RESUMEN
The oil overlay micro-drop system is widely used for cultures of mammalian gametes and embryos. We evaluated hereby the effects of two unaltered commercial oils- Sigma mineral oil (S-MO) and Nidoil paraffin oil (N-PO)-on in vitro embryo production (IVP) outcomes using a pig model. The results showed that while either oil apparently did not affect oocyte maturation and fertilization rates, S-MO negatively affected embryo cleavage rates, blastocyst formation rates, and, consequently, total blastocyst efficiency of the system. No differences in the oxidation state were found between the oils or culture media incubated under S-MO or N-PO. Although both oils slightly differed in elemental composition, there were no differences in the concentrations of elements between fresh media and media incubated under oils. By contrast, we demonstrated clear oil-type differences in both the composition of volatile organic compounds (VOC) and the transfer of some of these VOC´s (straight-chain alkanes and pentanal and 1,3-diethyl benzene) to the culture medium, which could have influenced embryonic development.
Asunto(s)
Embrión de Mamíferos/efectos de los fármacos , Desarrollo Embrionario/efectos de los fármacos , Aceites/farmacología , Blastocisto/efectos de los fármacos , Blastocisto/metabolismo , Línea Celular , Femenino , Fertilización In Vitro , Humanos , Peróxido de Hidrógeno/metabolismo , Aceites/clasificación , Oocitos/efectos de los fármacos , Oocitos/metabolismo , Oxidantes/metabolismo , Oxidación-Reducción , Embarazo , Especies Reactivas de Oxígeno/metabolismo , Compuestos Orgánicos Volátiles/farmacologíaRESUMEN
Fuel production from plastics is a promising way to reduce landfilling rates while obtaining valuable products. The usage of Ni-supported hierarchical Beta zeolite (h-Beta) for the hydroreforming of the oils coming from LDPE thermal cracking has proved to produce high selectivities to gasoline and diesel fuels (>80%). In the present work, the effect of the Ni loading on Ni/h-Beta is investigated in the hydroreforming of the oils form LDPE thermal cracking. h-Beta samples were impregnated with Ni nitrate, calcined and reduced in H2 up to 550°C to achieve different Ni contents: 1.5%, 4%, 7% and 10%. Larger and more easily reducible metal particles were obtained on Ni 7%/h-Beta and Ni 10%/h-Beta. Hydroreforming tests were carried out in autoclave reactor at 310°C, under 20 bar H2, for 45 min. Ni content progressively increased the amount of gases at the expenses of diesel fractions, while gasoline remained approximately constant about 52-54%. Maximum selectivity to automotive fuels (â¼81%) was obtained with Ni 7%/h-Beta. Ni loading also enhanced olefins saturation up to Ni 7%/h-Beta. High cetane indices (71-86) and octane numbers (89-91) were obtained over all the catalysts. Regarding the different studied Ni contents, Ni 7%/h-Beta constitutes a rather promising catalyst for obtaining high quality fuels from LDPE thermal cracking oils.
Asunto(s)
Gasolina/análisis , Níquel/química , Polietileno/química , Zeolitas/química , Catálisis , Aceites/clasificación , TemperaturaRESUMEN
O consumidor está cada vez mais consciente da relação entre dieta e doença, que tem impulsionado as pesquisas sobre alimentos funcionais e seus efeitos sobre o corpo. O papel dos óleos e gorduras na nutrição humana tem sido intensamente estudado e discutido por décadas. Tem sido enfatizada a importância da ingestão de ômega-3, ômega-6 e ômega-9 ácidos graxos redução de ácidos graxos saturados e, mais recentemente, controle da ingestão de ácidos graxos trans. Através da mistura e interesterificação química e enzimática de óleos e gorduras, gorduras trans-livre pode ser produzido. Mistura de gordura, foram formuladas por misturas ternárias de estearina de palma, uma gordura láurica (óleo de coco ou óleo de palmiste) e um óleo poliinsaturado (óleo de canola ou azeite de oliva) em diferentes proporções que foram interesterificadas. Neste trabalho, foram produzidos lipídios estruturados por interesterificação química e enzimática. A interesterificação química foi realizada nas seguintes condições: a 88 °C, 60 minutos de reação, 0,4% de catalisador metóxido de sódio, sob agitação e vácuo. A interesterificação enzimática, sendo realizada com duas lipases comerciais Thermomyces lanuginosa e Rhizomucor miehei, com seletividade sn-1,3. A interesterificação enzimática por batelada foi realizado seguindo um planejamento matriz central compósito rotativo em função da temperatura e da composição do meio, estearina de palma, óleo de palmiste e azeite de