HPLC-MS/MS法测定大鼠血浆中盐酸维拉帕米的血药浓度及其药动学研究

目的 建立HPLC-MS/MS法以测定大鼠血浆中盐酸维拉帕米的血药浓度,并考察其药动学特征。方法 采用ZORBAX Eclipse Plus C₁₈色谱柱（100 mm×2.1 mm,3.5 μm）,流动相为A相0.1%甲酸水,B相乙腈,梯度洗脱;体积流量为0.3 mL/min,柱温为30℃,进样量为5 μL。离子源为电喷雾离子源（ESI）,以多反应离子监测（MRM）进行正离子检测。盐酸维拉帕米监测离子对为m/z 455.3→m/z 165.0,内标地西泮监测离子对为m/z 285.0→m/z 154.1。6只SD大鼠在ig盐酸维拉帕米33.33 mg/kg后,对其进行药动学的研究。结果 盐酸维拉帕米在5~2 000 ng/mL显示线性关系良好;日内日间精密度（RSD）为1.3%~2.0%,准确度（RE）范围为0.1%~18.0%;提取回收率是90.87%~92.42%,基质效应为82.82%~101.99%。盐酸维拉帕米在大鼠体内主要药动学参数C_max、t_max、t_1/2、Ke、AUC_（0-tn）和AUC_（0-∞）分别为（922.1±300.4）ng/mL、（0.54±0.25）h、（6.46±3.18）h、（0.13±0.05）1/h、（7 634.1±4 436.6）h· ng/mL和（10 548.1±8 024.8）h· ng/mL。结论 该方法灵敏度高、专属性强,适用于测定大鼠血浆中盐酸维拉帕米的血药浓度及其药动学研究。     

UHPLC-MS/MS测定人血浆中4种一线抗癫痫药物浓度及其临床应用

目的 建立对人血浆中丙戊酸钠、卡马西平、拉莫三嗪和左乙拉西坦浓度测定的超高效液相-串联质谱方法，并进行临床实际运用。方法 血浆样本甲醇沉淀蛋白后，采用Waters Acquity UPLC BEH C₁₈色谱柱(100 mm×2.1 mm，1.7 μm)，流动相为0.1%甲酸水-乙腈，梯度洗脱，进样1 µL。选择正负离子同时监测模式分析，卡马西平、左乙拉西坦、拉莫三嗪、丙戊酸钠、替硝唑(内标)MRM通道分别为m/z 236.9→193.9，m/z 171.0→154.2，m/z 256.0→145.0，m/z 143.1→143.1，m/z 248.1→120.9；去簇电压和碰撞电压分别为70 V/21 V，90 V/10 V，90 V/23 V，–50 V/–10 V，90 V/42 V。结果 血浆样本中各代谢物丙戊酸钠(线性范围20~150 µg·mL^-1)、卡马西平(线性范围2~15 µg·mL^-1)、拉莫三嗪(线性范围0.5~15 µg·mL^-1)、左乙拉西坦(线性范围2~60 µg·mL^-1)在该方法下呈良好的线性关系，r²>0.997，血浆样品中各待测物的精密度与准确度试验均符合要求(RSD<6.7%，−12.9%<准确度<10.5%)。共收集77例2021年1月—2021年6月临床癫痫患者服药后血浆进行药物浓度检测分析，丙戊酸钠、卡马西平、拉莫三嗪和左乙拉西坦浓度治疗窗合格率分别是69.57%，70.00%，87.50%和36.11%。结论 本方法适用于临床上大样本量分析，为临床医技部门治疗药物浓度检测提供了一个便捷、可靠、科学的检测手段。     

