Judging the Greenness of Analytical Method using Ecological Foot Prints: A Green Metric Approach
Naga Prashant Koppuravuri, Suvarna Yenduri*, Varalakshmi H N
Faculty of Pharmacy, Sri Adichunchanagiri College of Pharmacy, Adichunchanagiri University, B.G. Nagar, Karnataka - 571448, India.
*Corresponding Author E-mail: suvarna.ph52@gmail.com
ABSTRACT:
Green Analytical Chemistry advocates for the utilization of environmentally friendly chemicals and reagents, energy conservation in laboratory equipment, and the reduction of waste to a minimum. Recent developments in analysis involve the reduction in size of analytical instruments, the use of solventless or solvent-minimized extraction techniques, and the utilization of less hazardous solvents. The twelve principles of Green Analytical Chemistry (GAC) guide these advancements, which include sustainable practices into analytical procedures. Although these guidelines give direction, unavoidable processes may still hinder green analytical techniques. Thus, analytical procedures must be assessed for their impacts on the environment and occupation and minimised if feasible. To measure the greenness of analytical methodologies, many criteria have been devised. The Analytical Eco-Scale, Analytical Greenness (AGREE) Metric, and Green Analytical Procedure Index (GAPI) calculate green indexes for analytical procedures by considering several components of the process. This overview explains the fundamentals of the tools or metrics and discusses their use in analytical methods. It also highlights user positives and downsides of various measures. Comparing evaluation findings based on solvents and reagents availability helps researchers identify the most eco-friendly strategy. This work intends to inspire new green analytical chemistry views and advances by illuminating these assessment techniques and their consequences.
KEYWORDS: Green Analytical Chemistry, Green Metrics, Eco-friendly, Green solvents, Miniaturisation.
INTRODUCTION:
GAC or Green analytical chemistry, advances laboratory sustainability. Miniaturization of analytical instruments and sample preparation, solventless extraction, and non-toxic solvents are all prerequisites for GAC1,2,3,4. Scientists recognize and implement these techniques in laboratories and institutions. Conventional analytical techniques consider LOD, recovery, linear range, and accuracy.
Development of analytical methods must incorporate GAC concepts. The selection of processes according to analytical performance, GAC values, and cost may enhance analytical techniques, according to studies5,6,7.
Thus, all these considerations must be considered while choosing an analytical method. Many measurement systems quantify the eco-friendliness of chemical activities, including organic compound synthesis8-12. The environmental impact factor, reaction mass efficiency, and atomic economy are utilized to assess the greenness of chemical processes. Nevertheless, pharmaceutical and perfumery companies may require more specific criteria13,14. These metrics are not feasible for green analytical chemistry due to their dependence on reaction product mass (Hanson et al., 2005). Green analytical chemistry metrics may be computed per analytical result and require energy and material inputs15,16.
Green Analytical chemistry and its Metrics:
The analytical procedure for environmental impact assessment has been enhanced by GAC17. As analytical procedures identify specific chemicals, they are more limited in scope compared to industrial processes. The contamination of analytical processes, in contrast to industrial contaminants, is dispersed. Since industrial chemical processes generate outputs, inconsequential inputs are considered refuse18. On the contrary, analytical methodologies aim to obtain precise results. While complete elimination of analytical waste is unachievable, it can be mitigated through refined procedures. Alternatives and analytical methods must be evaluated for their environmental impact. Scholars have the potential to advance green analytical chemistry through an examination of the environmental impacts associated with analytical methods. In accordance with the GAC principles, a number of instruments were developed to evaluate the environmental friendliness of an analytical method. NEMI, Ranie and Driver, Analytical Eco-scale, AGREE, GAPI, AMGS, and others are among them19.
