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Note 102: Identification of Contaminants in Powdered Beverages by Direct Extraction Thermal Desorption GC/MS

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Ronald E. Shomo, II, Christopher Baker, and John J. Manura
Scientific Instrument Services
1027 Old York Road, Ringoes, NJ 08551
(presented at ASMS 2016)

Introduction

The ability to identify volatile and semi-volatile contaminants present in powdered beverages without the use of solvent extractions has several advantages including improving sample throughput, reducing the chance of a volatile component being “lost” in the extraction process and eliminating the need for solvent disposal. This study utilizes the advantages of direct thermal extraction GC/MS to identify contaminants in powdered beverages. Direct Thermal Extraction GC/MS provides for fast analysis with no carryover problems that can be associated with other Thermal Desorption GC/MS techniques.

Materials and Methods

Samples of powdered beverages included the following items:
    Coffee Creamer - Non-Dairy
  1. Kids drink mix (tropical punch)
  2. Kids drink mix (grape)
  3. Kids drink mix (lemonade)
  4. Ice tea mix (artificial sweetener)
  5. Baby formula

Desorption tubes - 4 mm ID x 4” stainless steel Silco coated, were packed with a small plug of deactivated glass wool and conditioned for 4 hours at 320C with 20 mL/min of pure Nitrogen flowing through the tubes. Conditioning oven was an SIS model 781056 with a 24 tube capacity.

The samples analyzed were placed in these pre-conditioned tubes (1-10 mg) and a second plug of glass wool placed to contain the powder.

The loaded desorption tube is placed in a SIS model TD5 Thermal Desorption system. (Figure 1), and a 35 mm preconditioned desorption needle was attached. The TD5 was attached to an Agilent 5973 GC/MS coupled to a 6890 GC. The GC had a SIS cryotrap installed using liquid CO2 as the cryogen. The injector was cooled to -45C during the desorption process. The TD5 desorbed the samples at 150C for 5 minutes after a 1 minute non-heated purge to remove any residual oxygen present in the desorption tube. During the desorption process a divert valve is actuated by the desorption software and allows the injection port helium flow to pass through the desorption tube and attached needle into the injection port. After the desorption process is complete the diverter valve switches the flow of helium again to allow the normal injector flow to resume. (See Figure 2)

During desorption the cryotrap remains at -45C, after the 5 minute desorption period the cryotrap is ballistically heated to 250C for 3 miniutes and the GC/MS data acquisition is initiated. The MS is scanning a mass range of 35-450 with a 1 second scan rate.

The GC column used was an SGE BP5MS 0.25 mm id x 30 m with a 0.25 um film. The column has a 5 m silguard 0.32 mm guard column on the front end. The GC operated in the split mode with a 5:1 split ratio. All desorption parameters were controlled by the TD5 software that is integrated into Agilent Chemstation program. Mass spectral data was compared against the NIST14 library software for component identification.

A blank TD tube is run between each sample to verify no cross contamination or carry over has occurred.

Results & Discussions

Sample #1 was a store brand non-dairy creamer. Packaging was a HDPE plastic bottle. There were both dioctyl and diethyl phthalate present in the product. Phthaltes are plasticiers commonly found in the plastic packaging or introduced in the manufacturing process.1,2 Tris(dimethyldithiocarbamato)iron a common fungicide was also found at < 50 ppb levels. The Fungicide is commonly used on corn. The major component of this creamer was corn syrup3.

Figure 3 shows a typical chromatogram of the powdered beverages after direct extraction TD/GC/MS. The sample was #2, tropical punch. The tropical punch was packaged in a HDPF bottle. This sample contained BHT (a common preservative)4 as well as a number of compounds associated with plasticizers including the following, styrene, N-butylsulfonamide, diethyl phthalate, dioctyl phthalate, and butyl undecyl ester phthalic acid and bisphenol A1,2.

Sample #3 was a kids drink grape flavor, packaged in a foil pouch. The sample contained ethyl acetate, and diethyl phthalate.

Sample #4 was a kids drink lemon flavor, packaged in a foil pouch. The sample contained Phenol, BHT, and diethyl phthalate.

Sample #5 was an ice tea drink packaged in a hard polypropylene container. The sample contained methyl methacrylate, BHT (not indicated on the package) and diethyl & dioctyl phthalate. Methyl methacrylate is a precursor to forming plastics4.

Sample #6 was infant formula. The product container was an HDPE box. The formula contained approximately 10 ppm of BHT (not listed on the label) and dioctyl and diethyl phthalate compounds. Also found was a trace level (< 1 ppm) of N-butyl benzensulfonamide a common precursor used in the manufacturing of plastics1. Also present was BPA at < 100 ppb concentration.

Conclusion

Direct thermal extraction GC/MS is a quick way to identify contaminates in food products without the use of solvents. Each sample has its own unique transfer line (desorption needle) and this eliminates the problem of carry over or cross contamination that is frequently present in other Thermal Desorption GC/MS methods.

As the data indicates not one of the tested samples were free from “contaminates”. All of the samples contained some level of plasticizer contamination. Plasticizers most likely originated from the product packaging, but several samples were wrapped in a protective aluminum foil, so the origin of the plasticizers was unknown. There is a growing health concern surrounding the exposure to plasticizers and according to the CDC our diet is the main source of plasticizer intake for humans5.

There is also concerns about the presence of Bisphenol A (BPA). In January 2011 the EU banne the ode of BPA in baby bottles.7 France this year has proposed that any product with BPA over 0.1% must be labeled for consumer awareness.8

References

  1. David F. Cadogan and Christopher J. Howick, “Plasticizers” in Ullmann’s Encyclopedia of Industrial Chemistry 2000, Wiley-VCH, Weinheim, doi 10.1002/14356007.a20_439
  2. Malveda, Michael P (July 2015) “Chemical Economics Handbook Report on Plasticizers”
  3. Yehye, Wageeh A.; Rahman, Noorsaadah Abdul; Ariffin, Azhar; Abd Hamid, Sharifah Bee; Alhadi, Abeer A.; Kadir, Farkaad A.; Yaeghoobi, Marzieh (2015). "Understanding the chemistry behind the antioxidant activities of butylated hydroxytoluene (BHT): A review". European Journal of Medicinal Chemistry 101: 295–312. doi:10.1016/j.ejmech.2015.06.026. PMID 26150290
  4. Polymethyl acrylate and polyethyl acrylate, Encyclopædia Britannica. Encyclopedia Britannica. Retrieved 2012-05-09.
  5. Third National Report on Human Exposure to Environmental Chemicals, (PDF) U.S. CDC, July 2005. Archived April 1, 2007 at the Wayback Machine
  6. James Hamblin (11 February 2015). "The Food Babe: Enemy of Chemicals". The Atlantic. Retrieved 12 September 2015.
  7. “Umstrittene chemikalie: EU-Behorde Senkt Granzwert fur Bisphenol A.” Der Spiegel. January 21, 2015
  8. Current SVHC intentions – Bisphenol A