4th Annual Summer Symposium-Standards
Standardization in the Chemical Industry W. A. KIRKLIN
W. W. BECKER
AND
Hercules Experiment Station, Hercules Powder Go., Wilmington 99, Del.
The ever-changing processes of the chemical industry create more than ordinary problems in standardization. The plan followed by a typical chemical company for handling its analytical methods and specifications for chemical products is discussed. The role of the analytical chemist in standardization in the chemical industry, the advantages of interplant and of intercompany cooperation through trade associations and standardizing societies, the necessity for sustained analytical research, and the desirability of collating and publishing information on properties of matter are reviewed.
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TANDARDIZATIOK takev place throdghout the chemical industry in many more ways than are a t first apparent. The ceaselessly changing industry presents more than ordinary problems in a standardization program. However, if standardization is defined simply as selecting the best way to do a thing and then doing it that way until a better way is found, examples of standardization in the chemical industry become obvious The research chemist begins when he selects the matrrials and conditions for his desired reaction. The production man, in turn, selects his process and fixes his operating conditions in ordm to produce the desired product and ensure that his second drum or carload and each succeeding one will be comparable with the first. The salesman takes the new product to the customer. He must define it, with the result that specifications-an element of standardization-are evolved. The market develops, competition enters the field, and need for standardization of the quality of the product becomes necessary in order to minimize tailor-made production and facilitate procurement on the part of the consumer. Eventually, through a trade association or a standardizing society, a common specification is agreed upon with benefit to the producers, the consumers, and the public a t large. The analytical chemist plays an important role in this standardization from the beginning, and it is particularly with this role that this article is concerned. CHEMICAL PRODUCTS DEFINED BY ANALYSIS
Chemical products are defined on the basis of composition That phase of chemistry dealing with the identification and measurement of the composition of matter is analytical chemistry. The analytical chemist, then, is in the unique position of developing and supplying the information required for defining the products of the chemical industry-it is his information that is used in specifications and standards of quality. I n effect, his is the language for the commerce of chemistry. Analytical chemistry is complex. In its broader sense, it involves all of the science of chemistry together with many phases of physics and of other sciences. True, many of its manipulations, considered individually, are simple (and luckily can be routinized), but back of any accurate analysis lies a history of consideration and preparation. as measured by chemical and physical properties.
Take, for example, the apparently simple determination of the strength of a fuming sulfuric acid to within 0.10% by titration. First of all, a standard alkali solution must be made available. The preparation and standardization of this alkali solution involve several things-viz., purified water, a basic alkalimetric
standard, the proper indicator, a ood analytical balance, analytical weights, a buret, and a kermometer-at least seven different items. If of unknown accuracy, the weights, bur$, and thermometer must be calibrated before use; and finally, in the standardization operation a series of exacting manipulations must be carried out. The determination proper involves another series of operations, listed in Table I. Each operation must be carefully performed, as variations in any one will affect the results. In addition, the analyst must be constantly alert for possible sources of error, such as im roper preservation of the standard alkali solution, poorly creaned glassware, and interferences by atmospheric contamination, etc., as well as personal errors in arithmetic and the like. This is an example of a simple determination. Most analytical determinations are much more complicated, involving several solutions and reagents, sampling problems, separations, maintenance and calibration of complex instruments, and overcoming diffic$tly definable interfering constituents. For much of his work, the modern analyst has numerous methods and techniques from which t o choose; however, like a little boy with a nickel in a candy store, he must consider carefully before he makes his selections. To avoid obtaining results of restricted if not questionable value, each of the several phases of an analytical procedure must be carefully evaluated, and full consideration given t o the needs of the research chemist, the production man, and the salesman. Little has been written about this important phase of the industrial analytical laboratory. The plan followed by the authors’ company for the selection and standardization of analytical methods and the handling of specifications for chemical products is described. HERCULES’ STANDARDIZATION PLAN
