www.nuclmed.gr Hellenic Journal of Nuclear Medicine • January - April 2009 59 Murat Fani Bozkurt, Pınar Özgen Kiratli, Deniz Konyali, Fatma Metin Hacettepe University School of Medicine Department of Nuclear Medicine, Ankara, Turkey ✬✬✬ Keywords: 99m Tc - MAG3 - Quali- ty control - Chromatography - Thin layer chromatography - In- stant TLC Correspondence address: Murat Fani Bozkurt, M.D Hacettepe University School of Medicine Department of Nuclear Medicine, Sihhiye 06100 Ankara, Turkey e-mail: fanibozkurt@yahoo.com fanibozkurt@gmail.com Tel: +90 312 305 1336 GSM: +90 532 492 48 90 Fax: +90 312 309 35 08 Received: 09 November 2008 Accepted revised: 10 January 2009 Technical Note Quality control of instant kit 99m Tc-mercapto acetyl triglycine with inter- and intra-operator measurements Abstract This prospective study was aimed to assess inter- and intra-operator variability during routine quality control (QC) procedure for technetium-99m mercaptoacetyl triglycine ( 99m Tc-MAG3) instant kit for- mulation. A total of 160 QC analyses with thin layer chromatography (TLC) for 20 separate MAG3 re- constitutions were performed by 2 radiochemists. The percentage of free and hydrolysed 99m Tc as well as binding efficiency, were calculated according to standard TLC. Each QC analysis was done us- ing silica gel (SG), silica acrylic (SA), Whatman 1 (W1) and Whatman 3 (W3) TLC strips separately at 1h, following labeling MAG3 instant kit with 99m Tc-pertechnetate. To assess the radiochemical stability of 99m Tc-MAG3, the same analysis was performed 4h after kit reconstitution. Visual confirmation for QC with scintigraphy was also performed. At both time points, each radio-chemist repeated all the pro- cedure twice for each of the TLC paper types to analyze the intra-operator reliability. Crombach’s Test was used for the reliability analysis. High inter-operator correlation ratios (range: 0.821-0.920) per each TLC strip were found where the highest concordance rate was 0.921 for SA. Each TLC strip showed adequate kit reconstitution with acceptable free and hydrolysed 99m Tc percentages both at 1 and 4 h analyses, along with high binding efficiency values of 94.3 ± 2.9 and 92.5 ± 1.9 at 1 and 4 h respectively. Intra-observers reliability showed almost equal high concordance rates (range: 0.888-0.961) for all types of strips. In conclusion, all kinds of ITLC/TLC strips were reliable to assess sta- bility of the radiopharmaceutical at 1 and 4 h while analysis with the SA strip had the highest concor - dence rate. Inter- and intra-operator QC was also reliable. Hell J Nucl Med 2009; 12(1): 59-62 • Published on line: 24 January 2009 Introduction R adiochemical purity of the radiopharmaceuticals is defined as the proportion of the total radioactivity in the sample associated with desired radiolabeled species. Radio- chemical impurities may alter the biodistribution of the radiopharmaceuticals which may result to a distortion in the scintigraphic image leading to major diagnostic and thera- peutic failures. For this reason, a radiochemical purity ratio of 95% or above is desired for most of the diagnostic radiopharmaceuticals [1, 2]. In order to assess radiochemical purity, some physicochemical separation methods should be used. Paper chromatography, thin layer chromatography (TLC) and high performance thin layer chromatography are the major types of planar chromatography. All techniques share the same property of having a sample applied to a stationary medium with an appropriate mobile phase. Among many methods that have been used so far, planar chromatography is the most preferred and easily applied method for its advantage of quantification [1-5]. In order to increase the migration speed of the mobile phase, instant TLC (ITLC) materials have been produced and have gained wide acceptance throughout the world. These are composed of glass fibre web impregnated with the modified silica stationary phases, known as silica gel (ITLC-SG) and silicic acid (ITLC-SA). Many different mobile phase such as acetone, 0.9% saline, water and support/stationary phases for both ITLC-SA and ITLC-SG have been recommended for each radiopharmaceutical [2, 3]. Whatman No.1 (W1) and Whatman 3mm (W3) are the most suitable general purpose chromatography papers which are widely used in routine practice. 99m Tc-mercaptoacetyltriglycine ( 99m Tc-MAG3) is one of the most common renal radiop- harmaceuticals which has been in routine nuclear medicine practice since 1986 [6]. 99m Tc- MAG3 provides major advantages over 99m Tc-diethylen triamine pentaacetic acid ( 99m Tc-DT- PA) in renal imaging especially in patients with decreased renal function and with immature glomerular function, such as infants [7]. The correct interpretation of renal function with 99m Tc-MAG3 depends on the stability and ideal biodistribution of the radiopharmaceutical