GB/T 22930.2-2021Leather and fur - Chemical determination of metal content - Part 2: Total metal content (English PDF)

1 Scope

This document describes the test methods for the total contents of 24 metals: aluminum (Al), arsenic (As), barium (Ba), calcium (Ca), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), potassium (K), magnesium (Mg), sodium (Na), lead (Pb), manganese (Mn), molybdenum (Mo), nickel (Ni), mercury (Hg), antimony (Sb), selenium (Se), silicon (Si), tin (Sn), titanium (Ti), zinc (Zn) and zirconium (Zr).

This document is applicable to the determination of the total contents of 24 metals in various types of leather and fur, as well as the determination of non-metallic boron (B) content.

This document does not apply to the determination of total chromium content in chrome-tanned leather.

NOTE: for the determination of total chromium content in chrome-tanned leather, see QB/T 2720,

QB/T 5313, QB/T 5314 or QB/T 5315.

2 Normative References

The contents of the following documents constitute indispensable clauses of this document through the normative references in the text. In terms of references with a specified date, only versions with a specified date are applicable to this document. In terms of references without a specified date, the latest version (including all the modifications) is applicable to this document.

GB/T 6682 Water for Analytical Laboratory Use - Specification and Test Methods (GB/T 6682-2008, ISO 3696:1987, MOD)

GB/T 39364 Leather - Chemical, Physical, Mechanical and Fastness Tests - Sampling Location (GB/T 39364-2020, ISO 2418:2017, MOD)

QB/T 1267 Fur - Chemical, Physical and Mechanical and Fastness Tests - Sampling Location (QB/T 1267-2012, ISO 2418:2002, MOD)

QB/T 1272 Leather - Chemical Tests - Preparation of Chemical Test Samples (QB/T 1272-2012,

ISO 4044:2008, MOD)

QB/T 1273 Fur - Chemical Tests - Determination of Volatile Matter (QB/T 1273-2012, ISO 4684:2005, MOD)

QB/T 1276 Fur - Chemical Tests - Determination of Matter Soluble in Carbon Tetrachloride (QB/T 1276-2012, ISO 4048:2008, MOD)

QB/T 2716 Leather - Preparation of Chemical Test Samples (QB/T 2716-2018, ISO 4044:2008, MOD)

QB/T 2717 Leather - Chemical Tests - Determination of Volatile (QB/T 2717-2018, ISO 4684:2005, MOD)

QB/T 2718 Leather - Chemical Tests - Determination of Matter Soluble in Dichloromethane (QB/T 2718-2018, ISO 4048:2008, MOD)

3 Terms and Definitions

This document does not have terms or definitions that need to be defined.

4 Principle

Leather or fur specimen is completely digested by tribasic acid mixture (acid digestion method)

or microwave digestion apparatus (microwave digestion method). Use water to dissolve the residue, then, adopt the inductively coupled plasma optical emission spectrometer (ICP-OES), inductively coupled plasma mass spectrometer (ICP-MS), atomic absorption spectrometer (AAS) or atomic fluorescence spectrometer (AFS) to determine the metal concentration;

calculate the total metal content in the specimen.

NOTE: this document determines the total contents of metal elements in leather and fur, not the content of metal in a specific compound or oxidation state.

5 Reagents and Materials

Appendix C (Normative) Preparation of Standard Solution and Standard Working Solution of Elements to be

Tested C.1 Overall Requirements In accordance with different ranges of determination, different element standard solutions may be required. Under general circumstances, when preparing a multi-element mixed standard solution, pay attention to its chemical compatibility and possible hydrolysis of its components, so as to prevent chemical reactions (for example, precipitation) and spectral interference. In order to avoid interference, digestion reagents (such as: nitric acid, sulfuric acid and aqua regia, etc.) may be added to the mixed standard solution.

The formulations provided below also take into account the different sensitivities of different spectrometers.

The multi-element mixed standard solution usually has a shelf life of several months when stored in the dark.