Hercules Power Co. is a typical chemical company making a number of different chemical products in widely scattered plants. For marketing and distribution reasons, a number of these products are made simultaneously a t several plants. This has necessitated standardization not only of the processing operations but also of the inspection methods among the plants. Each plant has its own control and inspection laboratory. In addition t o these laboratories, a general analytical division is located a t the company’s central research laboratory for the analysis of research samples and for research on analytical methods and techniques. One section of this central analytical division is concerned solely with standardization of analytical methods and laboratory practices, checking on the use of these standardized methods by means of check samples and laboratory visits, preparation and review of specifications, and coordination of analytical methods
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V O L U M E 23, NO. 11, N O V E M B E R 1 9 5 1 with specifications throughout the company. An organization chart of this large general analytical division would show only two or three people in this standardization section, however, these few people are assisted by and are dependent upon many others for their working information both ~ i t h i nand without the division. AI A LYTICAL METHODS
-4 research program on a neiv product inevitably necessitate* modifications of existing analytical methods, and frequently the development of entirely new ones. This work on modification and development of methods is handled by the analytical research chemists in the central analytical division. The methods are then prepared in standard form by the standardization section of the analytical division, applied to subsequent pilot plant samples of the new product, and finally, if the product reaches the plant stage, are sent to the plant for use in control ot the neiv manufacturing process. The outline form for analytical methods is similar t o that used by many others, covering scope, principii, of method, reactions, special apparatus and reagents (including instructions for their standardization), and preparation of the sample. The procedure, written in the imperative voice lists the manipulations in chronological order, the observations to tie made, and special precautions required. The calculations shon- how the results are to be expressed. Whenever possible, a reproducil)ility value, ordinarily that obtainable by a qualified analykt working in one laboratory, is included; usually this is about oncs half the value obtainable by different operators working in different laboratories. References t o the literature, and to company reports covering development of the method, enable the a n n l j st to obtain Iiackground information which helps him to applj the mc,thod intelligently.
Table I. Steps Involved in Titration of an Acid Sample 1 Sampling the acid 2 Weighing the sample 3. Diluting the weighed sample with water 4. Adding the proper amount of indicator 6. Titrating to neutrality with the standard alkali solution 6. Reading the buret 7. Observing and recording the temperature of the standard alkali solution 8 . Applying any necessary weight buret, and temperature corrections, and calculating the results
The methods of analysis are multilithed on letter-size pages and are distributed among the company’s several laboratories, where they are filed in manuals. At present, the complete laboratory manual consists of eight volumes, each about 4 inches in thickness. I n addition to methods for process control and finished products, this manual contains methods for the analysis of raw materials, safety instructions, and other laboratory practices. Among the hundreds of refined and specific methods are procedures involving use of visible, ultraviolet, and infrared spectrometers-of the polarograph, p H meters, and organic reagents, as well as conventional gravimetric and titrimetric methods. These methods are constantly reviewed, added to, and revised to keep them up to date. CHECK SAMPLES
Once standard methods are established in the plant control laboratories, it is necessary t o check on their use. This is done with the aid of check samples of representative materials, selected to cover as many as possible of the standard solutions, precision apparatus, and techniques involved in daily control analysis.
