ORGANIC MICROCHEMISTRY C. I,. OGG AND C . 0. WILLITS Eastern Regional Research Laboratory, Philadelphia 18, Pa.
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'ClCST : ~ d v : ~ i i ~inc sbcpraticrn and purification techuiques
such as chromatography, countercurrent distribution, and ion ruchange have increased the demand for the development of qiiantitative micro and submicromethods of organic analysis, ptrticularly for specific compounds, different classes of conipounds. and functional groups, Regardless of this emphasis, rew~;trvhw to improve methods of elemental analysis have nnt sixcki~ti(d:ind rral advances have been made. ELEMENTAL 4N.4LY S1S
Carbon and Hydrogen. Recent advances in the "empty tube" inrt ho(l ('or carbon and hydrogen analysis, reported by Belchcr and Ingrain ( 7 ) ,resulted from a redesign of the apparatus. Thrse iniprovviiwnts were based upon increasing the length of thcL hot zonr of tliv combustion tube to 3.5 to 40 cm., maintaining a tcmp(3raturr of 900' C., and increasing the time the gasrs were in tlw hot z o i w . .\ mnipact apparat.us was described and baffles were (~mploycvltn secure adequate mising of the gases in the hot zone. :\ novel fbsiturr of the purification train was thr drying system, which pr(ividrd for ready rep1:tcenirnt of absorbents. S u g g ~ s t d c-ausesof ['rror wrrr inconipletc combustion because of too rapid ~ ~ o ~ n t i u s t ioofntht, sample, loss of water vapor from thc, soda:lShStlJS in the cart)on dioxide absorhr, and porosity of thr quartz conibustion tube. I?j:,ughton and F'rorlyma (83)proposed a gasoinetric method for thr mrasurrmcnt of the carbon dioxide and xvater formcd by thr cwmhstion. 1nt;trnd of h i r i g absorbrd, the combustion gases were caught i l l freeze-out traps of dry ice and liquid air. The water and carbon dioxide were measured nianonietrically after the Pystem was freed of osygen by evacuation. The method is olaimed t c l rrquirc' no more than 16 minutes for nonnitrogenous compounds. .I stutiy o f tlic. carbon and hydrogen deterinination I c d Kirstvn (58) t,o pr(ipnw :L I I P W n,pp:iratus arid nirthod. Rome of the inttwsting fcatuws w t w his use of :L single furn:tcc, :i conibustion tcmperaturc, c ~ f1000" C., a mcach:inically movrtl magnet t,o push the saniple into the furnace, p1:itinum hid nickc.1 t u b w iilsid(> quartz conibustion tulie to protect thc latter, and :I liquid wrubIler to remove oxides of nitrogen. The rcxnioval of the trouhlesoinr oxides of nitrogen wi~s(lisvussed \)y Korshun :tnd Kliniova (61). They proposed the use of c.ithttr potassium pernianganatr or potaesium dichroniatr i i t ronrentrated sulfuric wid i n A buhbk counter pl;ircd hrtwrcn thts watrr and carbon diosidtl ;tbsorptioii tubes. Untereaucher (123) :Lpplied sonie of the principlrs of thci tfirwt, oxygen determination to thc drtcrniination of carbon and liytirogen. Excess oxygen from the coinbustioil wns removed b y copper, the water wis ahsorbrd 1)y barium chloride, and the carbondioxide was convrrtcti t,o c:irl )oil monoxide by passing over c:irbon :it 1120" C. The c:trl)oii nionoxidc formed \vas dcterminrd iodometrically as i n thcl dirrct oxygrii aimlysis. The watrr absorbed by the barium chloride was liberated and passed over carlion a t 1120" C., and the resulting carbon monoxide was again detmnincd iodometrically. This involved proredurc seems to h:~ve vwy little practical ;tpplicat~ion. Nitrogen, Kjeldahl. .is usual, nitrogen deterinination hy the lijeldahl method has been the subject of a proportionately large number of papers. Parxias (91) recommended some minor iniprovements in his commonly used Parnas-Wagner apparatus. Further modifications were suggested by Silverstein and Prrt#hel (108) who, in addition, claimed t,o have simplifird the titration procedure by combining the use of boric acid as absorbant and potassium biiodatc as the acid titrant. 47
