techniques for detection of pesticides Flashcards by Nancy He

True/False: pesticide compounds share very similar chemical properties

False: represent WIDE RANGE of chemical groups; different properties and uses

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Where are the approved pesticides lists found, and from what governing bodies? (3)

USA: Glossary of Pesticide Chemicals (USFDA)
Canada: Registered Products (Health Canada)
EU: EU Pesticide Database (EC)

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What are the applications of pesticides?

Kill unwanted stuff

herbicides, fungicides, insecticides, acaricides (mites/ticks), crop bacteriocides, nematicides, molluscicides, rodenticides, repellent, biocides, growth regulators

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3 metal based pesticide types:

arsenic compounds
copper compounds
mercury compounds

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Organo_____, organo____, and organo____ are all examples of pesticide types

organotin, organophosphorus, organochlorine

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Carbamates are (organic/inorganic) compounds, and are (aromatic/non-aromatic), and contain ____. With the addition of ___, it becomes ___-carbamates.

organic
non-aromatic
N
S
thiocarbamates

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triazine and nitrophenols both contain ____ and ____.

N, ring structure

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Where can consumers get information about pesticide residues in food?

USDA’s pesticide data program (PDP) - Yearly report

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How are pesticides classified based on acute toxicity?

WHO classification by hazard: based on LD50 in rat (oral and dermal)

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The (higher/lower) the LD50, the less hazardous the substance.

higher

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What are the acute toxicity classes (from WHO) for pesticides?

Ia: extremely hazardous
Ib: highly hazardous
II: moderately hazardous
III: slightly hazardous
U: unlikely to be acute hazard

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In order for a pesticide to be considered U class, it ______.

Must have LD50 (both oral/dermal) 5000 or higher

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the LD50 tends to be (higher/lower) for the dermal application vs oral.

higher

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carbamates are also known as:

carbofurans

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What pesticide has been shown to pose a risk to bees?

Neonicotinoids

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How were standard pesticide safety tests conducted by Health Canada?

Animal tests (beagles)
Fed pesticides, kill and dissect for study
(mandatory 1 year testing)
*planned to abolish practice

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Coumarins can have what effect on human health?

disrupt vit K1 cycle; death at low dose

Organochlorines and _____ are classified as group ____ by IARC, meaning they are:

organophosphates
2B
possibly carcinogenic to humans

What pesticides can cause neurotoxicity in humans, and how?

carbamates

cholinesterase inhibition

The large food corporation ____ was recently brought to court to prove the safety of its pesticides, namely _____, a type of ____, which is widely used and linked to ____.

monsanto
glyphosate; herbicide
cancer

What are the regulatory guidelines for pesticide residues in food?

Canada: Pest Control Products Act (PCPA)
USA: Federal Food, Drug, and Cosmetics Act (FFDCA)
EU: No.396/2005 (EC)
*regulatory MRLs

What types of extraction are used for pesticide residues?

SPE
solvent
QuEChERS

What is “QuEChERS?”

streamlined and simplified preparation process (replace homogenizing, filtering, extraction)
agitate with acetonitrile and other reagents
centrifuge, take aliquots

What analysis technology is used for pesticides? (5)

LC-FLUO
LC-UV
LC-MS/MS

GC-MS
GC-MS/MS

what pesticides can be used with fluoremetric detection?

OPPs | can use HPLC-FLUO

What analytical techology is considered the gold standard? What separation type is it coupled to (3)?

MS/MS (tandem MS) | coupled to GC, HPLC, UHPLC

what are 3 emerging techniques for analysis of pesticides?

1. field portable tech 2. novel MS techniques 3. sensors and biosensors

What are portable field technologies and what advantage does it offer (3), and what are disadvantages (3)?

smaller machines that can be taken on site +doesn't require transport of sample (which could lead to contamination, losses); cheaper; fast -But less accurate and sensitive than bigger machine; more interference (less preparation of sample); *small gas container so need to analysis quickly

In portable analysis systems, there is much more _____ due to less sample prep and decreased ____.

interference; sensitivity of machine

An example of an emerging MS technique:

DART (direct analysis in real time)

What is the major advantage of DART systems? How does it compare to standard MS?

no sample prep! Use food sample directly not as accurate since lot of interference, but can give approximation much faster and easier

biosensors consist of a ___ and a ___. What is the role of these parts?

biological recognition element: recognize pesticide | physical transducer: translate into measurable signal

the 4 types of physical transducers for biosensors:

1. electrochemical 2. optical/optoelectronic 3. piezoelectric 4. thermal

Name the types of optical transducers: (5)

1. UV-vis 2. luminescence/fluorescence 3. surface plasmon resonance 4. light based potentiometric 5. total internal reflection

Name the 2 piezoelectric transducers:

1. quartz crystal microbalance | 2. surface acoustic wave sensor

The 3 types of biological recognition elements in biosensors:

1. whole cell-based 2. enzyme based 3. affinity biomolecule based

What are examples of enzyme based biol. recognition elements?

1. inhibiting cell respiration (more compound, less cell respiration) 2. induce specific catalytic protein (more compound, more active protein)

What are the 3 affinity biomolecule based biol. recognition elements?

1. antibodies 2. receptors 3. nucleic acids

What are the types of electrochemical transducers for biosensors? (3)

1. potentiometric 2. amperometric 3. calorimetric

What are the types of thermal sensors used as transducers? (2)

1. isothermal titration calorimetry | 2. heat sensitive changing color film

What are the enzyme based biol. recognition elements for biosensors? (3)

1. transforming substrates 2. measure INHIBITION of enzyme activity (more compound, more inhibition, less product made) 3. modulate cofactor enzyme

A biosensor using antibodies is known as an: How does it work? What has this been used for?

immunosensor analyte recognized by specific antibody or antibody fragment detect paraquat in potatoes