Elution Order of Selected Hydrocarbons from an Alumina Column SIR: In our experience we have observed a different c,lution order for acetylene from activated alumina chromatogral)hic columns than the one reported by Roger Philippe et al. in "Some Hydrocarbons of the Gas Phase of Cigarette Smoke," . ~ A LCHEM.36, 859 (1964). The elution order of eight hydrocarbon> found experirnentally in our laboratoriei and that reported by Philippr et al. are tabulated below: Hydrocarbon Methane Ethane Eth) lene Propane Propylene Propadiene Acetylene LIethyl acetylene
Our work
Philippe
1 2 3 4
1 2 3 4 6 7 5 8
5 6
7 8
h
et al.
We used an activattld alumina H-151 column of 1, ,-inch diameter, 7 feet long, and helium as carrier gas on an F & 11 JIodel 720 gas chromatograph. The elution order remain- unchanged with variation of carrier flow rate and tem1)erature (between 65" and 200" C.), even if the activated alumina is partially
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Figure 1 .
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Elution order of eight hydrocarbons Program rate: 2' C./minute
deactivated with moisture-e.g., carrier gaq passed over CuS04 5H20 a t 25" C. There also is no difference in the elution order if the column is operated isothermally or if it is linearly programmed. The presence of the acetylene peak was proven by comparing with the retention time of pure acetylene, enforcing the acetylene peak, as well as by
removing the acetylene by selective hydrogenation to ethane. Figure 1 represents a chromatogram obtained with our procedure. PETERPOLLAX OLAFC r s ~
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Determination of Acrolein and Furfural in Phenolic Resins by Gas Chromatography SIR: Recently n e described a gas chromatographic method (5) for determining unreacted phenol and formaldehyde in phenolic resins of the type commonly used in plywood adhesives. R e have since found that, this method can be applied to analysis of unrracted aldehydes in phenol-acrolein ( 4 ) and phenol-furfural ( I ) resins, as well as in phenol-formaldehyde resins modified with acrolein or furfural. The. procedure was worked out for aqueous resin solutions and is essentially the same as that described previously ( 5 ) . To improve resolution, flow rates of the two columns were changed as follolvs: Column h (12-foot by ,-inch copper tubing, Ilacked with l07'(( G E silicone SF-96 on Fluoropak, 105 ml.iminute). Column I3 (16-foot by '/,-inch copper tubing packed with 10% sucrose octaacetate on Teflon 6, 36 ml./minute). Other operating conditions were not changed.
Furfural and phenol were determined on column X with m-cresol as internal standard. Acrolein as well as formaldehyde was determined on column B using 1-butanol as internal standard. Samples for both determinations were prepared by the precipitation-extraction procedure described earlier (5) for phenol. Retention times are shown in Table I. Resolution of furfural on column A was excellent, (see Figure 1). (On Figures 1 and 2 , injection is a t time zero.) The factor for converting furfurallmcresol peak area ratios to weight ratios was determined by adding known amounts of furfural to a resin containing no free furfural and working up as described ( 5 ) . When furfural was present in amounts equal to or less than m-cresol, the factor was 1.76 f. 0.08. When about twice as much furfural as m-cresol was used, the factor was 2.03 f 0.11.
determined together by injecting aqueous solution into column 13 because the water peak completely overlaps that of acrolein. Instead, ether extracts are used as with furfural and phenol. Water is still present in substantial Table 1. Retention Times of Resin Ingredients, Solvents, and Internal Standards
Retention times, rnin a Column Column A* Bc
Conipound Formaldehyde 0 4 Ether 0 3 0 6 hlethanol 0 1 1 5 Acrolein 0 2 1 9 Rater
