Analysis of environmental chemical residues in products of emerging aquaculture industry in Uganda as case study for Sub-Saharan Africa

A study was conducted to analyse market-regulated heavy metals (lead, mercury and cadmium), organochlorine pesticides and total polychlorinated biphenyls (PCBs) in samples of 38 farmed fish comprising Nile tilapia (Oreochromis niloticus) (20 samples) and African catfish (Clarias gariepinus) (18 samples) from ten selected fish farms in Uganda. The goal of this case study was to understand the safety of aquaculture products from Sub-Saharan Africa. Lead was detected in all the 38 samples (maximum = 1.08 mg kg^?1 (dry weight)), mercury in 31 out of 38 samples (maximum = 0.35 mg kg^?1 (dry weight)), and cadmium in two samples (maximum = 0.03 mg kg^?1 (dry weight)). Total levels of PCBs were below the limit of detection of 0.02 mg kg^?1 (wet weight) in all the samples. Traces of 4,4′-dichloro-diphenyldichloroethylene (DDE) were detected in ten out of 38 samples (maximum = 0.01 mg kg^?1 (wet weight)) making it the most prevalent organochlorine pesticide. Other pesticides detected were: 4,4′-dichloro-diphenyl-trichloroethane (DDT) and endosulfan sulphate, which were found in one fish sample (both 0.002 mg kg^?1 (wet weight)). There was no statistically significant difference between the levels of lead and mercury in catfish and tilapia (t-test at p = 0.05). More catfish samples (eight) contained DDE as compared with tilapia (two). Cadmium, DDT and endosufan sulphate were only detected in catfish implying that catfish is more prone to contamination than tilapia. The levels of contaminants were below the US Food and Drug Administration (USFDA) action levels and European Union maximum residue limits (MRLs), indicating that such fish have the potential for export to these markets.     

Contamination of food samples from Malaysia with polychlorinated dibenzo-p-dioxins and dibenzofurans and estimation of human intake

A total of 126 food samples, categorised into three groups (seafood and seafood products, meat and meat products, as well as milk and dairy products) from Malaysia were analysed for polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). The concentration of PCDD/Fs that ranged from 0.16 to 0.25 pg WHO₀₅-TEQ g^?1 fw was found in these samples. According to the food consumption data from the Global Environment Monitoring System (GEMS) of the World Health Organization (WHO), the dietary exposures to PCDD/F from seafood and seafood products, meat and meat products, as well as milk and dairy products for the general population in Malaysia were 0.064, 0.183 and 0.736 pg WHO₀₅-TEQ kg^?1 bw day^?1, respectively. However, the exposure was higher in seafood and seafood products (0.415 pg WHO₀₅-TEQ kg^?1 bw day^?1) and meat and meat products (0.317 pg WHO₀₅-TEQ kg^?1 bw day^?1) when the data were estimated using the Malaysian food consumption statistics. The lower exposure was observed in dairy products with an estimation of 0.365 pg WHO₀₅-TEQ kg^?1 bw day^?1. Overall, these dietary exposure estimates were much lower than the tolerable daily intake (TDI) as recommended by WHO. Thus, it is suggested that the dietary exposure to PCDD/F does not represent a risk for human health in Malaysia.     

稻米中多氯联苯及多溴联苯醚残留及风险评估

通过分析稻米样品中指示型多氯联苯(PCBs)和12种代表性多溴联苯醚(PBDEs)的存留状况及含量水平,通过膳食风险评估,阐明PCBs和PBDEs在稻米中的安全风险。稻米样品粉碎后,采用直接提取法–酸性硅胶净化法对样品进行前处理,通过气相色谱–串联质谱法对其中7种指示型PCBs和12种代表性PBDEs进行同时检测。45个稻米样品中,PCBs的检出率为42%,合计含量水平在0～78pg/g干重之间,稻米中PCBs主要检出单体为PCB-28和PCB-52,特征符合我国多氯联苯的生产历史情况;仅在一个样品中检出PBDEs,合计含量为41 pg/g干重。稻米中的PCBs和PBDEs污染水平低,经过风险评估,其未造成稻米的食品安全风险。     

膜渗透蒸发/GC-MS测定纺织品中多氯联苯

采用膜渗透蒸发/气相色谱-质谱联用技术,建立了纺织品中多氯联苯的测定方法。优化的试验条件为料液浓度50~1 000 μg/L,温度43 ℃,Na2SO4含量0~1%,流速380 mL/min。本方法对目标化合物的检测限均低于0.03 mg/L,加标回收率在76.66%～118.71%,相对标准偏差小于12%。     

