ARcitive-S

FISHERIES RESEARCH BOARD OF CANADA

Translation Series No. 2932

Gas . chromatographic analysis of BHT, BHA and heat transfer media in fatty oils by precolunm method

by Toru Takagi, M. Yamazaki, K. Fukuzuki, T. Akiya and M. Aoyama

Original title: Purekaramu ho gasu kuromatogurafi ni voru vushichu no BHT, BHA oyobi netsu batai no bunseki

From: Yukagaku (Oil Chemistry), 22(7) : 357-362, 1973

Translated by the Translation Bureau( ac) Multilingual Services Division ,

'Department of the SecretarY of State of Canada

Department of the Environment Fisheries and Marine Service

Halifax Laboratory Halifax, N.S.

1974

20 pages typescript

TRANSLATED FROM TRADUCTION DE INTO , EN

English Japanese AUTHOR - AUTEUR

-DATE OF PUBLICA-TION ;DA-TE --pE:PIÙ.13141C.A-TION

ISSUE NO. NUMÉRO

7 1.973

syEAR .ANNéE

VOLUME

22

PUBLISHER - ÉDITEUR

Not given

—P„ASENUMBENS IN ORIGINAL ,NLIMÉROS -DES PAGES .DANS

— - .

357 362 PLACE OF PUBLICATION LIEU DE PUBLICATION

Not given (eapan).

— -,NUMBER- 0 FITYPED PAGES - NOMBRE .D E PAGES

DACTYLOGRAPHIÉES -

20

.._,,,..,....,,,,,,....,. , ., ., .. >m>.ki..u.,•,•,..e._.t.••■27J.re..t.ï:._:.. ,.27.--;.,...r»,..1,....:...,..,i“,.••-..u--.k,ie.,..-+..I..'u,...•:.n•a••n.,,-•..Wü •Z:•—•,oe.•••c.,..v.t.,.ilre,k,,,T. ..•••-i-Z•tà...,•..•ax.a...,.-;._.....•._......d.•a•-■.,--••••.-•—•.•••••••-.•—...•.....,.,_.—....---....—..--- !

. ''...... .

.

•

. .

• e..- • ., ..

DEPARTMENT OF THE SECRETARY OF STATE

TRANSLATION BUREAU

zee; CANADA

DIVISION MULTILINGUES •

_.%

•

MULTILIMGUAL SERVICES

SECRÉTARIAT D'ÉTAT

BUREAU DES TRADUCTIONS

DIVISION DES SERVICES

T. Takagi, M. Yamazaki, K. Fukuzuki, T. Akiya and.M. Aoyama.

TITLE IN ENGLISH .- TITRE ANGLAIS

Gas ChromatograPhic analysis of BHT, BHA.and heat transfer media.

in fatty oils by Precolumn method.

TITLE IN FOREIGN LANGUAGE (TRANSLITERATE FOREIGN CHARACTERS) TITRE EN LANGUE ÉTRANGÉRE (TRANSCRIRE EN CARACTÉRES ROMAINS)

Purekaramu ho gasu kuromatogurafi ni yoru.yushichu no

BHT, BHA oyobi netsu batai no bunseki. • REFERENCE IN FOREIGN LANGUAGE (NAME OF BOOK OR PUBLICATION) IN FULL. -TRAP-J .-SU TERATE..FOREIGN CHARACTERS.

RÉFÉRENCE EN LANGUE ÉTRANGÉRE (NOM DO LIVRE OU PUBLICATION), AU COMPLET, TRANSCRI RE EN CARACTÉRES ROMAINS.

Yukagaku 22 'No. 7, 3 57-362,. 1973.

REFERENCE IN ENGLISH .- RÉFÉRENC.E EN ANGLAIS

Journal of Japan Oil Ohemists' Society, 22 No, 7, 357,-362, 1973,

REQUESTING DEPARTMEN -T -Erw*ronment MINISTÈRE-CLIENT -DOSSIER -N°

-TeANSLLA-TOR LS) jwc DIRECTION OU DIVISION_ -TRADUCTEUR LES) •

-By.RE_AU NO. 165674

BRANCH OR DIVISION 511-elries Serv.ice

PERSON REQUESTING AIlan T. Reid DEMANDÉ PAR

YOUR NUMBER VOTRE DOSSIER NO

DATE OF REQUEST 05.--0274 - DATE DE LA DEMANDE

SOS.200.10.6 (R E V. 2/68)

