There are 3 ways of saliva drug screen:
Saliva drug screen by immunoassay
To detect drugs in saliva by immunoassay the laboratory analysis uses Narcoscreen tests.
Single Narcoscreen test for drug detection – is a fast immunoassay test for narcotic substances and their metabolites in human saliva. Immunoassay is used for saliva testing to detect the presence of narcotic substances and their metabolites in threshold concentration (level of quantification, minimum detectable concentration) for amphetamine (AMP) – 50 ng/ml; metamphetamine (MET) – 50 ng/ml; opiates (MOP) – 40 ng/ml; cocaine (COC) – 20 ng/ml; cannabinoides (THC) – 4 ng/ml; benzodiazepines (BZ0) – 40 ng/ml.
This type of drug tests provides preliminary results only. For proved analytical results the alternative chemical methods are recommended to use. Gas chromatography and mass spectrophotometry are preferable for verification of analysis results.
This screen is considered to be a high-quality immunoassay with visual method of readout. This way of drug testing uses unique antibodies for selective determination of drugs in saliva, with high level of specificity and sensitivity.
Principle of testing procedure
Testing device consists of chromatographic adsorbent, in which a drug or its metabolites from the sample get into reaction with specific conjugates (intended for a limited number of antibodies) on porous membranous base. When the test sample goes through adsorbent, the marked colored antibody conjugate gets combined with a free narcotic in the probe, forming antigen-antibody complex. This complex gets bound with immobilized antigen conjugate in the positive reaction site and doesn’t make a magenta strip appear, when the content of narcotic is higher than the threshold level recommended for immunoassay. Free colored conjugate bounds with reagents in the negative control zone and, by appearing magenta strip, it demonstrates that reagents and device are both in good order.
The negative result makes 2 separate color strips appear: one is in the test zone; the second one is in the control zone.
The positive result shows only one color strip in the control zone.
Collecting and preparing samples for test
10 ml of saliva needs to be placed into a clean dry plastic or glass container, containing no preservatives. In case of difficulties connected with saliva collecting, offer a patient to open a mouth and press his tongue to his hard palate. If there are many air bubbles in the sample, they should be moved off saliva with the help of clean pipette, because it can delay the pass of saliva through test adsorbent and slow down the test time. If the test can’t be done in the day of sampling, saliva samples may be stored in refrigerator at temperature 2-8 Celsius degrees up to 7 days, and then the samples can be frozen at -20 Celsius degrees and lower till the moment of screening. Chilled or frozen samples must be unfrozen to indoor temperature and carefully stirred before testing. The samples, containing the visible sediment or dimness, should be centrifuged before the screening.
Expected results
The drug test Narcoscreen detects narcotic substances and their metabolites in saliva at threshold level and higher. This test doesn’t allow detecting the exact concentration of narcotic substance in saliva. It is used for saliva screening to distinguish a negative result from a positive one. All positive results of testing should be confirmed by alternative methods.
Saliva drug testing by chemico-toxicological methods
The chemico-toxicological methods of drug testing are divided into:
1) Fluorescence polarization immunoassay (FPIA) for one of the following groups: opiates, methadone, cannabinoids, amphetamines, cocaine, barbiturates, phencyclidine, benzodiazepines;
2) Enzyme immunoassay (EIA) of narcotic and psychotropic substances for the group of narcotic and psychoactive substances (opiates and other groups);
3) Drug test by chromatography-mass spectrometry;
4) Alcohol test by gas-liquid chromatography.
Saliva drug tests performed with the help of chemico-toxicological analysis allow the specialists to prove the fact of drug abuse within 48-72 hours of using narcotics. Such drug screening is not to be a quick test. The tested saliva needs to be delivered to the laboratory and tested with the help of laboratory reagents and special equipment.
The result of saliva drug testing, performed by the chemico-toxicological method, is considered a legal fact and can be used in the court as evidence.
Saliva drug screen with the help of hardware analyzer
The system Drager DrugTest 5000 includes 2 main components: the kit Drager DrugTest and analyzer Drager DrugTest 5000. The system quickly and accurately checks saliva samples for narcotics, for example amphetamines, synthetic amphetamines, opiates, cocaine and its metabolites, benzodiazepines and cannabinoids, and provides also accurate diagnostic evaluation and data management.
Safe and easy to use analizer Drager DrugTest 5000 – is a mobile optoelectronic system for local and qualitative analyses of drugs, containing in saliva samples, collected with the help of Drager DrugTest kit. Using simple three-button control and color illuminated display, the users can run over interface menu in one of five languages. Built-in memory of analyzer data is able to store results of 500 tests. Besides, the analyzer can be easily connected to various data recording devices: PC, printer or barcode scanner.
This non-invasive diagnostics system helps to avoid difficulties and eliminates any possibility of wrong results interpretation. Diagnostic kits are easy to use and oriented for immediate use; they consist of 1 test cassette complete with saliva collector. The kit is very hygienic: it prevents the contact with a sample and its components.
