Noneffervescent Method for Catalysis-Based Palladium Detection with Color or Fluorescence

Abstract

Palladium is a highly valuable metal in automobile, chemical, and pharmaceutical industries. The metal is generally quantified by atomic absorption spectrometry or inductively coupled plasma mass spectrometry. These techniques are tedious and require expensive instruments that are operated mostly off site. As cost-effective and user-friendly alternatives to these techniques, we previously reported two practical fluorometric or colorimetric methods to quantify palladium. Both methods rely on the use of NaBH, which cannot be stored in solution for more than 10 days. Commercially available solutions of NaBH are partially or fully degraded to di- or triborohydride species and cannot be used for palladium(0)-catalyzed allylic C-O bond cleavage for quantification purposes. Here, we report a new method that replaces NaBH with NHNH for the palladium-catalyzed deallylation of fluorogenic and colorimetric chemodosimeter resorufin allyl ether. This method is slower but as sensitive as the most recent method from our laboratory. The method is selective for palladium and depends on the presence of tri(2-furyl)phosphine as a palladium ligand and NHNH as a palladium-reducing reagent.

Catalysis-Based Fluorometric Method for Trace Palladium Detection with Improved Convenience

“…27,30 RAE may be more convenient than allyl Pittsburgh Green ether because the RAE method provides both colorimetric and fluorometric measurements and visualization. We previously published three variants with RAE, 27,31,35 and the first-generation method has been routinely practiced at Merck Research Laboratories. These methods had shortcomings: first, sodium borohydride in aqueous sodium hydroxide (Figure 1b) is difficult to use.…”

“…Second, when we replaced sodium borohydride with hydrazine, the buffer salt was ammonium acetate (Figure 1c), but this buffer salt does not efficiently neutralize acids in API samples. 31 Third, replacing sodium borohydride with hydrazine substantially retarded the deallylation reaction, making the technique less sensitive. In the current communication, we describe the fourth-generation technology with RAE to quantify palladium, which overcomes some of these disadvantages (Figure 1d).…”

Direct fluorogenic detection of palladium and platinum organometallic complexes with proteins and nucleic acids in polyacrylamide gels

“…We have tested several reactions conditions based on previously published results. These included sodium borohydride (NaBH 4 ) 16 and hydrazine (NH 2 NH 2 ) 7 as the reducing agents in 20% acetonitrile (MeCN), dimethyl sulfoxide (DMSO), dimethylformamide (DMF), and in pure water. The use of triphenylphosphine (TPP) 9 resulted in fluorescent artefacts and was therefore excluded from further experiments.…”

“…Majority of chemical sensors for the detection of noble metals utilizes their catalytic properties 6 with Pd sensors often based on allyl or propargyl carbamates, carbonates, or ethers of phenolic fluorophores [6][7][8][9][10] . The fluorescent activation of the probes is based on the Tsuji-Trost allylic oxidative insertion mechanism 11 .…”

Multistimuli-Responsive Self-Healable and Moldable Nickel(II)-Based Gels for Reversible Gas Adsorption and Palladium Sequestration via Gel-to-Gel Transformation

“…Residual Pd is often found in the final product after reaction causing potential health hazards . Sensors based on fluorescent materials and mercapto-based precipitating reagents are mostly used to detect and remove Pd, aside from the use of expensive instruments such as atomic absorption spectroscopy, X-ray fluorescence, and so on. , Many precipitants that bind to Cu 2+ are also known to bind to Pd 2+ . The gels discussed in this work are stable in most common organic media and would find applicability in the detection and removal of Pd ions from organic solvents.…”