oliva e catalisado pelas lipases comerciais. O decréscimo do conteúdo de gordura sólida foi observado a 10 e 35 °C após a interesterificação. O biorreator contínuo foi operado nas seguintes condições: mistura de estearina de palma, óleo de palmiste, azeite de oliva (45:30:25), 10 gr de biocatalisador, 65 °C, com tempo de residência de 7 min e por 226 h para Thermomyces lanuginosa e 188 h para Rhizomucor miehei. A atividade do biocatalisador foi avaliada em termos da diminuição do conteúdo de gordura sólida a 35 °C, o qual é um parâmetro chave na produção de margarinas. O perfil de inativação do biocatalisador pode ser bem descrita pelo modelo de desativação de primeira ordem: meia-vida de 88 e 60 h foram estimados quando Thermomyces lanuginosa e Rhizomucor miehei, respectivamente, foram utilizados. Os óleos puros, as misturas originais e interesterificadas foram avaliados quanto à composição de ácidos graxos e triacilgliceróis, distribuição regioespecífica dos ácidos graxos nos triacilgliceróis, ponto de fusão e amolecimento, consistência, conteúdo de gordura sólida, comportamento de fusão e cristalização, estabilidade oxidativa, estrutura cristalina e polimorfismo. A interesterificação química e enzimática promoveram diminuição de triacilgliceróis trissaturados e triinsaturados e aumento dos monossaturados-diinsaturados e dissaturados-monoinsaturados, o que resultou no respectivo decréscimo dos pontos de fusão e amolecimento, consistência e conteúdo de gordura sólida, aumentando a plasticidade das gorduras. As curvas de fusão e cristalização das misturas foram modificadas pela alteração da composição dos triacilgliceróis pela interesterificação química e enzimática. Estabilidade térmica e a temperatura de oxidação da estearina de palma, óleo de coco e óleo de canola e suas misturas foram dependente da composição de ácidos graxos e independente da interesterificação química. Os resultados mostram que a interesterificação química e enzimática oferecem uma ferramenta útil para a concepção de gorduras com sintonizáveis propriedades físico-químicas, melhorando em relação a esse das gorduras de partida
The consumer is becoming more aware of the relationship between diet and disease, which has driven the research on functional foods and their effects on the body. The role of fats and oils in human nutrition has been intensively studied and discussed for decades. It has been emphasized the importance of intake of omega-3, omega-6 and omega-9 fatty acids, reduction of saturated fatty acids and, more recently, control of intake of trans fatty acids. Through the blend and interesterification of oils and fats, trans-free fats can be produced. Fat blends, formulated by ternary blends of palm stearin, lauric fat (coconut oil and palm kernel oil) and polyunsaturated oils (canola oil and olive oil) were done in different ratios. In this work, were produced by chemical and enzymatic interesterification. Chemical interesterification was performed under the following conditions: at 88°C, 60 minutes reaction times, 0.4% sodium methoxide, under agitation and vacuum. For enzymatic interesterification being carried out with two commercial lipases Thermomyces lanuginosa e Rhizomucor miehei, with selectivity sn-1,3. Batch enzymatic interesterification were performed, following central composite rotatable designs (CCRDs) as a function temperature and media of palm stearin, palm kernel oil and olive oil formulation and catalyzed by a commercial immobilized lipase. A decrease in all SFC values of the blends at 10 °C and 35°C was observed upon interesterification. The bioreactor operated continuously: mixture of palm stearin, palm kernel oil and olive oil (45:30:25, wt %), at 65 °C, at a residence time of 7 min and for 226 h to Thermomyces lanuginosa and 188 h to Rhizomucor miehei.. Biocatalyst activity was evaluated in terms of the decrease of the solid fat content at 35 °C of the blends, which is a key parameter in margarine manufacture. The inactivation profile of the biocatalyst could be well described by the first-order deactivation model: Half-lives of 88 and 60 h were estimated when Thermomyces lanuginose and Rhizomucor miehei, respectively, were used. Pure oil, the original and interesterified blends were examined for fatty acids and triacylglycerols composition, regiospecific distribution of fatty acids in triacylglycerols, melting and softening points, consistency, solid fat content, thermal behavior, oxidation stability, crystalline microstructure and polymorphism. Chemical and enzymatic interesterification caused reduction of trisaturated