固相萃取-气相色谱法测定螺旋藻中指示性 多氯联苯

目的建立气相色谱法测定螺旋藻中痕量多氯联苯的分析方法,以考查螺旋藻中7种指示性多氯联苯(polychlorinated biphenyls,PCBs)的残留情况。方法乙腈提取样品后,选用弗罗里矽柱对螺旋藻中指示性多氯联苯净化。色谱条件为:DB-17(30 m×0.25 mm,0.25μm)石英毛细管柱,采用程序升温分离,流速为1.0m L/min,进样量为1.00μL,电子捕获检测器检测。结果在优化的条件下,7种指示性多氯联苯在10~50μg/L范围内线性良好,相关系数(r)大于0.999,在螺旋藻空白样品中添加25、35、45μg/kg 3个水平的7种指示性多氯联苯,其加标回收率范围为90.8%~112%,相对标准偏差(RSD)范围为0.526%~3.89%。结论该方法具有操作简便、快速、准确的特点,适用于螺旋藻试样中指示性多氯联苯痕量残留的分析。     

Methods for determining pesticides and polychlorinated biphenyls in food samples--problems and challenges

Determination of residual amounts of pesticides and polychlorinated biphenyls (PCBs) in food samples requires the use of specific techniques regarding sample preparation as well as instrumental analysis which should be characterized by a very low detection limit. A problem associated with the use of pesticides and PCBs is the need for controlling their residues in the environment, particularly in food, as these chemicals show a propensity to accumulate. The analysis of food samples for the presence of pesticides and PCBs brings on many difficulties because of the specificity of sample preparation consisting of multistep purification procedures of samples that contain trace amounts of an analyte. Concentration determinations of pollutants that easily dissolve in complex matrices, particularly in the presence of a large apportionment of interfering substances, pose a big challenge. Therefore, the basic step in food analysis for the presence of pesticides and PCBs is sample preparation which mainly consists of analyte enrichment and the removal of interfering substances. But all steps of the analytical procedure that include sample collection and preparation, extraction of analytes from matrix, extract purification, and final determination, are very significant; their precision and correct application have a decisive effect on the final result.     

Supercritical carbon dioxide extraction of polyunsaturated fatty acids from Northern shrimp (Pandalus borealis Kreyer) processing by-products

This study investigated the potential of Northern shrimp (Pandelus borealis Kreyer) by-products as a source of omega-3 polyunsaturated fatty acids (ω-3 PUFAs). The by-products (heads, shell and tail) of processing accounted for approximately 50–60% of the catch. Supercritical CO₂ extraction (SFE) of the by-products at 35 MPa and 40 °C generated a deep red oil, rich in ω-3 PUFAs, specifically 7.8 ± 0.06% eicosapentaenoic acid (EPA) and 8.0 ± 0.07 % docosahexaenoic acid (DHA).     

超声波提取-气相色谱法测定海产品中的多氯联苯

本研究探讨了影响超声波提取海产品中多氯联苯的因素,包括提取温度、时间、功率、液料比和层析条件。根据结果选择的优化超声波条件为：温度40℃,超声波功率540W,时间120min,液料比7:1;层析时淋洗液的起始收集体积为10ml,共收集10ml。样品中的多氯联苯用气相色谱法测定。在选定条件下,方法对多氯联苯的回收率在72.66%～91.56% 之间,平均值87.93%。研究还用样品对选定方法进行了验证,结果表明,本研究所建立的方法可行。     

云南省淡水湖泊鱼虾中多氯联苯食用安全性评估

目的对云南省5个淡水湖泊中鱼虾体内的多氯联苯(polychorinated biphenyl,PCBs)污染水平进行调查研究。方法采用气相色谱-质谱联用仪进行检测分析,根据检测结果对云南省淡水湖泊中的鱼虾体内多氯联苯的含量进行食用安全性评估。结果云南省淡水湖泊中鱼虾体内的多氯联苯检出率为90%,多氯联苯的含量范围为ND～1.16μg/kg,平均含量为0.27μg/kg,低于国家标准限量。云南省淡水湖泊中鱼虾体内的多氯联苯按照世界卫生组织(World Health Organization,WHO)规定的多氯联苯毒性当量(toxic equivalent quantity,TEQ)分布于ND～6.51×10~(-5)μg/kg,平均值为1.21×10~(-5)μg/kg,低于欧盟的行动标准限量。结论云南省居民从云南省淡水湖泊鱼虾体内摄入持久性有机污染物多氯联苯的剂量较低,引起的健康风险较低。