7530-21-025-15733

-FEB 2 2 ig74

:UNEDITED TRANSLAT!ON • Tot

. Information seulement •

eDEPARTMENT OF THE SECRETARY OF STATE

TRANSLATION BUREAU SECRÉTARIAT D'ÉTAT

BUREAU DES TRADUCTIONS

MULTILINGUAL SERVICES

DIVISION DIVISION DES SERVICES

MULTILINGUES

CLIENTS NO. DEPARTMENT DI VISION/BRANCH CITY N° DU CLIENT MINISTÈRE DIVISION/DIRECTION VILLE

Environment Fisheries Service Ottawa, Ont. BUREAU NO. LANGUAGE TRANSLATOR (INITIALS)

N° DU BUREAU LANGUE TRADUCTEUR (INITIALES)

165674 Japanese JWC FEB 2 2 1974

Purekaramu ho gasu kuromatogurafi ni yoru yushichi

no BHT, BHA oyobi netsu batai no bunseki.

Yukagaku (Oil Chemistry), Vol. 22, No. 7, 1973.

SOS-200-1 o- 31

Gas Chromatographic Analysis of BHT, BHA and Heat Transfer

Medium in Fatty Oils.by Precolumn method

• ÔT11 TAKAGI, Meguiui YAMAZAK1*, Kazuo FUE.1)ZUMI, Toshirni AKIYA*

• and Masahiro AOYAMA

Faculty of Engineering, Nagoya University (Furo-cho, Chikusa-ku, Nagoya)

* Food Research Institute, Agricultural and Forestry Ministry (S.ioharla, Koto-lu. Tokyo)

Procedures for the rapid determination of BHT, BHA, Dowtherm and Neo-SK-oil in fatty oil were presented bY authors. Fatty oils containing antio-xidants or heat transfer medium are directly

'injected into precolurnn which i s attached to gas chromatocraph to protect the main column from contamination with the unvolatiles. Each analysis takes: only 20 min. at maximum. Gas chromato-

graph-mass spectroscopy system vas founci useful for the final identification of the antioxidant peaks.

Investigation of the change of BHT and BHA contents in heated oils by the precolumn method showed the monotonical decrease of the contents under the effective stirring at 180-210°C.

I. Foreword.

Gas chromatography is now.quite often used for the

analysis of small quantities of volatile components in

specimens of non-volatile oily substances. When the specimen

is not an oil but is solid, it may be possible to extract the

oil for analysis. This extraction may be by means of solvents,

by distillation or by sublimation and also by thin film

chromatography or gas chromatography, or by a éombination of

these methods. A quantitative concentration and separation

VNEDITEDTRANnUT;Cil

For iriC77;1é:iii:.?:"1 r:y

TRAE.311.7ir;, ;1 -Won-neon :getikuncrit

P357

2

may then be made by some method of gas chromatography, such

as the head-space method.

The authors have investigated and here report on a

method recently introduced by Hartman and Rose 1 for the

analysis of additives and adulterants in fatty oils. In

this method the fatty oils are introduced into a precolumn

which is used to protect the main column. The antioxidants

• are vaporized in the precolumn and it is found that they can

quickly be measured.

The methods in use for the quantitative measurement

of BHT and BHA include colorimetry2, ultra-violet absorption

4 spectroscopy 3 and gas chromatography. . In all these methods

pretreatment may be necessary to prevent interference from

components other than those sought. The time taken in this

pretreatment may be long and it may require much experience

and labour, and the pretreatment may also cause the loss of

some of the required component. The colorimetric and ultra-

violet absorption spectroscopy methods have the fault that

phenolic compounds also present in the specimens may interfere

with the measurement.

In the present investigation of the use of the

precolumn, the amount of BHT or BHA in a fatty oil was

measured, and the rate of loss of the BHT or BHA could be '

quickly determined. BHT or BHA could be assigned to a peak

by using the pure compound as a reference and obtaining the

retention time in the types of columns used, but in order to

• .1, •

3

obtain a high degree of certainty, gas chromatograph mass

spectroscopy could be used and the mass spectra of BHT and

BHA measured. The procedure was shown to be extremely

effective.

