Analysis and lnstrumentatio IndustriaI Hygiene
The wide variety of substances encountered and the broad spectrum of analytical methods employed characterize the modern industrial hygiene laboratory. Last month our feature described the role of analysts in public health and industrial hygiene. This month w e continue on this theme with a report on the present status of progress of analysis and instrumentation in industrial hygiene and future needs
H. H. Schrenk, research director
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of the lndiJstrial Hygiene Foundo-
1O AO ,-,, tion, Mell‘,, 1...1:1..&hos been active i n the field of public health and industrial hygiene since his college days (Ph.D., Wisconsin, 1928). While a student, he served as assistant state toxicologist. From 1928 to 1948 he worked at the Bureau of Mines, starting as assistant toxicologist and ending as chief of the Health Branch. After o year’s service as scientist director of the U. S. Public Health Service’s environmental investigations bronch, he took over his present position. He has been octive for many years in the AMERICAN CHEMICAL SOCIETY, American Public Health Associotion, American Industrial Hygiene Association, and American Association for the Advoncement of Science. He has done research on the toxicity of gases, vapors, ond dusts, evaluation and control of industrial environmental explosions, and air pollution. I
T H E analytical chemist has frcquently been labeled the forgotten man. However, in recent years there has been more recognition of the essential role which analysis plays in research, production, sales, and purchasing. The same is true in the field of industrial hygiene. Although attention is usually ditectcd to the physician, the engineer, or the toxicologist, the dependence which these disciplines place on the measurement of toxic substances and other environmental factors attests to the fundamental importance of this phase of activity to the over-all success of their endeavors. The recent publication of an “Eneyclopedia of Instrnmentation for Indnstrial Hygiene” is an outstanding recognition of measurements as the keystone of health protection in industry. A volume of over 1200 pages, it covers: I. Instruments for Sampling and Anelyzing Air for Contaminants in Industrial Environments; 11. Laboratory Type Instruments of Specific Application to Industrial Hygiene; 111. Instruments
V O L U M E 28, N O . 10, O C T O B E R 1 9 5 6
Sprcifically Designed for Atmospheric Pollution Evaluation and Meteorological Measurements; IV. Instrnments for Measuring Air Velocity and Metering Air; V. Instruments for Measuring Sound and Vibration; VI. Instruments for Measuring Ionizing Radiations; and VIS. Instruments for Measuring Ultraviolet, Visible, and Infrared Energy. The cooperative efforts of many industrial hygienists and the manufacturers of instruments were reqnircd to produce this comprehensive compilation of technical information and descriptions of constmetion, operation, and maintenance of numerous commercial and “home-assembled” instruments.
Scope of industrial Hygiene Measurements The industrial hygiene laboratory 1s characterized by the wide variety of substances encountered and broad spectrum of analytical methods employed. Somc substances are determincd routinely from day to day, othcrs 7A
REPORT FOR ANALYSTS
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Esso
Research 8. E n g i n e e r i n g C o
THE IDEAL PRESS FOR MAKING KBR PELLETS FOR INFRARED SPECTROSCOPE ANALYSIS 20
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intermittently, and others only occasionally. The precision and accuracy required range from rough semiquantitative measurements to the highest degree of accuracy at’tainablc. Quantities to be det’ermined niay be niicrograms or grams. T o meet these diverse demands, the indust’rial hygiene analyst must be skilled in adapting and niodifying existing methods, improvising equipment, aiid developing gadgets. The importance of obt’aining a nieaningful sample cannot be overemphasized. This is particularly true in obtaining samples of air-borne matc,i,ials, where the concentrations may lie changing rapidly on-ing to operational procedures. Many types of sampling devices have been developed to obtain Itgrab” or “spot” samples as n-cll as integrated or continuous samples. To prevent errors from such factors as insufficient sample, change in coniposition, and interfering elements, close supervision of sampling is requiretl. iinalyt,ical requirements are of three main types: (1) t’hose required in toxicological studies, ( 2 ) those i,equired in enviroiiniental investigations, and ( 3 ) those required to measure biological absorption and for diagnostic purposes. Toxicological Analysis