The use of boric acid was also advocated by Xohlau (86). h scheme of analysis by which Kjeldahl microdeterminations could be made without the use of a microbalance was described by Niederl and AlcBeth (86). Iiirk (56) stressed the importance of the digestion conditions of the Kjeldahl method for determining total nitrogen and raised questions concerning correct ratio of sample to sulfuric acid ; correct amount of salt to add; and the best catalyst to iiw. He concluded that mercury was the most efficirnt catalyst and could not be replaced satisfactorily by selenium. Developments in reducing the size of sample into the submicrogram range were predicted. The collaborative study conducted by Willits and Ogg (130) for the Association of Official Agricultural Chemists substantiated Kirk's opinion concerning the desirability of using :I mercury catalyst. The data obtained in this study shomrd t.hnt even nit,rogen in heterocyclic ring compounds, such as nirotinii' acid, citn he determined by the Kjeldahl method if mercury is thc catalyst, and if less than 30 mg. of sample are digested for I hours n t full boil in 2 ml. of sulfuric acid containing 1.3 grams of potassium sulfate. The boiling points of different mixtures of sulfuric. acid and potassium sulfate were reported by Ogg and Willits (88): the data indicated that a temperature of about 350" C. was necessary for decomposition of refractory nitrogen compounds. Thew and other recent papers stressed the necessity for longer digestion periods for ICjeldahl microanalysis than had formerly been considered necessary. During the past year four papers have d(wribed the determination of nitrogen on the microgram scale. Iluck et al. (63) discussed the application of Carlsberg technique to industrial practice. Doyle and Omoto (26) reported modifications of the Carlsberg nicthod which were designed to simplify the procedure. Workiilg with microgram quantities Schulrli and Foti (104) found that water was a satisfactory absorbant for thc ammoni:t. Fluid s:tinpl(~scont:iining less t.h:in 10 micrograms of nitrogen wcr(x :tnalymd 11jH l i : ~ wand Be:idlr (106) with 3. dmidard deviation of 0.02 to 0.04 niic!rogram. IIale et nl. (39) describrd a semimicroproccdurc. for deitrrniining tra,crs of nitrogclri in oils, which utilized spc.ctt,oplintoiiIc.tl'ir, measurrment :iftvr treatmrnt with Nessler's rc~agrnt. Nitrogen, Dumas. Colsou's study of thc Dunias method for nitrogen (21) resulted in his proposing a met,hod by which th(, analvsie tinie could he reduced k)y one half. A fourfold increase iri the normal length of met:-lllic copper made possible the use of :I m u c h fststvr e:irbi)n dioxide stream and consequently a shortw analysis tin;(,. llangeney (77)rcportrd a modification of Zimmernian's wutomatic combustion method. Unterzaucher (164) drscribed new automatic rquipnient for the microdetermination of nitrogen by the Dumas method. The sample was burned over cmpper oside i i i :i moist carlion tlioside-osygen stream arid tjhe oxygen, a f t r r c.oml)ust,ion, \vas rchmoved by heated copprr. Semimicioeainples of vol:ttile materials were analyzed by Buchanan et d.(f?), using the app:irat,us of Niederl and a special tpchniquc. for introducing :tir-frec, s:imple iiito thc sample bulb and lireaking the bulb. Halogens. The chromic-sull'uric: acid \wt-ashing procedure of T;iui.og: (-'haikoff, and Chancy \vas improved by Thomas et al. (119). Grodsky (38) determined chlorine and bromine by first fusing the sample with potassium, then t.itrating the resulting potassiuni halidr with silver nit,rate, using dichlorofluorescein. -4method for dcterniining microgram quantities of chlorine in large amounts of organic niat>ter was described by Judah (51). White and Kilpatrick (128) combined the Carius method with the iodonietric niet,hod for broniinr by preventing the volatilization of
ANALYTICAL CHEMISTRY
48