One of the present authors (Takagi) has already

published a method for the measurement by means of gas.

chromatography of small quantities of heat transfer media

such as diphenyl or diphenyl ether present in fatty oils 5 .

In that method the unsaponified compounds were separated and

concentrated by thin film chromatography and introduced

directly into the gas chromatograph. According to the author,

one fault of the method was that the entrance port of the

equipment was fouled by the fatty oil. In the present method

excellent results were obtained in this regard by the use of

gas chromatography with a precolumn. In the work on heat

transfer media Dowtherm A was used, but in the present work P358

Neo-SK-Oil and KSK-oil were also used for both qualitative

and quantitative measurements.

2. Zxperiments and results.

2.1 Experimental materials.

As experimental material a white extracted commercial

rape-seed oil was used. The BHT, the BHA, and the trans-

stilben used as an internal standard were commercial materials

purified by recrystallization. No'impurities could be

detected by gas chromatography or by thin film chromatograey.

The solvents used were all purified by distillation.

4

2,2 Apparatus,

A Shimadzu 4 APF gas chromatography apparatus with

hydrogen ion flame detection was used for the analysis. In

order to prevent contamination of the separation column, the

precolumn shown in Figure 1 was attached to the inlet.

Controlbollwater Wassvuol

Om 1

•

Glass wool or Glass liea'is i60-1201ne:•ht

Inside tube 200X3 ID "rnm Outside tube 20.2,6 ID

Fig.-1 Design of precolumn for rapid analysis.

' The tubular portion of the precolumn is of stainless

steel, attached to the main body of the precolumn by means

of brass screws and silver solder. It is wrapped in asbestos

cloth over which was wound a 0.5mm diameter chrome steel

heating wire with a 3mm spacing, on top of which asbestos

cord was wound. When from 20 V to 50 V were applied from a

Slidac, the temperature of all parts of the precolumn could

be raised to 300 °C or more. The column temperature was

measured with a thermocouple. Teflon packing was used round

the column inlet. The carrier gas was blocked off from its

normal inlet, and diverted through a stainless steel tube to

the precolumn. The precolumn was joined directly to the

direct entry to the Shimadzu 4 APF apparatus and fixed with

a metal support. The precolumn was removed and cleaned after

each 100 samples.

5

2.3 Chromatography of antioxidants in fatty oils.

Figure 2 shows an example of the results obtained by

gas chromatography with the precolumn when BHA, BHT and

trans-stilben (used as an internal standard) had been added.

Glass beads (80 to 120 mesh), glass wool and elite were

tried as packing material for the precolumn. Glass wool and

glass beads were found to give the best shape to the peak

and to . give the longest precolumn life. Glass beads were

better than glass wool for ease of packing.

2m (3mm II)) Stainless Column

XE-60,5% on Shimalite (50-80mesh) Precolumn • 200t, Column Injec.tor 250 -0

Sult.ent t. 10. rate Na 20mlimin Sensitivity 0.3X10'

BRA

--»-Retention time (min)

Fig.-2 Ga s chromatogram of BUT and BIIA.

In order to calibrate the apparatus known quantities

of BHT or BHA together with 1m1 of a solution of 0.0050 wt/vol

of trans-stilben in carbon disulphide were added to 1g of the

commercial rape-seed oil. A microsyringe was used to inject

2 to 3 c<l into the precolumn for analysis by gas chroma-

tography. A satisfactory relation between the recovery rate

of the antioxidant and its concentration in the fatty oil was

established over a range of concentrations from 0.0010% to

0.0800%. The content of the BHA or BHT could be determined

in units of parts per million. One sample could be analysed

in about 15 minutes.

BHA (PPm) =

6

Weight of stilben Area of BHA peak

Weight of sample Area of stilben peak

X 1.19 x lo6 :

BHT (PPm) =

Weight of stilben

Weight of sample

Area of BHT peak

x 0.99 x 10 6 . Area of stilben peak

The numbers 1.19 and 0.99 are response coefficients

used for quantitative determinations, and are derived from

the tests in which fatty oils with known concentrations of

antioxidants were used.

Figure 3 shows the graph used to determine these

response coefficients, which were obtained from the slopes

of the lines. In order to check the reproducibility of this

method of analysis, a sample of fatty oil with BHA added was

analyzed five times. The results are shown in Table I. The P359 standard deviation of 13.2 does not show a wholly satisfactory

reproducibility. It is thought that the reasons are that the

BHA and stilben peaks are somewhat different in shape, and

that the variation in height of the peaks has an influence

on the area measured.

