Determination of Ultratrace Levels of Lead in Infant Formula by Isotope Dilution Inductively Coupled Plasma Mass Spectrometry

1993 ◽  
Vol 76 (6) ◽  
pp. 1378-1384 ◽  
Author(s):  
Joseph J Thompson
Keyword(s):  
Mass Spectrometry ◽  
Infant Formula ◽  
Reference Materials ◽  
Isotope Dilution ◽  
Inductively Coupled Plasma ◽  
Standard Reference Materials ◽  
Inductively Coupled ◽  
Relative Standard ◽  
Plasma Mass Spectrometry

Abstract A simple method was developed for the accurate and precise determination of low- and sub-ppb (ng/g) concentrations of lead in infant formula by isotope dilution inductively coupled plasma mass spectrometry using ultrasonic nebulization. After addition of a known amount of 207Pb, samples were microwave digested and the ratio 207Pb/208Pb was measured in the digests. Agreement with certified values for lead in milk powder standard reference materials was good, and isotope dilution analysis using 206Pb yielded identical results for the standard reference materials. Lead concentrations determined for several infant nutritional products were verified by an independent method. Typically, relative standard deviations of <4% were obtained with this method for lead concentrations above 2 ppb. The recovery of 2 ng of lead from an aqueous standard carried through the microwave digestion was 104 ± 4%. Infant formula (containing 0.6 ppb lead) to which 0.4 ng of natural-abundance lead had been added, to simulate a formula containing 0.9 ppb lead, was analyzed by isotope dilution, and the result was 96 ± 18% of the theoretical value. Thus, differences of 0.3 ppb lead could be clearly distinguished, and the detection limit was estimated to be 0.1 ng lead per gram of infant formula. The keys to accuracy for this method are minimizing contamination and accurately determining the concentration of lead in the isotopically enriched standard.

scholarly journals Determination of Metals in Composite Diet Samples by Inductively Coupled Plasma-Mass Spectrometry

2003 ◽  
Vol 86 (2) ◽  
pp. 439-448 ◽  
Author(s):  
Lisa Jo Melnyk ◽  
Jeffrey N Morgan ◽  
Reshan Fernando ◽  
Edo D Pellizzari ◽  
Olujide Akinbo
Keyword(s):  
Mass Spectrometry ◽  
Atmospheric Pressure ◽  
Inductively Coupled Plasma ◽  
Microwave Digestion ◽  
Standard Reference Materials ◽  
Inductively Coupled ◽  
Icp Ms ◽  
Relative Standard ◽  
Plasma Mass Spectrometry

Abstract A study was conducted to evaluate the applicability of inductively coupled plasma-mass spectrometry (ICP-MS) techniques for determination of metals in composite diets. Aluminum, cadmium, chromium, copper, lead, manganese, nickel, vanadium, and zinc were determined by this method. Atmospheric pressure microwave digestion was used to solubilize analytes in homogenized composite diet samples, and this procedure was followed by ICP-MS analysis. Recovery of certified elements from standard reference materials ranged from 92 to 119% with relative standard deviations (RSDs) of 0.4–1.9%. Recovery of elements from fortified composite diet samples ranged from 75 to 129% with RSDs of 0–11.3%. Limits of detection ranged from 1 to 1700 ng/g; high values were due to significant amounts of certain elements naturally present in composite diets. Results of this study demonstrate that low-resolution quadrupole-based ICP-MS provides precise and accurate measurements of the elements tested in composite diet samples.

Simultaneous Determination of Arsenic, Cadmium, Mercury, and Lead in Raw Ingredients, Nutritional Products, and Infant Formula by Inductively Coupled Plasma Mass Spectrometry: Single-Laboratory Validation

2016 ◽  
Vol 99 (3) ◽  
pp. 766-775 ◽  
Author(s):  
Lawrence H Pacquette ◽  
Anil Anumula
Keyword(s):  
Mass Spectrometry ◽  
Infant Formula ◽  
Inductively Coupled Plasma ◽  
Control Sample ◽  
Standard Reference Materials ◽  
Inductively Coupled ◽  
Icp Ms ◽  
Validation Parameters ◽  
Plasma Mass Spectrometry

Abstract A method was developed for the determination of As, Cd, Hg, and Pb in raw ingredients, nutritional products, and infant formula using inductively coupled plasma mass spectrometry (ICP-MS). Three raw ingredients (acid casein, maltodextrin, skim milk powder) and three standard reference materials [NIST 1548a (Typical Diet), NIST 1577c (Bovine Liver), NIST SRM 1568b (Rice Flour)] obtained from the National Institute of Standards and Technology were analyzed by two analysts using two ICP-MS instruments in different laboratories. NIST SRM 1568b was used as the control sample. All protocol validation parameters (intermediate precision, accuracy, linearity, quantitation limit, specificity, and robustness) were met. The overall precision (n = 8) for analyte concentrations (2.5–300 ng/g) ranged from 2 to 14% RSD. Spike recoveries ranged from 88 to109% for spike levels between 25 and 200%. The overall average concentration of As, Cd, Hg, and Pb measured in all three NIST SRMs were within the certified value ranges. Good linearity (correlation coefficient (r) = 0.9995 or better) was obtained for all analytes. Control chart results for 8 independent days showed that the method is robust (precision values of 10% and all points within ±3 σ were obtained). Excellent specificity was also demonstrated when the analytes were measured in the presence of high concentrations of the other concomitants.

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