Using 16O35CL to Correct for Chloride Interference Improves Accuracy of Urine Arsenic Determinations by Inductively Coupled Plasma Mass Spectrometry

Abstract

We have observed inaccurate urine arsenic values with the method of isobaric fractionation, which was designed to correct for the 40Ar35Cl interference with 75As quantitation by inductively coupled plasma mass spectrometry. Isobaric fractionation, which is based on ion intensities at m/z 77 and 82, consistently underestimates the 40Ar35Cl interference and overestimates urine arsenic. We present an improved method for identifying the argon-chloride interference. We observed that signal intensities for the species 16O35Cl and 40Ar35Cl are proportional (I75 = 0.0295 x I51 - 14.7, r2 = 0.998; where Ix is the normalized ion intensity at m/z X) in water and urine, over a broad range of chloride concentrations (0-800 mmol/L). The proportionality constant is remarkably stable within a run (mean and SD, 0.0295 +/- 0.0023, based on 10 replicates of five chloride calibrators, 0, 100, 200, 400, and 800 mmol/L). Increased sensitivity (50-fold) for detecting the 40Ar35Cl interference provides improved accuracy for urine arsenic quantitation as demonstrated by a split-sample comparison with graphite-furnace atomic absorption spectrophotometry.

Determination of the total arsenic concentration in human urine by inductively coupled plasma mass spectrometry: a comparison of the accuracy of three analytical methods

“…The proportionality constant for 40 Ar 35 Cl and 16 O 35 Cl was obtained by linear regression of normalized I 51 vs I 75 data using the above HCl solutions. 10 2. Addition of N 2 to nebulizer or plasma gas flow.…”

“…3,[6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] The methods they have used fall into three categories: (1) mathematical correction using another molecular ion formed under the same analytical conditions; [9][10][11] (2) addition of N 2 to plasma gas; 3,[12][13][14][15] and (3) addition of organic solvents to the calibration standards and samples. 6,[16][17][18][19] In an attempt to find the most accurate method for measuring As in urine samples by ICP-MS, a comparative study of three procedures developed by other workers was conducted: (1) the use of two different correction procedures (i.e., the formation of 40 Ar 37 Cl and the formation of 16 O 35 Cl molecular ion to estimate the contribution of 40 Ar 35 Cl at m/z 75); [9][10][11] (2) the addition of Ar-N 2 to plasma and nebulizer gas flow; 3,[12][13][14][15] and (3) the addition of ethanol 6 to the plasma along with the sample and the calibration standards. In addition, to improve the accuracy and precision of As determination, an internal standard to correct for instrument instability, sample introduction efficiency, and signal enhancement was sought.…”

Metals: common clinical applications in inductively coupled plasma mass spectrometry

“…Par exemple, ils sont capables de différencier le 56 Fe du complexe 40 Arg 16 O (interférence polyatomique) et de séparer le 58 Fe du 58 Ni (interférences isobariques). Ils associent un secteur électrostatique (filtre en énergie) et un secteur magnétique (filtre de masse) [15]. Le secteur électrostatique, constitué d'un condensateur cylindrique, dévie les ions en fonction de leur énergie cinétique.…”

Development of Analytical Method for Quantification of Trace Metallic Impurities in U-Mo AlloyEmploying Time-of-Flight-based ICP-MS

“…The instrument was optimized on a daily basis, and the stability of the plasma was studied after a 2-hour ignition of the plasma. Spectroscopic interferences due to isobaric atomic or polyatomic ions were corrected according to the reports (40,41). Considering the low concentration of REEs (present in the sub-ppm range) and no detectable Ba in the U-Mo alloy, the individual analyte intensities were only considered without applying any polyatomic interference correction.…”