broiiiiiie t h o u g h the use of l o w trmperatures. JVliite and Secor (129) combined the Carius method for iodine with the Winkler iodometric titration. The method is specific with a favorable volunietric factor. .4micromethod for iodine employing radioactive iodide was described by Raben (97). Michel and Deltour (81) proposed a method for the simultaneous determination of iodine and bromine in halogenated proteins. Lachiver and Leloup (64) described a method for the determination of traces of iodine in serum or plasma with an error of only 3 to 7%. For iodometric titrations Steinitz (113) stabilized the starch solution by combining the potassium iodide and stnruh solutions. Oxygen. The increasing interest i n the microdetermination of oxygen was demonstrated by the tound table discussion held at, SOCIETY. the 118th -4nnual Meeting of tlic AMERICASCHBJIICAI. Even so, the method is not as yet l A n g reported on clxtensively, sincc only two papers on tliis subject were published during tlic past year, Deinum and Scliouten (24) devoted tlieir attention to lobvering the blank by more complete rc.moval of the oxygen in the nitrogen, and to a simple means of determining the carbon monoxide by oxidation with mercuric oside and titration of the rcsultiiig carbon dioxide. They showed that about 4 nig. of oxygen could be deternlined with a masiniuni error of 0.1 ing. and a mean error of 0.05 mg. Maylott and Lewis (79) compared tlie resultu obtained with tlie ter Meulen, Liebig, and Unterzaucher niethods for the deternunation of oxygen and concluded t,hat the Unterzaucher method was the best. Sulfur-containing conipounds w r e found to give erroneously high oxygen values by this method because of the formation of carbon disulfide aiid carbonyl sulfide. Thcw were not removed by an alkali scrubber but could be eliminated by a liquid nitrogen trap. Sulfur. The several sulfur methods reported in 1950 were almost unanimous in their effort to avoid the gravimetric determination of sulfur as the barium sulfate. %inimermann (1.35) and Reznik (99) reduced the sulfur to a sulfide by reaction with metallic potassium and then used an iodate osidation followd by thiosulfate titration, Kirsten (67) burned the sample in oxygen arid rtduced the resulting sulfur oxides in a hydrogen-oxygen tianie. The hydrogen sulfide was absorbed in strong alkali s o h tion and determined by oxidation with hypochlorite solution. T w o titrimetric procedures for sulfate were proposed, one by Erdos (30), who dissolved precipitated benzidine sulfate i n standard base and titrated the escess with acid, and the other by SoIbel'man (110), who used barium iodate to precipitate the sulfate and followed this by a thiosulfate titration. For determining trace amounts of sulfur, a wpheloiiletric met,hod was reported by Holetori and Liiich (Qf),2nd a gasometric method by Holter and LZvtrup (43), which was based on the catalytic action of sulfur compounds on the iodine-azide rcaction. Neudorffer (84) reported a nitithod for d(.terminiiig sulfllr i r k coinpouritis containing fluorinc!. GROUP ANALYSIS
The three methods for the deterriiinntioii of misaturation m:adc this the most reported-on analysis in tliis category. The method of Mead and Howton (80) used the Barcroft-Warburg apparatus to perform catalytic hydrogenations of less than 1-mg. samples of materials such as methyl oleate with results accurate to within *5%. Viollier (126) described a lialogenation micromethod for determining unsaturation in liver fat acids and Rrigoni (16) used a modified Hanus method on a semimicro scalr to analyze raw matrrials and commercial stearic mid. The, lithium aluminum liytlride reagent, \rIiicli is gaining considerable favor in analytical methods, was used by Lieb and ScliGniger (68)for the microdeterminatioii of active hydrogen with Solty's apparatus. Lieb et al. (6.9), irl studyilig the microdetermination of carbonyl, found that it M - ~ Spreferable to measure the ~ rather than by phenylhydrazine hydrochloride reagent I J weight
volume. Although the reaction wits n o t quantitative aiid uiiiform, it could be used to determine the numliei of carbonyl groups in compounds that reacted readily. Loss of acetic acid during removal of carbon dioside or sulfur dioxide in the acetyl determination was prevented by Kainz (53) by inserting a cold finger in the neck of the Erlenmeyer flask in which the boiling took place. Organic sulfur compounds were determined by Lennartz and Middeldorf (66) by treating the sample with a standard lead solution, filtering off the precipitated lead sulfur compound, and titrating the escess lead in the filtrate with ammonium molyhdate using tannin as the indicator. Iiainz and Pohm (54) determined organic bases by converting them to hydrochlorides, hydrobroniidcs, or iodine methylates and titrating with silver nitrate i n alcohol solution, using dichlorofluorescein indicator. JVoimd (132) described the preparation of a special copper p h o q h i t e suspension for the determination of a-amino nitrogen in amino acids or polypeptides. The method was useful in the analysis of fractions separated by paper chromtttographp. COMPOUNDS
