Samples decontamination

Soil samples Water samples Decontamination solutions Existing ROPs were tested... 

The Ninth Official Proficiency Test (2001) Organic liquid samples Decontamination solutions Emulsion samples... 

The Fourteenth Official Proficiency Test (2003) Organic liquid samples Water samples Decontamination solutions... 

The aim of this review is to present the different methodologies reported for cannabis detection in human hair (sample, decontamination, hydrolysis, internal standards [IS], extraction, derivatization, system of detection) and the analytical performances observed. 

The nature of our concern is best illustrated by a specific example. Blank and Kidwell use a cocaine solution of 100,000 ng/mL for their contamination experiments, to which they add approximately 1 pCi of tritium-labeled cocaine, i.e., approximately one million counts per minute. Therefore, they have approximately a sensitivity of 10 cpm/ng of sample. Decontamination of hair means that residual drug concentration must drop below the endogenous cutoff level of 5 ng/10 mg of hair, i.e., to 50 cpm/10 mg hair. Now if the labeled cocaine has a radiochemical impurity of as little as 0.1%, this corresponds to 1000 cpm or to 100 ng of residual cocaine equivalents. Since self-irradiation of tritium-labeled material tends to form polymeric impurities, and since these are likely to preferentially bind to hair, one incurs a major risk of concluding erroneously that the residual radioactivity represents residual cocaine contamination rather than contamination by polymeric degradation products. 

Date, duration, and frequency of sampling Homogeneity of the sample Contamination of the sample Decontamination of the sample Sample conservation and storage... 

At Site I, personnel and equipment decontamination procedures were not monitored for their effectiveness in accordance with HAZ-WOPER requirements. The Site I subcontractor did not have provisions for particulate sampling, evaluating exposure to pesticides and herbicides, or evaluating the effectiveness of site zone boundaries and personnel decontamination procedures. Additionally, monitoring had not been conducted to verify that decontamination was not necessary for employees who leave the exclusion zone and enter a clean zone without undergoing decontamination. 

Averaging Method. A drill rig and auger were used to collect columns of soil from depths of 0 to 6, 0 to 12, 0 to 24, 0 to 36, and 0 to 48 inches. The holes were drilled about one foot apart and the augers decontaminated between holes. Each of the five samples were transferred to a clean, stainless-steel pan and thoroughly blended prior to splitting into the sample containers. 

The grinding and mixing devices, as well as any sieves, must be carefully cleaned between each sample In order to avoid cross-contamination of the samples. The final rinse water should be sampled on 5% of the decontamination cycles In order to provide a blank for use In evaluating the decontamination efficiency. These samples should be submitted to the laboratory along with the other QA/QC samples. 

SFE. SFE has been established as the extraction method of choice for solid samples. The usefulness of SFE for soil samples has been demonstrated for carbamate,organophosphorus and organochlorine pesticides. However, SFE is more effective in extracting nonpolar than polar residues. In order to obtain a greater extraction efficiency for the polar residues of imidacloprid, the addition of 20% methanol as modifier is required. Extraction at 276 bar and 80 °C with a solvent consisting of supercritical carbon dioxide modified with methanol (5%) for 40 min gives a recovery of 97% (RSD = 3.6%, n = 10). It is possible to use process-scale SFE to decontaminate pesticide residues from dust waste. ... 

As much of the pulp as possible was removed but in the event the skin was punctured the fruit was discarded and the scraping tools decontaminated. The pulp taken from the individual fruits of the sample was pooled for subsequent processing. Separate samples of fruit were used for surface residue estimations (12). 

Procuring equipment protective ensembles, air monitoring devices, sampling equipment, decontamination apparatus, and supplies (disposables, tape, notebook, and so on)... 

Procuring on-site facilities for office and laboratory space, decontamination equipment, and vehicle maintenance and repair, and sample storage, as well as on-site water, electric, telephone, and sanitary utilities... 

Delineation of these three zones should be based on sampling and monitoring results and on an evaluation of the potential routes and amount of contaminant dispersion in the event of a release. Movement of personnel and equipment among these zones should be minimized and restricted to specific access control points to prevent cross-contamination from contaminated areas to clean areas. A decision for evaluating health and safety aspects of decontamination methods is presented in Figure 16.22.105... 

Cleaning is a form of maintenance which is particularly relevant where a piece of equipment is used repeatedly, but is also applicable to decontamination of equipment after use in dirty environments. The purpose of cleaning is to ensure that when the piece of equipment is used for an application or measurement, the risk of contamination from previous samples, chemicals, standards or the laboratory environment will be minimized. In the majority of cases, the process of cleaning introduces new chemicals to whatever is being cleaned. After cleaning, the equipment must be well rinsed to remove all traces of the cleaning chemicals, and then dried. 

---