Radioactive Source Localisation via Projective Linear Reconstruction.

Radiation mapping, through the detection of ionising gamma-ray emissions, is an important technique used across the nuclear industry to characterise environments over a range of length scales. In complex scenarios, the precise localisation and activity of radiological sources becomes difficult to determine due to the inability to directly image gamma photon emissions. This is a result of the potentially unknown number of sources combined with uncertainties associated with the source-detector separation-causing an apparent 'blurring' of the as-detected radiation field relative to the true distribution. Accurate delimitation of distinct sources is important for decommissioning, waste processing, and homeland security. Therefore, methods for estimating the precise, 'true' solution from radiation mapping measurements are required. Herein is presented a computational method of enhanced radiological source localisation from scanning survey measurements conducted with a robotic arm. The procedure uses an experimentally derived Detector Response Function (DRF) to perform a randomised-Kaczmarz deconvolution from robotically acquired radiation field measurements. The performance of the process is assessed on radiation maps obtained from a series of emulated waste processing scenarios. The results demonstrate a Projective Linear Reconstruction (PLR) algorithm can successfully locate a series of point sources to within 2 cm of the true locations, corresponding to resolution enhancements of between 5× and 10×.

Radiation Mapping and Laser Profiling Using a Robotic Manipulator.

The use of a robotic arm manipulator as a platform for coincident radiation mapping and laser profiling of radioactive sources on a flat surface is investigated in this work. A combined scanning head, integrating a micro-gamma spectrometer and Time of Flight (ToF) sensor were moved in a raster scan pattern across the surface, autonomously undertaken by the robot arm over a 600 × 260 mm survey area. A series of radioactive sources of different emission intensities were scanned in different configurations to test the accuracy and sensitivity of the system. We demonstrate that in each test configuration the system was able to generate a centimeter accurate 3D model complete with an overlaid radiation map detailing the emitted radiation intensity and the corrected surface dose rate.

Determination of Unsulfonated Aromatic Amines in FD&C Yellow No. 5 and FD&C Yellow No. 6 by Liquid Chromatography-Triple Quadrupole Mass Spectrometry.

Background: This paper describes a simple and sensitive ultra-HPLC-triple quadrupole MS (LC-MS/MS) method for the determination of six unsulfonated aromatic amines in the color additives FD&C Yellow No. 5 (Y5) and FD&C Yellow No. 6 (Y6). The six amines determined by this method are aniline (ANL), benzidine (BNZ), 4-aminobiphenyl (4ABP), 4-aminoazobenzene (4AAB), 2-aminobiphenyl (2ABP), and 4-aminobenzonitrile (4ABN). Objective: This method is intended for use in batch certification of the color additives by the U.S. Food and Drug Administration (FDA) to ensure that each lot meets published specifications for coloring foods, drugs, and cosmetics. Methods: A modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) procedure is used for extraction of the amines. Quantitative determination was performed in electrospray positive ionization and multiple-reaction monitoring modes. Results: Validation of the method demonstrated overall recovery of 101-115% and precision of 1.74-9.78% for all analytes. Excellent regression coefficients were obtained, with values >0.999. Conclusions: The validated method was successfully used for the analyses of 30 Y5 and Y6 samples and provided results that are consistent with results from the current method used by FDA, with greater sensitivity and low matrix effects. Highlights: The validation results demonstrate that the new LC-MS/MS method is applicable for use in routine batch certification.

Conventional high-performance liquid chromatography versus derivative spectrophotometry for the determination of 1,3,6-pyrenetrisulfonic acid trisodium salt and 1,3,6,8-pyrenetetrasulfonic acid tetrasodium salt in the color additive D&C Green No. 8 (Pyranine).

Specifications in the U.S. Code of Federal Regulations for the color additive D&C Green No. 8 (Colour Index No. 59040) limit the levels of the subsidiary colors 1,3,6-pyrenetrisulfonic acid trisodium salt (P3S) and 1,3,6,8-pyrenetetrasulfonic acid tetrasodium salt (P4S). The present paper describes a comparative study of two possible methods to replace the currently used multi-step TLC/spectrophotometry method of separating and quantifying the minor components P3S and P4S in G8. One of the new approaches uses conventional high-performance liquid chromatography (HPLC) and the other, derivative spectrophotometry. While the derivative spectrophotometric method was shown to be inadequate for the analysis of minor components overwhelmed by components of much higher concentration, the HPLC method was proven highly effective. The closely related, very polar compounds P3S and P4S were separated by the new HPLC method in less than 4 min using a conventional HPLC instrument. P3S and P4S were quantified by using five-point calibration curves with data points that ranged from 0.45 to 7.63% and from 0.13 to 1.82%, by weight, for P3S and P4S, respectively. The HPLC method was applied to the analysis of test portions from 20 batches of D&C Green No. 8 submitted to the U.S. Food and Drug Administration for certification.