Green analytical chemistry

Question 1

There are 12 principles of green chemistry, mention some

Answer 1

1. Prevention of waste
2. Atom economy
3. Less hazardous chemical synthesis
4. Designing safer chemicals
5. Safer solvents
6. Design for energy efficiency
7. Use of renewable feedstocks
8. Reduce derivatives
9. Catalysis
10. Design for degradation
11. Real time analysis for pollution prevention
12. Inherently safer chemistry for accident prevention

Question 2

There are 7 principles of green analytical chemistry. Mention some

Answer 2

1. Prevent or reduce formation of waste
2. Use less toxic chemicals
3. Design energy efficient analytical systems
4. Avoid chemical catalysts, derivatisation reagants, auxiliary substances
5. Catalysis is better than stoichiometric reactions
6. In situ analysis is better than off-line analysis
7. Use safer chemistry to prevent accidents

Question 3

Is hexane or heptane better to use (better for the environment)?

Answer 3

Heptane

Question 4

What are the steps of sample preparation?

Answer 4

Extraction
Homogenousation
Enrichment (increase concentration of analyte)
Removal of interferences (increased selectivity)
Trueness and precision

Question 5

Sample preparation is full of biases, mention a few.

Answer 5

From where you pick the sample (is it representative?)

How you extract it

Which solvent you use

Question 6

How do we design a “green” solvent?

Answer 6

Low toxicity to humans and environment
Naturally occurring (could be about an already installed infrastructure such as water)
Produced from renewable source
Energy efficient in terms of production and usage

Question 7

Which solvent is better methanol or ethanol?

Answer 7

Methanol is toxic to humans, ethanol is easily produced

Question 8

What is environmental performance?

Answer 8

It is how we calculate how “green” something is

Question 9

Are chlorinated solvents an issue?

Answer 9

Yes and currently no other solvents to replace it because the physiochemical properties of chlorinated solvents are hard to find in other solvents

Question 10

What is EHS?

Answer 10

Environment, Health and Safety. A standard industry uses a lot.

Question 11

Which organic solvents are the most “green”?

Answer 11

Ethanol and methyl acetate

Question 12

What is a solvent selection tool?

Answer 12

Simulation tool to help you decide on the best solvent to use. Calculates what chemical properties you need.

Question 13

Is supercritical carbon dioxide a sustainable alternative to organic solvents?

Answer 13

Yes

Question 14

Does supercritical CO2 dissolve polar compounds?

Answer 14

No

Question 15

Can pressured hot (subcritical) water be used as a solvent?

Answer 15

Yes

Question 16

Is CE a greener separation method?

Answer 16

Yes

Question 17

What is LCA?

Answer 17

Life cycle assessment

Question 18

What are CO2 equivalents?

Answer 18

A way to classify green house gasses, they are “translated into” CO2 to be able to compare

Question 19

Select 3 out of 12 principles of green chemistry and explain them in the context of green analytical chemistry methodology

Answer 19

Prevent waste
Safer chemicals
Efficient

Question 20

What are the biggest challenges to achieve greener analytical chemistry methods?

Answer 20

Solvents (especially hard to find replacement for chlorinated solvents)
Efficient systems

Question 21

What are the requirements for a solvent to be considered “green”?

Answer 21

From renewable sources
Not toxic to humans or environment
Not too energy demanding to use or produce
“Recyclable”

Question 22

What is contradictory about hexane and heptane with regards to which one is greener?

Answer 22

Hexane is toxic to the environment but heptane has a higher boiling point and thus requires more energy. It is more expensive too.

Question 23

Describe EHS and LCA as approaches to describe greenness

Question 24

Define the term functional unit from LCA

Answer 24

It is the aim of the study, a quantified function provided by the product/system that is being studied. When you compare things they have to have the same function. eg. a water bottle with tap water does not really have the same function as a sparkling water sold on a bottle.

Question 25

Define the term system boundaries from LCA

Answer 25

It is the scope of the study. Limits of time and geography. What should be included, machines and personnel? Start and end point of study

Question 26

Define the term hotspot analysis from LCA

Answer 26

You can divide up the system you are looking at into categories such as "resources", "production", "consumption" and "waste treatment"

Question 27

Define the term effect category from LCA

Question 28

What is miniaturisation?

Answer 28

Lab on a chip is an example. Uses less of everything. Smaller inner diameter of column and smaller/fewer stationary particles. Microfluidics

Question 29

What is hyphenation?

Answer 29

A technique where a separation technique is coupled with an online spectroscopic detection technology is known as hyphenated technique, e.g., GC–MS, LC-MS. Another example is that extraction and liquid chromatography happens in the same process

Question 30

Motivate why hyphenation and miniaturisation are two approaches in green analytical chemistry

Answer 30

Miniaturisation uses less of everything. Hyphenation does things more efficiently

Question 31

Why is in-situ analysis considered a green approach?

Answer 31

Samples do not have to be transported (?)

Question 32

List three examples of green solvents and motivate why they are considered green

Answer 32

Subcritical water (already installed infrastructure and not harmful to environment, the heating is an issue though) Supercritical CO2 (it will be reused and is a byproduct from other processes so very green, not toxic and does not contribute to greenhouse gasses) Ethanol (not toxic to humans or environment, relatively low boiling point, has a good low score on the EHS scale)

Question 33

Why is supercritical CO2 considered green?

Answer 33

it will be reused and is a byproduct from other processes so very green, not toxic and does not contribute to greenhouse gasses

Question 34

How would you compare two different analytical methods in terms of their environmental impact? Will you use methods/tools to enable comparison?

Answer 34

One could use the EHS score for the methods, looking at the solvents used, the energy used. Yes it is good to use well-established methods and tools

Question 35

An analytical method consists of 1) sample prep 2) chromatography 3) detection Explain how to make each step greener

Answer 35

1) Important to use a "green" solvent for dissolving the sample. Use an energy efficient way of extraction. Perhaps have the extraction and chromatography in the same process (hyphenation).

Question 36

Explain briefly the two concepts of sustainable development and green chemistry, what are similarities and differences?

Answer 36

Sustainable development is a very broad term that covers many different fields. Green chemistry is a subsection of sustainable development and is a way of making the chemical process more environtally friendly.

Question 37

In EHS each category has 3 points and sums up to a total of 9. What are the three points in each category (Environment, Health and Safety)

Answer 37

E: Pollution of water Pollution of air Biodegradability H: Chronic toxicity Irritability (breathing, eczema) Acute toxicity S: Reactivity Flammability/ explosivity Release potential

Question 38

Mention some organic solvents that have a good EHS score

Answer 38

Methyl acetate Ethanol Methanol Ethyl acetate Propanol Butyl acetate Butanol

Question 39

What is in-situ analysis?

Answer 39

analysis is conducted at the site where production happens

Question 40

How do you do an LCA?

Answer 40

Define aim (functional unit) and scope (system boundaries). Inventory (energy, materials) Assessment of environmental impact Interpretation of results