# Green Analytical Chemistry--Recent Innovations
## 3 Innovations in Green Analytical Techniques
### Real-Time and In-Process Monitoring
#### 3.3.2 Electrochemical Methods  
Electrochemical techniques play a crucial role in real-time and in-process monitoring, offering high sensitivity, rapid response times, and minimal environmental impact. These methods are widely used in industrial process control, environmental monitoring, and biomedical diagnostics, aligning with green analytical chemistry by reducing reagent consumption, minimizing waste, and enabling on-site analysis. Among these, electrochemical aptamer-based (EAB) sensors offer a unique capability for continuous, in vivo molecular monitoring. EAB sensors function independently of the chemical reactivity of their targets, enabling real-time detection of small molecules, drugs, and metabolites in complex biological environments [73]. These sensors have demonstrated high-frequency, seconds-resolved measurements of various analytes in live animal models, including therapeutic drugs and metabolic biomarkers, highlighting their potential in biomedical and environmental applications. The key advantage of EAB sensors lies in their modular design, which allows the selection of aptamers specific to a wide range of targets. This adaptability, combined with their ability to function in undiluted biological fluids, makes them a powerful tool for real-time monitoring in clinical and pharmaceutical settings. Recent advancements have focused on improving sensor stability and extending measurement duration, ensuring that these sensors remain functional for long-term in vivo applications. [PERSON] et al. [74] highlighted the significance of paper-based electrochemical analytical devices (ePADs) for real-time and in-process monitoring in pharmaceutical applications. These low-cost, sustainable sensors enable rapid detection of active pharmaceutical ingredients (APIs), excipients, and contaminants, ensuring efficient quality control. Advancements in screen-printed electrodes (SPEs) and carbon-based nanomaterials have improved ePAD sensitivity and selectivity while maintaining eco-friendly workflows. Multiplexing ePAD platforms further enhance simultaneous analyte detection, reinforcing green analytical chemistry principles. [PERSON] and co-workers [75] developed a wireless, transient electrochemical sensor for real-time nitric oxide (NO) detection, demonstrating high selectivity and a low detection limit (3.97 nM). This innovative sensor successfully monitored NO levels in cultured cells, organ tissues, and live mammals, highlighting its potential for biomedical diagnostics, environmental monitoring, and process control applications. A key advancement of this technology is its biodegradable sensor components, which minimize medical waste and eliminate the need for surgical removal in implanted applications. Additionally, its wireless data transmission capability enhances real-time monitoring without bulky instrumentation. These innovations reinforce the role of electrochemical sensors in sustainable, real-time analytical applications, aligning with green analytical chemistry principles. Electrochemical sensors have gained significant attention in green analytical chemistry due to their ability to provide rapid, cost-effective, and environmentally friendly detection of various analytes. These sensors are widely implemented across multiple industries, demonstrating their practical application in sustainable practices, as summarized in Table 3. In environmental monitoring, electrochemical sensors are used to detect heavy metals, greenhouse gases, and air quality parameters. Companies such as Sensorix (Bonn, Germany), Figaro USA Inc. (Rolling Meadows, IL, USA), and Cambridge Sensotec (St Ives, UK) have developed advanced sensor-based technologies that facilitate real-time pollution control, reducing environmental impact. Similarly, in agriculture, Multi Nano Sense Technologies (Nagpur, India) has integrated electrochemical sensors to monitor soil moisture, nutrient levels, and plant health, optimizing resource use and minimizing agricultural waste.