Jewellery and precious metals. Determination of gold. Cupellation method (fire assay)

2021 ◽  
Keyword(s):  
Precious Metals ◽  
Fire Assay

scholarly journals KAJI ULANG SNI 13-3487-2005 BARANG – BARANG EMAS DAN SNI 13-3771-1995 BARANG – BARANG EMAS MUDA

2021 ◽  
Vol 23 (1) ◽  
pp. 1
Author(s):  
Joni Setiawan ◽  
Euis Laela ◽  
Istihanah Nurul Eskani ◽  
Nikmah Widiharini ◽  
Farida Farida ◽  
...  
Keyword(s):  
Difference Method ◽  
Precious Metals ◽  
Icp Oes ◽  
Fire Assay ◽  
Purposive Sampling ◽  
Fine Gold ◽  
Gold Platinum

<p>Emas merupakan logam mulia yang dapat dijadikan investasi karena nilainya terus naik dari waktu ke waktu. Barang – barang emas dapat berbentuk batangan, granula, lembaran, perhiasan dan benda seni. Penjaminan mutu kadar emas diatur dalam SNI 13-3487-2005 Barang – barang emas dan SNI 13-3771-1995 Barang – barang emas muda. Pada saat ini emas yang beredar memiliki kadar mulai 3,33% hingga 99,99% (<em>fine gold</em>). Terdapat nilai kadar emas yang belum diatur dalam ke-dua SNI tersebut yaitu barang-barang emas dengan kadar 13,14,15,dan 16 karat. Sehingga perlu dilakukan pengujian untuk melihat kesesuaian kadar emas yang terkandung dalam barang – barang emas yang beredar di pasaran serta peninjauan kembali terhadap metode uji yang ada. Penelitian ini membahas hasil kaji ulang SNI 13-3487-2005 Barang – barang emas dan SNI 13-3771-1995 Barang – barang emas muda sebagai dasar penyusunan SNI barang – barang emas yang baru. Metode penelitian yang dilakukan adalah studi literatur, pengujian sampel barang – barang emas yang beredar yang diambil secara <em>purposive sampling</em>, kemudian dilakukan pengujian <em>fire assay</em> sesuai dengan SNI 13-3487-2005 Barang – barang emas dan ICP-OES sesuai dengan ISO  15093, <em>Jewellery — Determination of precious metals in 999 0 / 00 gold, platinum and palladium jewellery alloys</em> — <em>Difference method using ICP-OES</em>, kajian metode uji, dan penggalian informasi melalui rapat internal, rapat teknis dan rapat konsensus. Berdasarkan pembahasan maka dapat disimpulkan bahwa perlunya penggabungan dua SNI tersebut mencakup kadar 33,3% hingga 99,99%, menetapkan metode uji yang dipergunakan yaitu <em>fire assay</em> dan ICP-OES, dengan acuan normatif yang dipergunakan adalah standar ISO 11596 dan ISO 15039.</p>

Fire-Assay Emission Spectrographic Method for Platinum, Palladium, Rhodium, and Gold

1970 ◽  
Vol 24 (2) ◽  
pp. 225-228 ◽  
Author(s):  
A. B. Whitehead ◽  
H. H. Heady
Keyword(s):  
Coefficient Of Variation ◽  
Precious Metals ◽  
Matrix Elements ◽  
Graphite Electrodes ◽  
Internal Standards ◽  
Fire Assay ◽  
The Matrix ◽  
Spectrographic Method ◽  
Intensity Ratios

A method has been developed for the determination of microgram levels of Pt, Pd, Rh, and Au. A 10-mg Ag bead containing the precious metals, as extracted by fire assaying, is arced at 8 A dc in graphite electrodes in the presence of 10 mg of either Rh or Pt metal powder. The matrix elements, Ag and Pt, or Rh, serve as internal standards, and intensity ratios Pt/Rh or Rh/Pt, Pd/Rh, and Au/Ag are determined. Precision of the method is about ±5% coefficient of variation for Pt and Rh, ±15% for Pd, and ±19% for Au. Limits of detection are below 1 μg, giving analysis limits (for a 1-assay-ton sample) of about 1–30 ppb for these precious metals.

scholarly journals The determination of the content of gold and silver in geological samples