The increase in the development of inethotls for the microdetermination of acids was concurrent TTith the improvement in separations made possible by chromatographic methods. Black (11) described a method for separating and determining volatile fatty acids in :L mixture of acids. The microestimation of citric acid by the pentabroinoacetone procedure was discussed by Weilhlalherbc and Bone (12?), and the effcct of manganese trioxide osidiition on the det,ermination of lactic acid was studied by Linliardt and Reichold (70) who claimed that manganous sulfate waa not neccss:try when manganic acid was the osidant. Shimosawa (107) determined metholglucuronic acid with potassium ferricyanide, measuring the excess ferricyanide by reduct'ion with potassium iodide and titration of the iodine liberated. Tsao and Brown (19f)adapted the method of Friedemann and Hangen to the drternlination of as little as 0.5 to 10 microgranis of pyruvic acid in blood or urine. Aspartic and glutamic acids m r e determined in mixtures of amino acids by Froniageot and Colas (34) after chromatographie separation of the acid groups, conversion to the hydrosy acids, oxidation Lyith potassium permanganate, and determination of the acetaldehyde formed. As little as 10 to 120 microgrnms of ribonucleic acid were determined by a method described by Bergold add Pister (Y), which measured the furfural formed from the pentose colorimetrically. Zeile arid Oetzel (133) tltwribrd the microanalytical separation arid determination of amino acids through formation of t,heir azobcnzenc derivatives ant1 subsequent partition. The microdetermination of ureides and tryptophan in proteins was described by Orekhovich and Tustanovskii (89),and a method for the spectrophotometric determination of 5 to 10 mg. of protein bawd on the biuret reaction was proposed by Dustin (28). Rappaport, and Eichhorn (98) described an ultraniicromethod for the determination of urea based on its conversion to ammonia by urease and nesslerization of the ammonia formed. Three methods for the microdetermination of glucose in blood were reported. The colorimetric method of Sols (111) made use of the color developed by reaction with Somogyi's alkaline copper reagent and phosphomolybdic acid. Park and Johnson (90) used ferric alum and Duponol after osidtztion Kith ferricyanide. Pruner (94) suggested improvements in the method of Hagedorn and Jensen. Two modifications of the cyst,ein-hexose color reaction made it possible for Dische et al. (25) t o determine hexoses in mixtures with each other and with other sugars. A colorimetric method for determining lactose in concentrations from 0.05 to 0.27, was described by Rfalpress and Morrison (76). h modified Bertrand method F a s used by Lisitsyn ( 7 f ) for the semimicrodetermination of sugars in plants. Beck (6) proposed
V O L U M E 2 3 , NO. 1, J A N U A R Y 1 9 5 1 t wr new reagents for determining dextrose in l~looc-l:uid urine, one o i tli(%m bring sensitive to 0.5 my. of dextrose. In the determinatioii of mannitol in blood, Argant ( 3 ) oxidized the mannitol to foi,nialdehyde with periodic acid and determined the aldehyde by thr chromotropic acid method. llethanol was similarly determined by Agner and Belfrage (@, except t h a t the oxidation was t)y saturated permanganate. Determination of ethanol in blood by XtcLeod (73) depended on the diffusion of ethanol in a Con\v:iy (.ell into standard permangan:ite :ind titration of the excess 4>\-idaIit8 with thiourea. 