The Pennsylvania State University Behavioral Endocrinology Laboratory
Salivary Cotinine (DPC) Quality Contol Data
Sample Collection:
The following procedure for sample collection was followed:
1. Rinse mouth with water.
2. Wait for ten minutes.
3. Begin to collect saliva through a straw, or place a cotton Salivette roll in the side buccal cavity for two minutes, or chew on Trident Original Flavor gum for a designated time interval and collect via straw into a tube.
Caution: Do not use citric acid salivettes.
| Saliva Collected by straw into container- 5 samples | Background range 0.0-2.0 ng/ml |
| Saliva collected by Salivette- 4 samples | Background range 2.0-6.0 ng/ml |
| Saliva collected after 1 min. chewing on Trident – 5 samples | Background range 1.0-2.0 ng/ml |
| Saliva collected after 5 min. chewing Trident gum-5 samples | Background range 0.0-1.0 ng/ml |
Standard Curve Data:
The cumulative standard curve data can be summarized as follows:
Correlation Coefficient ~ 0.998
Standard Range 5-250 ng/ml
Level of Sensitivity ~1 ng/ml (Determined by interpolating the mean minus 2 SD cpm for 10 sets of duplicates of the zero standard.)
Serial Dilution of Smoker:
2 smokers were serially diluted by a factor of two from the original concentration and assayed in duplicate. The results are shown in the tables below.
Smoker 1
| Expected ng/ml | Observed ng/ml | Observed/Expected ng/ml |
210 |
210 |
100% |
105 |
84 |
80% |
53 |
40 |
75% |
26 |
23 |
88% |
13 |
12.5 |
96% |
6.6 |
5.3 |
80% |
3.3 |
3.4 |
103% |
Smoker 2
| Expected ng/ml | Observed ng/ml | Observed/Expected ng/ml |
132.6 |
132.6 |
100% |
66.3 |
69.6 |
105% |
33.15 |
34.5 |
104% |
16.6 |
20.4 |
123% |
Intraassay Sensitivity:
Three samples at different concentrations of cotinine were assayed 10 times within a single run.
Sample |
Mean (ng/ml) |
Coefficient of Variation |
Standard Deviation |
1 |
14.5 |
14.7 |
2.1 |
2 |
107.4 |
4.3 |
4.6 |
3 |
218.3 |
4.5 |
9.9 |
Interassay Sensitivity:
Duplicate tests of the high and low controls were run on five separate days. The average CV was calculated from the average mean of each control sample across five days.
Control |
N |
Mean (ng/ml) |
Standard Deviation |
Coeffient of Variation |
High |
5 |
183.0 |
14.8 |
8.1 |
Low |
5 |
18.9 |
2.6 |
14.0 |
Spike and Recovery I:
Three stripped saliva samples were spiked with the DPC supplied cotinine standard at three levels of concentration. The mean of each level was corrected for background interference and the results expressed in ng/ml are shown in the below.
Sample |
Level |
Observed (O) |
Expected (E) |
O/E % |
1 |
10 ng/ml |
14.8 ng/ml |
10 ng/ml |
124.2 |
2 |
100 ng/ml |
105.4 ng/ml |
100 ng/ml |
105.4 |
3 |
200 ng/ml |
106.4 ng/ml |
200 ng/ml |
106.4 |
Spike and Recovery II:
Two stripped saliva samples were spiked with a standard from a source other then the one supplied with the DPC reagents. A (-) cotinine standard, 99% in purity, from Sigma was used to prepare these solutions . The mean values were then corrected for background interference and the results in ng/ml reported in the table below.
Sample |
Level |
Observed (O) |
Expected (E) |
O/E % |
1 |
High |
287.1 |
269.1 |
106.7 |
2 |
Low |
11.7 |
10.8 |
109.0 |
The Pennsylvania State University Behavioral Endocrinology Laboratory