Trace elements are defined simply as those elements which (individually) make up no more than 0·01% of the dry weight of the body. Some, like lead, are non-essential but others are required for normal health, function and development. Both essential and non-essential elements can be toxic if present in tissues and fluids in unusually large concentrations. Evidence to determine whether or not an element is truly essential is incomplete in some instances but Cotzias' criteria for defining an element as essential are:

https://journals.sagepub.com/doi/pdf/10.1177/000456329603300603

Detection and Monitoring of Disorders of Essential Trace Elements

A multi-element ion-pair extraction method was described for the preconcentration of Cd(II), Co(II), Cr(III), Cu(II), Fe(III), Mn(II), Ni(II), Pb(II), and Zn(II) ions in environmental samples prior to their determinations by flame atomic absorption spectrometry (FAAS). As an ion-pair ligand 2-(4-methoxybenzoyl)-N 0 -benzylidene-3-(4-methoxyphenyl)-3-oxo-Nphenyl-propono hydrazide (MBMP) was used. Some analytical parameters such as pH of sample solution, amount of MBMP, shaking time, sample volume, and type of counter ion were investigated to establish optimum experimental conditions. No interferences due to major components and some metal ions of the samples were observed. The detection limits of the proposed method were found in the range of 0.33‐0.9 mgL � 1 for the analyte ions. Recoveries were found to be higher than 95% and the relative standard deviation (RSD) was less than 4%. The accuracy of the procedure was estimated by analyzing the two certified reference materials, LGC6019 river water and RTC-CRM044 soil.Thedevelopedmethod wasappliedtoseveral matricessuchaswater,hair,andfood samples.

A Multi‐Element Ion‐Pair Extraction for Trace Metals Determination in Environmental Samples

Spectrofluorimetric determination of zinc using 8-hydroxy-7-(4-sulfo-1-naphthylazo)-5-quinoline sulfonic acid.

A new method for the spectrofluorimetric determination of zinc with 1,2,4-Trihydroxyanthraquinone in a 80:20 (v/v) ethylene glycol/water medium and at an apparent pH 8.87 provided by an ammonia/ammonium chloride buffer (pH = 9.30) is proposed. The method allows the determination of zinc over the range 50–500 ng/ml and features a detection limit of 2.31 ng/ml. The influence of various chemical and physical variables affecting the reaction was evaluated and the effects of potential major interferences with the method are commented on. The proposed method has been successfully applied to the determination of zinc in several pharmaceutical preparations.

Spectrofluorimetric Determination of Zinc with 1,2,4-trihydroxyanthraquinone in Pharmaceutical Preparations

Spectrofluorimetric determination of Zn2+ ions in aqueous medium using 5-(4-flourophenyl)-quinolin-8-ol

An ICP-AES method for the determination of nickel subtraces after extraction of the metal into methyl isobutyl ketone(MIBK) containing 1,5-bis-(di-2-pyridylmethylene)thiocarbonohydrazide is suggested. The complex formed is quite soluble in MIBK, so that the determination of concentrations down to 15 times lower than those by the direct non-extractive method is possible. In addition, the extraction step enhances the selectivity. The described method was applied to the determination of nickel in various biological materials, such as red cabbage, algae, liver, kidney, brain and urine.

Determination of nickel in biological samples by inductively coupled plasma spectrometry after extraction with 1,5-bis(di-2-pyridylmethylene)thiocarbonohydrazide

Sensitive spectrofluorimetric determination of zinc at ultra-trace levels

An ultra-trace method based on the reaction of zinc with salicylcarbohydrazone (SACH) and Triton-X as non-ionic surfactant was developed for the fluorimetric determination of zinc present at picogram amounts. The yellow fluorescent complex is formed over a wide optimum pH range of 3.6–5. 2, in 60% ethanol medium. The detection limit is 10pg/ml, and the range of determination is 30 – 1000 pg/ml in solution. The relative standard deviations are: ±2.42% (30 – 100 pg/ml), ±1.83% (100 pg/ml – 1 ng/ml), ±0.89% (1 – 10 ng/ml), ±0.46% (10 – 100 ng/ml) and ±0.26% (100 – 1000 ng/ml). The effect of the interferences was studied and the procedure is simple, rapid and selective.

The use of triton-X for the enhancement of the fluorescence of Zn-salicylcarbohydrazone chelate and its application to zinc determination at ultratrace (part per trillion) level

A. K. Chakrabarti

Papers

Determination of nickel in biological samples by inductively coupled plasma spectrometry after extraction with 1,5-bis(di-2-pyridylmethylene)thiocarbonohydrazide

Sensitive spectrofluorimetric determination of zinc at ultra-trace levels

The use of triton-X for the enhancement of the fluorescence of Zn-salicylcarbohydrazone chelate and its application to zinc determination at ultratrace (part per trillion) level