翡翠红外光谱特征的测量与分析

通过傅立叶红外光谱仪（Nicolet 550型）对天然翡翠及其优化处理品种进行测量,分析出翡翠的样品特征红外峰为1162cm^-1,1079cm^-1,950cm^-1,其中1050cm^-1的频带最强,且400cm^-1～600cm^-1之间有四个频带。而B货的红外鉴定最主要的吸收峰为2870cm^-1、2927cm^-1、2960cm^-1、3035cm^-1、3058cm^-1。此外,在2200cm^-1～2600cm^-1范围,还可见到不太明显的多个吸收峰。     

鉴定翡翠A货、B货“晶界缝”是关键

翡翠的A货和B货的鉴定一直是珠宝消费者，商家，珠宝专家关注的问题，如何有效地鉴别翡翠A货和B货，内地与港台的珠宝专家都进行了许多研究。其中，台湾翡翠珠宝专家郑永镇先生通过大量地观察，试验和论证，得出：“晶界疑审翡翠A货和B货鉴定的关键”这一结论。     

翡翠的系统鉴定法

翡翠被称为"玉石之王",通过对翡翠的矿物成分及化学组成、物理化学特性、结构、品质及人工优化处理方法等内容进行深入了解和研究,对翡翠进行系统的鉴定,总结出天然A货翡翠、人工处理的B货和C货翡翠的肉眼鉴定、常规仪器鉴定和大型仪器鉴定的特征。     

局部充胶染色处理翡翠的特征及其鉴别

2004年的下半年，长沙珠宝市场上出现了一种局部充胶染色处理的翡翠饰品，以手镯最常见，偶见玉佩。这类翡翠饰品只对局部进行处理而大部分或绝大部分部位未经漂白充填，表面也没有蛛网纹，结构致密，呈典型的A货翡翠特征，由于这类翡翠饰品面市时间不久，还没有引起大家的广泛注意，稍不少心很容易把它们当作翡翠A货购进，在送检此类样品的商家中也包括一些经常和玉石打交道的行家，可见这类处理翡翠饰品具有很大的欺骗性。     

现代测试技术在优化处理翡翠鉴定中的应用

简要地评述了扫描电镜、电子探针、红外光谱、激光拉曼光谱、阴极发光等现代测试技术的基本原理和在鉴定翡翠A、B、C货中的应用进展。认为翡翠的鉴定还是要注意样品的结构特征，从翡翠的自身属性出发，遵循传统鉴定方法和现代测试技术相结合的综合鉴定原则，才能使翡翠无损鉴定技术更为实用。     

翡翠中川蜡质量分数的定量测试方法

根据最新版国家标准（GB／T16552—2003）,浸蜡的翡翠归为处理类。上蜡是翡翠加工中一项必不可少的工序。对含蜡翡翠究竟定义为传统的优化（“A货”）还是人工处理（“B货”）类型的判定问题,迄今仍众说纷纭。因此,测定翡翠中蜡的质量分数成为了其鉴定的重点。通过配置含不同质量分数川蜡的翡翠的KBr压片样品以及测定支配样品的红外光谱,运用基线法求出川蜡在2919cm^-1处的吸光度,得出其质量分数（C）与吸光度／KBr压片厚度（E／L）之间的关系方程式：E／L=1334．5C-0．068,提出了翡翠中川蜡质量分数的定量测试方法。     

关于翡翠饰品表面残留抛光粉问题的讨论

在日常检验工作中，经常遇到一些翡翠饰品的表面会残留绿色的抛光粉，尤其是一些低档次的翡翠。这些有抛光粉的翡翠应该把它当作天然翡翠（俗称A货），还是当作染色处理翡翠（俗称C货）？     

一种快速鉴别注胶处理翡翠的方法——翡翠的“莹光”

正胡博士:您好!我是刚入行的翡翠经营者,经常会去各地市场上淘货。但有时稍不留神,可能会买到一些B货或B+C货翡翠,虽然不多,但挺打击人心情的!看了不少翡翠鉴定书籍,都说翡翠"桔皮纹"和"酸蚀纹"是重要的鉴定特征,但这些特征都需要在放大镜下去观察,在市场上拿出手电筒照照还可以,但你要掏出放大镜来,那是会被别人看不起或笑话的,商家也觉得是对他的不信任,能卖的货都不卖了!请问胡博士,能否介绍一些简便、快捷、实用的方法,就凭肉眼观察就能鉴别出翡     

