A major concern in the biotechnology manufacturing industry today is how to be cost effective in the production area. Manufacturing methods are generally developed on the laboratory bench. Many of the techniques, which work efficiently in the laboratory, can become quite costly when scaled up to mass production. Buffer preparation and storage becomes a very important aspect of facility design for large manufacturing processes. Whether the buffers are needed for chromatography, ultra-filtration, or other process applications, conventional technology would require enormous tanks on the production floor, which are difficult to clean and maintain. However, using on-demand buffer preparation and in-line buffer dilution eliminates the need for large storage tanks and greatly reduces production cost.

TechniKrom® designs cGMP automated buffer preparation systems to literally "remove stored water from the production floor." This type of technology is being used by some of the largest biotech firms in the world to accomplish cGMP manufacturing of value added products with the lowest possible production cost. By storing the buffers as concentrates and diluting them on demand using an in-house purified water system, automated buffer preparation technology eliminates the need to store dilute buffers in large tanks. The portable, skid mounted systems can deliver buffers to several different process steps simultaneously. TechniKrom® systems are custom designed to meet all production requirements including sanitary cGMP operation with CIP (cleaning in place) and SIP (sanitizing in place) capability when necessary.

System Description
A typical TechniKrom® automated buffer preparation system is composed of three main modules: the preparation module, the storage module, and the delivery module - all controlled by PLC (programmable logic control).

Module I: Preparation
Desired buffers are produced as concentrates (typically 2M - 10M depending on the solubility of the buffer salt) in the preparation module, which consists of a specially passivated 316L stainless steel "preparation" tank mounted on weighing cells. The tank includes a magnetically driven mixer, pH transmitter, gear pump, dosing pump, and level sensor. The tank is also connected to the central purified water system. By adding proper amounts of salt crystals and water to the tank, an exact buffer concentrate can be prepared. The weighing cells and PLC are used to add the exact amount of water desired. When the operator enters a set point, a valve opens to allow gentle addition of purified water until the set point has been reached. The same feedback technology allows for accurate pH adjustment of the concentrate via the dosing pump and pH sensor. Alternatively, solvents can be introduced into die preparation tank from drums or remote storage tanks for acid or base additions.

Module II: Storage
Once the buffer concentrate is prepared, it is forced under nitrogen pressure through a filter to the storage module. This module consists of several skid mounted 316L stainless steel tanks which will store the buffer concentrates until prompted by the PLC to pump them to the next module. These storage tanks are sized depending on the amount of buffer required (e.g. for one day or one week). The storage tanks are typically 100 times smaller than those required for conventional dilute buffer storage through the use of smaller volume concentrates diluted on demand from facility water lines - WFI (water for injection), RO (reverse osmosis), or other polished water supplies. If needed, one of the storage tanks can be designated for purified water; this water may used for the in-line dilution of buffer concentrates or as a delivery tank when pure water is needed for an application. Multi-head diaphragm pumps send the proper amounts of water and buffer concentrate through an in-line mixer to the delivery module at the desired dilution. Level sensors will trigger an alarm when a tank is running low providing operators with ample time to prepare the appropriate concentrates.

Module III: Delivery
The delivery module consists of smaller skid mounted 316L stainless steel tanks, which hold the diluted buffers and send them to the desired process unit. Level sensors constantly monitor buffer levels to prevent overfilling or running empty; the PLC prompts the storage module to send more dilute buffer to the delivery tanks as needed. To discourage bacterial growth and provide adequate mixing, the delivery tanks are normally piped with recirculation lines and booster pumps.

Control and Validation
Automated buffer preparation technology allows for easy validation and ultimately better control of the manufacturing process. All piping is constructed of fully traceable 316L stainless steel and connections are made with sanitary, tri-clamp fittings. All pipes and tanks can be manually drained by simply opening a valve or cleaned using the CIP (cleaning in place) protocol in the PLC. The buffer unit is integrated with 21 CFR part 11 capable PC software to allow the operator to perform functions from a computer terminal. This also allows for easy validation by providing full documentation of process parameters such as pH, buffer make-up, temperature, and tank levels.

The PLC control and feedback mechanisms leave little room for operator error. Weighing cells allow only the correct amounts of materials to be introduced into the preparation tank. pH sensors ensure correct pH, and level sensors eliminate the possibility of buffer lines running dry.

Quality Assurance
The challenges created for QA/QC departments using traditional batch mode large tank buffers are several. Although SOP'S are established to "do the best we can", the following concerns are worth considerine. In a large volume tank, how do I take a representative sample for analysis? The presence of both temperature and concentration gradients along with the geometry of the tank and nozzle location affect the accuracy of results. What are the cost and operational issues to maintain pre-made buffers at desired temperatures? Jacketed tanks and heat exchangers add to facility and validation costs. What is the cost and time for the required QC procedures? When we include collecting the samples, lab delivery, analyst time, report generation, and production delays, this cost is significant. And when a large tank of buffer is out of specification, the time and cost of disposal, re-make and re-test is not insignificant. In addition, dilute buffers have a limited lifetime before bacterial growth renders them unusable and they have to be disposed of anyway. Using on-demand automated technology eliminates problems with temperature control, buffer mixing, and bacterial contamination. The TechniKrom® tanks are much smaller and therefore much easier to heat and/or cool. Recirculation lines with booster pumps ensure homogenous buffers and greatly reduce the risk of bacterial growth.

Reducing Overall Cost in the Production Plant
TechniKrom® equipment initially costs up to 25% more than a conventional buffer system, but the automated technology allows for massive reductions in facility and operational costs. Overall, the total cost of using the TechniKrom® system is 1/2 that of using the conventional method. Furthermore, the system is designed for industrial use. All components including weighing cells, pH probes, valves, and mixers are carefully chosen and integrated into a system that will not break down thus eliminating the cost associated with down time.

The automated buffer system requires 1/5 the facility floor space as conventional buffer preparation tanks and is mounted on portable stainless steel skids. The unit can be easily transported for use in many different facilities. As an example, a biotech company would have required three 20,000-liter tanks in order to provide enough volume of buffer for one week of operation. One of the buffers was 0.2-M ammonium sulfate. By using an automated dilution system, the tank size was reduced to 200 liters. The concentrated solution was automatically diluted from 2.0-M to 0.2-M in-line when needed and another tank of similar size was used to deliver the dilute buffer to a liquid chromatography system. When they moved to another manufacturing site, they relocated the buffer preparation system easily since piping and instrumentation is integrated on the skids. Additionally, the unit was placed in the basement of the facility with recirculating lines and drops in higher floors to production areas and quality control laboratories thus further reducing the required GMP production area.

In general, the TechniKrom® automated buffer preparation system requires only one operator to prepare buffer concentrates once per week. The preparation tank is small enough that it can be easily cleaned and sanitized after each preparation. Once the storage tanks are full with concentrated buffer, the PLC will send signals to continually produce dilute buffer and send it to the delivery tanks when needed. When the storage tanks reach low level, an alarm will sound to prompt the operator to prepare more concentrated buffer. The portable design allows the preparation tank to be placed in the same room as other systems thus allowing the operator to run and monitor other units simultaneously.

Companies who have used conventional buffer storage tanks know that it is common practice to dump unused buffer that is no longer needed or has been contaminated with bacteria, as mentioned earlier. Using smaller tanks and constantly recirculating the stored buffer can eliminate the unnecessary down time associated with dumping the liquid, cleaning the tanks, and re-making the buffer. Since the buffers are produced on demand, there is never any excess or unused buffer.