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I n the investigation of tlir toxicity of a compound, it is necessaiy to have analytical proceduies to iiieasuie and monitor the exposure conditions. It is also necessary to deterinine the compound in body tissues and fluids to establish the rate of absoiption, distiibution in the body, and rate of elimination. Another requirement is the dcteiniination of metabolites. nhich may piovide basic information on the site and type of injury likely to be produced and also niay serve as a iiica~uie of exposure or as a diagnostic sign. Benzene niay be taken as a typical example. ilt the start of an inrestigation of the physiological effects of benzrne, the analytical nirthod used to determine chamber air roncentiations and benzene in tissues v a s based on nitration of the benzene to m-dinitiobenzene and subsequent titration using standard titanous chloride and standard ferric alum solutions. This method was cunibersonie and rcquiied too large a sample for repeatrd blood analysis. Another method n-as developed. based on the aeration of the benzene from the blood, removal of carbon dioxide, combustion of the benzene to carbon dioxide, absorption in barium hydroxide, and determination by electrical conductivity. This procctluie was sufficiently sensitive to pciniit studying the rate of absorption and
elimination of benzene from the blootl, but, entailed extreme care in techniqiir and was time-consuming. Subsequently, a colorimetric method was devclopetl. based on the formation of a violet, color by nz-dinitrobenzene in the presence of butanone and strong sodiuni liydi,oside solution. This method is sufficiently sensitive and rapid to provide an excellent tool for the det’ermination of hrnzene in micro quantities in Iiody tissues and fluids and may also lie uscd for air analysis. Iluring the course of this same stud tlw analysis of urine specimens show tlx-it cxposurc to henzenr raused a clcc.i,cascin the inorganic sulfates in the urinc. Further stud:es in 11-hich animals were exposed to carefully cont,rolled benzene concentrations for various exposure periods demonstrated a quant,itatire relationshi11 bet,n-een thc decrease in inorganic sulfates in thc. urine aiid the magnitude of the exposure in terms of time and concentration. Thus, in this in\-estigat’ion, tn-o new analytical teehniqurs were cleveloped for t,he detcrmination of benzene in small cwic>entrations and a new procedure was discovered for measuring benzene absorption which can br used in t,lie prerention of injurious exposure t o Iimzrnr, in industry. Similar biological studies have resultctl in the development of new or modified procedures for determining niany toxic materials in body tissues aiid fluids. The results obtained by utilizing these analytical procedures have aided in the elucidat,ion of biological :wtion and provided diagnostic tools that are invaluable in the prevention of occsupational disease. .A fen- of the more coninion substances for which such data are available are lead. mercury, tric~hloroethylene,methanol, and toluene. Since tlicse tests usually require methods c~:ipableof determining amounts of the order of a fen- micrograms. application to other materials n-ill depend on the clcvdopnirmt of suitable analyt,ical procCdL1rt3. Environmental Analysis
The requirements of methods for measuring environmental factors are diverse and complex, depending on t,he purpose for which the samples are taken. There are several reasons for industrial air sampling-for exaniplt~. (1) to determine bhe major sources of dissemination of contaminants, ( 2 ) to appraise the performance of control equipment. and ( 3 ) to evaluate the environment in accordance with maxim u m allowable concentrations or hygienic standards. In gc,nei,al, the methods used in ANALYTICAL CHEMISTRY
REPORT FOR ANALYSTS
estahlishiiig sources of contamination do not necessarily require a high degree of accuracy, as even semiquantitative data may suffice in some instances. The same is true for checking perforniaii('e of control equipment. However, the evaluation of the potential hazard from esposure to the environment usually requires more comprehensive sampling and a higher degree of accuracy. 