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food toxicants and analysis > techniques for detection of pesticides > Flashcards

techniques for detection of pesticides Flashcards

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1
Q

True/False: pesticide compounds share very similar chemical properties

A

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

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2
Q

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

A

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

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3
Q

What are the applications of pesticides?

A

Kill unwanted stuff

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

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4
Q

3 metal based pesticide types:

A

arsenic compounds
copper compounds
mercury compounds

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5
Q

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

A

organotin, organophosphorus, organochlorine

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6
Q

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

A 
organic
non-aromatic
N
S
thiocarbamates
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7
Q

triazine and nitrophenols both contain ____ and ____.

A

N, ring structure

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8
Q

Where can consumers get information about pesticide residues in food?

A

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

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9
Q

How are pesticides classified based on acute toxicity?

A

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

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10
Q

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

A

higher

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11
Q

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

A 
Ia: extremely hazardous
Ib: highly hazardous
II: moderately hazardous
III: slightly hazardous
U: unlikely to be acute hazard
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12
Q

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

A

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

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13
Q

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

A

higher

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14
Q

carbamates are also known as:

A

carbofurans

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15
Q

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

A

Neonicotinoids

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16
Q

How were standard pesticide safety tests conducted by Health Canada?

A

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

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17
Q

Coumarins can have what effect on human health?

A

disrupt vit K1 cycle; death at low dose

18
Q

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

A

organophosphates
2B
possibly carcinogenic to humans

19
Q

What pesticides can cause neurotoxicity in humans, and how?

A

carbamates

cholinesterase inhibition

20
Q

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 ____.

A

monsanto
glyphosate; herbicide
cancer

21
Q

What are the regulatory guidelines for pesticide residues in food?

A

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

22
Q

What types of extraction are used for pesticide residues?

A

SPE
solvent
QuEChERS

23
Q

What is “QuEChERS?”

A

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

24
Q

What analysis technology is used for pesticides? (5)

A

LC-FLUO
LC-UV
LC-MS/MS

GC-MS
GC-MS/MS

25
Q

what pesticides can be used with fluoremetric detection?

A

OPPs

can use HPLC-FLUO

26
Q

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

A

MS/MS (tandem MS)

coupled to GC, HPLC, UHPLC

27
Q

what are 3 emerging techniques for analysis of pesticides?

A
  1. field portable tech
  2. novel MS techniques
  3. sensors and biosensors
28
Q

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

A

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

29
Q

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

A

interference; sensitivity of machine

30
Q

An example of an emerging MS technique:

A

DART (direct analysis in real time)

31
Q

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

A

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

32
Q

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

A

biological recognition element: recognize pesticide

physical transducer: translate into measurable signal

33
Q

the 4 types of physical transducers for biosensors:

A
  1. electrochemical
  2. optical/optoelectronic
  3. piezoelectric
  4. thermal
34
Q

Name the types of optical transducers: (5)

A
  1. UV-vis
  2. luminescence/fluorescence
  3. surface plasmon resonance
  4. light based potentiometric
  5. total internal reflection
35
Q

Name the 2 piezoelectric transducers:

A
  1. quartz crystal microbalance

2. surface acoustic wave sensor

36
Q

The 3 types of biological recognition elements in biosensors:

A
  1. whole cell-based
  2. enzyme based
  3. affinity biomolecule based
37
Q

What are examples of enzyme based biol. recognition elements?

A
  1. inhibiting cell respiration (more compound, less cell respiration)
  2. induce specific catalytic protein (more compound, more active protein)
38
Q

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

A
  1. antibodies
  2. receptors
  3. nucleic acids
39
Q

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

A
  1. potentiometric
  2. amperometric
  3. calorimetric
40
Q

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

A
  1. isothermal titration calorimetry

2. heat sensitive changing color film

41
Q

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

A
  1. transforming substrates
  2. measure INHIBITION of enzyme activity (more compound, more inhibition, less product made)
  3. modulate cofactor enzyme
42
Q

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

A

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

food toxicants and analysis (11 decks)

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