200

150

< 100

50

-if-- BUT

• ..1—___ 50 " 100 150 200

:Itiiioxitinsit in I.t1 (pm:, •

A=(wt of stilben/wt of sample) (Area of antioxidant • peak/Area of stilben peak)x 10'

Fig.-3 Relation of peak area and antioxidant contents.

• -- -

Table-1 .Reproduribility of determination in gas

chroMatography of 1311A with precolunin

method.

t No.

I I 'Determined 156.41 137.6! 11s1' 165.Q 162.0! 152.0

value - 1

* Standard deviation 13.2, BHA added; 150 ppm.

8

2:4 The colorimetry and gas-chromatography methods.

The BHA content of' fatty oils to which BHA had been

added was measured both by colorimetry and by precolumn

chromatography. A 10 gram sample of the oil was dissolved in

50m1 of a mixture of acetone and hexane in the proportion of

1 to 9 by volume and placed in a 100m1 separation funnel.

5m1 of a solution of 0.5% wthol of sodium nitrate in water

and 5m1 of 3N hydrochloric acid were added. The funnel was

immediately stoppered and shaken violently for 30 seconds.

Meanwhile a solution of sodium hydroxide and methanol in

water had been prepared by dissolving 40g of sodium hydroxide

in 500m1 of water, adding 500m1 of methanol, and then adding

enough water to make up one litre. 20m1 of this solution was

added to the funnel, which was again stoppered and shaken

violently for 30 seconds to extract the nitroso compounds.

After the liquids had been left to separate, the lower layer

was selected. It was put into a lcm cell and its light

absorption was measured at 480m/k. The original sodium

hydroxide-methanol solution was placed into the comparison

cell. Table 2 shows a comparison of the values obtained by

colorimetry and by gas chromatography. With both methods,

concentrations less than 1Oppm were too low to be measured,

but for 25ppm or more useful measurements were attained.

The general trend shows that for 100ppm or more, the

chromatographic method gave values closer to the amounts of

BHA actually added. When phenols were added, the amount of

9

BHA found by colorimetry increased but for the same degree

of admixture, the amount of BHA determined by gas chromatography

was unaffected. The gas chromatography of the mixtures was

done with SE - 30.

Table-2 Comparison of gas chromatographic and

colorimetrie determination of BHA in fatty oil.* (ppm)

BHA added Gas. chromatographically determined • determined

10 3.6

' 25 16.8

50 42.3

100 99.6

• 200 197.9

400 417.4 387.0

800 812.0 736.1

* The values shommi are average values of tripe mea- surements.

2.5 The loss of antioxidants from fatty oils when heated. •

200 grams of the fatty oil sample were placed in a

500m1 beaker. The depth of the oil layer was about 4cm, and

the area exposed to the atmosphere about 55cm2 . The

composition of the oil was 3.1% palmitic acid, 1.1% stearic

acid, 29.6% oleic acid,.19.4% linolic acid, 10.4% linolenic

and arachidic acids, 8.4% eicosanoic acid, and 27.8% erucic

acid. 0.02% of antioxidant was added to the oil. It was

then heated to 160 ° C or 185°C or 210 °C, and after it had

been kept at a steady . temperature for 30 minutes, 60 minutes

or 120 minutes, samples of the oil were taken. Each two

minutes during the heating it was stirred for one minute with

66 revolutions of a stirring rod. Following the standard

procedure for the analysis of fat 7 , the changes of the

acid value, of the peroxide value, and of the refractive

2.1

22.8

• 50.9

84.3

190.0

60

- rime (min)

Fig.-5 Loss of BHT in heated oil under effective stirring.

Table-3 Vartiation of characteristics of fatty oils in heating.

Antioxid., n-,' i Temp. Time . A.V. Peroxide

i ' (`C) (min) value n'»

160 180 0.08 I 4.5 1.4697

BHA 185 180 0.09 3.6 1.4698

210 180 0.13 2.1 1.4699

160 180 0.05 4.4 1.4697

BHT 185 180 I 0.09 2.6 1.4697 . 210 180 0.13 2.1 1.4698

1 210 0 0.09 4.2 1.4697 .iin 30 0.09 3.9 1.4697

1111A 210 60 0.09 4.2 1.9698 ! 210 120 0.10 3.9 1.4698 , 210 180 0.13 2.1 1.9699 I

1 0

•* Contents : 0.02% ii fatty oils.

l00-

1600

501- 210.0

---*

— P

erce

nt of 13

HT

0 60 120 ime ni in)

Fig.-4 Loss of BHA in heated oil under effective stirring.