111fact, particularly if the exposure is judged to be near the borderline, continuous rworders are the ideal solution. T h r available methods may lie classified into three groups: (1) equipiiieiit that is portable and can be used to oht,ain a reading or result without recourse to the laboratory, ( 2 ) iiiet'hods that require collection of a saniple n-1iic.h is subsequently analyzed in the laboratory, aiid ( 3 ) continuous recorders. Direct Recording Devices. I n making a n industrial hygiene appraisal of ~vorkroomenvironment the ideal device is one that permits obtaining results quickly ivith reasonable accuracy a t the site of sampling. With such a device? more analyses can be made aiid a iiioi'e detailed and nieaningful study in rrlatioii to operational procedures can be accmnplished in the shortest period of time. I t is easy to undrrstand the increased emphasis irhiczh has Iwen directed toward tlie drvelopment of in comparison n-it'li iiiethods ivliicli require collection of a saniple. transportation to tlie Inborntory. and a possible wait of sevrral days hefore the results are available. T h r tl(,termination of henzcne is an esc*cllrnt example of the progrcss t,liat' has b e m matl(,. I n an early environineiital study, the benzene \ v i s determined by adsorption on charcoal. This required cquililmtion of the sanipliiig train in the 1alJor:ttory. collection of the sample. antl rc3turn to the 1aboi.atory foi weighing. Obriously. this proc.rtlure i w s not one to encourage sampling. Titration and colorimetric pror(dui~(3s wrc1 tlevcloyc~d.n-1iic.h iiiatie saiiipling muc.11 easier, but still required t'he return of the sample to the lahoratory for anall-sis. Compare this with n complete detector kit nejghing less than 3 pouiitls. An aspirator bulb is uscd to draw air through a small glass tube ('011taiiiing graiiulc>s impregnated with sulfuric acid antl ~,araforInaltlehycIc. The length of the stain is iiieasurecl on a ~novable scal(~and is proportional to the concentration. There are a nurnber of other dc+c.tors based on the. usr of impregnated granul(~s. Prol)al>ly the best kno\rn is the dct'wtor for cwhon monoxide developed 11). the Satioiial Bureau of Standards. This nicthcd is based on the reaction of
carbon monoxide with a complex silicomolybdate compound catalyzed by palladium sulfate, producing a color change from yellow to green. I n this case, the intensity of the color is conipared n-ith a standard chart. Other detectors of this type are available for hydrogen cyanide. sulfur dioxide. and hydrogen sulfide. Test papers impregnated wit11 various chemicals are also widely used. Detectors utilizing this principle have been developed for ammonia, arsine, carbon monoxide, chlorine, hydrogen cyanide, hydrogen sulfide! mercury vapor. phosgene, phosphine, stibine, and sulfur dioxide. These methods, in general, are only seniiquaiititative but find inany useful applicixLions. Anot,her type of test giving ininiediate results employs liquids with suitable indicators and niay be considered as air titration. For example, sulfur dioxide can he d&miined 11s dram-ing air through a bubbler containing a measured volume of standard iodine solut'on and starch indicator. T h e concentration of sulfur dioxide can be calculated from the volume of air requiretl to change the color from blue to colorless Other substances for v-hic.h methods have been developed using this saiiie principle and suitable indicators are ammonia, aniline. benzene, carbon dioxidr,. carbon disulfide, chlorine, hydrogc~ncyanide. and nitrogen dioxide. One other p h c i p l e used in obtaining a cliiwt rcadirig is change in color of a flanie in the presence of certain coinpounds. The primary use of this type of device is tlie detection of halogenated hydrocarbons which are decomposed by a flame in rontact with copper and impart a greenish l h e color to flame. Kliile only roughly quantitative, it serves a useful purpose'. particxlarly for detection of Icaks. The ni:iin adrantage of the direct reading iiiethotls is that numerous results can lie obtained quickly. They ai'c particularly useful in determining s o u r ( ~ sof disseniination of contaniiiiante and checking contiol procedures. The accuracy of some of the methods leaves niuch to be desired; the presence of iiitcrferiiig suhstances niay limit their use uIitlcr rert'ain conditions? and recourse to tnore precisc3 methods may he neccssary. Swrrthelcss, thry are important tools of the industrial hyyienist and furth(.r development in this area can hi expected. Collectionof Samples for Laboratory Analysis. XIrthods for the collclction of saniplrs for laboratory analysis may be diridetl into four groups: (1) rollretion of a volunie of air in a suitable container, ( 2 ) al~sorptionin a liquid nicdiuni. ( 3 )
V O L U M E 28, NO. 10, O C T O B E R 1 9 5 6
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with L a b c o n c o Acid and Caustic Dispensing unit. Stored in c a b i n e t a t floor level, acid is vacuum-raised to b u r e t t e with s i m p l e push-button controls.