and triunsaturated and increase in monosaturated-diunsaturated and disaturated-monounsaturated, lowering the initial melting and softening points, consistency and solid fat content, increasing plasticity of fats. Melting and crystallization curves were significantly modified by changing the composition of triacylglycerols by chemical and enzymatic interesterification. The thermal stability and oxidation temperature of palm stearin, coconut oil and canola oil and their blends were dependent on fatty acid composition and independent on chemical interesterification. The results show that the chemical and enzymatic interesterification provides a useful tool to design fats with tunable physicochemical properties, improved compared to that of the starting fats
Asunto(s)
Aceites/clasificación , Aceite de Palma/clasificación , Brassica napus , Ácidos Grasos trans , Margarina/toxicidad , Polimorfismo Genético , Triglicéridos/farmacología , Fenómenos Químicos , LípidosRESUMEN
The phase behavior of well-defined C10E4/ester oil/water systems versus temperature was investigated. Fifteen ester oils were studied and their Equivalent Alkane Carbon Numbers (EACNs) were determined from the so-called fish-tail temperature T* of the fish diagrams obtained with an equal weight amount of oil and water (f(w)=0.5). The influence of the chemical structure of linear monoester on EACN was quantitatively rationalized in terms of ester bonds position and total carbon number, and explained by the influence of these polar oils on the "effective" packing parameter of the interfacial surfactant, which takes into account its entire physicochemical environment. In order to compare the behaviors of typical mono-, di-, and triester oils, three fish diagrams were entirely plotted with isopropyl myristate, bis (2-ethylhexyl) adipate, and glycerol trioctanoate. When the number of ester bonds increases, a more pronounced asymmetry of the three-phase body of the fish diagram with respect to T* is observed. In this case, T* is much closer to the upper limit temperature Tu than to the lower limit temperature Tl of the three-phase zone. This asymmetry is suggested to be linked to an increased solubility of the surfactant in the oil phase, which decreases the surfactant availability for the interfacial pseudo-phase. As a consequence, the asymmetry depends on the water-oil ratio, and a method is proposed to determine the fw value at which T* is located at the mean value of Tu and Tl.
Asunto(s)
Aceites/química , Aceites/clasificación , Polietilenglicoles/química , Agua/química , Ésteres , Relación Estructura-ActividadRESUMEN
Nanoemulsions can be used for the encapsulation and oral delivery of bioactive lipophilic components, such as nutraceuticals and pharmaceuticals. There is growing interest in the utilization of low-energy methods to produce edible nanoemulsions. In this study, we examined the influence of system composition and preparation conditions on the formation of edible nanoemulsions by the emulsion phase inversion (EPI) method. The EPI method involves titrating an aqueous phase (water) into an organic phase (oil+hydrophilic surfactant). The influence of oil type, surfactant type, surfactant-to-oil ratio (SOR), and initial surfactant location on the particle size distributions of the emulsions was studied. The droplet size produced by this method depended on: (i) oil type: medium chain triglycerides (MCT)Asunto(s)
Emulsiones/química
, Nanopartículas
, Aceites/química
, Tensoactivos/química
, Agua/química
, Aceites/clasificación
, Tamaño de la Partícula
RESUMEN
We report a new approach to identify swill-cooked oils that are recycled from tainted food and livestock waste from commercial vegetable and animal oils by means of carbon isotope values and relative abundance of fatty acids. We test this method using 40 cooking oil samples of different types with known sources. We found significant differences in both total organic carbon isotope as well as compound-specific isotope values and fatty acid C(14)/C(18) ratios between commercial vegetable oils refined from C(3) plants (from -35.7 to -27.0 and from 0 to 0.15) and animal oils (from -28.3 to -14.3 and from 0.1 to 0.6). Tested swill-cooked oils, which were generally refined by mixing with animal waste illegally, fall into a narrow δ(13)C/fatty acid ratio distribution: from -25.9 to -24.1 and from 0.1 to 0.2. Our data demonstrate that the index of a cross-plotting between fatty acid δ(13)C values and C(14)/C(18) ratios can be used to distinguish clean commercial cooking oils from illegal swill-cooked oils.
