edited by MALCOLM M. RENFREW University of Idaho Moscow, Idaho 83843
Experiments Integrating Evaluation of Chemical Hazards into the Chemistry Curriculum J. T. Pierce, S. M. McDonald, and M. S. Scogin University of North Alabama. Florence, AL 35632
One way of making students aware of the need for regular monitoring of laboratories is to offer an introduction to the science of industrial hygiene as part of the chemistry curriculum. Although laboratory safety and industrial hygiene may he discussed in a variety of laboratory settings, opportunities for students actually to sample and analyze contaminants are rare. We propose the use of two experiments that demonstrate important points concerning the desirability and the means of regular laboratory monitoring. During the past year we have undertaken to monitor our own laboratories and have sponsored senior industrial hygiene projecta directed to that end. We feel that these experiments have broader applicability and may be used as "whole class" experiments. Two momisine areas for monitorine apn o& to he t h i estimation of hvdroeei s k r - - ~ - ~ ~ fide lev& in thegrneral chemist& lnhratory dur~ngqualitative onolyrir and thrdrtermination of the concentration of organic vapors associated with organic chemistry lahoratories. One of the orohlems that besets those charged with Lboratory monitoring is the "selection" of suitable analytes given the large number of candidate materials. Given limited time and resources it may be desirable simply to select a few representative contaminants during preliminary stages. With the advent of microprocessor-controUed gas chromatography the ability to monitor large numbers of gases and vapors is enhanced. The methods we have selected allow the students to perform the sampling and analysis themselves relatively inexpensively. ~
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ks much as possible we use experiments that have been evaluated by the National Institute for Oeeupational Safety and Health (NIOSH). The methods described here are desimated bv NIOSH as P & CAM 127 (organic a h e n t s ~ and S4 (hydrogen sulfide). References from NIOSH outline the procedures for both samplmg and analysis of hydrogen sulfide and organic sulvent vapors in air, as well m m y other suhsmces 11-31. Vendors' infurmntion may also b~ u~eful. ~articularlvterhnicnl t,ulletins (41. Should diffieultiesarise concerning the availability of equipment or the interpretation ofreferences it is likely that an industrial hygienist in the area will be able to assist. Organizations e names of local industrial that can ~ m v i d the hygienists include the American Academy of Industrial Hygiene (certified industrial hy-
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0 Fieure 1. Calibration 01 impingel tube (b).
J. T. Plerce i6 an associate professorof indusbial hygiene at the University of North Alabama. and S. M. McDonald a d M. S. %win are senior industrial hygiene 61"-
Traditional industrial hygiene sampling has relied upon the use of small sampling pumps that could either be attached to a worker or placed in an area of interest. Such pumps individually cost several hundred dollars but are sometimes available on loan from a local industry. Those pumps selected should he capable of delivering air flowrates as indicated in references (1-3). In this work we used Du Pont Model P-30 Constant Flow Samplers. Pump calihratian is easily accomplished using an inverted buret in the form of a "soap bubble" calibrator in line as shown in Fipure 1. Further information on flow ral~hrnrionir summarized in common referencrs $5,fi,. In our work the hydrogen sulfidr war collected as cadmium sulfide when laboratory air was impinged in a cadmium sulfide solution. Arahinogalaetin (Sigma Chemical Co., St. Louis, MO) was added to the irnpinger solution to prevent the decomnosition of the cadmium sulfide eolIccted. It may he pospihle to use inexpensive plastic impingrrs t w thls nppliratim (ColeParmer Co., Chicago, IL). The collected sulfide was spectrophotometrically determined using a methylene-blue-type reaction (N, N-dimethyl-p-phenylenediamineand ferric chloride solutions). ~cti5,atrd-chnrroal-lilledtubes were used for the collpction of organic sulwnts. Care should be taken to insure the air makes contact first with the larger of the two charcoal sections of these adsorbent tubes. After sampling these tubes were opened, and the first charcoal laver was desorbed and analyzed. A gas chromatogrnph equipped with flame iunirarion was employed. A wriety of columns suitable ior common urganir materids may be used and an electronic integrator aids the analysis. Since this was a quantitative form of gas chromatography the solvent flush technique was employed as shown in F i m e 2. The laboratow's ahilitv to carw out such analyses proficiently may Ge checked by a proficiency analytical testing program such as the one currently carried out by NIOSH; samples are sent quarterly and results must
gienists) and the American Industrial Hygiene Association (both at 475 Wolf Ledges Parkway, Akron, OH) and the American Conference of Governmental Industrial Hygienists (6500 Glenway Ave., Cincinnati, OH).
Volume 61
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(Continued on page A85) Number 3
March 1984
A83
values for hvdroeen , .. sulfide'. do not indicate uverepusures, and, although other stud~es ofacademic iaborau,ries haw shown k ~ m ~ l a r results (7), inter-laboratory variation prevents mesningful generalization. Our laboratories were equipped with two 6-ft fume hoods which were not used during this work. We have since installed individual work station exhaustors so that each student has access t o ventilation. Although the specialized nature of lahoratory environments makes the application of Occupational Safety and Health Administration standards awkward, i t is still incumbent upon laboratory managers and educators t o provide a healthful environment far learning. The experiments we have discussed not only provide useful data for assessment of risk but may also instill an appreciation of the possible presence of airborne contaminants. ~~~
ibl CSz flush .r
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Figure 2. Solvent flush technique.
he returned arlthm fifteen workml: days Srlrctrd rrsuits from our work are shown In the rahle These resulta. exceptmg the
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Literature Cited (11 "NIOSH Manual ofhalytid Methods," vol. 1,md ed., 1977. (21 "NIOSH Manual of Analytical Methods,"Voi. 2,2nd ed.,1977.
(31 "NIOSH ManuslofSmpliozDataSheets,'. 1977. (41 Vendom' information: Du Pant Oaupational and E s vironmentsl Health Products. Wiimington, DE: Supeim, Ine.. Beiiefonte,PA. (51 Bdef,R. S.."Basic lnduatrial Hygiene,"E u o n Cow.. New York, 1975. (61 'The industrial Environmentits Evslvatian and Control,"Natimd lnstit"teforOrmpBti6ual Saf*and Health, 1973. (I1 Hertiein,IIi,F.,in"AaalytidTarhniqueainOeeupatioualChemistry,"Ameriuvl Chcmidsoeiety,Washington, DC, 1980.
1 Editor's
note: this high concentration of
H B demonstrates the need for caution when using thioacetamide outside of a fume hood.
(M.M.R.)
ResuHs ol Monitoring Contaminants In Academic Laboratories TYPE
P-MI Area Area Area
Conditions
Benrocaine preparation Paper chromatography Distillation of b n z e n d toluene mix Thioacetamide generation 01 H Z
'values
Location
Organic teaching lab General chemisby teaching lab Organic teaching lab Oeneral chemisby teaching lab
Time (m)
Volume (m3) Weight (mg)
180 155
0.024 0.015