conco Kjeldahl Apparatus, s h o w n h e r e installed in optional hood.. . ideal answer to the problem of e x c e s s i v e h e a t . Standard Labconco Kjeldahl a v a i l a b l e today w i t h as many as 48 heaters.
used for digestion. Gas or electric heat, variable heat c o n t r o l s , timers . . . no m a t t e r what your needs, Labconco has the right size and model Kjeldahl for you.
t h i s h a n d y Labconco K j e l d a h l S i n k . 6' hose has convenient grip valve for adding w a t e r to flasks on cart. Sink also
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REPORT FOR ANALYSTS :idsorption on solid granules, and (4) condensat,ion a t low temperatures. Equipment for collecting samples of air is of various types, the most coninion being evacuated flasks. The main clisadvantage of this method is the small volume of sample xhich can 1112 obtained and readily transported. Instead of using evacuated flasks, the sample can he taken by air displacement (purging a s:implt~ container), n-ater riisplacemcnt. and nirr'cury displacement,. Consideration must be given t o the reactivity of tlic pns bcing sampled-for exaniplc, \!-:iter emnot he usrd if the gas is n-atcisoluble. If the sample container is rloscd with stoppocks. substanws roluhlc in stopc*ock grease cannot be s:iniplcd. I n spite of these liniitat~ions, tlw Il!cthotl has proved c~x:inipl(~, in collecting n Thr c d l ( 4 o n of s:imples in liquids his \vide :ipidic:ition and has th(. advantxgc that large smiples of air c a n be sc~i,ul)l)cd,thus oh t ai ni ng :i sufieicn t amount of the (mitaminant for analysis w t m though prcwnt in vwy lo\v concc?ntixtions. The absorbing medium niay I)(> \v:itc,r for substances readily soluble or it may bc a solution which reacts example. with the, contaminant-for :ilkalinc) solutions for cdlcct,ion of acid gases, acid solutions for alkaline niatclri:ils, cadmiuni (ahloride for hydrogc.n sulfide, and iorlinc solutions for sulfur dioxide. Thc selection of the at)sorhing solution nil1 dcpeiirl not only on tlic suhstancc to be dt~tc~niined but also on possiblr interfering suhstances. ilrction of saniplcs on solid uch as artivatcd i~harcoaland is similar in principle to a1)soq)tion in a liquid medium and is iisotl priimirily for collection of organic y:ipoi's. Th;s nirdiod also has the m1v:int:igr of mnccntrating on a small \olunicx of adsorhrnt th(. material froin :i h g e \-olunic~of air. thus perniitting mor^ accurate analysis. Thv us(' of low temperatures ohtainecl hj- dry icac and acrtone or liquid air or nitrogrn t o contlensc the rontaniinant is fi,rquontly resorted to n-lic.re other nic~tliodsarc1 not considered applicable 01'tic~sirablrfor one reason or another. The main advantagc of mllection by thew mctliotls is the fact that relatively large :imounts can he ohtainc~land thus thcw is :t wide choir(, of analyticd proc ~ t i u r tand ~ instrumcntation that can hc applied in the laboratory. While ati:ipt:itions and modifications may be rcquirc~tl,the collectinn of samples and t ~ ~ t i u ~ ~ ~ o r t at ot i othcl i i laboratory 131'0vidv potential p r o r d u r w for virtually :iiij- cy)ntaniinant that is encountered. Continuous rders. The vast. that arc made to majority of an (~\-:iluiltc workroom exposures are ANALYTICAL CHEMISTRY
Haze measurement.a valuable analytical tool Photo-Nephelometry measures haze and turbidity in liquids, a t extremely low concentrations Clarity of Whiskey, Beer, and Other Beverages
One of the most widespread and effective applications of Coleman Photo-Nephelometry is the measurement of haze in whiskies, wines and other beverages. Evaluation of filters and filter media and the control of haze in bottled whiskies is now a standard procedure throughout the distilling industry. Nephelometry precisely predicts the final clarity of the finished product. Sterility of Biologicals
The measurement and control of clarity and sterility of parenterals such as Penicillin, Streptomycin, Dihydrostreptomycin, Neomycin Sulfate, and Vitamin Solutions is an iniportant use of Nephelometry. Precipitates in Industrial Waters Purity and suitability of industrial waters and other liquids is easily evaluated with the Nephelometer, especially at very low concentrations. For example: Electric generating plants now use Coleman Nephelometers for the evaluation and control of feed waters for high pressure boilers. Control is accomplished by Nephelometric measurement of calciuni (Range 0.0-0.5 PPM) in the feed water.
