Blanks reagent blank

REQUIRES A BLANK REQUIRES A BLANK REAGENT BLANK REAGENT BLANK REAGENT BLANK ... 

The blank (reagent blank) is a solution that contains all the substances present in the standards and the unknown (if possible) except for the analyte. A sample blank takes into account any chemical changes that may take place as the sample is taken or prepared. See Section 6.6.2 for an example. 

What is the purpose of a blank Distinguish method blank, reagent blank, and field blank. 

P Batch Size The batch size is defined as a group of calibration standards, matrix blanks, reagent blanks, QCs, and study samples that are processed via the same sample preparation procedure, analyzed through sequential LC-MS/MS injections, and calculated based on the calibration curve. As a part of the validation, an intended assay batch size (e.g., 96 or 192 injections) should be analyzed per run with acceptable precision and accuracy. 

Compensating for an interference in the sample s matrix is more difficult. If the identity and concentration of the interferent are known, then it can be added to the reagent blank. In most analyses, however, the identity or concentration of matrix interferents is not known, and their contribution to S stead, the signal from the interferent is included as an additional term... 

A proportional determinate error, in which the error s magnitude depends on the amount of sample, is more difficult to detect since the result of an analysis is independent of the amount of sample. Table 4.6 outlines an example showing the effect of a positive proportional error of 1.0% on the analysis of a sample that is 50.0% w/w in analyte. In terms of equations 4.4 and 4.5, the reagent blank, Sreag, is an example of a constant determinate error, and the sensitivity, k, may be affected by proportional errors. 

A propagation of uncertainty also helps in deciding how to improve the uncertainty in an analysis. In Example 4.7, for instance, we calculated the concentration of an analyte, obtaining a value of 126 ppm with an absolute uncertainty of 2 ppm and a relative uncertainty of 1.6%. How might we improve the analysis so that the absolute uncertainty is only 1 ppm (a relative uncertainty of 0.8%) Looking back on the calculation, we find that the relative uncertainty is determined by the relative uncertainty in the measured signal (corrected for the reagent blank)... 

A method s detection limit is the smallest amount or concentration of analyte that can be detected with statistical confidence. The International Union of Pure and Applied Chemistry (lUPAC) defines the detection limit as the smallest concentration or absolute amount of analyte that has a signal significantly larger than the signal arising from a reagent blank. Mathematically, the analyte s signal at the detection limit, (Sa)dl, is... 

To test a spectrophotometer for its accuracy, a solution of 60.06 ppm K2Cr207 in 5.0 mM H2SO4 is prepared and analyzed. This solution has a known absorbance of 0.640 at 350.0 nm in a 1.0-cm cell when using 5.0 mM H2SO4 as a reagent blank. Several aliquots of the solution are analyzed with the following results... 

In a single-point standardization, we assume that the reagent blank (the first row in Table 5.1) corrects for all constant sources of determinate error. If this is not the case, then the value of k determined by a singlepoint standardization will have a determinate error. 

In discussing ways to standardize a method, we assumed that an appropriate reagent blank had been used to correct S eas for signals originating from sources other than the analyte. At that time we did not ask an important question— What constitutes an appropriate reagent blank Surprisingly, the answer is not intuitively obvious. 

A reagent blank corrects the measured signal for signals due to reagents other than the sample that are used in an analysis. The most common reagent blank is prepared by omitting the sample. When a simple reagent blank does not compensate for all constant sources of determinate error, other types of blanks, such as the total Youden blank, can be used. 

Since all samples and standards are prepared using the same volume of ammonium acetate buffer, the contribution of this source of iron is accounted for by the calibration curve s reagent blank. 

Flow would you incorporate a reagent blank into the FIA analysis ... 

A reagent blank can be obtained by injecting a sample of distilled water in place of the external standard or sample. The reagent blank s absorbance is subtracted from the absorbances obtained for the standards and samples. 

The following data were obtained for a set of external phosphate standards. All absorbances have been corrected for a reagent blank. 

A reagent blank corrects the measured signal for signals dyi reagents other than the sample that are used in he... 

When a simple reagent blank does not compensa ant... 

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. 

Procedure. Use a solution containing 0.15-1.8 mg antimony per 100 mL it should be slightly acidic with sulphuric acid (1.2-1.5M). Transfer a 10 mL aliquot to a 50 mL graduated flask, add 25 mL of the potassium iodide-ascorbic acid reagent, and dilute to the mark with 25 per cent v/v sulphuric acid. Mix thoroughly and measure the absorbance at 425 nm or at 330 nm using a reagent blank as reference solution. 

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