Appendix 1: method procedure summaries analysis of
E355–7, E359: Adipic acid and its salts
179
Table 14.1
Summary of methods for adipic acid in foods a
Method Matrix
Sample preparation Method conditions
Detection Reference
GC Crackling
An alkaline solution of sample was The adipic acid in the concentrate FID
1 candy and
extracted with ethyl ether. H
2
SO
4
was was methylated using the soft drinks
added to water layer pH2. The diazomethane method
acidified layer was saturated with NaCl and then extracted with ether.
After drying the ether layer was concentrated
Capillary zone Wine
7.5 mM 4-aminobenzoic acid, Indirect UV absorbance
4 electrophoresis
10.5 mM trihydroxymethyl- and direct conductivity
CZE aminomethane, 0.1 mM tetra-
simultaneously decyltrimethylammonium bromide
pH 7.0 with LiOH GC
Food Olive oil simulant diluted with
Di2-ethylhexyladipate DEHA FID at 370 ºC 5
simulants n-
heptane. Other simulants not diluted Retention time 8.6 min. Column: BPX5 0.25
µm film. Temperature programmed 100–360 ºC. Carrier
gas: helium. Cold on column injector
GC–MS Food
Adipic acid esters migrated into GC–MS
6 wrapping
n -heptane
180 Analytical methods for food additives
Table 14.1 cont’d Method
Matrix Sample preparation
Method conditions Detection
Reference GC–MS
Packaging 1 g of packaging material was Soxhlet Di2-ethylhexyladipate DEHA FID at 370 ºC
7 materials
extracted with chloroform–methanol Column: HP-5MS 0.25
µm film. 2:1, 50 mL for 6 h. Extracts
Temperature programmed transferred to 50 mL vol flask and
70–280 ºC. Carrier gas: helium. made up to volume with chloroform– Split injector 1:25, 2
µL injection methanol. 1 mL transferred to vials for
GC–MS analysis GC
Starch Total adipate: sample saponified with Column: CP-sil 5CB 50 m ×
FID at 300 ºC 8
alkali and extracted with ethyl acetate, 0.32 mm, 0.12 µm film.
evaporated and silylated. Free adipate: Temperature programmed aqueous extraction, then extracted 4 × 130–290 ºC. Carrier gas: helium.
with ethyl acetate, evaporated and 0.3
µL injection. silylated
b Method
Matrix Sample preparationextraction
Column Mobile phase
Detection Reference
HPLC Urine
Extracted with diethyl ether and TSK-Gel,
Acetonitrile–water Fluorescence
3 converted into fluorescent derivatives octadecyl-silane
85:15, vv, 1.5 at em 412 nm,
with 9-anthryldiazomethane RP-type
mLmin, 20 µL
ex 365 nm injection
Ion-exclusion Ice lollies
TSK-Gel, SCX 2 mM H
3
PO
4
– 210 nm
2 chromatography
H
+
form at 40 ºC 1.5 acetonitrile
at 1 mLmin