Zinc Concentrate, CZn-4

APPLICATION NOTE

SUMMARY

The application note summarizes the digestion of CZn-4, a zinc concentrate certified reference material using ColdBlock Digestion Pro Series Technology.

Instrument:	ColdBlock CBM Pro-Series, chiller, HF liners, ICP-OES
Published:	May 2025
Digestion Time:	30 Minutes
Acid Used:	HNO₃, HCl, HF & H₃BO₃
Average ColdBlock Recovery vs. CRM:	102% lead 96% silver 101% zinc

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METHODOLOGY

Set the chiller temperature to -5°C.
Weigh 0.25 g of each sample and transfer into a ColdBlock Digestion vessel with liner
Add 20 mL of aqua regia (add HNO3 first, followed by HCl) and 3 mL of HF to each vessel.
Digest samples at 80% power for 20 minutes.
Add 20 mL of 4% boric acid (w/v) to each sample.
Digest samples again at 80% power for 10 minutes.
Cool the samples and adjust the volume to 50 mL with DI water

DISCUSSION

The addition of boric acid aids in the re-solubilization of insoluble fluorides and neutralizes residual hydrofluoric acid (HF). This step is crucial for sample dissolution and minimizing analyte loss during digestion.
Following the digestion process, the samples were visibly clear – indicating that the sample matrix had dissolved. A trace amount of material settled on the bottom of the tube

Figure 1- CZn-4 after bulking-up to 50mL

Results

CZn-4, Zinc Concentrate
Method:	0.25g – Add 20mL aqua regia + 3mL HF and digest at 80% power for 20 minutes. Add 20mL of 4% boric acid w/v and digest again at 80% power for 10 minutes. Let cool, and adjust the volume to 50mL with DI water
Element	CZn-4 Certified Values	ColdBlock Average n=5	ColdBlock Stdev +/–	ColdBlock RSD	ColdBlock Recovery vs Certified Value
Ag (µg/g)	51.4	49.1	1.5	3.1%	96%
Al (%)	0.0715	0.0740	0.0030	4.1%	103%
As (%)	0.0356	0.0342	0.0007	2.0%	96%
Cd (%)	0.2604	0.2713	0.004	1.3%	104%
Co (µg/g)	93.5	99.3	1.6	1.6%	106%
Cu (%)	0.403	0.4032	0.005	1.2%	100%
Pb (%)	0.1861	0.1898	0.0025	1.3%	102%
Fe (%)	9.02	9.03	0.08	0.9%	100%
S (%)	33.07	32.36	0.82	2.5%	98%
Se (µg/g)	86.7	83.8	4.7	5.6%	97%
Zn (%)	55.24	55.83	0.81	1.5%	101%

Click here to download the Application Note in PDF format.

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