采用便携式近红外矿物分析仪鉴别注胶翡翠

目前,采用传统的中红外光谱技术鉴别不透明注蜡与注胶翡翠有一定的难度.采用便携式近红外矿物分析仪检测鉴定了翡翠、注蜡与注胶翡翠样品,对其近红外反射光谱进行了分析与研究,同时对微透明样品作了中红外透射光谱的比对测试.研究结果表明,采用BJKF-1型便携式近红外矿物分析仪,能获得较好的透明或不透明翡翠、注蜡与注胶翡翠样品的近红外反射光谱,三者的近红外光谱特征存在着明显的差异.利用这些特征可有效地鉴别翡翠、注蜡翡翠与注胶翡翠.     

翡翠A，B，C货鉴定有关问题的讨论

翡翠A,B,C货的鉴定需要综合性的考虑,单一方法易出差错,翡翠鉴定首要任务是确定矿物组成,从而确定是否翡翠及翡翠的类型,其次确定是否有人工充填物及人工加色,从而区别A,B,C货。     

On-line determination of fatty acid composition in intramuscular fat of Iberian pork loin by NIRs with a remote reflectance fibre optic probe

A near infrared spectrometer equipped with a standard 210/210 bundle remote reflectance fibre-optic probe, with a 5×5 cm quartz window type, was used for the determination of fatty acids in the Longissimus dorsi muscle of Iberian breed swine. The fatty acids C14:0, C16:0, C16:1, C17:0, C17:1, C18:0, C18:1, C18:2, C18:3, Σpolyunsaturated, Σmonounsaturated and Σsaturated were determined in samples of intramuscular fat from Iberian breed swine by direct application of the fibre-optic probe onto the loin sample, with no treatment or manipulation of the sample. The regression method employed was modified partial least squares. The calibration results using the fibre-optic probe for 74 loin samples had multiple correlation coefficients (RSQ) for C14:0, C16:0, C16:1, C17:0, C17:1, C18:0, C18:1, C18:2, C18:3, Σpolyunsaturated, Σmonounsaturated and Σsaturated acid of 0.785, 0.798, 0.788, 0.825, 0.762, 0.765, 0.696, 0.859, 0.878, 0.807, 0.943, 0.858, respectively, and standard errors of prediction corrected for the same fatty acids (%) of 0.08, 0.63, 0.26, 0.02, 0.02, 0.51, 0,77, 0.64, 0.05, 1.06, 0.34, 0.70, respectively. The robustness of the method was checked by applying the fibre-optic probe to unknown samples of Iberian breed pork loin in a slaughterhouse, using 15 samples for the external validation.     

Effect of connective tissue on the shape of reflectance spectra obtained with a fibre-optic fat-depth probe in beef

A fat-depth probe was fitted with optical fibres to combine depth detection with spectrophotometry and fluorometry. Measurements were made through forelimb flexor, triceps brachii and longissimus thoracis muscles on 22 beef carcasses in a meat cooler. All strong fluorescence peaks had matching strong reflectance peaks (presumably connective tissue), but some strong reflectance peaks did not have equivalent fluorescence peaks (presumably adipose tissue). When the probe stopped at full depth and a complete reflectance spectrum was obtained, no effect from adipose tissue at the optical window of the probe was detected, whereas connective tissue increased reflectance across the visible spectrum (P < 0.005). The strongest effect was at 600 nm. Thus, spuriously high reflectance readings obtained with a fibre-optic meat probe are more likely to originate from connective tissue than from intramuscular adipose tissue.     