13ricke.r and Vail (1.5) reported thc c1etc~riiiin:itionof micw :iiiiounts of formaldehyde in the presence of large concentrations o f othclr organic compounds. The interfering compounds were reniowd by evaporation after the addition of chromotropie acid to I.ct:tin the formaldehyde. The method for niethy1:tnline proposed Iry Cromwell (22) was based on the reaction of the amine with ninfiydrin to form formaldehyde, JT-hirli rcactcd with c r o m o h p i c :icitl and was measured colorimetrically. T h i ~two methods reported for the microtlrtc,i,rilinntion of vitamin 1 were less susceptible to water interfrrence. Xogiady’s I)roc:eclure (87) mas based on the Carr-Prire reaction, but used tric1iloro:tcetic acid instead of antimony trichloride. Sobel and Itosi~ii1)erg(109) used activated I ,3-dichloro-2-propariol for thr siniultaneous determination of vitamin h :tnd c:irotene in 1 nil. or I I ~ Wo f milk, measuring the absorption :it 455 :tnd 800 millimicrons, rcspc~tively. A colorimetric method o f :tn:tlysis for less than 100 iiiii:rogranis of ascorbic acid was reported by Xannelli (78) and it tluoroinetric method for alloxail ~norioliydr:ttc:is rit)oflitvin was ihcd by Tipson and Cretcher (120). -1scmiinicromethod for caffeine by Rower ct al. (IS) required :ci)prosimately one fourth of the time neccssnry for the official .1.0.-i.C. method. A method of dcterminirig fat based on the fi1rm:ttion of monolayer films was described by Jones (50). Stinsitive methods for determining butancdiol fermentation products using the soluble red diiiicthylglyoxinic-tetravalent nickel complex were described by Hoorenian (44). Sinall amounts of water m r e determined by Roherts and Levin (100) using azeotropic distillation followsd by titration with Karl 1’isvhc.r rragent. Johansson (48) modified the Fischer method by d d i r i g bromine to oxidize the hydroiodic acid to iodic acid, deterniining t,his by iodometry. Each mole of water required 12 moles o i sodium thiosulfate in the final titr:ttioii, thus iucrc&ng the. wnsitivit? of t,he method. METHODS AND APPARATCS
Sul,linYation procedures for the separation :~iidpurification of niiuro amounts of material vere rcportcd by 1Inliss:t (Ti), Rosentlinler (101), and Gettler et al. (a6). The remova1)le trarisparent plastic film used by Gettler and eo-authors to rcoeivr the subr liiiiatc. m:tde i t possible to remove the sul)lini:itr intact f ( ~ es:iniin:ttion or chemical test. Fischrr :tnd Srup:tuer (33) recommrndtd the determination of critic:tl mixing trniper:tturrs for th(s idriitific-:ition and determination of sniall aniouiits of liquids. T l i ~ ydcsoril)ed the method and listed the tc~iiip(~riitui,w for 100 compouiitls. -4method for t h e :iceur:ttc rnc~tc~ring of liquid flows o f 0.005 ml. per second as drscril,td I)? C’:ilcot(a ( f z l ) . Blakr ( I d ) t1escril)ed three surface-tension deviccBs fur niwsuring and delivering minute quantities of liquids. L1irrose;ile tests of petroleum 1)roducts for pour point, titer, and vapor prc’ssure were reported 1)y Lrvin et al. (67). A vitpor prcwmtt method for molecular Lveight nurrodetermination was rc,portLJd by Puddington (95). A clifferrnti:il manometer was used to ine:tsure vapor pressure diffrrrncrs between solvent and solution, and with this instrument 3 - m g . s:imples were analyzed with less than =t2Y0error. S e w designs of microapparatus are constantly tieing devised. ltecrntly att.entiOn has been directed towir(1 improvements in the ulti,ainicrobalance. Korennian and Fertel’meister (60) described :t t):ilmor having either a quartz or steel fihrr which was capable of :I 3 to S70:xccuracy when u s i d in thr 20- to GO-mierogrmi range.
49 1ngr:iiii (.is)(ksrribcd the developrncnt of a su1~mic~rot)alaricc having a grenter range of application to quantitative methods. Benedet’ti-Pichler (8) proposed a method for the calibration of weights and discussed the substitution method of Gauss. He pointed out th:it the method of Richards provides internal constancy, \\-hich is of greater imp:)rtance to the chemist than is the k n o d e d g c of alJsolute vieights. A mrans of controlling the swings of a microt~:il:iric:cby a n air jet attachment w a s drscrilxd by Stock and Fill ( I f , $ ) , Minij-:t and Iiarnnda ( l l d ) , Stock :tnd Fill (115), atid I h g u t h (1.9) tlcsrril)cd modifications of microbui,ets. 1,azaron. (6.5) described it universal holder for syringes of 0.25-inl. 10-ml. capacity. 