5
Another sample was prepared from beer that has
been spiked with different amounts of nitrosamines.
All nitrosamine compounds have been detected and
quantified in a low concentration range of 9 – 13 ppb, see
Table 5. Each quantified peak passed the ion ratio quality
control and could be positively confirmed at this low
level by calculating the product ion ratios for each of the
compounds.
Conclusions
With the described GC-MS/MS method on the TSQ 8000
system all nitrosamine compounds under investigation
could be safely detected and precisely quantified at the
required low levels for a safe food control.
The LODs of all compounds have been determined to be
below 1 ppb, using 1 ppb as the lowest concentration for
the quantitative calibration.
The TSQ 8000 GC-MS/MS shows a wide linearity in
the range of 1-500 ppb with very good precision. All
calibration curves have been shown to be strictly linear
with R
2
better than 0.99.
The TSQ 8000 GC-MS/MS shows great ion ratio stability
for the confirmation of positive samples. The RSD% of
the ion ratio of all compounds is lower than 4% even at
LOQ level.
The use, setup and maintenance of a GC-MS/MS method
for nitrosamines is easy. The unique AutoSRM software
finds and optimizes the SRM transitions and collision
energy automatically, even facing new and yet unknown
components.
Based on the demonstrated GC-MS/MS method, the
TSQ 8000 GC-MS/MS can successfully quantify the
concentration of nitrosamine components in real samples
without any uncertainty.
The described GC-MS/MS method for food nitrosamines
on the TSQ 8000 GC-MS/MS can serve as a turnkey
method for routine use in food safety control. It is using
standard GC-MS/MS triple quadrupole instrumentation
which is also common for many other areas of regular
food safety control, e.g. pesticides, POPs or polyaromatic
hydrocarbons. The presented method is fast, allows high
sample throughput, and provides results with very high
sensitivity and precision. With this standard EI ionization
method setup this presented method for low level
nitrosamine quantitation is recommended to be employed
as a productive alternative to the earlier described
chemical ionization ion trap procedure using liquid CI
reagents.
Concentration (ppb)
1
5
10
25
100
250
500
AVG RSD (%)
NDMA
70.7
67.9
68.0
69.8
69.1
71.9
69.6
69.6
2.01
NDEA
20.8
22.1
22.5
22.4
22.5
22.5
22.5
22.2
2.84
NDBA
102.4 102.4
98.2
98.6
96.1
93.4
99.2
98.6
3.28
NPIP
6.1
5.5
6.2
5.9
6.0
6.1
6.2
6.0
3.88
NPYR
-
64.6
62.4
66.2
66.9
68.1
66.7
65.8
3.06
Table 3. Precision of the confirming ion ratios from 1 ppb – 500 ppb
Compound
Area
ISTD Area
Area Ratio Ion Ratio Confirmation Calculated Amount (ppb)
NDMA
2591.368
2028129.842
0.001
Pass (65.1%)
0.74*
NDEA
1875.386
2028129.842
0.001
Fail (0%)
N/A
NDBA
6806.996
2028129.842
0.003
Fail (81.1%)
N/A
NPIP
N/A
2028129.842
N/A
N/A
N/A
NPYR
N/A
2028129.842
N/A
N/A
N/A
NMOR
4415.782
2028129.842
0.002
Fail (0%)
N/A
Table 4. Results of a blank sample
*Below LOQ
Compound
Area
ISTD Area
Area Ratio
Ion Rato
Calculated Amount (ppb)
NDMA
91318.135
2282168.009
0.040
Pass (68.3%)
12.0
NDEA
480955.478
2282168.009
0.211
Pass (22.0%
9.4
NDBA
402754.561
2282168.009
0.176
Pass (96.8%)
13.2
NPIP
280162.125
2282168.009
0.123
Pass (5.9%)
10.1
NPYR
318081.273
2282168.009
0.139
Pass (68.9%)
13.3
NMOR
1145719.054
2282168.009
0.502
Pass (67.9%)
10.1
Table 5. Results from a spiked beer sample