NEMI (National Environmental Method Index) pictogram is a circle with four quadrants representing analytical approach components. First, method compounds must not be Persistent, bio-accumulative, or Toxic. Second, the plan must not employ K, F, P, U hazardous wastes. Third, avoid corrosive analysis by keeping the sample's pH 2–12. The fourth and final criteria requires less than 50g of waste. Visualising the NEMI symbol shows the procedure's environmental impact. However, NEMI labelling has limitations such as giving broad data without numbers and also there is need to compare each chemical to lists to determine status20. A novel RP-HPLC method for the determination of Piperine obtained from black pepper in different dosage forms was taken as a model for application of green metrics as the greenness assessment was not done for this method21 The optimized chromatographic conditions for selected method include Mobile phase- 0.1% OPA: ACN (50:50), Flow rate of 1 ml/min, Diluent is Water: ACN (50:50), Run time is 5 min, Column - BDS C8 (150mm x 4.6mm x 5µ, Rt is 2.4min. The existing analytical method for Piperine measurement is simple, fast, economical, specific, however its environmental friendliness was not reviewed. NEMI was used to analyse greenness step-by-step. Figure 1 shows the pictogram. Analysis uses buffer (0.1% OPA) and TRI-listed mobile phase Acetonitrile; therefore, the pictogram's first quadrant is blank. Orthophosphoric acid and acetonitrile are hazardous waste in this procedure, second-quadrant is blank. OPA corrodes, pictogram's empty third quarter. Less than 50ml sample waste, Green fourth quarter. In their 2011 study, de la Guardia and Armenta suggested simplifying the NEMIpictogram.1
Figure 1: NEMI Pictogram for the selected HPLC method
The analytical greenness assessment method by Raynie et al. (2014) uses green chemistry. The study addresses Health, Safety, Environmental, Energy, and Waste risks. NFPA SECTION 704 process chemical toxicity and flammability values evaluated risk. A score of 1–3 for considered parameters were given. In this pentagram, environmental impact colours each criterion green, yellow, or red. It visualises contradictory green criteria to assist researchers draw decisions22. The semi-quantitative Raynie and Driver tool or AGP (Analytical Greenness Profile) provides more detail than NEMI labelling. Table-1 presents the Raynie and Driver tool approach and technique greenness characteristics.
Kucharski and Namieśnik (2012) proposed a color-coded pentagram technique to assess the environmental impact of analytical techniques, improving their greenness rating. Though basic, Raynie and Driver omit GAC necessities. Better solutions employing all 12 GAC principles lower its popularity. AGP was used to measure HPLC greenness. ACN and orthophosphoric acid are NFPA health hazards 2 and 3. NFPA rated ACN and Orthophosphoric acids three for flammability and instability, making the second pentagram yellow. HPLC produced a yellow third pentagram in 1.5 kWh. Since one sample produced less than 50ml of rubbish, the run time was green. Pictogram was green and safe since volume was less than 50 ml (Figure 2).
Table 1: AGP procedure for Raynie and Driver tool
|
S. No |
Criteria |
Green |
Yellow |
Red |
|
1 |
Health hazard (NFPA health hazard score) |
Slightly toxic (0 or 1) |
Moderately toxic (2 or 3) |
Highly toxic or carcinogenic (4) |
|
2 |
Safety hazard (NFPA flammability score) |
0 or 1 |
2 or 3 |
4 |
|
3 |
Environmental hazard (Amount of chemicals) |
< 50g |
50 – 250 g |
> 250g |
|
4 |
Energy |
Low energy methods like titration, Spectrometers |
HPLC, GC, UPLC |
LC-MS, GC-MS |
|
5 |
Waste (ml (g)/ sample) |
< 50 |
50 – 250 |
250 |
Figure 2: Pictogram by Raynie and Driver tool for HPLC method
The Analytical Eco-Scale (AES), created by Namiesnik et.al., evaluates analytical techniques semi-quantitatively. Academics can utilise this tool for several purposes like choose and compare green methods. AES recommends energy, waste, and chemical reduction. Complete environmental analysis scores 100. Green analysis deviations cause reagent and solvent amounts, risks, waste, and energy penalties. Multiply sub-total PPs by danger amount to get total PPs. Formula-based Eco-Scale uses total PPs. Technique environmental safety score. Penalty-free, 100 points for greenest. Energy and environmental impacts of catalysts, reagents, and dangerous solvents are punished. Technique is green for 75+ and 50–75. Under 50 is poor green analysis. Icons of danger Tab-2 showed selective method penalties. Non-toxic chemicals aren't punished or pictogrammed. Higher risks have higher punishments. Pictograms for chemicals say "danger" not "warning". Discriminate against hazardous chemicals. Multiply by 1 for <10mL or 10g, 2 for 10-100mL (g), and 3 for 100+ mL or 100g. During analysis, vapours triple penalties. Waste is penalised with 1 point for <1mL or 1g, 3 for 1-10mL (g), and 5 for greater quantities. Trash scores 3. Safety papers and pictograms punish chemicals. Ranking analytical approaches. The score doesn't represent procedure hazards. This does not enhance methods. Half-quantitative hazard evaluations23.