盐酸苯海拉明咖啡因复方在大鼠体内的药动学研究

目的 建立UPLC-MS/MS方法测定大鼠血浆中盐酸苯海拉明与咖啡因的浓度,用于药动学研究。方法 色谱柱为ACE 3 C₁₈-PFP（3.0 mm×150 mm,3 μm）,流动相系统采用0.1%甲酸水溶液-乙腈（62∶38,V/V）,等度洗脱;质谱采用AJS-ESI离子源,正离子模式,多重反应监测（MRM）,盐酸苯海拉明256.2.0→167.0（m/z）,盐酸苯海拉明-D6（IS）262.0→167.0（m/z）,咖啡因 195.0→138.0（m/z）,内标咖啡因-D9（IS）204.0→116.2（m/z）。结果 大鼠血浆中盐酸苯海拉明在1～1×10³ ng/ml范围内线性关系良好（r=0.999 6）,定量下限1 ng/ml;咖啡因在15～1.5×10⁵ ng/ml范围内线性关系良好（r=0.999 9）,定量下限15 ng/ml。盐酸苯海拉明和咖啡因低、中、高3个浓度水平的日内和日间精密度和准确度均良好（RSD<10%,RE<±10%）。药动学研究结果显示,灌胃给予盐酸苯海拉明10～30 mg/kg和咖啡因24～72 mg/kg后,药动学参数呈线性代谢动力学特征;同时两种成分在大鼠体内代谢存在性别差异,雌性大鼠灌胃给药后,体内盐酸苯海拉明及咖啡因的达峰浓度（c_max）及药时曲线下面积（AUC）均大于雄性。结论 该方法准确、快速且灵敏度高,能准确检测大鼠血浆样品中的盐酸苯海拉明和咖啡因的浓度用于药动学研究,大鼠体内药动学研究结果为该复方的临床应用提供了可靠的数据支持。     

UHPLC-MS/MS同时检测大鼠血浆中5种CYP450探针药物

目的 采用UHPLC-MS/MS同时检测大鼠血浆中非那西丁、甲苯磺丁脲、奥美拉唑、美托洛尔、咪达唑仑的血药浓度。方法 血浆样品经乙腈沉淀,采用Agilent ZORBAX Eclipse Plus C₁₈色谱柱（2.1 mm×50 mm,1.8 μm）;流动相为乙腈-含0.1%甲酸的水,梯度洗脱,流速为0.4 mL·min^-1。检测采用电喷雾离子源,多反应监测。非那西丁：[M+H]⁺,m/z 180.1→109.9;甲苯磺丁脲：[M+H]⁺,m/z 271.1→91.0;奥美拉唑：[M+H]⁺,m/z 346.1→135.9;美托洛尔：[M+H]⁺,m/z 268.2→115.0;咪达唑仑：[M+H]⁺,m/z 326.1→290.8;内标卡马西平：[M+H]⁺,m/z 237.1→194.0。6只♂ SD大鼠,单剂量口服灌胃10 mg·kg^-1非那西丁,1 mg·kg^-1甲苯磺丁脲,10 mg·kg^-1奥美拉唑,10 mg·kg^-1美托洛尔和10 mg·kg^-1咪达唑仑,分别在给药后多点尾静脉采血。用DAS计算药动学参数。结果 血浆中非那西丁、甲苯磺丁脲、奥美拉唑、美托洛尔和咪达唑仑在各自浓度范围内线性关系良好。日内及日间RSD均<15%,提取回收率>75%,稳定性考察结果良好。非那西丁的AUC_0-t为（5 868.30±2 062.87）ng·mL^-1·h;甲苯磺丁脲的AUC_0-t为（58 056.34±15 569.16）ng·mL^-1·h;奥美拉唑的AUC_0-t为（14 181.67±4 085.40）ng·mL^-1·h;美托洛尔的AUC_0-t为（1 123.67±180.469）ng·mL^-1·h;咪达唑仑的AUC_0-t为（946.91±322.03）ng·mL^-1·h。结论 该方法灵敏度高、操作方便、结果准确,可作为CYP450酶活性及相关研究的测定方法。     

UPLC-MS/MS检测大鼠血浆中阿帕替尼的浓度及其药动学研究

目的 采用UPLC-MS/MS建立快速检测大鼠血浆中阿帕替尼浓度的方法,并应用于药动学研究。方法 大鼠血浆样本用乙腈沉淀蛋白,液质联用技术检测浓度,流动相为乙腈-水（含0.1%甲酸）,梯度洗脱,流速为0.3 mL·min^-1,柱温40℃,内标为氯唑沙宗;质谱条件：电喷雾离子化源（ESI）,负离子监测模式,检测离子对阿帕替尼为m/z 396.2→210.0和m/z 396.2→158.0,氯唑沙宗m/z 168.0→132.0。结果 阿帕替尼和内标氯唑沙宗的保留时间分别为1.07 min和1.40 min,线性范围为10~2 000 ng·mL^-1（r²=0.993）,检测限为1 ng·mL^-1,准确度为90.65%~111.50%,基质效应为89.14%~104.65%,平均回收率>86%,日内、日间精密度RSD均<10%。常温下放置24 h、冻融2次和-80℃冻存30 d的RSD均<10%。药动学研究结果显示,大鼠单次灌胃阿帕替尼76.5 mg·kg^-1,AUC_（0-t）为（6 114.41±645.99）ng·mL^-1·h,CL_z/F为（12.21±1.08）L·h^-1·kg^-1,V_z/F为（75.70±38）L·kg^-1,T_1/2为（4.23±1.94）h,T_max为（2±0.71）h,C_max为（1 377.7±284.54）μg·L^-1。结论 该法操作简便,重复性好,准确可靠,适用于大鼠血浆中阿帕替尼的浓度检测及其药动学研究。     