1)cblivery w i s measured by a displac‘cniont g:igc’ calih a t e d in microlitc~rs. Aititration apparat,us of unique cicsign for ml. was clescribc,tl hy D;timltrr mc.:isuriiig liquitl volumes of (23). The inrtrunicwt utilized a radio indicitting cimuit :ind the (~l(:ctroni:tgtic~tici)i,c,:ikirig of a suspension which servc~tl ns a liquid dispI:wnient nicc1i:tnisni. The cdilx:ttion of mic~i~ohurets by :in :ir?:tI I l i ( ’ ~ ~ i ( J \vas d proposed by Buck et crl. (18). l k a s u r e mrxnt of tlir :tr(’:t i ) f spots produced on filter p:Lper by droplets of dye solution \ v : i ~ i.c.lntec1 exponentially to the’ corresponding volunic~s. Tlii.; iiic~thod\WS uscful ill cht~ekingv:iri:ttions h ~ t w - e t ~ n rept>:ttc k l i v ~ ~ voIuni(1s. ry Scliiiiiigvr (102) utilintd thc, method of U:i~.ei.lcfor the gi*n(sr:ttion of Iiydrogc~iil)y thc electrolyuis of dilutc Iiydrochloiic acid with tlw (,.ni.f. tlt~vc~lopedb y a pl:ttiiiuni--:tiii:ilg:rin:itc~d zinc couplv. Thcs :ipp:iratus was so constructed that w h c ~ n the gas prerrule r t x v h t d :t iiwtl value, a mercury Ievc.1 device lii.okc, the circuit, $toppiiig gas grucwition. Niederl :tnd (:li:gg (85)reported that l)y making tht) middle joint o f the Kipp generator gas-tight (using GIypt:il SO.1201) and maintaining it slight vacuum iii the uppc’r ch:tmt)t~r,sufficiently pure carlion tlioside could 1 ) o11t:iiiicd ~ from :I siiigltx gviicixtor. Rickford (10) niotlificd a Squihl, separ:Ltory f u i i w l for use in micro \vork l)y inHc.rting a length of glass tuliiiig (0.5 cm. in inside di:tinc,ter) I)vt\ret.ri t,he pear-shaped portion of thc fuiinr~l:in(\ t lit, stopmck. Irliri :inti Hruns (47) dencribetl tht: c:onstruc+ion of :I distill:~tioncLolumniii which 1 cm. was equiv:thint to o i i r throrvtic:il plat,(, :tnd cquililirium was attairietl in 5 tjo 0 niinutt,s. Ellis arid Braiitlt (29) describrd a photoelectric coloiiiiit~tc~r suit:tlik for iiiicroitnitlysis n-hieh u I LL variety of cuvvttes, incluc-ling O I I ~ ’ with a length of 10 cui, arid it v:ip:tcity of 0.4 ml. 1iinsc.y (56) dcwril)ed an assembly for positioiiing tlicl cuvvttes used iii micrn:tiidysis with a Reckman spc,ctrol)hutoiii[,t(,r. For nicasuriiig pII with indicators, Schulze (10-5) tlrvc~lopcd a comparator with :i vertioal series of three g h s s (:ups mntaining stand:irtls, :tg:iiiist which was compnrcd :L singlo cup cont:tining the trst solution. Iiofii~r:tnd I i o f l ~ r(59) described an e1rctric:illy he:rtod sheet m r t d strip for determination of melting poiirt. Thc tc’mpc’rature of thv strip v:iricd from 50” C. a t one end to 260” :it t h r other. T h r sample \vas slo\vly moved along thrb strip until it inc~ltedand the teniperaturc~\vas determined from the distance betwwn the point of nitaltiiig :tnd one end of the strip. For the dct,csrniination of mrlting points lxlow room temperature, Tschamler (182) used a strcsani of dry :tir :it tempcsratures as lorn its -40” C. Fogging \\-itsprtv,nted I)>- regulation of the s p e d of the :tir :ind thc usc of :i plnst,ic vic.\ving window. Al)r:thumson ( 1 ) used a plaster of Paris cylinder to support the sample in the solvent extraction of cholesterol. The stainless steel :tpparatus clrscrihetf by Erdos (31) was usc,ful in t,he study of chlorosulfonic :tcitl, in microhydrogenations, and as a microbomb. Ingram (.io) used a new split-type furnace for mirroconibustioiis. Stock nnd Fill (116 , 1 1 7 ) tlePcribed several new holding and clamping devices and an adaptation of magnetic stirring to microtechniques. An electrically heated autoclave for small volumes of liquids (5 to 30 nil.) IWS described by Schoniger (103). Stock et a l , (118) also reported on a modification of the Lindst,one-Wilson hydrogcn sulfide microgenerator. Cannon (20) gave in detail the
50
ANALYTICAL CHEMISTRY
rneclianisni used to move the gas mmple burner 011 the Dumas nitrogen apparatus. A thermal nlicromanometer utilizing a resistance bridge calibrated in pressure readings giving a precisioii of better than 1% \vas described by Dunoyer ( 2 7 ) . MISCELLANEOUS
