Collection of saliva , Collection devices
Peel et al. (1984) asked ‘driving-while-intoxicated’ suspects to spit into a test tube with or without sour candy stimulus, and a similar approach was taken by Cone (1993) at the Addiction Research Center in their many controlled administration drug studies. The Salivette col lector (Sarstedt, Germany; Fig. 1) employs a dental cotton (polyester) roll, which is chewed by the donor for 30–45 seconds with or without citric acid stimulation. After being soaked with oral fluid, the cotton roll is placed in a container that fits into a centrifuge tube. During centrifugation the saliva passes from the cotton roll into the lower part of the tube. Cellular particles are retained at the bottom of the tube. The cotton roll reliably absorbs 1–1.5 mL of oral fluid. The disadvantage of the cotton roll is that it may adsorb analyte molecules or give off compounds that interfere in the hormone and drug assays (Hold et al. 1995). Modern oral-fluid collection devices generally use an absorbent material on a stick similar to that employed for saliva alcohol tests. For example, the Epitope (now Intercept) saliva sampling device (Fig. 2) consists of an absorbent paper pad impregnated with buffered salts on a plastic rod. The pad is placed in the mouth for 2–5 minutes. After collection, the paper is placed in a tube with preservative liquid and shipped to the laboratory for analysis. The Intercept pad is estimated to absorb approximately 0.4 mL of oral fluid, which is diluted 1:3 by 0.8 mL preservative fluid. The Cozart RapiScan collector (Cozart BioScience, Abing don, UK) uses a detachable absorbent cotton pad on an indicator handle (Fig.3). After the indicator has turned from white to blue, which indicates that 1 mL of saliva has been collected on the pad, the pad can be detached and kept in a test tube that contains preservative buffer until analysis. The Finger collector (Avitar, Canton, MA, USA; Fig. 4) uses a proprietary dental absorbent (AccuSorb foam), which absorbs saliva when placed in the mouth for a few minutes. Saliva is expressed from the absorbent using finger pressure. The Drug Wipe saliva test (Securitec, Munich, Germany; Fig. 5) attempts to wipe the tongue with a wiping pin and transfer the oral fluid collected by washing it onto a test strip (Frontline urine test strip, Boehringer Mannheim GmbH, Germany) developed to test surfaces for traces of drugs (Kintz et al. 1998). Pichini et al. (2002) reported that the Drug Wipe wiping pin holds at most 2 μL of fluid and that placing 2 μL saliva on the Schramm and Smith (1991) and Schramm (1993) developed a small plastic sack (Saliva Sac, BioQuant) composed of semipermeable mem branes that contains sugars of high relative molecular mass. When it is placed in the mouth, osmotic pressure drives an ultrafiltrate of saliva into the interior of the sack. The drawback is that the sack requires from 10 to 20 minutes (depending on the sack size) to collect sufficient fluid for testing. Liang et al. (2000) developed an aspirator (Life Point, Rancho Cucamonga, CA, USA) that draws saliva directly from the mouth of the test subject through a tube with a disposable individual sterile mouthpiece. For on-site testing the saliva passes directly into the analyser, which eliminates the need to elute saliva from the collector pad with a buffer and transfer it into an immunoassay cartridge. For the collection of saliva, generally parotid saliva, small intraoral cups (Schaeffer cup, Curby cup) are available which can be placed over Stensen’s duct of the parotid gland. The collection cup is placed in the buccal vestibule with the opening over the duct orifice. Gentle pressure on the cheek over the cup causes air to be expressed from the cup and creates a slight negative pressure that keeps the cup in place until sufficient saliva is collected. The collection device or method has been shown to influence the pH of the saliva by stimulating saliva flow and hence the drug content of oral fluid according to the Henderson Hasselbalch equation (O’Neal et al. 2000; Kintz and Samyn 2002). Collection devices can also affect the recovery of drugs from oral fluid through retention of the oral fluid in the absorbent, adsorption of the drug on device components and drug recovery from device buffers (O’Neal et al. 2000). After the controlled administration of codeine, oral-fluid codeine concentrations were higher in specimens obtained by spitting than in those obtained by absorption devices (O’Neal et al. 2000).
Figure 1 The Salivette collection device.
Figure 2 The Intercept collection device.
Figure 3 The Cozart RapiScan collection device.
Figure 4 The Avitar collection device.
Figure 5 The DrugWipe collection device.
