# Experimental Setup and Graphical User Interface for Zero-Length Column Chromatography
## 1 Introduction  
Any important developments in the area of new materials should be accompanied by the creation of experimental facilities for studying them. The number of new molecular sieves discovered every day has been increasing. Examples include: zeolites [1, 2], metal-organic frameworks [3, 4, 5], mesoporous silicas [6], microporous carbons [7], polymers of intrinsic microporosity [8, 9], and metal-organic framework with dual functionalities [1, 4]. This rapid growth of the available molecular sieves imposes the challenge of understanding the sorption kinetics and equilibrium of a large number of adsorbates of industrial interest. Multicomponent kinetic and equilibrium data are also of great interest due to the vast number of applications found in separation science and technologies [10, 11]. Consequently, the need arises to develop accurate and efficient experimental techniques that allow the comprehensive evaluation of properties often involving a large number of adsorbent samples [12, 13].  
The inverse chromatography method known as zero-length column (ZLC) was developed as a simple, inexpensive, and time-efficient method for the determination of adsorption kinetics and equilibrium [14]. The ZLC experiment is quick, uses a small sample mass, and provides good accuracy with reliable results on pure and multicomponent systems [15; 16; 17]. All these features can be combined in a single experimental setup. However, this is not often the case. Most of the reported experimental setups focus on the study of pure gases. Nevertheless, it has been shown that reliable binary adsorption data can be obtained, subject to certain limitations [18]. When they include multicomponent analysis is because they have mass spectrometers that are significantly more expensive. As far as the authors of this work are aware, no design has been reported that provides the possibility of performing ZLC experiments under kinetic and equilibrium conditions for single and multicomponent systems without the use of mass spectrometers.  
An alternative to mass spectrometry is gas chromatography (GC). However, the introduction of GC is accompanied by an increased number of elements in the zero-length column (ZLC) system. This makes ZLC experiments a complex task susceptible to errors [19]. To overcome this challenge, the ZLC could be combined with a powerful tool as a graphical user interface (GUI) for setting and manipulating the elements of the systems, which significantly improved experimental times and measurement errors. Nevertheless, no report offers the design of a ZLC system accompanied by a GUI with open source code, allowing the scientific and industrial community to build and automate the system. In addition, the community effort in the development of the GUI could contribute to reducing the implementation costs and performing more complex experiments and analyses.  
This research presents the implementation of a semi-automatic ZLC system (hardware and GUI). The instrument can operate under both kinetic and equilibrium conditions and can also deal with multicomponent systems. The analysis in multicomponent systems is performed on GC basis which makes it more cost-effective than the systems commonly used. Experimental run time is remarkably reduced by avoiding degassing processes between experiments. On the other hand, since the same sample can be used to carry out a complete study, the waste of time and resources required for previous characterizations is avoided. This latter issue is of great relevance in the case of novel prototype materials for which no large sample volume is available. In addition, the same sample for all experiments avoids sampling errors.