Asunto(s)
Ácidos Grasos/análisis , Contaminación de Alimentos/análisis , Aceites de Plantas/química , Aceites de Plantas/clasificación , Animales , Isótopos de Carbono/análisis , Aceites/química , Aceites/clasificaciónRESUMEN
Distilled tall oil (DTO) is a natural product, often added as an emulsifying ingredient in cutting fluids used as lubricants and coolants in metal working. The in vitro model used to test the skin compatibility of these substances, was the isolated perfused ex vivo bovine udder skin (BUS) model. After three exposure periods (0.5, 1, and 5 hours), cytotoxic effects were determined by using the 3-(4,5-dimethylthiazol- 2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and tissue levels of the pre-inflammatory mediator prostaglandin E2 (PGE2) in treated whole skin biopsies were assessed by using an enzyme immunoassay. The BUS standard study design, involving a single application, was previously developed to investigate the skin irritation potential of cosmetics and chemicals. In the current study, four different batches of undiluted DTO, and tall oil fatty acids as a reference compound, were applied both singly and repeatedly (three times), under open conditions which were in line with the potential usage conditions in the work place. Under the standardised single application conditions, no major differences in cytotoxic effects or PGE2 levels between the samples were apparent, so no indication of a skin irritation potential could be concluded. This result is in accordance with prior in vivo studies for acute dermal toxicity. Under repeated application conditions, signs of cytotoxicity were observed after the application of one of the DTO samples, which was known to be derived from different raw materials. Therefore, it was concluded that, generally, the presence of DTO at a concentration of up to 10% in cutting fluids, is not expected to result in any DTO-related deterioration of the skin.
Asunto(s)
Alternativas a las Pruebas en Animales , Irritantes/toxicidad , Glándulas Mamarias Animales/efectos de los fármacos , Aceites/toxicidad , Pruebas de Irritación de la Piel , Piel/efectos de los fármacos , Animales , Bovinos , Supervivencia Celular/efectos de los fármacos , Dinoprostona/metabolismo , Femenino , Irritantes/clasificación , Glándulas Mamarias Animales/metabolismo , Glándulas Mamarias Animales/patología , Modelos Animales , Aceites/clasificación , Piel/metabolismo , Piel/patología , Sales de Tetrazolio/metabolismo , Tiazoles/metabolismo , Técnicas de Cultivo de TejidosRESUMEN
Hydrodeoxygenated pyrolysis oils (HDO) are considered promising renewable liquid energy carriers. To gain insights in the various reaction pathways taking place during the hydrodeoxygenation reaction of pyrolysis oil, two-dimensional gas chromatography with time-of-flight mass spectrometric analyses (2D-GC-TOF-MS) was applied on the feedstock and product oil. Chromatographic parameters like injection temperature and column choice of the 1D-(2)D ensemble are discussed. Fractionation of the oils by hexane extraction was applied to show the distribution of analytes over the phases. Some 1000 and 2000 components in the pyrolysis and HDO oil, respectively could be identified and classified. The TOF-MS detection considerably improved the understanding of the molecular distribution over the 1D-(2)D retention time fields in the contour plot, in order to classify the analytes in functional groups. By group-type classification of the main components (>0.3% relative area), it was possible to characterize the oils by 250 and 350 analytes, respectively pyrolysis oil and HDO oil, describing 75% of the chromatographable fraction. The 2D-GC-TOF-MS method showed to be a useful and fast technique to determine the composition of (upgraded) pyrolysis oil and is potentially a very useful tool for exploratory catalyst research and kinetic studies. The 2D-GC-TOF-MS technique is not only useful for the chemical study as such, but also provides the basic knowledge for method transfer to a 2D-GC-FID (flame ionization detector) application.
Asunto(s)
Cromatografía de Gases/métodos , Espectrometría de Masas/métodos , Aceites/química , Catálisis , Interpretación Estadística de Datos , Calor , Hidrógeno/química , Peso Molecular , Aceites/clasificación , Oxígeno/químicaRESUMEN
Spironolactone is a steroidal diuretic showing incomplete oral behaviour because of its low solubility and slow dissolution rate. In this study, we applied the nanoprecipitation method to prepare spironolactone-loaded nanocapsules, at laboratory-scale and pilot-scale. The effect of several formulation variables on the spironolactone-loaded nanocapsules properties (average size, drug release rate and drug entrapment) was investigated. The optimized formulations at laboratory-scale and pilot-scale lead to the preparation of spironolactone-loaded nanocapsules with a mean size of 320 and 400 nm, respectively, a high encapsulation efficiency (96.21% and 90.56% respectively), both stable for 6 months. The release of spironolactone from nanocapsules was rapid and complete in a simulated gastric fluid, therefore recourse to spironolactone nanoencapsulation should enhance its oral bioavailability and probably its efficiency. The optimized formulations lead to a high drug-concentration in the liquid preparation (1.5 mg/ml) allowing minimizing the preparation volume administered for children medication.