LC-MS/MS法分析人血浆中利培酮浓度及健康人体的药动学研究

目的 建立一种简便、灵敏的液相串联质谱（LC-MS/MS）法测定人血浆中利培酮的浓度,并应用于健康人体的药动学研究。方法 血浆样品经乙腈沉淀蛋白后,使用ZORBAX Eclipse XDB-C₁₈ （50 mm×4.6 mm,5 μm）色谱柱分离,以60%乙腈-40%甲醇、0.1%甲酸-5%乙腈-10 mmol/L乙酸铵水溶液作为流动相,梯度洗脱;在电喷雾离子化源（ESI）正离子检测条件下,采用多反应离子监测模式（MRM）对利培酮及内标利培酮-d4进行定量分析,检测离子对分别为m/z 411.3→191.2、m/z 415.3→195.2;进行专属性、系统适用性、准确度、精密度、基质效应、提取回收率、稳定性等方法学验证;8名健康成年受试者（无脱落）空腹单次口服利培酮片1 mg后,分别于给药前0 h和给药后10、20、30、45 min,1.00、1.25、1.50、2.00、3.00、4.00、5.00、6.00、8.00、12.00、16.00、24.00、36.00、48.00 h采集血样至含有肝素钠的抗凝管中,分离血浆样品,进行LC-MS/MS分析。结果 建立的LC-MS/MS法专属性良好,系统适用性良好,内标与待测物之间不存在交叉影响,人血浆中利培酮的线性范围为0.1～20.0 ng/mL,定量下限（LLOQ）为0.1 ng/mL,利培酮在空腹血浆、餐后血浆及溶血血浆中经内标归一化的基质效应分别为0.991～1.00、1.00～1.01和0.994～0.999,利培酮在人血浆中的平均提取回收率为96.8%～99.7%,准确度、精密度以及稳定性等均符合有关要求。健康受试者单次口服利培酮片1 mg后,主要药动学参数t_max、C_max、AUC_0~t、t_1/2分别为（0.969±0.248）h、（7.83±2.24）ng/mL、（25.5±12.0）h·ng/mL、（3.31±1.74）h。结论 建立的LC-MS/MS法前处理简便快速,灵敏度高,满足生物分析的法规要求,可应用于利培酮在健康人体中的药动学研究。     

帕唑帕尼在大鼠体内药动学研究

目的 建立大鼠血浆中检测帕唑帕尼的超高效液相色谱-质谱（UPLC-MS）的方法,研究帕唑帕尼在大鼠体内的药动学过程。方法 大鼠血浆样品用乙腈沉淀后检测。采用Acquity U-HPLC BEH C₁₈柱为分离柱,流动相采用乙腈-0.1%甲酸体系,梯度洗脱;采用AB Sciex QTRAP 5500三重四级杆质谱仪（电喷雾离子源）进行质谱检测,帕唑帕尼和内标地西泮采用多反应监测（MRM）的方法检测,帕唑帕尼和内标地西泮（ISTD）的MRM分别为m/z 438.3→357.2 和 m/z 285.2→193.1;雄性SD大鼠6只,灌胃给予80 mg/kg 帕唑帕尼,在给药前和给药后的不同时间点于大鼠尾静脉取血。用建立的方法测定血浆中帕唑帕尼的浓度。用DAS 3.0计算主要药动学参数。结果 大鼠血浆中帕唑帕尼浓度在0.25~40.00 μg/ml范围内线性关系良好（r=0.999 2）;低、中、高3个质量浓度（0.50、10.00、30.00 μg/ml）的日内精密度RSD分别为6.17%、2.73%和2.54 %,日间精密度RSD分别为7.56%、5.98%和2.84%,回收率分别为（78.4±4.8）%、（85.9±3.5）%和（81.1±4.2）%,基质效应分别为（106.7±5.3）%、（101.3±6.7）%和（97.6±4.4）%;血浆帕唑帕尼的主要药动学参数：峰值浓度c_max为（20.22±1.95）μg/ml,达峰时间t_max为（1.75±0.76）h,半衰期t_1/2为（7.35±2.31）h,药-时曲线下面积AUC_0-t为（213.16±39.92）μg·h/L,AUC_0-∞为（215.79±39.84）μg·h/L,表观分布容积Vd为（4.10±1.78）L/kg,清除率CL为（0.38±0.07）L/h。用房室模型拟合,帕唑帕尼在大鼠体内呈一级消除的二室模型。结论 本研究建立用UPLC-MS检测大鼠血浆帕唑帕尼的方法,专属性高,分离完全,检测时间短;适合帕唑帕尼的药动学和药物相互作用研究。     