11

index were measured, and the values shown in Table 3 were

obtained. Figure 4 and Figure 5 show how the BHT or BHA

was lost. The rate of loss does not remain constant with

time. The amount lost is not proportional to the quantity

of antioxidant present in the oil, but has a tendency to be

proportional to the time. After heating at 210 00 for, four

hours (240 minutes) the antioxidant was almost completely

lost. As the temperature increases the rate at which the

antioxidant is lost increases rapidly and, as is shown in

Figure 4 and Figure 5, in the range of temperature in which

foods are fried, the loss of the antioxidants BHA and BHT

increases by 5% for a rise in temperature of 10 °C. At 180 0 0

there is a loss of 20% each hour, and after 5 hours the

antioxidant is almost completely lost.

The rate of stirring during the heating will affect

the rate of loss of the antioxidant. In these experiments

the stirring was fairly efficient, but if the stirring

efficiency was low, the rate of loss would probably be

different. Since the antioxidant is presumably lost from

the surface, the diffusion coefficient of the antioxidant in

the oil will influ'enCe the loss, and in the limit when the

concentration of the antioxidant is low, this will probably

be important.

p360

12

2.6 Analysis .of BHA and BHT by as chromatography

and mass spectroscom.

The analytic equipments used were a Hitachi K-53

gas chromatograph connected to a Hitachi MRS-4 mass

spectrograph through a Biemann separator. The column packing

material used for gas chromatography was Shimalite (60 to

80 mesh) with a stationary phase of 5% XE - 60. The conditions

of analysis were column temperature 180 0 0 , injection

temperature 200 ° C, ionization level in the ion chamber of the

mass spectrometer 80eV, ion chamber temperature 200 ° C, scanning

speed 1 to 300 (m/e) in 10 seconds. Figures 6 and 7 show

examples of the mass spectra obtained when BHA or BHT alone,

or oils containing BHT or BHA are first separated by gas

chromatography and then ahalyzéd by the mass spectrograph.

In Figure 6* the parent peak of the BHA molecular ion

is at m/e 180. The peak at m/e 165 is the parent peak minus

15 ( OH3), and the peak at m/e 165 corresponds to the parent

peak minus 43 ( OH3

+ C2114 ) which presents a fragmentation

similar to that of 2 - trans-butylbenzene 8 . The m/e 107 peak

is produced by breaking of the ether junction in the m/e

137 ion9 , with consequent loss of 0H20. The m/e 91 peak is

the benzyl ion produced by a further loss of oxygen, and the

m/e 65 peak is created by separation of CHeH from the

m/e 91 peak. The m/e 57 peak is due to tert-butyl ions

separated from the 2- or 3- position, and the m/e 55 and

* Translated as written, but Figures 6 and 7 are interchanged. Translator.

13

• C.. e•e•

57

205

l 65 91 111 21 I 1/49 220

1 )[ 111111 h 1

1

IV I - I 50 11 -00 -- 150 ?00

ni/ c

Mass spectrum of

137 los

180

11111 1°-I s 1 1 11 1 1 ,11 65 91

50 0 15 200 mie

Fig.-7 lass spectrum•of

14

53 peaks are thought to be produced by splitting of the

benzene ring after dislocation of the hydrogen.

In Figure 7*

, the m/e 205 peak is the parent peak of

BHT. The m/e 205 peak is the parent peak minus 15 (CH3),

the m/e 177 peak corresponds to the parent peak minus 43

( OH3 + 02H4 ). These peaks are of the same-type as those from

BHA. With BHT the butyl ion peak at m/e 57, which in.the

conditions of these investigations was a base peak, is

remarkably weak. By making use of spectra with these patterns,

it will be possible to confirm the presence of BHT or BHA in

an unknown material.