Asunto(s)
Composición de Medicamentos/métodos , Nanocápsulas/química , Espironolactona/farmacocinética , Antiinflamatorios no Esteroideos/química , Antiinflamatorios no Esteroideos/farmacocinética , Química Farmacéutica/métodos , Composición de Medicamentos/instrumentación , Estabilidad de Medicamentos , Almacenaje de Medicamentos , Microscopía Electrónica de Transmisión/métodos , Peso Molecular , Nanocápsulas/ultraestructura , Nanotecnología/instrumentación , Nanotecnología/métodos , Aceites/química , Aceites/clasificación , Tamaño de la Partícula , Poloxámero/química , Poliésteres/química , Solubilidad , Solventes/química , Espironolactona/química , Factores de TiempoRESUMEN
This paper describes the development of practical Fourier transform infrared (FT-IR) methods for the determination of acid number (AN) and base number (BN) in lubricants through the combined use of signal transduction via stoichiometric reactions and differential spectroscopy to circumvent matrix effects. Trifluoroacetic acid and potassium phthalimide were used as stoichiometric reactants to provide infrared (IR) signals proportional to the basic and acidic constituents present in oils. Samples were initially diluted with 1-propanol, then split, with one half treated with the stoichiometric reactant and the other half with a blank reagent, their spectra collected, and a differential spectrum obtained to ratio out the invariant spectral contributions from the sample. Quantitation for AN and BN was based on measurement of the peak height of the v(C = O) or v(COO) absorptions, respectively, of the products of the corresponding stoichiometric reactions, yielding a standard error of calibration of < 0.1 mg KOH/g oil. The AN/BN FT-IR methods were validated by the analysis of a wide range of new and used oils supplied by third parties, which had been analyzed by ASTM methods. Good correlations were obtained between the chemical and FT-IR methods, indicating that the measures are on the whole comparable. From a practical perspective, these new FT-IR methods have significant advantages over ASTM titrimetric methods in terms of environmental considerations, sample size, and speed of analysis, as well as the variety of oil types that can be handled. FT-IR analysis combining stoichiometric signal transduction with differential spectroscopy may be of wider utility as an alternative to titration in the determination of acid or basic constituents in complex nonaqueous systems.
Asunto(s)
Algoritmos , Técnicas Químicas Combinatorias/métodos , Aceites/análisis , Aceites/química , Espectroscopía Infrarroja por Transformada de Fourier/métodos , Concentración de Iones de Hidrógeno , Indicadores y Reactivos , Lubrificación , Aceites/clasificación , Aceites/normas , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Estados UnidosAsunto(s)
Glicerol/farmacología , Hidróxido de Calcio/farmacología , Necrosis de la Pulpa Dental/etiología , Necrosis de la Pulpa Dental/inducido químicamente , Necrosis de la Pulpa Dental/terapia , Aceites/clasificación , Aceites/farmacología , Ozono/farmacología , Tratamiento del Conducto Radicular , Diente no VitalRESUMEN
Utilizamos 36 ratos que tiveram o incisivo superior extraído e mantido em meio seco por 60 minutos. Após a biomecânica, os canais permaneceram vazios no grupo I, e nos grupos II e III foram preenchidos com pasta de hidróxido de cálcio utilizando-se um veículo aquoso e oleoso, respectivamente. Os dentes foram reimplantados e, após períodos de 10 e 60 dias, os animais foram sacrificados. Houve predominância de reabsorçäo inflamatória no grupo I. Menor incidência de reabsorçäo foi encontrada no grupo II no período inicial, aumentando no período final. As reabsorçöes encontradas no grupo III se mantiveram constantes aos 10 e 60 dias. Isso nos levou a concluir que tipo de veículo da pasta pode influir no reparo do dente reimplantado
Asunto(s)
Animales , Ratas , Hidróxido de Calcio/uso terapéutico , Aceites/clasificación , Aceites/uso terapéutico , Reimplante DentalRESUMEN