HPLC-MS/MS测定大鼠血浆中普萘洛尔的含量及其药动学研究

目的 建立大鼠血浆中普萘洛尔的高效液相色谱-质谱联用（HPLC-MS/MS）定量分析方法,考察大鼠口服给药后,普萘洛尔在其体内的药动学特征。方法 血浆样品用甲醇沉淀蛋白法处理后,以盐酸美西律为内标,采用LC-MS/MS分析方法,测定大鼠血浆中普萘洛尔的浓度。色谱柱为ZORBAX Eclipse Plus C₁₈柱（2.1 mm×100 mm,3.5 μm）,流动相为0.1%甲酸水溶液-乙腈（70：30）等度洗脱;采用ESI离子源,正离子模式,多反应离子监测（MRM）m/z 260.2→116.2（普萘洛尔）和m/z 180.2→58.2（内标盐酸美西律）。结果 普萘洛尔在5~1 000 ng·mL^-1内线性关系良好;日内、日间精密度RSD为0.36%~6.39%,准确度为96.19%~113.38%;提取回收率为86.82%~96.12%;基质效应为100.1%~103.1%。结论 本方法经方法学验证,可用于大鼠血浆中普萘洛尔的测定及其药动学研究。     

UPLC-MS/MS测定大鼠血浆多柔比星浓度方法的建立及毒代动力学应用

目的 建立一种简便、快速、灵敏的测定大鼠多柔比星血药浓度的超高效液相-质谱联用（UPLC-MS/MS）法,并将其应用于注射用盐酸多柔比星大鼠体内毒代动力学实验。方法 采用ACQUITY UPLC^® BEH C₁₈（50 mm×2.1 mm,1.7 μm）色谱柱,流动相为0.1%甲酸（含2 mmol/L甲酸铵）水溶液-乙腈,梯度洗脱。体积流量为0.4 mL/min,进样量为10 μL。采用电喷雾离子源（ESI）,多反应监测（MRM）方式扫描,以正离子方式进行检测,蛋白沉淀法提取样品。用于定量分析的离子对分别为多柔比星m/z 544.43→m/z 397.08,内标地西泮m/z 285.02→154.40。SD大鼠30只,按体质量随机分为3组,分别单次iv 52.2、61.4、72.3 mg/m²盐酸多柔比星后测定血药浓度,并用DAS 3.1.4软件计算毒代参数。结果 血浆中内源性物质不干扰待测物和内标的测定,多柔比星在0.5～100 ng/mL范围内线性关系良好,定量下限为0.5 ng/mL。多柔比星在0.5、1、20、80 ng/mL 4个浓度的批内批间精密度RSD值为3.21%～12.79%。多柔比星在1、80 ng/mL的提取回收率和基质效应分别为102.00%～103.75%和79.27%～89.34%。SD大鼠分别单次iv给予注射用盐酸多柔比星52.2、61.4、72.3 mg/m²后,多柔比星在大鼠体内的AUC_0-t分别为（2 318.78±282.65）、（3 203.11±829.41）和（3 326.96±546.04） ng·h/mL,C_0.083h分别为（1 720.50±851.19）、（3 363.00±1 458.84）和（2 156.50±919.90）ng/mL。结论 建立的UPLC-MS/MS分析方法灵敏度高、样品处理方法简单、样品分析时间短,可以应用于大鼠多柔比星毒代动力学试验中。     

