Q. L. QUINLIVAN E. I. du Pont de Nemours & Co., Inc., Polychemicals Department, Wilmington, Delaware
Tm
SAMPLE RECORD SYSTEM
Presented as psrt of the Symposium on An Analysis Group in an Industrial Research Organization before the Divisions of Chemical Education and Analytical Chemistry a t the 130th Meeting of the American Chemical Society, Atlantic City, September, 1956.
The sample record system used is basically the same as the one originally described by Hale and Stillman (I). Only those parts of the system which we have modified t o meet our changing needs will be discussed. All samples submitted for analysis must have attached a standard label. To identify types of samples, labels are available in three colors. I n addition to the white label regularly used for most samples, red ones are supplied for hazardous materials, and green ones for high priority work. Space is provided on the labels for all of the information considered necessary for routine samples. Pertinent information on samples must also be entered on a log sheet on which the chemist or his helper records essentially the same information as that on the
chemical development and service group provides a variety of important services. Its primary duty is to analyze all samples requiring chemical methods for elemental and functional group analyses, and to perform separations and physical constants measurements. Other duties include record-keeping on all samples received for both chemical and instrumental analyses, regular reporting on the status of all analytical work. and coordination, which includes the issuance of test procedures for a departmental-wide manual of test methods.
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slip is returned to thc analytical service ofica. 'lh! clerk typist then removes the corresponding "Kcysort" cards from the file. A final check of the rards aud tlm slips is made by the service supervisor part,icnlarly n.here multiple analyses are involved. The slips arc then filed consecutively and the cards are r:ount,cd, coded, punched, and filed under project numbers. MANUAL OF TEST METHODS
Completed Sample Report for Determination oi C and H. The f r o n t of the Report is on the Lett, the Bark is on the Right.
sample label. From this information the typists fill out the sample report forms without having to handle the samples directly. This system eliminates interruptions in the analysis schedule and also reduces hazards of leakage or hreakage. For unusual samples a sample information sheet is available for recording more detailed information than can he shown on the label or on the log sheet. On this sheet space is provided for recording the history of the sample, the specific information needed by the chemist from the analysis, and known impurities, if any. The chemist can record on this sheet methods of analysis which he thinks might be useful together with any special instructions that should be followed in handling the sample. Usually a consultation has been held with oue of the analytical supervisors before this form is completed. Space is available to note the name of the consultant. With such a system lost motion ill expeditiug unusual samples through the analysis group is reduced to a minimum. From the log sheet, the typist fills out the analytical report form (a three-part, "no carbon required" form) plus a "Keysort" card as described in reference (1). If analyses are to be made by more than onc group, one set of slips is typed for each. The typed slips and the cards are checked by the service supervisor and the slips are then distributed to each group supervisor. By means of the cards a daily count is kept of sample receipts. The yellow slips are kept as a record of work assignments. The analyst receives the two combined top white slips. On completion of the analyses his results are recorded on the front of the top white sheet which is duplicat,ed on the second sheet. Calculations and other pert,inent data are recorded on the back of the top sheet. A typical completed sample report form is shown in the figure. Analyses for nitrogen and oxygen which have also been requested would normally be reported on separat,e forms. Having been checked and approved by the technical man in charge, the duplicat,e sheet with the final resnlts is sent to the sample submitter, and the top
Our departmental manual of test methods is maintained by an analytical coordination commit,tee composed of an expert from the Research Division and onc from Production. The committee has three principal objectives: (1) to bring all departmental lahorntorics into agreement regarding standardization of analytic:~l and test procedures; (2) to maintain and issue proccdures for the standard manual of analytical and physical test methods; and (3) to issue standard samples for checking procedures bet~veenlaboratories. The presenl manual consists of a procedure section, a reagent sect,ion and an index. Two addit,ional sections !Till 11c added, one for special apparatus and one for gcncral techniques. The procedure section contains general nrcthods, methods specific to one product, and abbreviated ones ralled work sheets. The first two types are quite detailed, providing within a standard format all available pertiucnt information on applicability, and reliability as well as procedural details. All general and specific methods must list the following