Process of Instrumental Measurement - Instrumental Analytical Chemistry - Lecture Slides, Slides of Analytical Chemistry

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The Process of Instrumental Measurement : Energy System Analytical source under information study Figure 1-1 Block diagram showing the overall process of an instrumental measurement. ® Docsity.com Components TABLE 1-2 Some Examples of Instrament Components Data Domain Energy Source Analytical Ingpmt of Transduced Information Instrument (stimulus) Information Transducer Informetion Processor Readsart Photometer Tangstert lamp, Attenuated light Photocell Electrical Meter scale Current Blasa filter beam conrent meter Atomlc emission = Flame UY or visible “Photomultiplier Electrical Amplifier, Chart spectrometer radiation tube potential deqmodulator, recomer fownochromator chopper Coulometer DC source Cell current Electrodes Bleotzical Amplifier Chart current recorder pH neter Somple/glasa Hydrogen ion Glass-calomel Electrical Amplifier, Digital nnit electode activity electrodes potential digitizer X-Ray powder X-Ray tube, Diffracted Photographic Latent Chemicel Black difftactometer sample radiation film image developer images on film Color Sunlight Calor Bye Optic nerve Brain Visual Docsity.com  TABLE 1-3 Numerical Criteria for Selecting Analytical Methods Criterion Figure of Merit L, Precision 2. Bias wo . Sensitivity 4, Detection limit 5, Concentration range a . Selectivity Absolute standard deviation, telative standard deviation, coefficient of variation, variance Absolute systematic error, telative systematic error Calibration sensitivity, analytical sensitivity Blank plus three times standard deviation of a blank Concentration limit of quantitation (LOQ) to concentration limit of linearity (LOL) Coefficient of selectivity Docsity.com TABLE 1-4 Other Characteristics to Be Considered in Method Choice | 1. Speed 2. Ease and convenience 3. Skill required of operator 4. Cost and availability of equipment 5. Per-sample cost Docsity.com TABLE 1-5 Figures of Merit for Precision of Analytical Methods er Terms Definition* Absolute standard deviation, s Relative standard deviation RSD = = (RSD) * Standard deviation of the 5m = tN mean, 5) Coefficient of variation, CV = < * 100% Variance st re gee! “a; = numerical value of the ith measurement, i 1 ¥ = mewn of N measurements = Docsity.com Chapter 2 Ohm’s Law V=IR Power Law P=IV R VP 2 = Docsity.com a ™ f=h=h=h-h VeVi+h+ Vy Rak) + Ry t Ry eure 22° Resistors in Seties; a voltage divider. The cur- t in each resistor is the same in a series circuit. Docsity.com Y-f yy = 0 V= GR, For the loop containing Vand Ro, V = Ro For the loop containing V ahd R3, V = 43 A . —_—— —_— — v= fh rler, nf Se, bh) SR, Figure 2-3 Resistors in parallel. The voltage across each eo is equal to V, the battery voltage. e : Docsity.com B 0 Low-pass filter A 1.0 RB A High-pass filter Low-paas filter High-pass fi 3 ~10 - 0.8 be: = = 0b S206 = S = 30h Se o4 oo 2 -4o b 0.2 g O01 O10 10 100 1000 10,000 0.01 0.1 1.0 10 160 1000 10,000 ~~ Fr wency. Hz , Frequency, Hz 4 o (a) “Figure 2-12 (a) Frequency response of high-pass and low-pass filters, (b) Bode diagram for high-pass and low- pass filters. For the high-pass filter, R = 10 kn and ¢ = 0, #E For the Jow-pass filter, R = 1 MO and C = 1 pk Docsity.com  Resistance-to- voltage converter Analog-to- digital converter Ac-to-de converter Current-to- voltage converter Figure 2-14 Block diagram of a digital multimeter. (rom H. Vi Malmstadt, C. G. Enke, and 5, R. Crouch, Electronics and Instrumentation for Scientists. Menlo Park, CA; Benjamin/Cummings, 1981. With permission.) & Docsity.com  prmglou | ¢@ ‘5 18 é oe Lt Desinion pte le oO &) 4 Tt region m-Tegion 1 AeTogiOn, 4 é cigs Figure 2-15 A pn junction diode, + LL I (a) Physical appearance of one type formed by diffusion of a p-type impurity into an n-type semiconductor, (b) symbol for a diode, (c) current under forward bias, (@) resistance to current under reverse bias. Docsity.com tc) td) Chapter 3 + 4 ¢ Amplifiers * Digital Electronics ® Docsity.com  o J o Circuit common Figure 3-1 Equivalent circuit diagram of an, operational amplifier. Docsity.com Light /\ source Photo- tube Meter | [O42 0] | J &=*% Figure 3-8 Application of an operational amplifier to the measurement of a small photocurrent J,. Docsity.com  manner lado J l 0 too 200 300 400 Frequency, Hz Figure 5-2 Effect of signal-to-noise ratio on the NMR spectrum of progesterone: A, S/N = 4,3; B, S/N = 43. {Adapted from R. R. Ernst and W. A. Anderson, Rev, Sci, Inst., 1966, 37, 101, With pennission.) Docsity.com  Power per cycle ——» [Arbitery units) S > | Year! Temp, Power line 180- Good quiet Tego =AM Tv \ L 120- —-Tadio Figure §-3 Some sources of envi- 1? ronmental nolse in a wulversity lab Environmental 240- oratory, Note the frequency depen- noise lI \ dence and regions where various 1 potois toy ep | r types of interference occur, (From io® i Lo4 lo? 1 1g? 167 106 10® Frequency, Hz ——» T; Cooy, J. Cher. Educ, 1968, 45, 4540: With permission.) Docsity.com A 8 c 10°) Original = 10° Amplified signal 105 | Demodulated signal ius aise signal P Demodulation to de ‘en after filtering E | Modulation to 400 Hz followed by 5 . 5 \ 2g, \ amplification by 106° al A = a % = = bb a | a“ z Atnplifier noise 0 i o ‘4 ol | 0.001 0.01 1.0 10.0 100 1000 = 0.001 6.010 Frequency, Hz Frequency, Hz Frequency, Hz Figure 5-6 Annplification of a dc signal with a chopper amplifier. (Adapied from T, Coor, J. Chem. Educ., 1968, 45, AS40. With permission.) Docsity.com