单次和多次口服氯乙酰左卡尼汀片在健康人体的药动学研究

目的 采用LC-MS/MS测定人血浆中乙酰左卡尼汀的浓度并用于氯乙酰左卡尼汀片在健康受试者体内的药动学研究。方法 健康受试者单次给药0.5,1.0,1.5 g和多次给予0.5 g后,0~24 h采集血样。通过测定单次和多次给药后血浆中乙酰左卡尼汀的绝对浓度,计算其药动学参数。米屈肼为内标,经甲醇沉淀蛋白后进行LC-MS/MS分析。ESI离子源正离子模式监测,检测离子m/z 204.3→145.2（乙酰左卡尼汀）,m/z 147.2→58.2（米屈肼）;色谱柱为EC 250/4.6 NUCLEOSIL100-5CN,流动相为甲醇-10 mmol·L^-1乙酸铵溶液（含0.1%甲酸）（85：15）。结果 乙酰左卡尼汀在20~3 000 μg·L^-1内线性良好（r=0.999 1）,最低定量限为20 μg·L^-1。批内、批间精密度及基质效应RSD均<15%。单次给药3个剂量组（0.5,1.0,1.5 g）的主要药动学参数为：AUC_0-t为（4 181.77±2 473.24）μg·h·L^-1、（6 099.54±1 939.41）μg·h·L^-1和（8 064.71±3 575.99）μg·h·L^-1,C_max为（611.42±270.76）μg·L^-1,（830.92±233.19）μg·L^-1和（1 004.67±414.95）μg·L^-1,t_1/2z为（4.50±2.93）h、（6.25±3.65）h和（5.76±3.94）h;多次给药后主要的药动学参数：AUC_0-t为（13 728.82±6 493.04）μg·h·L^-1,C_max为（1 129.00±374.05）μg·L^-1,t_1/2z为（8.57±4.42）h。结论 本方法准确、灵敏、专属性强,适用于人体内乙酰左卡尼汀药动学研究。单次和多次给予氯乙酰左卡尼汀片后药动学参数有明显差异,性别间无差异,健康受试者对药物的耐受性良好。     

Efficacy of gut lavage,hemodialysis, and hemoperfusion in the therapy of paraquat or diquat intoxication

Clinical and in vitro investigations were carried out to test the efficacy of gut lavage, hemodialysis, and hemoperfusion in the treatment of poisoning with paraquat or diquat. In a patient suffering from diquat intoxication 130 times more diquat was removed by gut lavage 30 h after ingestion than was removed by complete aspiration of the gastric contents.Determination of in vitro clearances for paraquat and diquat by hemodialysis showed that, at serum concentrations of 1–2 ppm, such as are frequently encountered in poisoning in man, toxicologically relevant quantities of herbicide cannot be removed from the body. At a concentration of 20 ppm, on the other hand, hemodialysis proved to be effective, the clearance being 70 ml/min at a blood flow rate of 100 ml/min. The efficacy of hemoperfusion with coated activated charcoal was on the whole better. Especially at concentrations around 1–2 ppm, the clearance values for hemoperfusion were some 5–7 times higher than those for hemodialysis.In a patient suffering from paraquat poisoning, both hemodialysis as well as hemoperfusion were carried out. The in vitro results could be confirmed: At serum concentrations of paraquat less than 1 ppm no clearance could be obtained by hemodialysis while by hemoperfusion with activated charcoal quite high clearance values were measured and the serum level dropped down to zero.

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Zusammenfassung Klinische Untersuchungen und Laboratoriumsversuche wurden durchgeführt, um die Wirksamkeit von Darmspülung, Hämodialyse und Hämoperfusion bei Paraquat- und Deiquat-Vergiftungen zu prüfen.Bei einem Patienten wurde 30 Std nach Deiquat-Aufnahme durch Darmspülung 130mal mehr Deiquat entfernt als durch vollständige Aspiration des Mageninhaltes. In vitro-Versuche ergaben, daß bei Blutserumkonzentrationen von 1–2 ppm, die bei Vergiftungen oft gemessen werden, durch Hämodialyse keine toxikologisch relevanten Paraquat- oder Deiquat-Mengen entfernt werden können. Dagegen erwies sich die Hämodialyse bei 20 ppm und einer Blutumlaufgeschwindigkeit von 100 ml/min mit einer Clearance von 70 ml/min als wirksam. Die Hämoperfusion mit beschicheter Aktivkohle war in diesen Versuchen aber eindeutig überlegen, denn insbesondere bei Konzentrationen um 1–2 ppm waren die Clearance-Werte 5–7mal höher als bei der Hämodialyse.Die in vitro-Ergebnisse wurden bei einem Patienten mit einer Paraquat-Vergiftung bestätigt: Bei Konzentrationen unter 1 ppm war die Hämodialyse wirkungslos, während durch Hämoperfusion relativ hohe Clearance-Werte erreicht wurden, so daß der Serumspiegel rasch unter die Nachweisgrenze abfiel.

