Rapid spectrophotometric determination of manganese(II) with 4-(2-thiazolylazo)-resorcinol

Summary Manganese forms a red chelate with 4-(2-thiazolylazo)-resorcinol at pH 8.8 (borate buffer), and absorbance is measured after 30 s, at 540 nm in the presence of 20%tert-butyl alcohol (by volume). The 12 complex obeys Beer's law for manganese concentration of 0.04–1.4g per ml, has molar absorptivity 4.176 x 10⁴ and Sandell sensitivity 0.0013g cm^–2. The formation constant (logK) is found to be 9.32, and relative standard deviation ±0.22%. Of the 48 ions studied for interference, only Co(II), Zn(II), Cd(II), Pb(II) and EDTA^2– are found to interfere. This method has been applied for the determination of manganese content in alloy steels.

---

Spektrophotometrische Bestimmung von Mangan(II) mit 4-(2-Thiazolylazo)-resorcin

Zusammenfassung Mangan bildet bei pH 8,8 (Boratpuffer) mit 4-(2-Thiazolylazo)-resorcin ein rotes Chelat, dessen Absorbanz nach 30 sec bei 540 nm in Gegenwart von 20% tert. Butylalkohol gemessen wird. Dieser 12-Komplex entspricht bei einer Mangan-Konzentration von 0,04–1,4g/ml dem Beerschen Gesetz; seine molare Absorption beträgt 4,176 x 10⁴, die Empfindlichkeit nach Sandell 0,0013g·cm^–2. Die Bildungskonstante (log K) beträgt 9,32, die rel. Standardabweichung ±0,22%. Unter 48 untersuchten Ionen erwiesen sich nur Co(II), Zn(II), Cd(II), Pb(II) und EDTA als störend.-Das Verfahren wurde zur Bestimmung des Mangangehaltes in Stahl verwendet.

     

Spectrophotometric studies on the simultaneous determination of cadmium and mercury with 4-(2-pyridylazo)-resorcinol

A new method for direct spectrophotometric determination of cadmium with 4-(2-pyridylazo)-resorcinol is reported. Absorption maximum, molar absorptivity and Sandell's sensitivity of the 1:1 (M:L) complex are 510 nm, 2.5 x 10(5) l mol(-1) cm(-1) and 3.55 ng cm(-2), respectively. A linear calibration graph is obtained up to 4.49 microg ml(-1). The zero-crossing measurement technique is found suitable for the direct measurement of the first-derivative value at the specified wavelengths. Cadmium(II) (0.42-9.2 microg ml(-1)) and mercury(II) (0.35-7.4 microg ml(-1)) in different ratios have been determined simultaneously. A critical evaluation of the proposed method is performed by statistical analysis of the experimental data. The developed method was applied to the simultaneous spectrophotometric determination of Cd and Hg in some synthetic mixtures and was found to give satisfactory results.     

Spectrophotometric determination of chromium(III) with 4-(2-thiazolylazo)-resorcinol

Summary The red complex formed between chromium(III) and 4-(2-thiazolylazo)-resorcinol (1 2) at pH 5.0, on heating the reactants to 90° for 45 minutes, is used for Spectrophotometric determination of chromium, the absorbance being measured at 525 nm. Beer's law is obeyed for chromium concentration of 0.06 to 1.1g per ml. Molar absorptivity is 4.98×10⁴ and Sandell sensitivity 0.001g cm^–2. This method has been applied to the determination of chromium content in steel samples.

---

Zusammenfassung Der 1 2-Komplex von Chrom(III) mit 4-(2-Thiazolylazo)resorcin bildet sich bei pH 5,0 und 90° C in 45 min. Er eignet sich zur spektrophotometrischen Chrombestimmung. Die Extinktion wird bei 525 nm gemessen. Das Beersche Gesetz ist zwischen 0,06 und 1,1g Cr/ml erfüllt. Die molare Extinktion beträgt 4,98 · 10⁴, die Empfindlichkeit nach Sandell 0,0001g · cm^–2. Die Methode wurde zur Chrombestimmung in Stahlproben angewandt.

     

Spectrophotometric determination of palladium with 4-(2-pyridylazo)-resorcinol (PAR)

Summary A spectrophotometric method for the determination of palladium is described using 4-(2-pyridylazo)-resorcinol as reagent. The method involves the formation of two red coloured chelates of palladium-PAR at p_H 4.0 and 10.5 respectively. The colour reactions have sensitivity of 0.0085g cm^–2 and 0.0071g cm^–2 for logI ₀/I= 0.001. The effects of p_H, time, order of addition of reagents, temperature etc. have been investigated. The composition of the complexes (metalreagent) have been confirmed by two methods as 11 (at p_H 4.0) and 32 (at p_H 10.5).

---

Zusammenfassung Eine spektrophotometrische Methode zur Palladiumbestimmung mit PAR [4-(2-Pyridylazo)-resorcin] wurde beschrieben. Zwei rotgefärbte Chelate werden bei p_H 4,0 bzw. 10,5 gebildet. Die Empfindlichkeit der beiden Reaktionen beträgt 0,0085 bzw. 0,0071g · cm^–2. Der Einfluß von p_H, Zeit, Reihenfolge der Reagenzien, Temperatur usw. wurde untersucht. Die Zusammensetzung der Komplexe entspricht dem Molverhältnis Pd: Reagens= =11 bei p_H 4,0 bzw. 32 bei p_H 10,5.

