The Analytical Approach Edited by Claude A. Lucchesi
Barex p 210
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 i nd development of a new family of barrier resins several years ago plummeted Sohio analytical chemists into an unusual problemsolving area. The 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 Barex® 210, and the importance of analytical chemistry in obtaining it. Analytical 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. The 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
Composition and Process Discoveries Property Evaluations
Economics Defined Marketing Goals Defined
Development of Manufacturing Technics Pilot-Scale Product Manufacture
Applications and Market Development
Semicommercial—Commercial Manufacture
Migration Studies—Petition FDA—Petition Granted
ANALYTICAL CHEMISTRY, VOL. 46, NO. 1 1 , SEPTEMBER
1974 • 897 A
tracted, 302 liters (80 gal) of ultrapure water was used, 168 liters (44 gal) of extract was slowly evaporated from 100-ml evaporating dishes, and 1,053 analytical determinations were made.
FDA TEAM Attorney
[Business Management [Legal Staff
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.
FOOD
&
Polymer Chemist
DRUG ADMINISTRATION
I Analytical Chemist
Chemical Analysis Spectroscopy Electroanalysis
Figure 2 . Organization approach for obtaining FDA approval
Table 1. General Approach to Migration Studies Polymer f o r m studied
Bottles
Food simulating solvents
Water for aqueous foods Aq acetic acid for acidic foods Aq ethanol for alcoholic beverages Heptane for oily foods
Exposure conditions
125° and 15CPF until m a x i m u m (equilit)riurr migration levels are reached
Requirements for Food Packaging Regulation 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, i.e., 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 at 125° or 150°F to equilibrium, i.e., 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-
I Polymer Research & Duv A Polymer Manufacture jCommorcial Development
Figure 3. S e q u e n c e of FDA approval project
898 A • ANALYTICAL CHEMISTRY, VOL. 46, NO. 11, SEPTEMBER
1974
MIGRANTS MEASURED Weighing
Nonvolatile Migrants 0.2-1.0 ppm
Evaporation
Evaporation Residue
Infrared Spectroscopy
Soluble Polymer 0.01-0.05 ppm
Solvent Extraction
Stabilizer Concentrate
Ultraviolet Spectroscopy
Stabilizer 0.1-0.5 ppm Emulsifier 0.1-0.5 ppm
Colonmetric Analysis Polar ography (Caihodic Stripping Voltammetry) BAREX*210 BOTTLE
Distillation with Methanol
AEeotrope of Monomers
Chain Transfer Agent < 0 . 0 4 ppm
Polarography (Linear Sweep Voltammetry)
Monomers 0.01-0.05 ppm
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
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, at 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 (
