Swabbing methods

Nishannon A. Pokja M.S. (1977) Comparative studies ofmicrohial contamination of surfaces hy the contact plate and swab methods. 7,4/7/)/ Bacterial, 42, 53-63. 

To minimize disruptions to critical operations, surface sampling should be performed at the stop or the end of operations. Surface sampling may be accomplished by the use of contact plates or by the swabbing method. 

Although swab assays are different conceptually than both the impurity and the potency assay, the same scientific rationale governs the development of these assays. Many of the references listed in Table 15.4 outline different validation approaches. Seno outlined validation practices in the Japanese pharmaceutical industry for cleaning verification,23 and Kirsch outlined an approach for swab method validation that is consistent with ICH guidelines for method development.24 An important aspect of any cleaning-verification assay begins with swabbing the... 

The limit of quantitation, as opposed to the limit of detection, is the most important attribute of the swab method because it has been previously determined, from a safety and cross-contamination standpoint, that residual material above the cleaning acceptance limit is of serious concern. The LOQ is defined as a percentage relative standard deviation (percent RSD) of 10%, and the LOD is defined as a percentage RSD... 

Robustness is the capacity to remain unaffected by small, but deliberate, variations in method parameters. In a typical HPLC validation this exercise would include minor variations in flow rate or pH of the buffer. When considering cleaning verification, this parameter may be extended to extraction time of the swabs, pH of extraction solvent, etc. However, it is fairly uncommon to evaluate such parameters due to the above-mentioned variability that may be found in swab methods. 

Quantitative development is also possibleJ The main advantage of the swab method is accessibility to difficult-to-reach equipment surfaces and areas of the production environment. Limitations are excessive time consumption, increased potential for adventitious contamination due to the cumbersome nature of the procedure, and failure of enumeration processes to correlate to full recovery of organisms. 

Niskanen, A. Pohja, M.S. Comparative studies on the sampling and investigation of microbial contamination of surfaces by the contact plate and swab method. J. Appl. Bacti. 1977, 42, 53-63. 

This conversion is normally accompHshed by immersion, but spraying, swabbing, bmshing, and electrolytic methods are also employed (178) (see Metal SURFACE treatments). The metals that benefit from chromium surface conversion are aluminum, cadmium, copper, magnesium, silver, and 2inc. Zinc is the largest consumer of chromium conversion baths, and more formulations are developed for 2inc than for any other metal. 

In restaurant operations, steriliza tion of dishes is an additional requirement (see STERILIZATION TECHNIQUES). Steriliza tion is deterrnined by the usual swabbing and culturing methods or by employing bacteria tagged with radioactive phosphoms and counting residual radioactivity on the washed dishes (108). 

This is a clear liquid that vaporizes and, on contact with damp air, combines with w ater to produce a dense acid mist. Titanium tetrachloride can be painted on to surfaces, such as fume cupboard sills, from which it will evaporate over a period of several seconds showing the airflow patterns close to the surface. (Airflow patterns close to a surface could also be visualized by fastening short filaments of wool or cotton to the surface). Titanium tetrachloride can also be used, when soaked onto a cotton swab, in a similar way to a smoke tube. It is a simple and inexpensive method but the production of smoke, which is toxic and corrosive, is uncontrollable. 

Brush plating is a special technique which dispenses with a container and uses a swab soaked in electrolyte applied to the work. In jet plating a stream of electrolyte is applied to the cathode. Both are methods of selective plating, applying an electrodeposit to only a part of an article. Little has been published about the techniques or the properties of coatings they produce. 

It is possible to also test semi-solid antibacterial preparations on the skin itself, as described for liquid disinfectants (section 3.5.1). A portion of the skin— the backs of the fingers between the joints is a useful spot— is treated with the test organism, the preparation is then applied and after a suitable interval the area is swabbed and the swab incubated in a suitable medium. Alternatively, the method employing pig skin, described in section 3.5.1, may well be adapted to the problem of testing semi-solid skin disinfectants. 

May be sterile fer use in ceriain circumstances Absorbent cotton wool Swabbing, cleaning. Any method... 

The first mechanical variant uses a presoaked cotton swab on the surface covered with the disinfectant solution, the second variant uses a presoaked swab without disinfectant on the test surface. Both methods have been tested by Prof. Koller in Vienna and the first variant showed a higher efficacy than the second (using more disinfectant on the surface). 

It may be desirable to first clean the pipeline with a polyurethane foam swab. This material can be purchased commercially either in specific cut sizes, or in bulk, which can be cut to the desired size. Swabs will effectively remove soft scales and loose material. Their method of use is identical to that of the pig. 

Before adopting this method at the ordnance plant, sections of pipelines were chosen for test samples, to determine if the swab and pig method would satisfactorily clean these contaminated pipes. One half the sections were cleaned by this method and the other half was thoroughly flushed with water. They were allowed to dry and then were subjected to initiation by fires. The sections that had been flushed with water ignited and burned vigorously. The sections that had been subjected to cleaning with the swab and pig had no product remaining that would support combustion. 

Fig. 20.2 Pheromone delivery in Desmognathus ocoee salamanders and the method of pheromone delivery used during behavioural trials. A receptive female places her chin on the tail base of the male and typically straddles his tail. The male turns back towards the female and places his submandibular mental gland on her dorsum. The male then uses his premaxillary teeth to scratch the site on her dorsum that he has swabbed with his mental gland secretions. To mimic pheromone delivery in behavioural trials, each male was deglanded and a treatment solution was delivered to each female in a treatment patch (TrP) placed on her dorsum just posterior to the head. Photograph by Stevan J. Arnold...

Of the explosives listed in Table 4, only those such as NG with vapour pressures greater than 10 Pa at 25°C are good candidates for the direct detection of vapour by current instrumental techniques. However, vapour pressure rises markedly with temperature. In addition, consideration of the thermal stability data in Table 4 offers the possibility of heating samples containing traces of involatile explosives such as RDX or PETN to increase their vapour pressure and render them detectable. This is the basis of the common technique of combining a heated inlet system with a vapour-type detector, for example, the method of desorption from a swab on a heated stage often used with IMS or TEA systems. This approach has greatly broadened the scope of what were previously viewed as vapour-type detectors and is now standard practice such instruments are now known as particle detectors. 

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