Sampling by mixing

Ferguson PL, Iden CR, Brownawell BJ (2001) Analysis of nonylphenol and nonylphenol ethoxylates in environmental samples by mixed-mode high performance liquid chromatography-electrospray mass spectrometry. J Chromatogr A 938 79-91... 

Either field or laboratory personnel prepare composite samples by mixing equal aliquots of grab samples and taking an aliquot of a well-mixed composite of sufficient weight for laboratory analysis. Grab samples selected for compositing must be of the same type of bulk PCB remediation waste the TSCA does not allow compositing of different types of PCB waste. 

Lunar, L., S. Rubio, and D. Perez-Bendito. 2006. Analysis of linear alkylbenzene sulfonate homologues in environmental water samples by mixed admicelle-based extraction and hquid chromatography/mass spectrometry. Analyst 131 835-841. 

Prepare the column sample by mixing 0.1 ml bromophenol blue (step 5-26) and 0.5 ml blue dextran solution (step 5-27). 

Sample preparation techniques involve the chemical separation of the specific chemical forms of a radionuclide, and the preparation of the counting sample by mixing the separated nuclides with the proper liquid scintillator. 

Prepare a blank sample by mixing 20 pi of concentrated hydrochloric acid, 20 pi of hydroxylamine hydrochloride solution, 200 pi of ammonium acetate buffer, 80 pi of 1,10-phenanthroline solution, and 880pl of water (see Note... 

Liberation of CO from carboxyhaemoglobin (present in the blood sample) by mixing with ferricyanide in a headspace vial followed by GC on a column packed with 60/80 mesh 0.3 nm molecular sieve, is a conve-nient method of analysis. CO itself does not respond on the FID, but reduction to methane by reaction with hydrogen in the presence of a nickel catalyst allows an FID to be used. 

Carlisle et al. (26) used a similar technique to measure Ci-C7 hydrocarbons in sediment samples by mixing sediment, water, and gas in a sealed mixer (such as Waring). They also report evidence of submarine seeps in samples collected in the Gulf of Mexico. Hunt (27), using the technique of Carlisle, documented the apparent generation of small amounts of butane-through-heptane hydrocarbons in deep-sea drilling project cores, from burial depths of 28-800 m. 

Zhao, X., Li, J., Shi, Y, Cai, Y, Mou, S., and Jiang G. 2007. Determination of perfluorinated compounds in wastewater and river water samples by mixed hemimicelle-based solid-phase extraction before liquid chromatography-electrospray tandem mass spectrometry detection. J. Chromatogr. A 1154 52-59. 

Prepare protease sample by mixing equal volumes of the starting material and the protein preparation buffer. Incubate at room temperature for 15 min. Do not heat. 

Figure 10.54 Separation of iodide in a natural seawater sample by mixed-mode liquid chromatography using UV detection. Separator column Acclaim Mixed-Mode WAX-1, 5 pm column dimensions 150 mm x 2.1 mm i.d. eluent 50 50 (v/v) MeOH/120mmol/L...

A Fourier transform infrared spectrophotometer (FTIR, model-IR Prestige-21, Schimadzu Corporation, Japan) was used for the structural determination of functional groups and compounds. The FTIR spectra of modified and unmodified clay in the solid state using potassium bromide (KBr) as a reference material were recorded by diffuse reflectance spectroscopy (DRS technique). This technique consists of preparation of sample by mixing about 0.5 mg of powder sample with 50 mg of high-purity infrared-grade KBr powder (Aldrich). The KBr was previously oven dried to reduce the interference of water. The spectra were recorded in the wave number range of 4000—400 cm with a resolution of 4 cm and 20 scans were carried for each sample in transmittance mode. 

Liquid test materials do not present any special difficulties or problems, especially if the total quantity is susceptible to thorough mixing, thus guaranteeing uniformity. In cases where individual liquid samples are drawn and must then be united, it is important to obtain correct samples by mixing and taking the individual portions from different locations of the entire liquid mass. 

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