Sensitive reversed-phase liquid chromatographic determination of fluoride based on its ternary systems with zirconium(IV) or hafnium(IV) and 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol

Abstract

Optimum conditions for the direct reversed-phase LC determination of fluoride based on the ternary M-(F-)-(5-Br-PADAP) complexes [M = ZrIV or HfIV and 5-Br-PADAP = 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol] were evaluated. Chromatographic separation was performed with C18 end-capped column with an eluent consisting of acetonitrile-water (85 + 15 v/v) mixture of pH 4.0 +/- 0.3 (flow rate 1 ml min-1), and the eluate was monitored spectrophotometrically at lambda max = 585 nm. The calibration curves were linear over a wide range of fluoride concentrations: from 1 to 110 and 150 ng ml-1 for the ZrIV-(F-)-(5-Br-PADAP) and HfIV-(F-)-(5-Br-PADAP) systems, respectively (using a 20 microliters loop). Under such conditions the detection limits were 0.8 and 0.7 ng ml-1, respectively, and the quantification limit is 1.0 ng ml-1 for both methods. When a 100 microliters loop was used, the limits of both detection and quantification in the method based on the zirconium system were 0.2 ng ml-1. Using the proposed method, fluoride was determined directly in tap water, saliva and an anti-cancer agent for prostatic cancer (Leuprolid).

Determination of fluoride as fluorosilane derivative using reversed‐phase HPLC with UV detection for determination of total organic fluorine

“…Although reported RP‐HPLC methods of fluoride determination 33, 34 present lower values of LOD, they suffer from poor complex stability, impeding measurements of large batches of samples 34, and require strict control over pH of analyzed samples, difficult to carry out for small sample volume 33 and highly alkaline solution – a consequence of using SBP reagent.…”

“…Considering that HPLC equipment is a standard apparatus found in most analytical laboratories, the developed method of TOF determination can be thought of as an easily accessible alternative to other instrumental methods. Fluoride derivatization procedure consists of a simple mixing of solutions and does not require precise pH adjustment, as in the previously published RP‐HPLC methods 33, 34. The product of the derivatization is more stable over time, allowing simultaneous preparation of numerous samples for automated analyses, easily achievable with conventional HPLC equipment.…”

“…Derivatization procedures are straightforward; however, the complexation reactions must be conducted at tightly controlled environment with the reaction yields very sensitive to small pH changes. In addition, the reaction products are not stable for longer than 24 h 33 and 2 h 34.…”

“…HPLC with RP mode columns and UV detection is a foundation of many analytical methods in contemporary routine and research laboratories. It is somewhat surprising that only a few articles could be found describing application of RP‐HPLC in the determination of fluoride 33, 34. Both cited methods achieved the same LOD of 0.2 ppb and are based on the formation of a ternary complex between fluoride and metal–dye complex.…”

Spectrophotometric Research Into Multi-Ligand Complexes Formed by Zirconium (Iv) With Stilbazole and Cetylpyridinium Chloride

“…Examples of various spectro-analytical methods include the molecular fluorescence spectrophotometry [1], atomic absorption spectroscopy [2], laser ablation inductively coupled plasma optical emission spectrometry [3], spectrophotometric method [4,5], solid phase extraction and spectrophotometric determination [6,7], plasma atomic emission spectrophotometric determination [8], inductively coupled plasma atomic emission spectroscopy [9], UV-Vis spectrophotometry [10,11] and flotation-spectrophotometric method [12]. Moreover, work was done to separate zirconium from mixtures with hafnium and for analytical determination [13][14][15][16][17].…”