A new micromethod for colorimetric determination of zinc in serum

Concentrations of trace elements in human blood serum from different places in Norway determined by neutron activation analysis

The concentrations of As, Fe, Hg, Sb, Se and Zn in 281 serum samples from people living in nine municipalities in Norway were determined by radiochemical neutron activation analysis. The concentrations of Br, Cl, Cs, Na, Rb, Se and Zn were determined in another set of 157 serum samples from four of the municipalities by instrumental neutron activation analysis. Higher arsenic concentrations were found in the coastal districts than in inland municipalities; otherwise no significant difference in mean values was observed between the districts. Except for Na-Cl and Rb-Cs, none of the elements was significantly correlated with any other element studied.

A simple and sensitive colorimetric assay of zinc in serum using cationic porphyrin

A direct colorimetric method is presented for simple and sensitive determination of serum zinc in 0.05-ml samples, using a cationic porphyrin, alpha,beta,gamma,delta-tetrakis(4-N-trimethylaminophenyl) porphine tetratoluenesulfonate salt (ttmapp, epsilon = 41.5 x 10(4) l/mol per cm at 421 nm). 7-Iodo-8-hydroxyquinoline-5-sulfonic acid (Ferron) as an accelerator for the incorporation of zinc into ttmapp was most effective. Interference of iron, copper and conjugated bilirubin in serum can be eliminated in the presence of proteins such as albumin in serum. Within-run and between-run coefficients of variation (CV) were in the ranges of 0.76-3.59 and 2.08-5.20%. A good correlation was observed between this method and atomic absorption spectrometry (AAS).

A sensitive, direct colorimetric assay of serum zinc using nitro-PAPS and microwell plates

A direct colorimetric assay of zinc in 0.02-ml of serum using a new, water-soluble reagent, 2-(5-nitro-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)phenol disodium salt dihydrate (nitro-PAPS epsilon = 14.5 X 10(4) l/mol per cm at 574 nm), is presented. Use of microwell plates allowed a reduction in the sizes of samples and reagents without affecting the sensitivity or the precision. Zinc and interfering metal ions in serum are bound as cyanide complexes; the zinc ions are preferentially demasked by use of the chloral hydrate, permitting a colorimetric reaction with the chromogen. Within-run and between-run coefficients of variation (CV) were in the ranges of 1.6-2.3% and 1.8-5.2%. This method correlated well with atomic absorption spectrometry.

Evaluation of a commercially available kit for the colorimetric determination of zinc in human seminal plasma

A kit from Wako Pure Chemical Industries for colorimetric determination of zinc has been evaluated for its possible use in the determination of zinc in human seminal plasma. The within-assay variation for 15 replicates of each of two seminal plasma samples having zinc concentrations (mM) of 0.43 +/- 0.025 and 6.06 +/- 0.125 (mean +/- SD) was 5.7% and 2.1%, respectively. The between-assay variation after analysis of 15 replicates of a seminal plasma sample (zinc conc. 5.6 mM) on different days was 2.3%. No interference from other metal ions present in seminal plasma was observed. The average % recovery of zinc added to seminal plasma was 102.7 +/- 1.77 (mean +/- SD). A close correlation (r = 0.996, n = 105) was found between the levels of zinc determined by the colorimetric method and that determined by atomic absorption spectrophotometry as reference method. It is concluded that the present colorimetric method, which is fast, sensitive and linear over the entire concentration range of zinc present in human seminal plasma, can be recommended for use in semen analysis laboratories.

A highly sensitive colorimetric determination of serum zinc using water-soluble pyridylazo dye

A colorimetric method for precise and accurate determination of zinc in serum is presented. Only 0.3 ml of sample is necessary, because of the use of a new, highly sensitive reagent, 2-(5-bromo-2-pyridylazo)-5-(N-n-propyl-N-3-sulfopropylamino)-phenol (epsilon 554nm = 1.3 X 10(5) 1 . mol-1 . cm-1), which is water-soluble and has long-term stability. Interference of iron and copper in serum can be removed by co-precipitation of the iron fluoride complex with trichloroacetic acid precipitated proteins and the copper dithiocarboxy sarcosine complex, respectively. Within-run and day-to-day precision (CV) are in the range of 0.3-3.5% and 1.9-3.1%, respectively, depending on the serum zinc content. A good correlation (r = 0.98, p less than 0.05) was obtained between this method and atomic absorption spectrometry. In contrast to previous colorimetric methods, the present method does not involve heating, extraction with organic solvents, or a cyanide masking system.