Blank procedures

Develop, formalize and implement vessel entry procedures, tag out / lock out procedures, blanking procedures, and line breaking procedures... [Pg.137]

Cleaning and blanking procedures, therefore, must be carefully evaluated to assure reliable results from broad spectrum analyses of large volumes of water. Many questions arise about the reliability of present methods because researchers have based large-volume sampling procedures on results from low-volume procedures. [Pg.271]

Blanking Procedures. A true blank would be pure water passed through cleaned resin by using the field procedure. An experiment was performed to individually blank the use of XAD-8 and XAD-2 resins. Resin columns of 100 mL (5 cm diameter) were prepared by the Soxhlet procedure, and CH2C12 was used as the elution solvent. Figures 4 and 5 show a series of three chromatograms for XAD-2 and XAD-8 resins, respectively. An explanation of the chromatograms follows ... [Pg.284]

Blanks. "Procedure blanks", samples of the same matrix material that will subsequently be analyzed in the study but known to lack detectable levels of the compounds of interest, must be put through the entire procedure including storage for the same (mean) length of time in the same environment as the test samples. Extraction and cleanup procedures applied to these "blanks" must involve the same amounts of solvents and chromatographic media as will be used on the real samples. In no other way can the likelihood of interferences (false positives) be convincingly assessed. [Pg.442]

Adjust instrument sensitivity, baseline stability and perform instrument blanking procedures following manufacturer s guidelines. [Pg.903]

Hypothetical Data Used to Study Procedures for Method Blanks... [Pg.128]

Spike recoveries on method blanks and field blanks are used to evaluate the general performance of an analytical procedure. The concentration of analyte added to the blank should be between 5 and 50 times the method s detection limit. Systematic errors occurring during sampling and transport will result in an unacceptable recovery for the field blank, but not for the method blank. Systematic errors occurring in the laboratory, however, will affect the recoveries for both the field and method blanks. [Pg.711]

The analytical uncertainty should be reduced to one-third or less of sampling uncertainty (16). Poor results obtained because of reagent contamination, operator errors ia procedure or data handling, biased methods, and so on, can be controlled by proper use of blanks, standards, and reference samples. [Pg.241]

Whatever treatment is used to clean specimens after a corrosion test, its effect in removing metal should be determined, and the weight loss should be corrected accordingly. A blank specimen should be weighed before and after exposure to the cleaning procedure to estabhsh this weight loss. [Pg.2427]

Procedure To an aliquot of the sample solution containing 12.5 - 305 p.g of platinum(IV) were added 5 ml of hydrochloric acid - sodium acetate buffer of pH 2.1, 1 ml of O.IM Cu(II) sulphate solution, and 3.0 ml of 0.5% propericiazine solution. The solution was diluted to 25 ml with distilled water, mixed thoroughly, and the absorbance measured at 520 nm against a reagent blank solution after 10 min. The platinum concentration of the sample solution was determined using a standar d calibration curve. [Pg.117]

In order to select the instmmental conditions for carrying out the ATR measurements several parameters including the number of accumulated scans per spectra or nominal resolution were tested. To avoid the crosscontamination and to establish an appropriate strategy for cleaning the ATR cell between samples, several procedures were tested using background and blank controls. Moreover, the possible sample sedimentation on the ATR plate cell due to the complexity of the sample matrix during the spectra acquisition was also checked. [Pg.142]

The methods I- 4 of sample preparation are classics. As a mle they give a high value of blank and some of them take a lot of time. Microwave sample preparation is perspective, more convenient and much more faster procedure than classical mineralization. There are some problems with the combination Cendall-Kolthoff s kinetic method and microwave sample preparation which discussed. The experimental data of different complex organic matrix are demonstrated (food products on fat, peptides, hydrocarbone matrix, urine etc). [Pg.281]

Don t change record blanks without authorized changes to the related procedure. Don t leave records lying around. [Pg.506]

Procedure. To 10.0 mL of the solution containing up to 200 fig of copper in a separatory funnel, add 5.0 mL of 10 per cent hydroxylammonium chloride solution to reduce Cu(II) to Cu(I), and 10 mL of a 30 per cent sodium citrate solution to complex any other metals which may be present. Add ammonia solution until the pH is about 4 (Congo red paper), followed by lOmL of a 0.1 per cent solution of neo-cuproin in absolute ethanol. Shake for about 30 seconds with 10 mL of chloroform and allow the layers to separate. Repeat the extraction with a further 5 mL of chloroform. Measure the absorbance at 457 nm against a blank on the reagents which have been treated similarly to the sample. [Pg.178]

Procedure. Weigh out 0.0226 g of hydrated ammonium iron(III) sulphate and dissolve it in 1 L of water in a graduated flask 50 mL of this solution contain 100 g of iron. Place 50.0 mL of the solution in a 100 mL separatory funnel, add 10 mL of a 1 per cent oxine (analytical grade) solution in chloroform and shake for 1 minute. Separate the chloroform layer. Transfer a portion of the latter to a 1.0 cm absorption cell. Determine the absorbance at 470 nm in a spectrophotometer, using the solvent as a blank or reference. Repeat the extraction with a further 10 mL of 1 per cent oxine solution in chloroform, and measure the absorbance to confirm that all the iron was extracted. [Pg.178]

Procedure. Dissolve 0.0079 g of pure lead nitrate in 1 L of water in a graduated flask. To 10.0 mL of this solution (containing about 50 p.g of lead) contained in a 250 mL separatory funnel, add 75 mL of ammonia-cyanide-sulphite mixture (Note 1), adjust the pH of the solution to 9.5 (pH meter) by the cautious addition of hydrochloric acid (CARE ), then add 7.5 mL of a 0.005 per cent solution of dithizone in chloroform (Note 2), followed by 17.5 mL of chloroform. Shake for 1 minute, and allow the phases to separate. Determine the absorbance at 510 nm against a blank solution in a 1.0 cm absorption cell. A further extraction of the same solution gives zero absorption indicative of the complete extraction of the lead. Almost the same absorbance is obtained in the presence of 100 pg of copper ion and 100 pg of zinc ion. [Pg.180]

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