The Analytical Approach Edited by Claude A. Lucchesi
Analytical Chemists Vital in Commercialization of New Food Packaging Material V. F. Gaylor The Standard Oil Company (Ohio) 4440 Warrensville Road Cleveland, Ohio 44128
Discovery t nd development of a new family of barrier resins several years ago plummeted Sohio analytical chemists into a n unusual problemsolving area. T h e thermoplastic, impact-resistant resins developed by the polymer research chemists were very effective barriers against transmission of oxygen, carbon dioxide, and most other vapors. Food packaging was thus a logical marketing goal for Sohio’s first commercialized resin. Concurrent with this marketing decision, management recognized the need for obtaining FDA approval for the new resin, trade named E3arexm 210, and the importance of analytical chemistry in obtaining it. *4nalytical research on this problem was therefore initiated early in the development program and became a vital part of the whole commercialization process as shown in Figure 1. T h e extent of the analytical work is indicated by the following figures. At least 1.632 Barex 210 bottles were ex-
Figure 1. Role of analytical research in commercialization of new food packaging
material GROUP
TIME
L
Composition and Process Discoveries Property Evatuattons
Economics Defined Marketing Goals Defined
Development of Manufacturing Technics Pilot-Scale Product Manufacture
1
Applications and Market Development
Semicommercial-Commercial
Migration Studies-Petition
FDA-Petitlon
Manufacture
Granted
A N A L Y T I C A L CHEMISTRY, VOL. 46. NO. 11, SEPTEMBER 1974
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tracted, 302 liters (80 gal) of ultrapure water was used, 168 liters (44gal) of extract was slowly evaporated from 100-ml evaporating dishes, and 1,053 analytical determinations were made. Organization
Responsibility for obtaining an FDA regulation for Barex@210 was delegated to a team representing three different disciplines. The team and its interaction with FDA and with the appropriate parts of the company are shown in Figure 2. The three team members represented a spectrum of expertise in administrative law; resin composition, properties, and processing characteristics; and instrumental and chemical analysis technics. Each member of this multidiscipline team had access to the total scientific resources of the R&D organization; thus, good two-way communication with all the various scientific and business groups involved in the resin development system was insured. Additionally, the team took advantage of advice and help available from FDA officials in the Petitions Control Branch of the Bureau of Foods. Invaluable advice on the required analysis program and on the supporting documentation requirements was received. The information developed in these joint meetings also helped the team guide process development pertaining to specific ingredients of the resin, i.e., potential migrants, and associated limitations.
Requirements for Regulation
Figure 2. Organization approach for obtaining FDA approval
Food Packaging
Before regulating a new food packaging material, the FDA must be convinced that no harmful materials migrate from the container to the food. Migration levels are determined experimentally by contacting or extracting the packaging material with food or food simulating solvents. The exposed foods or solvents are then analyzed for any migrants, Le., indirect food additives, extracted from the packaging material. Migration studies on our food packaging candidate, Barex@210, were carried out in bottles made from the new resin and with the food simulating solvents listed in Table I. The solvents were “cooked” in the resin bottles a t 125’ or 150°F to equilibrium, Le., until migrant levels measured in the solvents showed no increase with time. The complete program consisted of the sequential steps outlined in Figure 3. Exploratory extraction experiments defined temperatures and approximate equilibrium times for each food simulating solvent. Nonvolatile mi-
Figure 3. Sequence of FDA approval project
8 9 8 A * ANALYTICAL CHEMISTRY, VOL. 46,
NO. 1 1 , SEPTEMBER 1974
There have been loads of nitrogen-selective detectors for gas chromatography.The difference is, Perkin-Elmer'snew one really works. And it's absolutely routine. I
SAMPLE
8 AMPHETAMINE
SAMPLE: NITROSAMINES
@
2.5 x 10' GRAMS EACH
METHAMPHETAMINE DIPHENYLAMINE (INT STD ) 0 UNKNOWN @ PHENMETRAZINE @ METHYLPHENIDATE @ UNKNOWN @ LIPID
3
0N-NITROSODIMETHYLAMINE @ N-NITROSODIETHYLAMINE
@ N-NITROSODIPROPYLAMINE @ N-NITROSODIBUTYLAMINE @ N-NITROSOPYRROLIDINE @ N-NITROSOPIPERIDINE
0
--5
10
MINUTES
Fig. 1.