2.7 Gas chromatography of heat tran2fer media in fatty oilq.

Quantitative methods of detection in fatty oils by

gas chromatography have already been reported5 . In one

method a quantity of oil is saimnified, the unsaponified

substances are extracted and separated, dissolved in càrbon

disulphide, and injected into the gas chromatograph for

analysis. In another method, the unsaponified substances

are separated by thin film chromatography, the hydrocarbon

portion is dissolved in carbon disulphide and injected for

analysis. In these methods, the heat transfer media are

concentrated in order to avoid contamination of the apparatus

by direct injection of the fatty oils. When the present

precolumn method is used for the analysis of heat transfer

media the accuracy is somewhat reduced, but it is possible

* Actually Figure 6. Translator.

Spi CS.: solution of Dowthemn A in salad oil injected (olumn: SE - 30,5% on Clir,,mosorb \V it) sq) m esh

2m 3niii '11)) Sitittu ien 4t' 2201% vinas \: •

D o eteetr 2.1o.e, Injection 220 C, 'Join/. n iit Il 35 ut! *min

Sensitit ity 0.4 • PO

10

Retention time (min)

Fig.-8 Gas chromatogram of Dowthel lit A.

0

CS, solution of Neo-KS•iii1.260 25 mutt in sa lad oil injected. Column: SE-30, 5 SI imal ite 50 -1'4/ mesh .■

2m ',..3mm (11)) Sh imnilzu 0m:column 220C. column 150 c Detector 2-10'C, in jei lion 220 -C, 1): 2 30m l. ni in . IL: 25m! *min Sensitivity 0.1 •:10'

A

125pmn.

r\ 1

15 2u 25

netent ion t ime

Fig.-9 Gas chromatogram uf Neo-SK -oil-260.

5p1 CS:: solution of 25ppin in sa .:;o1 oil tr.:rued

Column: SE-30, 5% ■ nt 2rn X3min •,11)) -

Sliimndzu ..1AP I', pi eco Ilona oluten Detector 2401*.injection 220 C, Nz Win 1. min. 11_ 35m 1 mia Sensitit ity 0.1 10 1 •

littention time im in/

Fig.-10 Gan chromatogram of KSK-oil-260..

16

by means of a simple extraction to work to a content of .

0.5 ppm and in a large number of tests it was shown to be a

rapid method of analysis.

Figures 8, 9 and 10 show examples of gas chromatograms

of Dowtherm A, Neo-SK-oil 260 and KSK-oil 260. The conditions

of analysis are shown on the Figures.

Dowtherm A contains 26.5% diphenyl and 73.5%

diphenylether melted together. As shown in Figure 8, two

peaks could be distinguished when the temperature of the SE-30

column was below 150 00, but at temperatures above 150 00 the

peaks came closer together, and above 180 00 there was only a

single peak. In a polar liquid phase column, such as DEGS

or XE - 60, the diphenyl and diphenylether peaks are not

distinguished and form one single peak. The SE - 30 column•

is therefore best for the extraction of Dowtherm A, and

because it has a long life SE - 30 was mostly used for analysis

in this investigation.

The principal components of Neo-SK-oil are 2-6 and

1-6 dimethyl napthalene, naphthalene, diphenyl, diphenyiether

and acenaphthene. If all of them are shown in the chromatogram

there will be nine peaks in all, which is too many. In

Figure 9, five peaks are present.

The principal components of KSK-oil-260 are 33.6%

mono-isopropyl-tetra-hydro-naphthalene, and 31.3% mono-

isopropyl-naphthalene, but it is also reported11 to contain

a total of 32.8% of di-isopropyl-naphthalene and di-isopropyl-

tetra-hydro-naphthalene, and 2.3% of diphenyl. Five peaks

are present in Figure 10.

17

The difference in conditions between Figures 9

and 10 and Figure 8 is in the column temperature, and there

is no great change in the relative positions of the peaks,

but the retention times come together and the peaks become

larger. The oils used were all dissolved in carbon disulphide

and injected.

Trans-stilbene was used as the internal standard in

the analyses shown in Figures 8, 9, and 10, and the amounts

of heat transfer media contained were calculated by means of

the response ratios shown in Table 4. The quantitative

accuracy is shown in Table 5.

The lowest concentration to be measured is lower with

heat transfer media than with antioxidants, and as Figures 8

to 10 show, the injection of the fatty oil directly into the

precolumn requires extremely high sensitivity of the hydrogen

flame detector. When the quantity injected is 5?1, no

noticeable disturbance of the base line could be found after

100 injections, but the precolumn was replaced. In the

conditions of Figure 8, most of the commercial oils showed

small peaks with retention times of about 9 minute, but

there was no interference with the analysis.