     

Metal complexes of 4-(2'-thiazolylazo)-resorcinol A comparative study with 4-(2'-pyridylazo)-resorcinol

The acid dissociation constants of 4-(2'-thiazolylazo)-resorcinol (TAR) and the formation constants of the metal complexes formed by this reagent with Cu(II), Ni(II), Co(II), Zn(II) and Mn(II) have been determined potentiometrically at 25° in 50% v/v mixtures of dioxane and water. The values obtained for TAR and the metal complexes are contrasted with similar values for the reagent 4-(2'-pyridylazo)-resorcinol (PAR). Differences and similarities between the co-ordinating tendencies of these two reagents are revealed in terms of the proton displacement constant and the acid dissociation constants of the metal complexes. Evidence is presented which suggests that both TAR and PAR may act as terdentate ligands toward some bivalent metal ions.     

The extraction-spectrophotometric determination of chromium(III) with 4-(2-pyridylazo)-resorcinol

The extraction-spectrophotometric determination of chromium(III) with 4-(2-pyridylazo)-resorcinol (PAR) is described. PAR(H₂R) forms a 1:3 complex with chromium(III) in a boiling acetate buffer solution at pH 5. The complex forms an ion-association compound with tetradecyldimethylbenzylammonium ion (TDBA⁺):Cr(R)(HR)₂^--TDBA⁺ which can be extracted into chloroform, the molar absorptivity being 4.7 ·10⁴ at 540 nm. If EDTA is added as a masking agent after the Cr(HR)₃ has been formed, only iron, cobalt and nickel interfere seriously, and the method can be made specific for chromium by a preliminary extraction of these metals with cupferron. The sensitivity of the method is seven times higher than that of the diphenylcarbazide method.     

Spectrophotometric determination of niobium in steels with 4-(2-pyridylazo)-resorcinol

A direct method is presented for the spectrophotometric determination of niobium with PAR in mild and alloy steels. Interference is caused only by tantalum and large amounts of copper. A compensating solution is used to correct for coloured ions and for the copper-PAR complex. The method covers the range 0–100 mg of niobium, and Beer's law is obeyed from 0 to 2.0μg Nb/ml. A molar absorptivity of 14,400 at 536 nm was found for the niobium-PAR complex, with a relative standard deviation of ±0.6%.     

Spectrophotometric extractive determination of thiolactams with 4-(2-pyridylazo)-resorcinol and copper

The thiolactams: thiopyrolidon, thiopiperidon, thiocaprolactam, thioenantolactam and thiocaprylolactam form a complex with the ion Cu(II) and PAR in which the ratio Cu:PAR:T1 = 1:2:4. The formation of a ternary complex was used in the spectrophotometric determination of thiolactams in a concentration range of 0.25-4.0 μg/ml thiolactam.     

Spectrophotometric determination of lanthanides using 4-(2-Pyridylazo) resorcinol

Summary The formation of red colour produced by the interaction of 4-(2-pyridylazo) resorcinol (PAR) and rare earths has been studied to determine the composition, stability and other characteristics of the chelates formed. The _max of all the chelates was found to be 515 nm atph 6.2 whereas the _max of the PAR reagent at this p_H is 410 nm. The composition of the chelates was found to be 12 (metalPAR) and has been established by two different methods. The stability constant values have been calculated by three different methods. The values of logK, lies in the range of 9.2–10.4 for different rare earth chelates. The chelates are stable over a wide range of p_H. A tentative suggestion has also been made for the position of the chelate ring.

---

Zusammenfassung Die rote Farbreaktion von 4-(2-Pyridylazo)-resorcin (PAR) mit Seltenen Erden wurde untersucht, um die Zusammensetzung, die Stabilität und andere Merkmale der dabei entstehenden Chelate zu bestimmen. Beiph 6,2 wurde das Absorptionsmaximum aller Chelate bei 515 nm, das Absorptionsmaximum von PAR bei 410 nm gefunden. Die Zusammensetzung entspricht dem Verhältnis Metall: PAR=12; sie wurde nach zwei verschiedenen Methoden ermittelt. Die Komplexkonstante wurde auf drei verschiedenen Wegen bestimmt. logK liegt bei den verschiedenen Seltenen Erdmetall-Chelaten zwischen 9,2 und 10,4. Die Chelate sind in einem weitenph-Bereich beständig. Die Lage des Chelatrings wurde erörtert.

     

Spectrophotometric determination of diethyllead and diethyltin ions with 4-(2-pyridylazo)-resorcinol

A study was made of the reaction of diethyllead and diethyltin ions with 4-(2-pyridylazo)-resorcinol; the compositions and the molar extinction coefficients of the compounds formed were determined. Methods are outlined for the determination of these organometallic cations. A method is described for the determination of lead chloride in the presence of (C₂H₅)₂PbCl₂.     

4-(2-Pyridylazo)-resorcin (PAR)

Ohne Zusammenfassung     

4-(2-Pyridylazo)-resorcin (PAR)

Ohne Zusammenfassung     

Extraction-spectrophotometric determination of zinc(ii) with 4-(2-pyridylazo)-resorcinol and a quaternary ammonium salt

A simple and sélective extraction spectrophotometric determination of zinc is described. The complex [Zn(PAR)(2)](CDBA)(2), where PAR is the 4-(2-pyridylazo)resorcinol anion and CDBA is cetyldimethylbenzylammonium ion, is extracted from a solution buffered at pH 9.7 with carbonate/bicarbonate. Beer's law is obeyed over the range 0.2-1.2 ppm zinc, the molar absorptivity being 9.2 x 10(4) 1 .mole(-1).cm(-1). The precision in this range is 0.0056 ppm. Cadmium in up to a 50-fold w w ratio may be masked with diethyldithiocarbamate.