Autonomous Buffer Preparation

Abstract

Every laboratory involved with liquid chromatography (LC) has to solve the issue of a supply of mobile phase. In the case of reversed-phase liquid chromatography the mobile phase is polar in nature and most commonly aqueous solutions. With a source of distilled water in-house the possibility of creating a mobile phase supply is within reach. A pair of retired LC systems is being repurposed for an automated mobile phase production, and these solutions should have buffering capacity. This thesis will be dedicated to deliver buffer solutions by mixing conjugating acid/base salt stock solutions with distilled water by automating said systems.
The automation is made possible by the Python-based Orbit library developed at Department of Chemical Engineering, Lund University. Both experimental setup and programming had to be employed for this endeavour. An signal called "accumulated volume" was experimentally investigated for reliability and accuracy, to be used as a run criteria in automation programming. It was found to be able to deliver volumes
within 1.5% difference to target volume (7 ml) at high flowrates (100 ml/min). Programming work spawned new programs with the tasks of keeping track of inventory of a system as well as receiving requests of buffer solution and construct scripts in order to deliver.
Conclusively, the current state of the material involved in this project is not a finished automated buffer system. However it is significantly progressed and promising for being an addition to the plethora of tools available for the LC laboratory.

Popular Abstract

A quest for the construction of a laboratorys equivalent of a vending machine, an automated production system of buffer solutions. Laboratories that analyze samples and then could tell you with confidence what is in it, they employ instruments that do some kind of process to separate the different kinds of chemical compounds. To use these instruments with the sample one needs a material that could allow the sample travelling through the instrument, or make sure the analysis is done during stable conditions. In the end, the quantity of this material adds up and the time preparing it grows in proportion. Relieving this work time is advantageous in the long run and thus creating a system which is able to produce such material with minimal interaction is desirable. Using the coding language Python with a repurposed system of pumps, tubing, valves and sensors progress has been made towards the envisioned laboratory vending machine.
At the Department of Chemical Engineering a subgroup called the Chromatography Group is looking into analysis of primarily proteins using a high pressure liquid chromatography (HPLC) method. Their self-developed Python-based code library, called Orbit, allows for complex execution of a HPLC method and communication between different machines previously not linked. With this code library an automated mobile phase preparation system to supply their HPLC is reachable possibility.
The mobile phase is the material running through the tubings, pumps et.c. and making the analysis function. In this case, the main category of mobile phases is the aqueous buffer solutions, meaning their
primary component is distilled water with addition of weak bases and acids generating the buffering capacity.
A buffer is the name of a liquid solution that resist changes in acidity. Since proteins behaves different depending on their surroundings a factor like acidity is a important to control when performing analysis of them.
This project is further delving into components that an automated system needs to run itself. First, do the system have some computer signal that reflects how much volume it has pumped? Yes, one signal
called ”accumulated volume” which is the sum of all volume that have passed through the pumps until a point in time. This signal could be retrieved and used to accurately deliver desired volumes of chemical
components to a mixing flask.
Secondly, a couple of new Python programs were created to give the system an ability to remember its own inventory and how to mix certain buffer solutions.
Information like quantity, concentration, position in system and how much has been expended is now stored for the system to remember until next buffer preparation. This was done in an effort to decrease
the amount of surveillance an user have to do of basic ingredients available to the system.
Finally, a program working on setting up a proposed run sequence to produce requested buffer solutions. It retrieves the system inventory information, compares it to the recipes and required quantities to calculate what it can and can not produce.
The project progressed close to completion of the Python programs but did unfortunately not involve test running a finished and functioning automated system. However, large steps towards realisation of
such a system has been taken and will remain to be a possibility for the future.

• author: Önnestam, Lukas
• supervisor: Niklas Andersson
• organization: Chemical Engineering (M.Sc.Eng.)
• course: KETM05 20201
• year: 2020
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Buffer, Python, Automation, pH, Chemical engineering, Kemiteknik
• language: English
• id: 9028176
• date added to LUP: 2020-09-15 10:55:48
• date last changed: 2020-09-15 10:55:48