An investigation was made of the solvents to be

used for injection into the precolumn, with the results

shown in Table 6. The sign •d means that the peaks remained

p3 6a

very close to the base line but that the presence of the

heat transfer media could be detected.

Table-4 Response ratio of heat transfer medium to trans-stilbcn (f).

18

Dowtherm A Neo-SK-oil 260. NSK-oil 260

Response I 1.082 I 1.016' ) . I 1.071b) ratio

a) Calculated from area of five large peaks, b) Calculated from area of four large peaks,

Heat transfer medium : HTM. FiTm(ppin)= ( stilben wt \ x ( FITM peak area \

‘‘ Sample wt J stilben peak area

xfx1OG

• .Table-5 Determination of heat to nsfer medium in fatty oil by precolumn method.

Dowtherm A Neo-SK-oil 260 KSK-oil 260 (PPm) I (1Wm) (ppm)

Added Found Addedi Found Added Found

1.20 1.09+0.46! 1.53 1.45±0.39 1.70 1.75±0.19

2.91 3.01±0.15 4.87 ; 4.02-'0.32 5.96 6.07±-0.35

10.85 10.92±0.43,I4.29 :15.10+0.57 12.16 13.05±0.50

Average of triplicz.te analysis.

Table-6 Limits of Dowrtherm A concentration for gasehromategraphic determination in various solvents.

Temperature 150 Suivent (` C)

130

Conc. ( x 1(wt/vol) 1000 500 100 1000 500 100 10

Nonane x x x L.. x x x

DMS0 x x x .:,. x x x ,

Hexane x x 0 ,.:1. x x

Acetonitril 0 2:,. x 0 0 .._ X

CC1, 0 ‘.. X 0 0 .f X

Acetone 0 ..---:-. x 0 0 z:_, x

CS: " 0 0 0 0 0 0 0

0 possible, X impossible, — border line.

a) 150C 10 x 10- '96 1 x 10-'9; (5 pl

injected).

Sensitivity, (Shimadxu AFF) 1000 x 0.8 x 10', 500 x 10 - '96 0.4 x 10', 100 x 10-696 ().8

x io4, 10X10'% 0 .2 1 pl injected. Column, SE-30 5% on Chro-mosorb (W 60-80 mesh)

injection 220`C, detector 240`C, N: 30 mi/min,

35 milinin, air 1.1 kecm".

1 9

These results show that when the concentration of

heat transfer media is low and they are to be injected into

the precolumn without pre-concentration, solvents other

than carbon disulphide cannot be used,

(Received 10 April 1973).

, References.

1) C.11. Anglin, .1. Aur. Food Chem., 4, 1018 (1956) ; C.R. Szalkov,-ski, J.B. Garber, ibid., 10, • 911 (1962)

2) N.J. Alicino, J. Ayr. Food Chem., 11, 196 (1963); T.K. Choy, ibid., 11, 349 (1963)

3) K.T. Hartman, L.C. Rose, J. Amer. Oit Chemist'

Soc., 47, 7 (1970)

4. Takagi.

Yukagaku. 12 279 (1970).

Journal of the Japan Oil Chemists' Society.

12 279 (1970).

5. Takagi.

Yukagaku. 18 235 (1969).

Journal of the Japan Oil Chemists' Society.

18 235 (1969).

6. D.P.Johnson.

J. Assoc. Offic. Anal. Chem. IC/ 1238 (1967).

7. Nihon yukagaku kyokai hen.

"Kijun yushi bunseki shiken ho (1960)".

Asakura shoten.

Japanese Society of Oil Chemists. (Compilation).

"Standard methods of fat analysis (1960)".

Published by Asakura. 8) A.N.H. Yeo, 15.14. Williams, On:gar-tic Mass

SPectrametry, 5, 135 (1971) 9) 1`.1..M. b'ursey, Organic Mass Spectrometry., 1, 31

(196'8) 10) T . Ace!, I LE. Lumpkin, Anal. Chem., 32, 1819

(1960) •

20

11. Soken kagaku kabushiki kaisha shiryo.

Data from the Soken Kagaku Company.