# Green Analytical Chemistry--Recent Innovations
## 3 Innovations in Green Analytical Techniques  
### Green Separation Techniques  
#### 3.1.1 Green Gas Chromatography (GC) and Liquid Chromatography (LC)  
The pursuit of environmentally friendly analytical techniques has led to significant advancements in green gas chromatography (GC) and liquid chromatography (LC). In gas chromatography, efforts to enhance sustainability have focused on reducing or eliminating the use of toxic solvents and gases. For instance, the adoption of hydrogen as a carrier gas, instead of traditional helium, not only mitigates environmental hazards but also addresses the scarcity and high cost associated with helium. Hydrogen offers chromatographic advantages, including faster analysis times and improved resolution due to its higher diffusivity and lower viscosity compared to helium. Studies, such as those by [PERSON] et al. (2015) demonstrate its successful application in multiresidue pesticide analysis using GC-MS/MS, achieving comparable sensitivity, reproducibility, and linearity to helium-based methods. Hydrogen's renewable production via water electrolysis and reduced carbon footprint further align with green chemistry goals, making it a sustainable and cost-effective alternative for routine analytical applications ([PERSON], 2016). [PERSON] et al. (2017) developed a novel GC-MS/MS method using hydrogen as a carrier gas for the analysis of persistent organic pollutants (POPs) like dioxins and PCBs. Their approach reduced analysis time by 2.5 times while maintaining baseline resolution for critical congeners. Although sensitivity was slightly reduced, the method proved to be cost-effective, environmentally friendly, and reliable for long-term environmental analysis. This study highlights hydrogen's potential as a sustainable alternative to helium in advanced analytical applications. While hydrogen (H\({}_{2}\)) offers advantages as a sustainable carrier gas in gas chromatography, its flammability and explosion risk require careful management. Modern GC systems incorporate several safety features to mitigate these risks, including built-in leak detectors, automatic shut-off valves, and controlled flow regulation. Additionally, on-demand electrolytic hydrogen generators reduce the need for high-pressure storage, further enhancing safety ([PERSON], 2016). These advancements ensure that H\({}_{2}\) can be used efficiently while minimizing potential hazards, making it a viable alternative to helium in analytical applications. Additionally, the development of low thermal mass (LTM) technology in GC systems has substantially decreased energy consumption by enabling rapid heating and cooling cycles, thereby improving analytical efficiency ([PERSON] et al., 2017). Recently, [PERSON] et al. (2017) demonstrated the application of LTM in a portable GC-LIT-MS system for the analysis of VOCs in water. The LTM column facilitated rapid separation, achieving detection limits below 1.18 \(\upmu\)g/L for 55 VOCs within a 4 min runtime, highlighting its potential for high-throughput, energy-efficient, and field-based analytical applications. Figure 2 shows the schematic of the portable GC-LIT system. Comprehensive two-dimensional gas chromatography (GC \(\times\) GC) has also emerged as a powerful tool, offering enhanced separation capabilities while maintaining a commitment to green chemistry principles [21]. [PERSON] et al. [22] demonstrated the potential of comprehensive two-dimensional gas chromatography (GC \(\times\) GC) as a green analytical tool, emphasizing its enhanced separation efficiency and sensitivity for complex matrices. By integrating GC \(\times\) GC with triple quadrupole mass spectrometry, their method minimized the need for extensive sample preparation and solvent consumption, aligning with green chemistry principles. The GC \(\times\) GC-QqQMS method provided superior separation, effectively distinguishing co-eluting phthalates like DiNP and DiDP, ensuring accurate quantification in complex vegetable oil matrices.