You mount the new nitrogenphosphorus detector (NPD) in place of the FID on a Perkin-Elmer Model 3920 Gas Chromatograph (or a 900/ 990). After the very simple installation, you're ready to get results, just as easily as with an FID. Nitrosamines are determined with ease. Figure 1 is a mixture of low concentrations of carcinogenic nitrosamines reportedly found in foodstuffs. This analysis, which used to be difficult, is now routine. The NPD provides the necessary sensitivity (picogram level) and selectivity (essentially blind to the solvent matrix). A great improvement for stimulants. Figure 2 compares the response of an FID and the new detector to some commonly abused stimulants in a blood serum. The nitrogen detector gives at least a 50-fold increase in sensitivity. (The FID chromatogram was recorded on range 10 while the NPD was used at range 100). Also, the nitrogen detector does not see peak 8, a lipid, which is the largest peak in the FID run. Such selectivity greatly reduces the possibility of peak misidentification in the chromatographic methods used in drug screening.
STIMULANTS IN SERUM 5xlO7GRAMS EACH
3
NITROGEN DETECTOR 100 x 32
I1
iJ
And it's easy. What is not obvious from these chromatograms is the high level of stability and reliability which this detector offers. You have to use it to appreciate how convenient it is. The secret is in independent control. The source of the sensitivity and selectivity of the nitrogen detector is a rubidium glass bead placed over the flame jet. That alone doesn't make it very different from all of the unstable detectors of the past. The difference (patent pending) is an independent electrical circuit to heat the bead. In past detectors, the poor old flame had both to burn the sample and provide heat to the source, so did neither very well. With the independent control circuit, the detector is everything that one might hope. That is, it's 50 times more sensitive than the FID for nitrogen, 500 times more sensitive for phosphorus, and 10,000 times less sensitive to hydrocarbons.
You may need an accessory: the Model 3920. If you already have a modern Perkin-Elmer chromatograph, all you need is the new detector (it uses the same amplifier as the FID). If not, a
Fig. 2.
moderately-priced accessory is required-a Model 3920 Gas Chromatograph. The Model 3920 is worth having on its own terms, for the nitrogen detector is only one of a series of Perkin-Elmer exclusives to which it gives you access. Consider some of the others. Direct injection of solid and/or viscous samples with the MS-41 Capsule Sampler. A 4X increase in resolution or a 4 X decrease in analytical time, with Pe rki n-E I me r's exclusive SCOT columns. PEP-2, the world's most powerful chromatography data system now equipped to work with 16 chromatographs simultaneously, a simple but versatile programming language, and a direct telephone link to large central computer systems. There's only one way you can enjoy the whole world of gas chromatography-with the Model 3920. For more information write: The Instrument Division, Perkin-Elmer Corporation, Main Avenue, Norwalk, Conn. 06856.
*
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PERKIN- ELMER
CIRCLE 193 ON READER SERVICE CARD
A N A L Y T I C A L C H E M I S T R Y , VOL. 46, NO. 11. S E P T E M B E R 1974
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Figure 4. Analytical methods and results
grants were identified qualitatively by IR and UV spectrometry inspection of evaporation residues. Methods for quantitative measurements of both total and single migrants were then developed, in preparation for equilibrium extraction studies on several different resin batches. Quality control tests and specifications for a foodgrade resin product were defined concurrently by relating bulk properties to results of the migration studies. The formal petition for the food packaging regulation contained the complete results of all the analytical studies, along with written procedures and copies of original records. Analytical Methods and Results
Requirements for analyzing extracts of a new food packaging material partly depend on composition. As a minimum, the FDA requires measurement and identification of total nonvolatile extractables. Nonvolatile extractables of Barex” 210 were primarily emulsifier and stabilizer, both FDA-regulated food additives. Each of these was measured quantitatively by spectrophotometric procedures. We were also required to analyze the extracts for monomers, polymer, and chain transfer agent. The complete analysis system is outlined in Figure 4. Total nonvolatile migrants were measured by weighing evaporation residues, as required by the FDA. Nonvolatile migrants from 900A
Barex@210 totaled less than 1.0 ppm in most cases. Gravimetric measurement of these low levels required the highest standards of solvent purity, clean room handling technics, and a controlled humidity atmosphere for tare and final weight measurements. The amount of polymer in the evaporation residue was measured by infrared spectrometry. A considerable amount of technic development was needed to develop a quantitative IR method. The evaporation residues were often invisible to the eye and, a t best, looked like stains in the platinum evaporating dishes. Quantitative transfer for IR analysis was achieved by redissolving the “stains” and evaporating the solutions on KBr. Analysis of the resulting KBr pellet for the low levels (