The previous tools don't evaluate the analytical method's greenness using all 12 GAC principles; hence SIGNIFICANCE (Figure-3) must be measured. Numerous factors determine environmental friendliness. Productivity, waste, energy, analyst safety, and analysis strategy. Analysis may precede pretreatment and equipment placement. Simple, reagent-efficient, and waste-free analytical applications may be prioritised. Weighting criteria by context helps and results in Weights impact pictogram representation. Normalising all twelve inputs 0–1 24. Final assessments are calculated by multiplying major assessments. This clock-like graph displays the overall score and colour designation. Red-yellow-green colour segments indicate the procedure's performance in each principle, and each segment's breadth represents the principle's weight25. User-friendly software automatically generates the graph and assessment report, making assessment easy. Figure- 3 shows the results of utilising the same literature data to evaluate greenness using AGREE metrics.
Table 2: Calculation method for analytical eco scale
|
|
Reagents |
Sub-total PP |
Reagents PP Amount pp x Hazard pp |
PP of selected method |
|
Amount |
<10ml (g) |
1 |
|
ACN = 2PP x 1 = 2PP
OPA = 1PP x 1 = 1PP |
|
10-100ml (g) |
2 |
|
||
|
>100ml (g) |
3 |
|
||
|
Hazard (physical, environmental, health) |
None |
0 |
|
|
|
Less hazard Warning |
1 |
|
||
|
Moderate hazard or Danger |
2 |
|
||
|
Technique |
Energy used |
PP |
|
|
|
Titration, UV-Vis Spectrometry, fluorometry Immunoassay, FTIR, UPLC |
<0.1 kWh/spl |
1 |
HPLC = 1PP |
|
|
AAS, GC, ICP-MS, LC |
≤ 1.5 kWh/spl |
2 |
||
|
LC-MS, GC-MS, NMR, XRD |
>1.5 kWh/spl |
3 |
||
|
Occupational hazard |
Analytical process hermitization |
0 |
0 PP |
|
|
Emission of vapours and gases to the air |
3 |
|||
|
Waste |
None |
0 |
10 ml = 3PP
No treatment = 3PP |
|
|
<1ml(g) |
1 |
|||
|
1-10 ml (g) |
3 |
|||
|
>10 ml (g) |
5 |
|||
|
Recycling |
0 |
|||
|
Degradation |
1 |
|||
|
Passivation |
2 |
|||
|
No treatment |
3 |
|||
|
Total Penalty points |
∑ = |
10 PP |
||
|
Analytical Eco-scale score = 100 – Total penalty points |
100-10 = 90 |
|||
Figure 3: AGREE assessment result for selected HPLC method
Color-coded pictograms in the GAPI (Green Analytical Procedure Index) tool assess each analytical procedure environmental impact. The five-pentagram sign represents low, medium, and high environmental effect at each level 26. Glance at each analytical method's coloured fields (Figure-4). Fields green under certain conditions. GAPI tool parameters are in Table-3. Semi quantitative GAPI enhances lab practice and education. Its analytical defect detection makes GAPI suited for greener techniques 27. Evaluation results are in Figure 4. Criteria 7 and 15 are analytically weak. Waste recycling and solvents green the approach. Changing criteria 1, 4, 5, 10, 11, 12, 14 may green the procedure.
