Ian Ronningen- Pesticides and Toxins in fragrances and natural flavors
The focus of my analytical problem is the presence of residual pesticides, or natural toxins in natural flavors and fragrances. The raw materials for natural flavors and perfumes are frequently sourced from fruits, spices, herbs, flowers, microbial fermentation and a number of other agricultural sources (1). Extraction is commonly done via steam distillation, expression, tincturing, distillation, and a number solvent extraction techniques. These are then commonly concentrated for a number of reasons, including added stability and ease of transportation (1). Any toxins, pesticides compounds present would also be concentrated, which would eventually reach the consumer (3). Produce is generally cleaned and treated before the fragrance or flavor is extracted but treatments are kept mild to preserve the character of the raw material. Another aspect to this is flavor and fragrance companies sourcing rare and unique raw materials from remote and undeveloped countries that may have sup-par quality control measures, accidental inclusion of heavy metals from groundwater, or use of banned pesticides still remain and issue. Part of my interest in this topic is consumer perception that "naturally" flavored products are healthier than artificial flavors.
The hypothesis is that these toxins and pesticides are concentrated in the raw materials for naturally flavors and fragrances. These could have an acute or chronic health impact on human health. Additional financial impact could stem from levels of contaminants below a level that could pose harm to the consumer.
Target analytes include common pesticides, naturally produced plant toxins, heavy metals.
These matrixes will commonly be alcohol, powdered, in oil emulsions, and occasionally in water. Matrices will be complex, and methodology will require high throughput, high sensitivity, and rapid multi-residue detection for application (2).
(1) Reineccius, Gary. Flavor Chemistry and Technology. Boca Raton : Taylor & Francis, c2006.
(2) Seiber, J N. "Contributions of Pesticide Residue Chemistry to Improving Food and Environmental Safety: Past and Present Accomplishments and Future Challenges." Journal of agricultural and food chemistry 59.14 (2011):7536-7543.
(3) Culliney, T W. "Pesticides and natural toxicants in foods." Agriculture, ecosystems & environment 41.3-4 (1992):297-320.
UV-Vis Absorption Spectrometry-
Driss et al (1993) has shown application of UV-Vis absorption in water at a wavelength of 254 nm in water, for simultaneous detection of parathion-methyl, parathion, fenitrothion, diazinon, azinphos-methyl, azinphos methyl, phosmet, carbaryl. Additionally another study reported detection of a mixture of seven insecticides using a wave length of 220 nm in a 80:20 or 70:30 methanol to water solution (Farran, 1988). A wave length of 290 nm was selected by Sultatos et al, however in this publication they did note that the maximum variation of each compound did vary somewhat, their detection included: Parathion, Paraxon, p-Nitrophenol, Chlorpyrifos, Chlorpyrifos Oxon, Trichloro-2-pyridinol, Methyl Chlorpyrifos, Methyl Chlorpyrifos Oxon, Azinphos Methyl, Coumaphos. Two of these papers also took time to analyze the oxon form of these toxins as oxons are converted into compounds with higher toxicity, and fat solubility in the human liver than their native form (Davies, 1975). All three of these methods use a separation method before detection, in many methods this is either gas or liquid chromatography. The structural differences between the various pesticides is limited and as such distinction between them using UV-Vis without a separation technique would be extremely challenging, if not impossible.
Molar absorptivity has been a challenge to find for all potentially applied pesticides, however research has been done to investigate molar absorptivity on some organophosphates, and some chloroacetanilides. These include: ε = 466 ± 41 for alachlor, ε = 3558 ± 323 for diazinon, ε = 5.5 ± 0.5 for dichlorvos, in units M-1cm-1 (Feigenbrugel, 2005). Although some literature values were identified, extensive literature was not found relating to the molar absorptivity of potential contaminants, this could stem from the application of mass spectroscopy for complex food matrices, do note this is speculative.
With identified analytes UV-vis absorption is expected, especially considering many of the organophosphates have a phenolic ring, or a nitrogen containing ring such as pyridine, pyrazine, pyrimidine. These compounds alone can be detected using UV-Vis spectroscopy, and additional ring substitutions would most likely enhance the likelihood of detection.
Please see comment on fruit proteins allergen post.
BLOG 6. Chemical structure and standards
Analytical Standard Sources-
Atrazine-Fluka 99% Pure- 250mg for $35.20. Product # 45330
Alachlor- Fluka 99% Pure- 250 mg for $20.70. Product # 45316 (C13 labeled 10mg for $282.50, #34086)
Diazinon- Fluka 99% Pure- 250 mg for $30.90. Product# 45428 (Deterium- 10mg for $691.10, Fluka Product# 492175)
Warfarin- Fluka 99% Pure- 250 mg for $34.50. Product#45706
Standard Preparation- Prepare samples through dilution of sample to analytical range. Using equally spaced concentrations prepared through serial dilution, analyzed in triplicate (more depending on time). Standard curve should cover potential range of analyte concentration, as an example if the expected concnetration is 50 ppm, a calibration curve should include many points (5-100 ppm) and be linear in that region. Additionally standard addition of a selected (potentially a not present pesticide which is spiked at a certain level) could be used in this case.
Mass Spectra for Atrazine (ESI Positive Mode):
Source is (4) Schreiber, A. "Application of spectral libraries for high-performance liquid chromatography-atmospheric pressure ionisation mass spectrometry to the analysis of pesticide and explosive residues in environmental samples." Journal of chromatography 869.1-2 (2000):411.
Atrazine Spectra: For Blog 7:
Davies J, Barquet A, Vaclavek C, et al. Human Pesticide Poisonings by a Fat-Soluble Organophosphate Insecticide. Archives of Environmental Health. December 1975;30(12):608.
Driss, M R. "Determination of carbaryl and some organophosphorus pesticides in drinking water using on-line liquid chromatographic pre-concentration techniques." Journal of chromatography 639.2 (1993):352-358.
Farran, A. "Identification of organophosphorus insecticides and their hydrolysis products by liquid chromatography in combination with UV and thermospray-mass spectrometric detection." Journal of chromatography 455(1988):163.
Feigenbrugel, V. "Near-UV molar absorptivities of acetone, alachlor, metolachlor, diazinon and dichlorvos in aqueous solution." Journal of photochemistry and photobiology. A, Chemistry 174.1 (2005):76
Sultatos, L G. "Determination of organophosphorus insecticides, their oxygen analogs and metabolites by high pressure liquid chromatography." Chromatographia 15.10 (1982):669.