     

In vitro studies on sterically stabilized liposomes (SL) as enzyme carriers in organophosphorus (OP) antagonism

This study describes a new approach for organophosphorous (OP) antidotal treatment by encapsulating an OP hydrolyzing enzyme, OPA anhydrolase (OPAA), within sterically stabilized liposomes. The recombinant OPAA enzyme was derived from Alteromonas strain JD6. It has broad substrate specificity to a wide range of OP compounds: DFP and the nerve agents, soman and sarin. Liposomes encapsulating OPAA (SL)* were made by mechanical dispersion method. Hydrolysis of DFP by (SL)* was measured by following an increase of fluoride ion concentration using a fluoride ion selective electrode. OPAA entrapped in the carrier liposomes rapidly hydrolyze DFP, with the rate of DFP hydrolysis directly proportional to the amount of (SL)* added to the solution. Liposomal carriers containing no enzyme did not hydrolyze DFP. The reaction was linear and the rate of hydrolysis was first order in the substrate. This enzyme carrier system serves as a biodegradable protective environment for the recombinant OP-metabolizing enzyme, OPAA, resulting in prolongation of enzymatic concentration in the body. These studies suggest that the protection of OP intoxication can be strikingly enhanced by adding OPAA encapsulated within (SL)* to pralidoxime and atropine.     

Synthesis,Cytotoxicity and Antileishmanial Activity of Some N-(2-(indol-3-yl)ethyl)-7-chloroquinolin-4-amines

We report herein the condensation of 4,7-dichloroquinoline (1) with tryptamine (2) and D-tryptophan methyl ester (3) . Hydrolysis of the methyl ester adduct (5) yielded the free acid (6) . The compounds were evaluated in vitro for activity against four different species of Leishmania promastigote forms and for cytotoxic activity against Kb and Vero cells. Compound (5) showed good activity against the Leishmania species tested, while all three compounds displayed moderate activity in both Kb and Vero cells.     

Steroidal sapogenin contents in some domestic plants

In order to find out the values of the steroid resources for the future use. the compositions and contents of steroidal sapogenins from 13 domestic plants have been investigated. As a result,Dioscorea nipponica, D. quinqueloba andSmilax china were found to have large amount of diosgenin. And pennogenin inTrillium kamtschaticum andParis verticillata, yuccagenin inAllium fistulosum, hecogenin inAgave americana and neochlorogenin inSolanum nigum were appeared to be major steroidal sapogenins.     

Aquatic Insects and Trace Metals: Bioavailability,Bioaccumulation, and Toxicity

Abstract

The uptake of metals from food and water sources by insects is thought to be additive. For a given metal, the proportions taken up from water and food will depend both on the bioavailable concentration of the metal associated with each source and the mechanism and rate by which the metal enters the insect. Attempts to correlate insect trace metal concentrations with the trophic level of insects should be made with a knowledge of the feeding relationships of the individual taxa concerned. Pathways for the uptake of essential metals, such as copper and zinc, exist at the cellular level, and other nonessential metals, such as cadmium, also appear to enter via these routes. Within cells, trace metals can be bound to proteins or stored in granules. The internal distribution of metals among body tissues is very heterogeneous, and distribution patterns tend to be both metal and taxon specific. Trace metals associated with insects can be both bound on the surface of their chitinous exoskeleton and incorporated into body tissues. The quantities of trace meals accumulated by an individual reflect the net balance between the rate of metal influx from both dissolved and particulate sources and the rate of metal efflux from the organism. The toxicity of metals has been demonstrated at all levels of biological organization: cell, tissue, individual, population, and community. Much of the literature pertaining to the toxic effects of metals on aquatic insects is based on laboratory observations and, as such, it is difficult to extrapolate the data to insects in nature. The few experimental studies in nature suggest that trace metal contaminants can affect both the distribution and the abundance of aquatic insects. Insects have a largely unexploited potential as biomonitors of metal contamination in nature. A better understanding of the physico-chemical and biological mechanisms mediating trace metal bioavailability and exchange will facilitate the development of general predictive models relating trace metal concentrations in insects to those in their environment. Such models will facilitate the use of insects as contaminant biomonitors.