ou are developing a Ca detection method for a graphite furnace AA instrument. Your analysis of ten blank samples gives a standard deviation of 0.265 ppb. To establish your limit of detection (LOD), what concentration of Ca should be spiked into your blanks?
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- A titrimetric method for the determination of calcium in limestone was tested by analysis of an NIST limestone containing 30.15% CaO. The mean result of four analyses was 30.26% CaO, with a standard deviation of 0.085%. By pooling data from several analyses, it was established that s = 0.094% CaO.a. Do the data indicate the presence of a systematic error at the 95% confidence level?b. Do the data indicate the presence of systematic error at the 95% confidence level if no pooled value for s was available?Titration of an oxalate sample gave the following percentages: 15.07 % , 15.58 % , and 15.42 % . Calculate the average. Calculate the standard deviation.A titrimetric method for the determination of calcium in limestone was tested with the analysis of a NIST limestone containing 30.15% CaO. The mean of the four analyzes is 30.26% CaO with a standard deviation of 0.085%. From the data accumulated from many analyzes, s→ϭ=0.094% CaO was found.a) Do the data indicate the presence of systematic error at the 95% confidence level?b) When a value for ϭ is unknown, do the data show a systematic error at the 95% confidence level?
- 8) Two different analytical methods are compared for determining Ca. The following are two sets of data. Set 1 Set 2 155.779 155.784 155.787 155.787 155.813 155.765 155.781 155.793 i. i. Determine the mean and the standard deviation in Set 1. Calculate the 95% confidence limit for data in Set 1. Identify a possible outlier in Set 2. Use the Q-test to determine whether it can be retained or rejected at 95% confidence level. ii.As part of an analytical chemistry laboratory course, a student measured the Ca2+ content in two water samples, city-supplied drinking water and well-supplied drinking water, using two different analytical methods, flame atomic absorption spectrometry (FAAS) and EDTA complexometric titration. The results of this experiment are given in the table as the mean Ca2+concentration (?¯) and standard deviation (?) in parts per million (ppm). Each sample was measured five times (n=5) by each method. Method City-Supplied Drinking Water (?¯±?x¯±s) Well-Supplied Drinking Water (?¯±?x¯±s) FAAS 57.57±0.68 ppm 64.77±0.70 ppm EDTA titration 58.32±0.96 ppm 65.62±0.97 ppm Method Comparison: For each drinking water sample (city and well), compare the Ca2+ content measured by FAAS and EDTA titration. Calculate the ? value for each sample. Do the methods produce statistically different results at the 95% confidence level when measuring the Ca2+content of the city-supplied drinking water? Do the…A method for the detection of morphine is used to generate a calibration curve in which the assay response (y) is plotted versus morphine concentration (x, in mg/L). This gives a straight line with a slope (m) of 0.241 and a y-intercept (b) of 0.011, where y = mx + b. The slope of this line has a standard deviation of ±0.007, and the standard deviation of the intercept is ±0.006. If the sample from an athlete gives a response of 0.506 ± 0.013 in this method, what is the concentration of morphine in the sample and estimated precision of this concentration?
- What are the differences between systematic and random errors and how do they effect accuracy and precision? In what circumstances would you use standard addition (versus a normal calibration curve) to determine the amount of an analyte in a sample? A urine sample, containing analyte Z is analysed by the standard addition method where 5 mL of the original sample was mixed with increasing amounts of a Z standard and each solution diluted to a volume of 50 mL prior to analysis. A plot of the final concentration of the standard in each of the 50 mL samples (x axis) versus The measured signal from the analysis of each 50 mL sample (on y axis) produced a straight line with the general equation: y = 44.72x + 4.06 what was the final concentration of Z in the 50 mL standard addition sample? what was the initial concentration of Z in the original urine sample?A young researcher was evaluating a standard method for determining the methylmercury content in blue fin tuna using high performance liquid chromatography (HPLC). She determined the standard deviation (?)(s) for the method to be 0.440.44 ppb and assumed that ?s was a good approximation of ?σ . As a test, she used this method to evaluate the methylmercury content in a National Institutes of Standards and Technology (NIST) standard and determined the unknown amount to be within 0.210.21 ppb (?)(μ) of the known mean with 99% probability. How many replicate measurements of the NIST standard did the researcher perform?A solution of Ba (OH), was standardized against 0.1208 g of primary-standard-grade benzoic acid, C6H5 COOH (122.12 g/mol). An end point was observed after addition of 43.94 mL of base. a. Calculate the molar concentration of the base. Concentration M b. Calculate the standard deviation of the molar concentration if the standard deviation for the mass measurement was ±0.4 mg and that for the volume measurement was +0.02 mL. Standard deviation M c. Assuming an error of -0.3 mg in the mass measurement, calculate the absolute and relative systematic error in the molar concentration. Absolute systematic error = M Relative systematic error = |ppt
- In a volumetric determination of an analyte A, the data obtained and their standard deviations are as follows: Initial buret reading 0.19 mL 0.02 mL Final buret reading 7.86 mL 0.03 mL Sample mass 63.0 mg 0.2 mg From the data, find the coefficient of variation of the final result for the %A that is obtained by using the equation that follows and assuming there is no uncertainty in the equivalent mass. %A= titrant volume x equivalent mass x 100 %/ sample mass Coefficient of variation = Submit Answer % Try Another Version 10 item attempts remainingA new method was created to determine arsenic in rice. To validate this method, a reference standard was used with a certified concentration of 2.1 ppm of Arsenic, with a standard deviation of 0.7 ppm . When analyzing the reference standard 7 times, with the new method, an average of 2.87 ppm was obtained with a standard deviation of 0.4 ppm. These results show that the new method Has it been validated? Does it have systematic errors? Has a precision similar to that of the reference standardA solution is prepared by weighing 5.0000 g of cesium iodide into a 100-mL volumetric flask. The balance used has a precision of 0.2 mg reported as a standard deviation, and the volumetric flask could be filled with a precision of 0.15mL also reported as a standard deviation. What is the estimated standard deviation of concentration (g/mL)?