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Such samples are periodically issued to or requested from all the laboratories concerned with the particular product-with the request that they be analyzed by the analysts regularly performing the work, and that the results be reported to the central analytical divieion, Lvhich independently analyzes the same samples. Usually the central analytical division’s values, M hivh are obtained with the utmost care, are used as the standards for comparison. A resume of all the results on each check sample is sent to the participating laboratories : m y deviations outside specified limits are called to the attention of the laboratory involved, and suggestions are made for correction I n addition to these check samples, the control laboratories are encouraged to have standard, or well analyzed, samples of typical products on hand, which they can submit to their analysts as a further check on the uniformity of the work. Khile these check samples and standard samples do not provide a complete coverage of the work of the control laboratories, their iange and frequency are such as to give a running picture of the quality of the work in the several laboratorire and greatly aid in keeping their results on a comparable basis. To check further on the use of standard methods, visits are made to the control laboratories, and the chemists from the control laboratories are encouraged t o visit the central research laboratory. They are also asked to criticize and to offer suggestions on any method a t any time. I n these ways, better understandings result all the way around, and mutual confidence is established. Another activity of the standardization section is the checking and calibration of precision measuring equipment like analytical weights, volumetric glassware, and thermometers, which are centrally purchased for issuance to the plant control laboratories as needed. Special reagents and basic standards, like 20% hydrochloric acid, not otherwise procurable, are prepared, standardized, and issued t o these laboratories. I n this capacity, the division acts as a bureau of standards for the company. SPECIFICATIONS FOR CHE.\IICAL PRODUCTS
Chemical products are defined on the basis of composition as measured by chemical and physical properties. Specifications and analytical methods are t’hus intimately related. Specifications for the raw materials required in the various processing operations a t the plants are prepared in standard form by the standardization section. Scope, sampling, detailed requirements, arid references to the methods of testing and to the origin of the specification are covered. I n the preparation of these specifications, tentative requirements for a given raw material first are set up by the operating departments. These are checked with the Purchasing Department, which in turn checks with potential suppliers. I n so far as possible, the requirements and methods of test are made to conform \vit,h those of the suppliers. Special requirements are, of course, necessary, a t times, to ensure that the material \vi11 be suitable for a particular purpose-for example, the absence of “grit” in a material intended for a dynamite ingredient. Generally, effort is made to hold the requirements to bare essentials, just sufficient to characberize the material properly, but not limit the supplier unduly. Finished product specifications generally are formulated by the sales departments in cooperation with the operating departments. Such specifications are, of course, governed by the consumers’ requirements, together with what can be effectively produced. These specifications, too, are kept under constant review to ensure that they are properly integrated 1vit.h analytical and test procedures. I n the selection of test procedures for finished producte, special consideration is given to methods already existent and acceptable to the consuming industry involved. This makes easy t,he
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duplication of measurements in the customer’s laboratory if desired. Considerable help is obtained in the selection and preparation of these standard methods and specifications from the work of trade associations and standardizing societies like the American Society for Testing Materials. Representatives of the standardization section participate actively in work of these societies. Useful information is also obtained from such sources as the National Directory of Commodity Specifications, from Chemical Industries “Buyers’ Guide Section,” and from Federal Specifications. It is obvious that these standardization activities involve many departments of the company, and necessitate a knowledge of the research, the raw materials, the processing, and the utilization of the company’s products, as well as a broad knowledge of analytical chemistry. The success of a standardization program depends upon the full cooperation of all departments concerned. The ceaseless change of the chemical industry makes it a neverending job. STANDARDIZATION ACTIVITIES