Batt (5) proposed a scniiquantitative procedure for the estimation of nitrogen, sulfur, phosphorus, and the halogens in organicmmples. After fusion with sodium, the sample was dissolved in water and aliquots were taken for estimating the various elrnients by comparing the color or volume of precipitates. A matliematical schenie for expressing t,he se~isit~ivity of inicrochenlical reactions was described by Malissa (76). T h r sensitivity number was exprrsstd as the negative logarithm of thr rffectivc concrntration (in g r a m per milliliter) of the constituent sought. The following classification of the nurnlms was proposed: below 3, not sensitive; betnerii 3 and 5 , srnsitivt.; m t i at)ove 5 very sensitivr, with 0 rrscrvrd to indicate unreliablr t,rst s. Johnson (49) estimated nonvolatile organic niattcr t)y oxidation with standard sodium dichromate solution followed t1.v colorimrtric determination of thr excess oxidant. Korshun and Lavrovskaya (62) modified the Boteius procrdure, making possible thi. microdetermination of mcirury in organic compounds regardless of the other elements prestxnt. Micromethods for blood, swum, and plasma analysis include t>lie determination of plasma phospholipides by Zilversniit and Davis (134), blood penicillin by Hildick-Smith and Fell (do), hydroxyproline by Wiss ( Z S Z ) , tocopherols by Quaife et al. (96), basic drugs by Porter and Silber (93), cholesterol by Gleiss and Hinsberg (36), and histamine by Luhschez ( 7 2 ) . Other micromethods reported for blood analysis were those of Ventura (226) for determining true glycrmia and galactemia, and of Gohr and Scholl ($7) for silicic acid. A method for the determination of globin in natural mrdia was rrported by Polonovski and Bourillon (929. Fischpr and Go11 (32)recommended the use of adsorption agents to shorten and simplify tosic,ological analysis. They reported on a series of studies using activated carbon, alumina, and wofatitr to separate many of the alkaloids coninionly determined. Recent reviews of progress in organic microanalysis were mad(% by Kahane (52) in France, and Batalin (4) in Russia. 1Iioromethods in histochemistry and cytochemistry were reviewed by Holter and Understrom-Lang (4.2). ACKNOWLEDGMENT
iii
The authors are indebted t80Frances J. Cooper for h r r :issist:tiim> preparing t,his review. LITERATURE CITED
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(19) (20) (21) (22) (23) (24)
Calcote, H. F., ANAL.CHEM.,22, 1058-60 (1950). -4., Chemist-Analyst, 39, 64-6 (1960). Cannon, UT. Colson, A. F., A n a l y s t , 75, 264-8 (1950). Cromwell, B. T., Biochem. J., 45, 84-6 (1949). Daimler, B. H., C h m . Ing. Tech., 22, 104-6 (1950). and Schouten, A., Anal. Chim. A c t a , 4, 286-99 Deinum, H. W., (1950). (25) Dische, Z., Shettles, L. B., and Osnos, A I . , Arch. Biochem., 22, 169-84 (1949). (26) Doyle, W.L., and Omoto, J. H., ANAL.CHEbf.,22, 6 0 3 4 (19501. (27) Dunoyer, Louis, L e V i d e , 4, 603-18, 643-60 (1949). (28) Dustin, J. P., Arch. intern. physiol., 57, 95-7 11949). (29) Ellis, G. H., and Brandt, C. S., ANAL. CHEM.,21, 1540 -5 (1949). (30) Erdos, J., Mikrochemie w r . Mikrochim. Acta, 34, 286-8 (1949). (31) Ibid., 35, 236-7 (1950). (32) Fischer, R., and Goll, H., Ibid., 35, 63-79 (1950). (33) Fischer, R., and Neupauer, E., Ibid., 34, 319-35 (1949). (34) Fromageot, C., and Colas, R., Biochim. et Biophys. Actu, 3, 417-21 (1949) (in French). (35) Gettler, A. O., Umberger, C. J., and Coldbaum, Leo, AkS.41.. CHEM.,22, 600-3 (1950). (36) Gleiss, J., and Hinsberg, K., 2. physiol. Chem., 284, l 5 G 6 3 (1949). (37) Gohr, H., and Scholl, O., Beitr. KZin. Y‘uberk., 102, 29-37 (1949). (38) Grodsky, Joseph, A N ~ LCHEar., . 21, 1651-3 (1949). (39) Hale, C. H., Hale, M. N., and Jones, W. H., Ibid., 21, 1549-51 (1949). (40) Hildiok-Smith, G., and Fell, h l . , J . Lab. Clin. ‘Wed., 34, 168791 (1949). (41) Holeton, R. E., and Lineh, .4. L., Axar.. CHEY., 22, 819 -22 (1950). (42) Holter, H., and Linderstrom-Lang, K., Rczsearch ( L o n d o n ) , 3, 315-20 (1950). (43) Holter, H., and Lglvtrup, Sglren, Compt. l e n d trac. lab. Cnrl.6berg, Ser. chim., 27, 72-8 (1949). (44) Hooreman, hl., A n a l . Chim.A c t a , 3, 606-27 (1949). (45) Ingram, G., Metallurgia, 40, 231-2, 283-4 (1949). (46) Ibid., 41, 54-5 (1949). (47) Irlin, -1.L., and Bruns, B. P., Z h u r . -4nnL. Khim., 5, 44 7 (1950). (48) Johansson, Axel, Acta Chem. Scand., 3, 1058-66 (1949). (49) Johnson, ?if. J., J. Biol. Chew&.,181, 707-11 (1949). (50) Jones, K. K., Science, 111, 9-10 (1950). (51) Judah, J. D., Biochem. J., 45, 60-5 (1949). (52) Kahane, Ernest, B u l l . soc. chim. France, 1950, D1-D12. (53) Kainz, G., Mikrochemie uer. Mikrochirn. Acta, 35, 89-93 (195111, (54) Kainz, G., and Pohm, M., Ibid., 35, 189-93 (1950). (55) Kinsey, V. E., ANAL.CHEM.,22, 362-3 (1950). (56) Kirk, P. L., Ibid., 22, 354-8 (1950). (57) Kirsten, W., M i k r o c h e m i ~ i w . Mikrochiw. d c t n , 35, 171 5 (1950). (58) Ibid., pp. 217-35. (59) Kofler. L.. and Kofler. W.. Ihid.. 34. 