Operation is simple. Routine work can easily be handled by people w i t h limited training.
Bacteriological Growth Rates and Effects of Nutrients and Inhibitors
In bacteriology the study of the effects of nutrients and inhibitors on growth rates of bacteria has been given new impetus and significance by the simplicity and precision of the Nephelometric method. These studies include a wide variety of bacterial types, including: Leptospira, Actinomyces Bovis, Tubercle Bacilli, Esch. Coli, Staphylococci. Measurement of Oils and Fats
The Nephelometer is useful in determination of butter fat content in dairy products, and has similarly been helpful in assay of cholesterol in blood chemistry.
Coleman Ccrtifird NephelosStandards express entire haze range on a continuous numcrical scale.
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A Precise Notation for Haze
The Coleman Nephelos Standards used with a Coleman Nephelometer provide an accurate numerical notation system. Haze data can be expressed on a fixed, numerical scale to set standards or reDroduce Drocedures.
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a
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4
Two models. Coleman Sephelometer (Model 7) for Kephelometry, and Coleman Nepho-Colorimeter (Model 9) for Nephelometry and Colorimetry, Ask for Bulletins B-213 and B-215.
COLEMAN NEPHELOS SYSTEM ..
for complete data. write Dept. A, Coleman Instruments, Inc., 31 8 Madison St., Maywood, 111.
For further information, circle number 11 A on Roaderr’ Service Card, page 73 A
V O L U M E 28, NO. 10, O C T O B E R 1 9 5 6
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REPORT FOR ANALYSTS
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obtained with the detector-type devices or by sampling and analysis. However, there are conditions where continuous analysis is either desirable or essential. An excellent example. although not an industrial operation, is the continuous carbon monoxide I ecorders for monitoring the air in vehicular tunnels. A continuous record of the carbon monoxide in the air in the tunnel permits regulation of the ventilation to keep the concentration a t safe levels and a t the same time has economical advantages in that the ventilation requirements can be geared to the volume of traffic. hIany operations in industry are so regulated that spot checks give a good index of the potential hazard. On the other hand, there are operations where the dissemination of a contaminant is so irregular in occurrence and amount, plus unusual incidents such as spills or breaks, that spot checks are unsatisfactory. Under these circumstances. a continuous recorder is the ideal solution. S o t only does this give a realistic measure of exposure conditions, but i t frequently helps to improve operations in that attention is directed to careless handling of material and equipnirnt which results in undue wastage. Continuous recorders have been developed for a number of substances in addition to carbon monoxide, examples being recorders for sulfur dioxide, hydrogen sulfide, carbon disulfide, chlorinated hydrocarbons, and combustible gases. Continuous recorders for many other substances, based paiticularly on spectrophotometric nieasurements in either the ultraviolet or infrared, are being and can be developed. Although the original cost of these instruments is considerable. the saving in time, ininiediate results, and complete record of concentration changes offset the cost i t m . Future Needs
internationally Known As “The Workhorse Of The Modern Research Laboratory.”
A% truly portable instrument, with separate transformer for remote control, easily operated in cold rooms, incubators, or practically any desired location
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The two major trends in new derelopnients in the field of indmtrial hygiene analysis and instrumentation are the development of detectors and indicatois and continuous recorders. It niay appear from this trend that the activities are becoming one of “gadgets” and oversimplification, on the one hand, or dial reading of unduly coniplev niachincs on the other. However. these devrlopnients require well-rounded training in chemistry and physics. and the euperienced specialist will be needed to suprrvise the proper use and maintenawe of this equipment. There is a need and opportunity for those n h o have the proper training and experience to make north-while contributions toward bettrr environmental working conditions and protection of the health of Jvorkers. ANALYTICAL CHEMISTRY