The analytical chemist too often gives insufficient thought to the importance of standardization. It is well to review some of the activities which benefit his work and in which he should participate. Atomic Weights and Nomenclature. The standardization of atomic weights and nomenclature is basic. The work of the ACS committee with the International Union of Chemistry on atomic weights and the work of several committees of the AMERICAN CHEMICAL SOCIETY and other societies on standardization of nomenclature need the support of all analytical chemists. Standard Samples of National Bureau of Standards. Much of quantitative analytical chemistry is simply comparison of unknowns with knon.ns. Full support of the continuation, and, if possible, expansion of the bureau’s program on standard samples should be given by the entire chemical industry. Standards for organic chemicals particularly need attention. Reagent Chemicals. Seldom does the modern analytical chemist have to resort to purification of his reagents before proceeding with an analysis. The continual refinement of our analytical methods will permit no letup in the excellent work of the ACS Committee on Standards for Reagent Chemicals. Basic Data. Such data as melting points, densities, optical rotations, and solubilities are conveniently available in reference books. A somewhat different situation exists relative to the data being obtained by the n e w r analytical tools, however. Infrared and ultraviolet absorption curves are examples. The American Petroleum Institute program on products from the petroleum industry is well known. Committees of the American Society for Testing Materials and of other societies are beginning to recognize and to give attention to the need for similar information on other products. Many industrial laboratories have useful information on their commercial products which might be made generally available. Means should be sought for publishing these data in a systematic manner, with provision for periodic review, pending refinement of the absolute values on the pure compounds. Jf this can be done, extension of the use of these newer analytical tools will be facilitated. Standardization of Laboratory Apparatus. This has been carried on cooperatively by the ACS Committee on Standard Apparatus and the Scientific Apparatus Makers of America, v, ith benefit to chemists and manufacturers alike. The American Society for Testing Materials long has had committees on thermometers, volumetric glassnare, and ceramic and metal R are. Continuation of these programs also needs the assistance of all analytical chemists. Instrumentation. PIIuch has been done to improve the pre-
cision as well as the efficiency of analyses by instrumentation. I t is in this field, particularly, that the physicist is aiding the analyst, and relieving him of much of the drudgery and routine. Most instruments must be calibrated, eithcr by comparison with accurate chemical methods, or with carefully prepared knowns, synthesized to simulate the unknowns which are to be analyzed. The analytical chemist must continue to work closely with the physicist and with the instrument maker further to simplify and improve the stability and accuracy of analytical instruments, Company, National, and International Standardization. Standardization of an analytical method must, of course, start with selected procedures for a specific material in one company’s laboratory; however, standardization cannot stop within a single company. I n the buying and selling of materials, standardization among companies is necessary in order to reach agreements and to avoid misunderstandings. Currently, there are over 500 trade associations, technical and professional societies, and government agencies in this country alone engaged in standardization activities. Some have large staffs. Correlating the activities of many of these societies is the American Standards A4ssociation, which is the recognized authoritative American channel of cooperation in international matters. The American Standards Association works with the International Standardization Organization, which in turn is allied with the Economic and Social Council of the United Kations. Outside of those trade associations which may be related t o the specific products of our respective companies, the American Society for Testing Materials probably is of most general interest to industrial analytical chemists. This society covers a wide range of materials. Its committees maintain a balance of producer, consumer, and general interests, and its regulations require periodic review of all its standards, Need exists for better dissemination of information on the activities of these standardizing associations. At times there is duplication of effort among different societies, which leads to dissimilar standards. Means should be found to periodically publish a list of these activities for the industry’s information. This is hardly a function of the AMERICAN CHEMICAL SOCIETY, but it might be undertaken by the American Society for Testing Materials or the American Standards Association, and possibly by the Sational Bureau of Standards. Freedom of these activities should not be interfered with, however, as each consuming group may have different needs, and benefits are derived from independent approaches. The h r E m c a s CHEXIC%L SOCIETYfacilitates standardization through its publication of new methods and of reviexvs. The authors of many papers, hon-ever, can aid the adoption of their methods by more critically examining and publishing information on potential interferences, also by evaluating and expressing the accuracy of their methods more uniformly. Statistical Techniques. These have provided a better measure of the prccision and accuracy of analytical methods in recent years. Hovievcr, the many steps involved-even in thc simplest analytical procedure-must not be forgotten; the final result with which the statisticians so frequently work may be affected by an error in any one of these steps. The analytical chemist must educate the statistician to analytical chemistry, or bptter, learn statistical methods himself and apply them in his work. Research. The whole chemical industry is based upon research. The continuous development of new products, and the increasing requirements placed on existing products, demand continual improvements in the methods of analytical chemistry. The analytical research chemists and physicists, therefore, must be constantly alert t o the latest discoveries in all domains of science and turn such of them as are indicated into analytical procedures; they also must be aggressively critical of any established methods, specifications, or practices. REch1vr.n i u g l l s t 17, 1931
