وظیفه تکنیک های استخراج سبز در شیمی تجزیه سبز

ABSTRACT The role of green extraction techniques in Green Analytical Chemistry

In a changing world, with the tremendous impact of human presence, the urgent need for sustainability of all of our activities has accelerated the evolution from the chemurgical paradigm to the ecological paradigm in which the environmental side effects of our chemical activities must be seriously taken into consideration [1]. Green Chemistry [2–4] and Green Analytical Chemistry (GAC) [5–9] evolved from the academic sphere to the real world, so there is a tremendous research activity on greening all aspects concerning the analysis of any kinds of sample, not only those for environmental studies. We are absolutely convinced that GAC will be really useful in the years ahead. The application of cheap, fast and environmentally safe procedures in environmental, clinical and food analysis will improve the quality of life in developing countries [10]. So, it can be seen that GAC has been the key tool to move from the chemurgical paradigm to the ecological paradigm in analytical chemistry and to create sustainable tools for challenges in the increasing demand in analysis for a clever combination of environment-friendly and cheap methodologies (see Fig. 1).

Based on the 12 principles of GAC [11], many green methods were proposed in recent years, and scientific journals have published special issues regarding GAC practice in research and applied laboratories, as can be observed in Table 1, so creating a wave that modified the concepts and the practice of analysis. In summary, GAC has been well accepted by the scientific community. However, the change from qualitative to quantitative observation of the green character of analytical methodologies has evolved much more slowly than the scientific production in the field.

In this sense, Life Cycle Assessment (LCA), a holistic tool encompassing all environmental exchanges (i.e., resources, energy, emissions, and waste) occurring during all stages of the life cycle of activities, is a useful tool, especially when applied to products or services for which the life-cycle concept and its stages are clearly defined [12]. An additional semi-quantitative criterion was developed by the Green Chemistry Institute (GCI) of the American Chemical Society (ACS). The criterion was applied to the National Environmental Methods Index (NEMI), a free Internet-searchable database of environmental methods [13]. The profile criterion was based on four key terms concerning reagents employed as:

1. persistent, bioaccumulative and toxic (PBT);
2. hazardous;
3. corrosive; and,
4. the amount and the nature of waste.

A similar criterion includes energy as a key point to be considered [14]. The addition of energy as a criterion is important due to the high reliance on non-renewable resources for production of electrical energy.

In recent years, an ecological scale was developed for the evaluation of analytical methods based on the introduction of penalty points [15]. According to it, a 100 score corresponds to a completely eco-friendly methodology, but subtracting penalty points of the method due to the volume and the toxicity of reagents consumed, energy consumed, emissions, operator hazard and waste generation. Methods are classified according to the eco-scale as:

• excellent green analysis (> 75 points);
• acceptable green analysis (> 50 points); and,
• inadequate green analysis (<50 points).

More recently, a new criterion was proposed to relate the penalty-point values to the volumes of reagents consumed and wastes generated using mathematical expressions and to associate the eco-scale value to a category class (A–G) in a so-called Green Certificate [16].