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Monitoring Metals Hypersensitivity by Measuring Chromium, Cobalt and Molybdenum

in Whole BloodElzbieta (Ela) Bakowska, Judy Vinosky and Michael Welsh

NMS Labs, Willow Grove, Pennsylvania, USA

There are many challenges associated with measurements of Cr, Co and Mo in whole blood: individual patients variability, contamination issues and analytical instruments’ complexities.Cobalt and chromium blood levels can change depending on physical condition of the patient, working environment, individual feeding and metabolism.The normal range for Chromium in blood is listed as 0.5 - 5 mcg/L, for Cobalt in blood is 0.5-3.9 mcg/L, and for Molybdenum in blood is below 3 mcg/L. Dealing with such low levels in biological materials presents additional challenges.Use of non-certified for trace element analysis collection tubes may cause contamination. The contamination control during the specimens’ preparation and analysis required additional attention. The samples preparation and analyses were performed in a clean-room environment.Agilent 7500ce ICP-MS was used for the determination of Cobalt and Molybdenum. In order to further minimize the contamination, the standard nebulizer system was replaced with 100% PFA cross-flow nebulizer from Savillex.Determination of Molybdenum at very low levels is additionally complicated by the potential of carry-over from measuring of a specimen with elevated levels. It was established that a rinse time of up to 10 minutes was required to minimize the carry-over issue. This would negatively affect the productivity, if the sample-to-sample analysis time will be approximately 12 minutes, this would allow only 5 samples to be analyzed within 1 hour.

•http://www.medichecks.com/test.cfm?test=MELI\“Handbook on Metals in Clinical and Analytical Chemistry”, H.G. Seiler, A. Sigel and H. Sigel, Eds.“Metals-derivatized Major Metals Histocompatibility Complex: Zeroing in on Contact Hypersensitivity”, J. Loh and J. Fraser, The Journal of Experimental Medicine, Vol. 197, No.5, March 3, 2003, pp.349-552“The release of metals from metal-on-metal surface arthroplasty of the hip”, I. Iavicoli et al., Journal of Trace Elements in Medicine and Biology, Vol. 20, No.1, (2006), pp..25-31

Molybdenum Precision within run: 5.2 – 9.2% Accuracy within run: +/- 12% Precision between runs: 8.0 – 10%

Cobalt Precision within run: 0.9 – 4.9% Accuracy within run: +/- 12% Precision between runs: 2.2 – 7.0%

Chromium Precision within run: 4.4 – 5.9% Accuracy within run: +/- 11% Precision between runs: 3.5 – 7.0%

INTRODUCTION

Sample Preparation

INSTRUMENTATION

METHODOLOGY

Results

REFERENCES

For determination of Cobalt and Molybdenum by ICP-MS sample was diluted For determination of Cobalt and Molybdenum by ICP-MS sample was diluted 1:20 with Internal standard solution and analyzed against aqueous calibrators. 1:20 with Internal standard solution and analyzed against aqueous calibrators. For determination of Chromium by GFAAS the samples were diluted 1:2 with For determination of Chromium by GFAAS the samples were diluted 1:2 with 0.2% Triton-X and analyzed against matrix-matched calibrators. 0.2% Triton-X and analyzed against matrix-matched calibrators. For matrix-matching blood of non-diabetics was utilized.For matrix-matching blood of non-diabetics was utilized.

Metal hypersensitivity is commonly reported in the literature and can include hypersensitivity related to pacemakers, dental implants and orthopedic hardware. Up to 13% of people are reported to be sensitive to nickel, cobalt, or chromium.Some patients who have undergone an orthopedic joint replacement, are monitored for Chromium, Cobalt and Molybdenum levels in blood.

•To include Chromium in ICP-MS panel•To include additional analytes (Ni, V, Mn) in the panel

Instrumentation - 1Agilent 7500ce Inductively Coupled Plasma Mass Spectrometry, CETAC ASX-510 Autosampler, Savillex cross-flow Nebulizer

The Agilent’s 7500ce ICP-MS software provided the “intelligent rinse” option. This option involved monitoring of the Molybdenum’s signal during the rinse cycle and comparing it with a pre-set threshold value. As a result, the rinse time was reduced down to 3 minutes for most of the samples.At a systemic level, chronic trace metal release could potentially cause adverse clinical effects.The developed methods facilitate monitoring of metals (especially Chromium, Cobalt and Molybdenum) in the patients with arthroplasties.The analytical protocols were developed to approximate GLP environment.

CONCLUSIONS

Challenges and Solutions

Chromium by GFAASWavelength: 357.9 nm, peakSlit Width: 0.7 nm, lowMeasurement: Peak areaCuvette: THGA tube/platform with endcapsInjection volume: 20 mcL sample; 10mcL modifierSample-to-sample: ~3 min/single injection

Future Work

Instrumentation - 2Perkin-Elmer AAnalyst 600 Atomic Absorption Spectrometer with AS-800 Autosampler, THGA Furnace,

Cobalt/Molybdenum by ICP-MSCones: NickelCell: OffIntelligent rise: OnSample-to-sample: ~3 min/triple measurement