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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 |