374-81 (1949). (60) Kovenman, I. M., and Fertel’meistek, Ya. N.,Zavodskaya Lo’! , 15, 785-96 (1949). ( H I ) Korshiiri, hl. O., and Klimova, V. -I.,Zhur. -4nal. Khim..4 , 292--7 (1949). (62) Elwshuii, L f . O., ai>dLavrovskaya, E. V., Ibid.,3, 322-8 (194s I . (63) Kuck, J. -1..Kingsley, A , Kinsey, D., Sheehan, F., and Swigeit, G . P.,;\SAL. CHEM.,22, 604-11 (1950). (04) Lar:hirev, Franpois, and Leloiip, Jacques, Bd1. soc. chim. hid., 31, 1128-43 (1949). (65) Laaarow, Arnold, J . Lnh. C / h . -lied., 35, 810-14 (1950). (6ti) Leniiartz, T. A., and Midrlrldorf. R . , ,SuddetLt. S p o t h . Ztg., 89, 593-5 (1949). (67) Levin, H.. Morrison, -4. R..n n d Reed. C . R.. ASAI.. CHEM.,22, 188-91 (1950). (68) Iieh, H., and Schoniger, IY..31 ikroclwniie c w . Mikrochim. .4ci
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IN0RGANlC MICROCHEMISTRY PHILIP W. WEST Louisiana S t a t e Unicersity, Baton Rouge, La.
I
SORGAMC niicrocliernistry embraces many fields and
techniques, and the reader is referred to accompanying review on spectroscopy, polarography, light microscopy, electron micros1 opy, nucleonics, fluorometry, and chromatography for correlative information. T h e scope of the present discussion is essentially the same as that of the previous review (287). The articles I onsidered are those that were included in Chemical Abstracts lip to and including the September 20, 1950, number. BOOKS AND REVIEWS
A number of reviews have appeared dealing with various phases 01’microchemistry. T h e life and work of Pregl have been dewribed by Lieb (166), and biographical sketches of Eniich have twen written by Benedetti-Pichler (20) and Llacer (169). McDonne11 and Wilson ( 1 7 3 ) have discussed the use of organic rcsagents and spot test procedures in qualitative analysis 8s a part or a series of excellent papers reviem-ing the various schemes for group separations used in qualitative inorganic analyais. An outstanding discussion of the uses of organic reagents for specific, selective, and sensitive reactions has been presented by Feigl ( 7 5 ) . West (288) has considered sources of error and their rlimination in the use of organic reagents. Absorption (spectral) methods in analytical chemistry have been discussed h y Coumou (62),Duycltaerts (M),3layer (184),
and Milbauer (190). Other review include a discussion of the microchemical identification of metals ( d g l ) , the determination of residual chlorine concentrations (117), and the status of niicrochemistry in Russia ( 1 7 ) . Mirnik (193) has revierred methods for quantitative inorganic microanalysis. A book on inorganic microanalysis by Longo (170) is noteworthy. Although relatively short (164 pages), this book contains excellent sections on organic reagents, spot tests, mirroscopical procedures (including some mention of polarized light microscopy), and group separations of anions and cations: a chapter is included on quantitative methods of microanalysis anti there are discussions of various special techniques. Unfortunately for many, the book is written in Spanish. booklet by Gaddis (90) on semimicro methods of quantitative analysis should be of interest to those considering the use of such methods in the teaching of quantitative analysis APPARATUS
Development of measuring devices is of prime importance in analytical chemistry and is especially valuable in microchemical work. A rugged balance for use in the submicro range has been described by Ingram (127) and its applications pointed out. Elorenman has described a torsion microbalance (142) together with its applications. A torsion microbalance designed for use