O objetivo do presente trabalho foi avaliar radiográfica, histológica e histobacteriologicamente o efeito da medicaçäo intracanal com o óleo ozonizado ou com a pasta de hidróxido de cálcio, paramonoclorofenol canforado e glicerina (HPG) no tratamento endodôntico de dentes despolpados com lesäo perirradicular associada. Foram utilizados 84 canais radiculares de pré-molares e incisivos inferiores de 6 cäes. Para a induçäo das lesöes perirradiculares, a polpa foi removida e o canal inoculado com Enterococcus faecalis, sendo os dentes em seguida selados coronariamente com resina composta fotopolimerizável por 90 dias. Decorrido este período foi realizado exame radiográfico e, uma vez constatado o desenvolvimento de lesäo perirradicular, procedeu-se o tratamento endodôntico. Os dentes submetidos ao tratamento endodôntico foram divididos em 3 grupos experimentais: tratamento dendôntico em sessäo única; tratamento em 2 sessöes com medicaçäo com HPG e tratamento em 2 sessöes com medicaçäo intracanal com óleo ozonizado. Como controles positivos foram utilizados os seguintes grupos: instrumentaçäo sem obturaçäo e dentes com infecçäo sem realizar tratamento; e como controle negativo, dentes com polpa viva tratados em sessäo única. Após o término do preparo químico-mecânico e decorridos 7 dias do curativo de demora com o óleo ozonizado ou com a pasta HPG, os canais foram obturados e as cavidades coronárias seladas com resina composta fotopolimerizável. Decorridos 180 dias após a obturaçäo, os dentes doram radiografados e os animais sacrificados por sobredose anestésica. As peças foram preparadas, fixadas em formalina a 10 por cento e posteriormente desmineralizadas em EDTA. Após o processamento histológico de rotina, os cortes com 5 µm de espessura foram corados por H. E. ou por Brown e Brenn. Tanto a análise radiográfica quanto a histolatológica e a histobacteriológica demonstraram que näo houve diferença significativa na resposta tecidual perirradicular aos dois medicamentos utilizados. Os resultados entäo sugerem que o óleo ozonizado tem o potencial de ser utilizado na endodontia como medicamento intracanal
Asunto(s)
Animales , Perros , Glicerol , Hidróxido de Calcio/farmacología , Necrosis de la Pulpa Dental/etiología , Necrosis de la Pulpa Dental/inducido químicamente , Necrosis de la Pulpa Dental/terapia , Aceites/clasificación , Aceites/farmacología , Ozono/farmacología , Tratamiento del Conducto Radicular , Diente no VitalRESUMEN
In sexual assault cases, lubricant trace evidence may supplement biological evidence, or may be the primary physical evidence where biological evidence is unavailable. This study considered a total of 50 lubricants from condoms and personal lubricant products available in Australia. Differentiation of the samples was attempted using fluorescence examination, Fourier transform infrared spectroscopy (DRIFTS), gas chromatography-mass spectrometry, liquid chromatography-tandem mass spectrometry, and pyrolysis gas chromatography-mass spectrometry. Eleven of the samples were uniquely identified by the analysis scheme, while the remainder of the samples were separated into nine groups. As a result of this study, a recommended protocol for the detection and analysis of an "unknown" biological swab was produced.
Asunto(s)
Condones/clasificación , Medicina Legal/métodos , Aceites/análisis , Violación , Australia , Femenino , Cromatografía de Gases y Espectrometría de Masas , Humanos , Lubrificación , Masculino , Aceites/clasificación , Espectroscopía Infrarroja por Transformada de FourierRESUMEN
The cone oil droplets of 19 species of birds from 11 families were examined by microspectrophotometry. Individual droplets were expanded with mineral oil, suspended in aqueous glycerol, and absorbance spectra measured between 700 and 320 nm. A classification of oil droplets is proposed, in which objective measurements of their carotenoids are related to the size, position and visual appearance of the droplets under the microscope. Some droplets contain no carotenoid and are transparent at wavelengths longer than 320 nm. Other droplets appear colorless but contain carotenoids absorbing at 385 or 402 nm. The pale droplets that have traditionally been described as greenish contain a mixture of two carotenoids. All of these types are distinct from yellow and red droplets. Red droplets contain astaxanthin esters, and yellow droplets contain a carotenoid with a spectrum similar to zeaxanthin. The 402 nm chromophore is galloxanthin, a C27 apo-carotenoid with 8 double bonds. The in vivo optical densities are 1-4 in the paler droplets, range up to about 8 in the yellow droplets, and can exceed 20 in the red droplets. All droplets that contain carotenoid can exhibit substantial absorption in the near u.v. The frequencies of the several droplet types in the retinas of different species suggests that these organelles respond readily to natural selection and may be involved in more than one function.