Figure 4: Pictogram obtained for the described HPLC method by GAPI tool
Hicks et al. developed the semi-quantitative Analytical Method Greenness Score in 2019 to check analytical processes environmental impact. Several factors affect solvent safety, including geometric mean-based SHE computation. Scores shouldn't define an approach's sustainability. AMGS scores reduce eco-friendliness 28. AMGS studies Solvent Health, Safety and Environmental impact of method. AMGS prioritises solvent, instrument, and safety. Interesting analytes normalise In Figure-5. Standard and sample preparation, system sensitivity, and mobile phase selection employ solvents. The gradient, flow rate, and solvent concentration determine greenness. The AMGS tool displays several ways. Lower for sustainable solvents and faster separation equipment. Analysts should decrease sample preparation for environmental solvents. Due to bulk production, commercial, certified, and ready-to-use reference standards may reduce solvent waste. Scientists should analyse solvent waste and instrument power. AMGS compares research methodologies by evaluating each methodcomponent29.
Figure 5: AMGS Score for the chosen HPLC method
Table 3: Parameters studied in GAPI tool
|
S. No |
Parameters |
Green |
Yellow |
Red |
|
1 |
Collection of samples |
In-line |
Online or At-line |
Off-line |
|
2 |
Preservation of sample |
None |
Chemical or Physical |
Physicochemical |
|
3 |
Transport |
None |
- |
Required |
|
4 |
Storage |
None |
normal conditions |
special conditions |
|
5 |
Type of method |
No sample preparation |
Simple procedure |
Extraction |
|
6 |
Scale of extraction |
Nano-extraction |
Micro-extraction |
Macro-extraction |
|
7 |
Solvents/ Reagents used |
None |
Green solvents |
Non-green solvents |
|
8 |
Additional treatment |
None |
Simple treatment |
Advanced treatment |
|
9 |
Solvent/ reagent amount (ml or g) |
< 10 |
10-100 |
>100 |
|
10 |
Health hazard (NFPA score) |
Slightly toxic (0 or 1) |
Moderately toxic (2 or 3) |
Carcinogenic (4) |
|
11 |
Safety Hazard (NFPA flammability score) |
0 or 1 |
2 or 3 |
4 |
|
12 |
Energy (kWh/sample) |
≤ 0.1 |
≤ 1.5 |
>1.5 |
|
13 |
Occupational hazard |
Hermetic sealing |
- |
Emission of gases or vapours |
|
14 |
Waste (ml or g) |
<1 |
1-10 |
>10 |
|
15 |
Waste treatment |
Recycling |
Degradation or Passivation |
No-treatment |
CONCLUSION:
Environmentally friendly analytical methods reduce chemicals, waste, energy, and solvents. This review evaluated the method's greenness using various green criteria and documented the methodology. Researchers must manually produce pictograms for green technologies like NEMI and Ranie-driver, but AGREE and GAPI online tools may generate them using method parameters, making representation easier. AGREE and GAPI analyse more GAC principles than previous methods. Analytical eco-scale punitive points assist analysts pick reagents, chemicals, precautions, and recycling. AMGS targets HPLC's bigger waste. The analyst is encouraged to reduce solvents and waste. All green tools follow GAC. Eco-friendly solvent selection and use are critical in waste-intensive chromatographic processes. Green metrics allow analysts choose a greener approach based on facilities. Green metrics also improve analyst awareness and urge them to design sustainable analytical processes and use eco-friendly facilities. This research helps analysts evaluate GAC-compliant substances in new ways.
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Received on 08.11.2023 Revised on 18.05.2024 Accepted on 10.09.2024 Published on 24.12.2024 Available online from December 27, 2024 Research J. Pharmacy and Technology. 2024;17(12):6132-6136. DOI: 10.52711/0974-360X.2024.00930 © RJPT All right reserved
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