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Food Contaminants

Food Analysis Final Exam

What are the three main types of food contaminants? Chemical, mycotoxin, microbiological
Define tolerance level. The threshold level below which no adverse effects are observed.
Tolerance levels are established the ____ and enforced by either the ____ or ____. EPA, FDA, USDA
What are the two types of analytical methods for looking at food contaminants? Screening, quantitative
What is the purpose of screening methods? To quickly assay a large number of samples for presence of one or more contaminants.
Name three types of screening methods. TLC, enzyme inhibition, immunoassays
Name three types of quantitative methods. GC, HPLC, ELISA
What are the general steps of sample preparation when looking for contaminants in a sample? Homogenization, extraction, fractionation/clean-up, concentration, derivatization.
Chromatographic analysis is used for _____ in analysis of contaminants and residues. separation
What are the three classes of analytes for extraction and cleanup? Volatile, sem-volatile, and non-volatile organic compounds.
____ are analyzed by using headspace techniques. VOC
____ are analyzed by GC. SVOC
____ are analyzed by HPLC. NVOC
Describe solid-phase microextraction. Analyzte is partitioned between sample matrix and headspace and polymer-coated fiber.
What is QuEChERS used for? To extract multiple pesticide residues.
Describe microwave-assisted solvent extraction. Uses electromagnetic radiation to desorb organics from their solid matrix.
Describe accelerated-solvent extraction. Uses a limited amount of organic solvents at elevated temperatures to extract solid samples in short amount of time.
Describe derivatization. Process of structural modification of analyte through multiple chemical reactions.
Give three reasons why derivitization is used as a sample preparation technique. Enhance thermal stability/volatility, increase selectivity of detection, increase sensitivity of detection.
T or F: GC, HPLC, and immunoassays can be used to quantify all three types of contaminants. True
T or F: TLC can be used to screen for antibiotics. False
Name the three classes of pesticides. Herbicides, insecticides, fungicides
What does NOAEL stand for? No Observed Adverse Effect Level
Risk assessments are used to establish what three parameters for pesticides? NOAEL, ADI, MRL
What are the steps for both MRM and SRM? Sampling, extraction, fractionation/cleanup, chromatographic separation.
T or F: HPLC is the most routinely used method for pesticide residue determination. False
What types of detectors can be used in combination with HPLC? UV, fluorescence, MS
What types of detectors can be used in combination with GC? Flame photometer, electron capture, thermoionic, MS
Name three of the major classes of mycotoxins. Alfatoxins, ochratoxins, patulin, fumonisins.
T or F: The sampling step is the largest contributor to total error in mycotoxin analysis. True
The use of drugs in animal feeds is regulated by what agency? Center of Veterinary Medicine (CVM)
Microbial growth inhibition is a method used to analyze _____ residues. antibiotic
What methods are used to analyze GMOs? DNA methods such as PCR, protein methods such as immunoassays
What is the major concern with analysis of other chemical constituents? Time-consuming and expensive methods, limiot of detection major concern.
T or F: It is possible to measure all forms of sulfite in foods. False
What methods can be used to measure sulfites in food? Monier-Williams method, Ripper method, enzymatic method, ion chromatography, HPLC
Why is the illegal substance melamine added to foods? Increases apparent protein content.
What method is used to measure 4-methylbenzophenone in foods? LCMS
What methods are used to measure BPA in foods? GCMS, LCMS, ELISA
What methods are used to measure melamine in foods? LCMS, GCMS, IR, immunoassays
What method is used to measure furans in foods? Headspace and GCMS
What method is used to measure benzene in foods? Headspace and GCMS
What method is used to measure 3-monochloropropane in foods? GCMS
What method is used to measure perchlorate in foods? Ion chromatography-tandem MS
Created by: goberoi
 

 



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