Spectrophotometric determination of trimethylamine-nitrogen in cadaver tissues for the estimation of late postmortem interval: A pilot study

Abstract

To study the relationship between the late postmortem interval (PMI) and trimethylamine-nitrogen (TMA-N) in postmortem tissues of cadaver, TMA-N in muscles, livers and kidneys of rats was measured at different postmortem intervals (PMI) by using a modified spectrophotometric method. The results indicated that the detection sensitivity of TMA-N was 1 mg/L, and there was a good linear correlation between the value of absorbance (A value) and TMA-N at the concentration of 1–10 mg/L (R² = 0.9991). Although TMA variation in muscles was different from that in inner organs during the time since death, TMA-N changes in cadaver tissues was positively correlated with PMI. During 2 to 7 d since death, the best correlation between PMI and TMA-N concentration was found in muscles. With PMI as an independent variable, the cubic polynomial regression equation was y= −0.457x³+6.519x²−24.574x+27.207 (R²=0.969). During 3 to 8 days since death, PMI was best correlated with TMA-N concentration in inner organs. With PMI as the independent variable, the cubic polynomial regression equation was y=0.509x³−9.153x²+55.727x−95.819 (R²=0.953). It was concluded that TMA-N in tissues could be used as a new estimator for late PMI. The method used in this study offered advantages such as accuracy, sensitivity, little samples required and wide PMI estimation.

Keywords

forensic medicine / postmortem interval / spectrophotometry / trimethylamine-nitrogen / spoilage product

References

[1] HenssgeC., MadeaB.. Estimation of the time since death in the early post-mortem period. Forensic Sci Int, 2004, 144(2–3): 167-175

[2] WolratH., StåhlbomB., HallenA., et al.. Trimethylamine and trimethylamine oxide levels in normal women and women with bacterial vaginosis reflect a local metabolism in vaginal secretion as compared to urine. APMIS, 2005, 113: 513-516

[3] Barrett E L, Kwan H S. Bacterial reduction of trimethylamine oxide. Annu Rev Microbiol, 1985(39):131–149

[4] WongK., GillT. A.. Enzymatic determination of trimethylamine and its relationship to fish quality. J Food Sci, 1987, 52(6): 1-3

[5] LiX. M., ZhongA. G.. Detection of Trimethyl amine in ambient air by gas chromatography. Chin J Spectrosc Lab (Chinese), 2006, 23(2): 353-355

[6] DyerW. J.. Amines in fish muscle. I. Colorimetric determination of trimethylamine as the picrate salt. J Fish Res Board Can, 1945, 6: 351-358

[7] State Standard of the People’s Republic of China. Determination of Trimethylamine Nitrogen in Ham. GB/T 5009.179-2003

[8] XuL. F., YuF. L., HuZ. Y., et al.. Amendment of Method for Determination of Trimethylamine Nitrogen in Ham. Prey Med Trib, 2005, 11(6): 641-643

[9] HaoL. G., DengS. X., ZhaoX. C.. Recent advancement in relationship between DNA degradation and postmortem interval. Fa Yi Xue Za Zhi (Chinese), 2007, 23(2): 145-147

[10] FinehoutE. J., FranckZ., RelkinN., et al.. Proteomic analysis of cerebrospinal fluid changes related to postmortem interval. Clin Chem, 2006, 52(10): 1906-1913

[11] SinghD., PrashadR., SharmaS. K.. Estimation of postmortem interval from human pericardial fluid electrolytes concentrations in Chandigarh zone of India: log transformed linear regression model. Leg Med (Tokyo), 2006, 8(5): 279-287

[12] GongZ. Q., ZengX. B., SunY. G., et al.. Study on the relationship between PMI and the concentration of 21 elements in vitreous humor of rabbit after death. Fa Yi Xue Za Zhi (Chinese), 2005, 18(2): 67-69

[13] LuoG. H., ChenY. C., ChengJ. D., et al.. Relationship between DNA degradation and postmortem interval of corrupt corpse. Fa Yi Xue Za Zhi (Chinese), 2006, 22(1): 7-9

[14] HenssgeC., KnightB., KrompecherT., et al.. The estimation of the time since death in the early postmortem period, 1995, London, Edward Arnold: 106-137

[15] Bocaz-BeneventiG., TagliaroF., BortolottiF., et al.. Capillary zone electrophoresis and artificial neural networks for estimation of the post-mortem interval (PMI) using electrolytes measurements in human vitreous humour. Int J Legal Med, 2002, 116(1): 5-11