2001 ◽  
Vol 66 (1) ◽  
pp. 45-52 ◽  
Author(s):  
N. Petrovic ◽  
D. Budjelan ◽  
S. Cokic ◽  
B. Nesic
Keyword(s):  
Graphite Furnace ◽  
Precious Metals ◽  
Atomic Absorption Spectrophotometry ◽  
Assay Method ◽  
Determination Limit ◽  
Geological Samples ◽  
Aqua Regia ◽  
Fire Assay ◽  
Content Of Gold

Amethod has been elaborated for the determination of the content of gold and silver in geological samples by atomic absorption spectrophotometry (AAS) in combination with the fire assay method. The weight of sample used for analysis was 10 g. Sulphur present as sulphide, which is an undesirable element in smelting, was removed by the addition of iron to the charge. The sample was smelted with fluxes and lead oxide to replace the silver and gold by lead and to transfer non-precious elements to slag. Lead was separated from precious metals by cupellation. The separated silver and gold alloy was dissolved with aqua regia with addition of hydrochloric acid in excess. Silver and gold were determined from the same solution. For determination of the silver content, the AAS method with an air-acetylene flamewas used. Goldwas determined in a graphite furnace with the addition of a matrix modifier in an argon current, at an atomization temperature of t = 2200 ?C. The lower determination limit for silver was 0.05 g/t and for gold 0.005 g/t. The results of the analysis for silver and gold obtained with the proposed method showed good agreement with the results of the analysis of the same samples with the fire assay method.

Simultaneous determination of ultra-trace Pt, Pd, Rh and Ir in geochemical samples by inductively coupled plasma mass spectrometry following tin fire assay preconcentration and microwave digestion

2020 ◽  
Vol 16 ◽  
Author(s):  
Wenshan Ni ◽  
Xiangju Mao ◽  
Hongli Zhang ◽  
Lu Liu ◽  
Xiaorui Guo ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Nickel Oxide ◽  
Inductively Coupled Plasma ◽  
Lead Oxide ◽  
Microwave Digestion ◽  
Fire Assay ◽  
Inductively Coupled ◽  
Plasma Mass Spectrometry ◽  
Ultra Trace

Background: Platinum (Pt), palladium (Pd), rhodium (Rh) and iridium (Ir) are platinum group elements (PGEs) and also important elements of geochemistry and environmental chemistry with the similar physic-chemical properties, which have been widely used in industry and laboratory. However, due to the low abundance and inhomogeneous distribution in natural ore as well as the nugget effect, the accurate determination of PGEs has been a challenge to analytical chemistry. Methods: In this work, a novel fire assay method was reported for the determination of ultra-trace Pt, Pd, Rh and Ir in geochemical samples. Tin powder (Sn) instead of stannic oxide (SnO2) was used as fire assay collector to reduce the melting temperature from 1250 oC to 1050 oC, the escape of molten material caused by high temperature was successfully avoided. Tin bead was compressed into thin slice and dissolved by HCl. For the target Pt, Pd, Rh and Ir, HCl insoluble substance such as PtSn4, PdSn4, RhSn4 and Ir3Sn7 were formed and separated from matrix by filtering. The metal compounds precipitate together with filter paper were microwave-assisted completely digested by aqua regia (50%, v/v), thence the sample solution were determined by inductively coupled plasma mass spectrometry (ICP-MS). Results: Compared with nickel oxide and lead oxide in nickel sulfide /lead fire assay, the reagent blank of tin powder were relatively low and could be directly employed in tin fire assay to collect Pt, Pd, Rh and Ir without purifying. Moreover, the harm of nickel oxide and lead oxide to the analyst and environment was avoided by using the non-toxic tin powder. The decomposition method of chromite and black shale were investigated as well as the amount of tin powder and flour, microwave digestion program for the determination of Pt, Pd, Rh and Ir were optimized. Besides, the influence of mass spectrum interference of co-existing elements was discussed and the standard mode and kinetic energy discrimination collision pool mode were compared. Under the optimal conditions, excellent curve fitting of Pt, Pd, Rh and Ir were obtained between 0.01～100 ng mL-1 , with the correlation coefficients exceeding 0.9996. The detection limits were from 0.003 ng g -1 to 0.057 ng g -1 . Conclusion: The developed method was applied to analyze the Chinese Certified Reference Materials and the determined values were in good agreement with the certified values.

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