Hua-Shan Zhang

Spectrofluorimetic determination of cysteine based on the fluorescence inhibition of Cd(II)-8-hydroxyquinoline-5-sulphonic acid complex by cysteine.

A spectrofluorimetric method for the determination of cysteine at trace and ultra trace levels (0-1.82 x 10(-5) mol l(-1)) has been developed. It is based on the efficient inhibition action of cysteine on the fluorescent system of Cd(II)-8-hydroxyquinoline-5-sulphonic acid complex (Cd(II)-HQS) (lambda(ex) 364.8 nm, lambda(em) 510.4 nm) solution at pH 8.5. The method has been applied to protein hydrolysate and cystine electrolyte samples.

Studies on 2-(2-thiazolylazo)-5-diethylaminophenol as a precolumn derivatizing reagent in the separation of platinum group metals by high performance liquid chromatography

Five platinum group metals, Pt(II), Ir(IV), Ru(III), Rh(III) and Os(IV) have been separated by high performance liquid chromatography (HPLC) using 2-(2-thiazolylazo)-5-diethylaminophenol (TADAP) as a precolumn derivatizing reagent. The whole analysis was completed on a C(18) column in 23 min at 574 nm, with the mobile phase of methanol-water (69.5:30.5, v:v) containing 4 mmol l(-1) tetrabutylammonium bromide (TBA Br) and 10 mmol l(-1) pH6.0 acetate buffer. The detection limits (S/N=3) of Pt(II), Ir(IV), Ru(III), Rh(III) and Os(IV) were 0.39, 9.74, 1.64, 0.29 and 1.29 ng ml(-1), respectively. This method was rapid, sensitive and simple.

The determination of impurities in caprolactam by capillary gas chromatography-mass spectrometry

A capillary gas chromatography-mass spectrometry (GC-MS) technique has been developed for the determination of impurities in caprolactam. The residual solution of the crude product extracted by benzene was analyzed. A total of 28 compounds in the residual solution were separated. In comparison with the mass spectra obtained with those published in data tables, 24 compounds of the 28 were identified. The possible origination of these impurities was discussed and could be significant in the industrial control of caprolactam.

Determination of Nb(V), V(V), Co(II), Fe(III), Ni(II), Ru(III) and Pd(II) as their 4-(5-nitro-2-pyridylazo) resorcinol chelates by reversed-phase high performance liquid chromatography

This paper reports the separation and determination of Nb(V), V(V), Co(II), Fe(III), Ni(II), Ru(III) and Pd(II) by reversed-phase HPLC using the new reagent, 4-(5-nitro-2-pyridylazo) resorcinol (5-NO2-PAR) as a precolumn derivatization reagent. On a C18 column, the seven metal chelates can be separated quantitatively with methanol/water (52∶48, v/v) containing 15 mmol/l pH 5.0 acetate buffer and 10 mmol/l tetrabutylammonium bromide (TBA·Br). The detection limits for Nb(V), V(V), Co(II), Fe(III), Ni(II), Ru(III) and Pd(II) are 0.65 ppb, 0.94 ppb, 0.10 ppb, 0.15 ppb, 0.18 ppb, 3.02 ppb and 2.35 ppb, respectively when the ratio of signal to noise (S/N) is 3. This method is simple and rapid, and has been used in the analysis of rain and liquor with satisfactory results.

Determination of V(V), Nb(V) and Ta(V) as their 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol chelates by reversed-phase HPLC

This paper reports the separation and determination of V(V), Nb(V) and Ta(V) by RP-HPLC using 5-Br-PADAP as a precolumn derivatizing reagent. On C(18) column, the three metal chelates can be separated on a baseline in 9 min with the mobile phase of methanol-water (59:41, v/v) containing tartaric acid (0.2%) and acetate buffer (pH 3.5, 10 mM). The detection limits of V(V), Nb(V) and Ta(V) are 0.13 ppb, 0.22 ppb and 1.79 ppb, respectively when S/N is 3. This method is simple and rapid, and has been used in mineral analysis with satisfactory results.

Synthesis and analytical application of 2,6-dichloroarsenazo as a new chromogenic reagent for bismuth

Abstract A new sensitive chromogenic reagent, 2-(2-arsonophenylazo)-7-(2,6-dichlorophenylazo)-1,8-dihydroxynaphthalene-3,6-disulfonic acid (2,6-dichloroarsenazo), has been synthesized and used in the spectrophotometric determination of bismuth. In aqueous 0.6xa0molxa0l −1 HClO 4 , 2,6-dichloroarsenazo can react with bismuth(III) immediately at room temperature to form a deep blue complex with a maximum absorption at 631xa0nm. The apparent molar absorptivity ( ϵ ) is 9.87×10 4 xa0lxa0mol −1 xa0cm −1 . Beers law is obeyed over the bismuth concentration range 0–1xa0μgxa0ml −1 . Macroamounts of foreign ions do not interfere. The proposed method has been applied to the determination of bismuth in copper alloys without prior treatment.

Determination of V(V), Nb(V) and Ta(V) as their 2-(5-nitro-2-pyridylazo)-5-diethylaminophenol complexes by reversed-phase high performance liquid chromatography

A method for the reversed-phase liquid chromatographic separation and determination of V(V), Nb(V) and Ta(V) as 2-(5-nitro-2-pyridylazo)-5 diethylaminophenol (5-NO2-PADAP) complexes is reported. The metal complexes were eluted in 9 min with a mobile phase of methanol-water (54 : 46, v/v) containing 10 mmol L−1 acetate buffer (pH 3.0) on an ODS column. The detection limits for V, Nb and Ta were 0.09, 0.13 and 1.41 ng mL−1, respectively, with S/N=3. The analysis of a reference sample of a mineral is discussed. The results corresponded to the certified values, and recoveries of 98.3–101.4% have been obtained.

N-Hydroxysuccinimidyl-α-naphthylacetate as a derivatizing reagent for amino acids and oligopeptides in RP-HPLC

A new derivatizing reagent, N-hydroxysuccinimidyl-α-naphthylacetate (SINA), has been used as a precolumn derivatizing reagent for the separation and determination of amino acids (AAs) and oligopeptides with HPLC. The spectral properties of SINA derivatives with AAs and oligopeptides have been studied. The derivatization and separation conditions of SINA derivatives with most amino acids and some oligopeptides have been investigated. With spectrophotometric detection at 280 nm, the detection limits were in the range of 0.49–2.76 pmol; with fluorescence detection at λex/λem = 299/338 nm, the detection limits were in the range of 19–376 fmol when the ratio of signal to noise (S/N = 3) was 3.

Speciation of Thulium Porphyrin Complexes by Reversed‐Phase HPLC

Abstract Six new thulium porphyrin complexes have been separated by high performance liquid chromatography with triethanolamine (TEOLA) and acetic acid (HAc) as additives in the methanol–water mixture. The function of TEOLA and HAc has been described. The whole analysis was completed on a C18 column in 16 min at a flow rate of 0.5 mL min−1, with the mobile phase of methanol–water (93:7,v:v) containing 75 mmol L−1 TEOLA and 200 mmol L−1 HAc. The detection limits (S/N = 3) of thulium porphyrins at 420 nm were 1.0, 1.0, 1.0, 1.0, 5.0, and 5.0 ng mL−1, respectively. Compared with the methanol system, it can attain the equivalent separation with the mobile phase of ethanol–water (90:10,v:v) containing 25 mmol L−1 TEOLA and 200 mmol L−1 HAc pumped at 0.25 mL min−1.