NOTE: since Ba and B may precipitate under certain circumstances, it is recommended to prepare a single-element standard solution for the determination (see C.2.3 and C.2.4).

C.2 Preparation of Metal Element Standard Solution C.2.1 Multi-element mixed standard solution A  (Al, Cd, Co, Cr, Cu, Fe, Pb, Mn, Mo, Ni, Si, Zn, Zr) = 1 mg/L.

Transfer about 250 mL of water (5.8) to a 1,000 mL volumetric flask (6.14); add 5 mL of nitric acid (5.2); accurately transfer-take 1 mL of the metal element (Al, Cd, Co, Cr, Cu, Fe, Pb, Mn, Mo, Ni, Si, Zn, Zr) standard stock solution (5.6) to the 1,000 mL volumetric flask (6.14). Use water (5.8) to dilute to a constant volume to the scale, then, transfer into a suitable storage bottle.

C.2.2 Multi-element mixed standard solution B  (Sn, Ti, As, Se, Sb) = 10 mg/L.

Transfer about 250 mL of water (5.8) to a 1,000 mL volumetric flask (6.14); add 5 mL of hydrochloric acid (5.7); accurately transfer-take 10 mL of the metal element (Sn, Ti, As, Se, Sb)

standard stock solution (5.6) into the volumetric flask (6.14). Use water (5.8) to dilute to a constant volume to the scale, then, transfer into a suitable storage bottle.

C.2.3 Barium standard solution C  (Ba) = 0.1 mg/L.

Transfer about 250 mL of water (5.8) to a 1,000 mL volumetric flask (6.14); add 5 mL of nitric acid (5.2); accurately transfer-take 0.1 mL of the metal element (Ba) standard stock solution (5.6) to the volumetric flask. Use water (5.8) to dilute to a constant volume to the scale, then, transfer into a suitable storage bottle.

C.2.4 Boron standard solution D  (B) = 10 mg/L.

Transfer about 250 mL of water (5.8) to a 1,000 mL volumetric flask (6.14); add 5 mL of nitric acid (5.2); accurately transfer-take 10 mL of boron (B) standard stock solution (with a concentration of 1,000 mg/L) to the volumetric flask. Use water (5.8) to dilute to a constant volume to the scale.

NOTE: there will be an obvious loss of boron element during the sample injection process, which may lead to relatively high results after multiple tests; in order to avoid the residual boron element in the sample injection system, the concentration of the boron element standard solution should be as low as possible.

C.2.5 Mercury standard solution E  (Hg) = 1 mg/L.

Accurately transfer-take 1 mL of the metal element (Hg) standard stock solution (5.6) to a 1,000 mL volumetric flask (6.14); add 5 mL of nitric acid (5.2). Use water (5.8) to dilute to a constant volume to the scale, then, transfer into a suitable storage bottle.

C.2.6 Multi-element mixed standard solution F  (Ca, Mg, Na, K) = 100 mg/L.

Accurately transfer-take 100 mL of the metal element (Ca, Mg, Na, K) standard stock solution (5.6) to a 1,000 mL volumetric flask (6.14); add 5 mL of nitric acid (5.2). Use water (5.8) to dilute to a constant volume to the scale, then, transfer into a suitable storage bottle.

C.3 Preparation of Metal Element Standard Working Solution In accordance with the actual demands, dilute the metal element standard solution (C.2) step-by-step to prepare the metal element standard working solution with a series of concentrations.

The shelf life of the standard working solution with concentrations below 1 mg/L and 100 g/L respectively should not exceed 1 month and 1 day.

Example: respectively transfer-take 200 L, 400 L, 600 L, 800 L and 1,000 L of the multi-element mixed standard solution A (C.2.1) in a 100 mL volumetric flask; add the same amount of acid as in the specimen digestion solution. After cooling (if necessary), use water (5.8) to dilute to a constant volume; prepare the metal element standard working