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GC_FF00977
Column:
Rtx
®
-5MS, 30m, 0.25mm ID, 0.25µm (cat.# 12623)
Sample:
melamine, cyanuric acid, ammelide, ammeline, benzoguanamine
(10µg/mL prederivatized)
Inj.:
1µL, splitless (hold 1 min.), 3.5mm splitless inlet liner (cat.# 22286)
Inj. temp.:
280°C
Carrier gas:
helium, constant flow
Flow rate:
1mL/min.
Oven temp.:
75°C to 320°C @ 15°C/min. (hold 4 min.)
Det:
MS
Transfer line temp.: 290°C
Ionization:
EI
Mode:
SIM
1. cyanuric acid
2. ammelide
3. ammeline
4. melamine
5. benzoguanamine
Rtx®-5MS—Low-bleed GC/MS Columns
(fused silica)
(Crossbond
®
5% diphenyl/95% dimethyl polysiloxane)
ID df (µm)
temp. limits
length cat. #
price
0.25mm 0.25 -60 to 330/350°C 30-Meter 12623
Splitless Liners for Shimadzu 17A, 2010, and
2014 GCs
ID* x OD & Length (mm)
qty.
cat.#
price
3.5mm Splitless
3.5 ID x 5.0 OD x 95
ea.
22286
3.5 ID x 5.0 OD x 95
5-pk.
22287
*Nominal ID at syringe needle expulsion point.
Compound
CAS# cat.#
price
BSTFA w/1% TMCS (N,O-bis[trimethylsilyltrifluoroacetamide] w/1%
trimethylchlorosilane)
10-pk. (10x1g)
25561-30-2 35606
25g Flex Tube
25561-30-2 35607
Silylation Derivatization Reagents
Figure 4
Melamine production analytes are easily identified in cat
food using SIM analysis (50μg/g spike).
Figure 3
Excellent separation of melamine and related compound
using modified conditions (10μg/mL standard).
1. cyanuric acid
2. ammelide
3. ammeline
4. melamine
5. benzoguanamine
GC_FF00978
See Figure 3 for conditions.
the scan method was modified to begin scanning
at m/z 85. The solvent delay was also increased to
approximately 8 min. due to the high background
levels. This extra time helps increase the filament
lifetime and ensures all the analytes will be detected.
This method provides excellent separation of
melamine and cyanuric acid, the suspected toxic
compounds, as well as ammelide and ammeline
(Figure 3). Reproducible and reliable retention
times were obtained for matrix spikes; this, along
with SIM mass spectrometric detection, allows
easy identification of analytes at both the high and
low spike levels (Figure 4).
Conclusions
This work demonstrates that the FDA method is a
valuable guideline for analysts screening melamine
and related analogs. Using an Rtx®-5MS column
and modifying the original method provides addi-
tional benefits: 1) decreasing the derivitization
reagent volume results in longer column lifetime
and less inlet maintenance, and 2) increasing the
solvent delay decreases pyridine ion background,
resulting in higher sensitivity, approximately 5
times higher, for the analytes of interest.
References
GC-MS Method for Screening and Confirmation of Melamine and
Related Analogs, Version 2, May 7, 2007, U.S Food and Drug
Administration,
http://www.fda.gov/cvm/GCMSscreen.htm.Modified method uses
less derivitization
reagent, extending
column lifetime.
Reliable
identifications
in matrix
Sample:
melamine, cyanuric acid, ammelide, ammeline, benzoguanamine
in dry cat food (10µg/mL prederivatized)