samples can be analysed in approximately 1 minute. The WinDiss ARGUS software offers full flexibility in programming the sampling and measuring times so that you can adapt the timing to the release behaviour of the samples being tested.