subheadings: I. Applicability; 11. Unusual Safety Considerations; 111. Principle of the Method; IV. Fuoda~nental Equat,ions; V. Interferences; VI. Sensitivity, Precision, and Accuracy; 7'11. Apparatus; VIII. Reagents; IX. Procedure; X. Calculations; XI. Comnicnts; XII. References. The work sheets coutain only the information nceded for carrying out the analysis or test in the lahorat,ory, and usually reqnire only safety considerations (111, procedure (1x1, and calculations (X). Work sheets must always refer t,o a detailed procedure. The preparation of this manual requires the work and cooperation of many people in the Research Division and in the plant laboratories. General methods are usually prepared by members of the Kesearch Division. Most of the specific methods are prepared by plant personnel. This major endeavor has proceeded a t a good rate, and to date has been eminently surcessful. Since 1952 over 1100 procedures h a w been issued, requiring 16 volumes of S1/2 X 11 loosc-leaf notebooks. CHEMICAL SERVICE
The chemical service group is particularly concerned x~iththe precision and accuracy of results. Mcthods are checked regularly against standard compounds or kuown mixtures. The results are carefully tabulated for use in calculating reliability of the analyses and for clues to sources of error, both of which may lead to modifications or improvements of methods to fit a particular type of sample. The table shows results on a number of typ~calclemental analyses made in our laboratory over an cxtended period, usually by two or more analysts JOURNAL OF CHEMICAL EDUCATION
Statistical Data o n Typical Elemental Analyses
Weight %
Anal!,sis lor
C" C" Hb Ob Nb
Nb CIS
F" Se
Method Wet comb. Dry comb. Dry comb. Modified Unteraaucher Dumas Kjeldahl (semimicro) Titrimetric Titrimetric Gravimetric
Detna. 18 130 130
Cale. Found o 40.00 39.98 0.09 71.09 71.23 0.14 6.71 6.69 0.14
25 26
11.84 l l . 9 1 0.24 10.36 10.35 0.06
25 30 5 24
10.36 17.49 75.98 14.94
10.34 17.40 75.79 14.88
0.04 0.25 0.52 0.12
C o x ~ o o ~ n s*: = dextrose; b = acetanilide; ' = benzyliso= polybetrafluoroethylene; ' = sodium pthiourea.HC1; chlo~.abenzenosulfonate. NOTES: Carbon in dextrose by a sensitive weedry combustion method (8). Dry combustion for nitrogen (Dumas) by the procedure of Coleon (S),and for carbon and hydrogen by the met,hod of Nicderl (4). Oxygen by the Schiitse-Unterzaucher met,hod as modified by Dund,v and Stehr (5). Halogen and sulfur by t,he Parr peroxide bomb procedure for decomposition. Chloride hv the Volhard method. Fluoride bv the Haslam and 1l7hett,&nprocedure ( 8 )modified to use H& in place of HC10, during the distillation step. Sulfur gravimetrically as bsrium
Existing methods often must be modified to analyze samples differing in many respects from those for which a method was originally developed. Thus a special t,erhnique was needed for microdeterminations of carbon and hydrogen in samples which were highly unstable in contact with air. Transfers could not be made conveniently in the typical bulky "dry box." A system was devised in which transparent polyethylene bags were used in the transfer of samples from the containers in which they were received to a combust,ion boat, and later to the combustion tube. The advantages of the polyethylene bag technique are: complete visibility, easy manipulation directly from outside of the bag, and easy evacuation and filling of the bag with inert gases. Less important but worth
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consideration is the fact that when not in use the bags require a minimum of storage space. Modifications in ashing techniques have saved time and provided more reliable results. A special dropping funnel has been used for controlled delivery of liquid samples to crucibles (7). For ashing of solids, which are received as fine powders or fluffs, pellets can be made. In pellet form samples can be weighed, transferred and burned without losses and consequeut errors. Pellets usually burn more smoothly and faster than powders and require less attention. In addition to improved accuracy, therefore, the use of pellets has proved to be a time saver. While there is a considerable amount of routine analytical work required in any chemical research organization, there is a constant heavy demand for special analyses. No single group of any reasonable size can hope to take care of this special work along with the usual routine demands. Other sections of the research organization should provide for their own analytical services when their needs become routine. The analytical group does develop unitized equipment and prepares detailed instructions for making standard analyses. The manual of test methods is of considerable value in this respect since it gives complete procedural details. Where feasible, of course, continuous analyzers are provided. LITERATURE CITED Anal. Chem... 24.. 143 (1) HALE,A. H.. AND J. W. STILLMAN. (1952). (2) PICKHARDT, W. P., A. N. OEMLER,and J . MITCHELL,JR., A n d . Chm., 27, 1784 (1955). (3) COLSON, A. F.,Analyst, 7 5 , 264 (1950). (4) NIEDERL,J . B., AND V. NIEDERL,"Organic Quantitative Microandlysis," 2nd ed., John Wiley & Sons, Inc., New York, 1942. (5) DUNDY, M., AND E. STERR,Anal. Chem., 23,1408 (1951). J., AND S. M. A. WKETPX~M, J. Appl. Chem., 2, 339 (6) HASLAM, (1952). J., JR., AND J. W. HENDERSON, Anal. C h a . , 22, (7) MITCHELL, 374 (1950).