The application of near infrared spectroscopy technology and a remote reflectance fibre-optic probe for the determination of peptides in cheeses (cow’s,ewe’s and goat’s) with different ripening times

The use of near infrared spectroscopy (NIRS) technology employing a remote reflectance fibre-optic probe (with a 5 cm × 5 cm quartz window) for the analysis of the hydrophilic (HI) and hydrophobic (HO) peptides and the ratio HO/HI was assayed. To do so, cheeses with known and varying percentages of cow’s, ewe’s and goat’s milk were elaborated (112 samples). Ripening controls were performed over 6 months, and the chemical data obtained by reversed-phase high performance liquid chromatography used as reference. The regression method employed was modified partial least squares (MPLS). The multiple correlation coefficients (RSQ) and prediction corrected standard errors (SEP (C)) obtained 0.879 and 1.83% for hydrophilic (HI) and 0.879 and 1.83% for hydrophobic (HO) peptides, respectively, and 0.890 and 0.03% for the ratio HO/HI. The method allows immediate control by direct application of the fibre-optic probe to the cheese without prior sample treatment or destruction.     

Determination of fatty acids in the subcutaneous fat of Iberian breed swine by near infrared spectroscopy (NIRS) with a fibre-optic probe

A near infrared spectrometer equipped with a standard 1210/210 bundle remote reflectance fibre-optic probe, with a 5×5 cm quartz window, was used for the determination of fatty acids in the subcutaneous fat of Iberian pigs. A comparative study was made of the determination of fatty acids (C14:0, C16:0, C18:0, C18:1, C18:2, C18:3, C20: 1, Σpolyunsaturated, Σmonounsaturated and Σsaturated) in samples of subcutaneous fat from Iberian pigs by direct application of the fibre-optic probe on samples of whole subcutaneous fat and with cam-lock cups, assessing extracts of total lipids with diethyl ether. The regression method employed was modified partial least squares (MPLS). Calibration of 157 samples, using the fibre optic probe, allowed determination of fatty acids in the following ranges: C14:0 (0.78-1.77), C16:0 (15.87-29.74), C18:0 (4.61-15.90), C18:1 (43.50-61.27), C18:2 (2.03-13.94), C18:3 (0.13-1.14), C20:1 (0.45-2.32), Σpolyunsaturated (2.31-14.82), Σmonounsaturated (47.37-65.62), Σsaturated (22.09-47.31), with corrected standard errors of prediction SEP(C) of 0.093, 0.56, 0.67, 0.94, 0.42, 0.10, 0.20, 0.46, 0.94, 0.83, respectively. The robustness of the method using the fibre-optic probe was tested in a slaughterhouse using 23 samples for external validation, giving multiple correlation coefficients (RSQ) for C14:0, C16:0, C18:0, C18:1, C18:2, C18:3 C20:1, Σpolyunsaturated, Σmonounsaturated, Σsaturated acids of 0.72, 0.94, 0.72, 0.79, 0.88, 0.55, 0.17, 0.88, 0.74, and 0.90, respectively, and a corrected standard error of prediction [SEP(C)] for these acids (%) of 0.11, 0.60, 0.84, 1.20, 0.77, 0.11, 0.30, 0.76, 1.21, and 1.18, respectively.     

Non-destructive determination of fat,moisture and protein in salmon fillets by use of near-infrared diffuse spectroscopy

Near infrared (NIR) diffuse spectroscopy was used to determine the fat, moisture and protein contents in whole and ground farmed atlantic salmon fillets. A remote fibre-optic probe was used for NIR measurements on 50 whole salmon fillets. The constituent ranges were: 91-205 g kg^?1 fat, 599-709g kg^?1 moisture and 186-209 g kg^?1 protein. Principal component regression resulted in the following prediction errors for ground salmon fillets, expressed as root mean square error of cross validation: 6.6 g kg-1 fat, 3.8 g kg^?1 moisture and 2.0 g kg^?1 protein. The corresponding prediction errors for non-destructive measurements on whole salmon fillets were 10.8 g kg^?1 fat, 8.5 g kg^?1 moisture and 3.7 g kg^?1 protein. Regression models using the 760-1100 m range gave lower prediction errors than models using the 1100-2500 mm or 760-2500 nm ranges. The results show that fibre-optic probe NIR instruments are suited to determine fat and moisture in whole salmon fillets non-destructively.     

Non-invasive and non-destructive percutaneous analysis of farmed salmon flesh by near infra-red spectroscopy

Near infra-red (NIR) reflectance spectroscopy (700–1100 nm wavelength range) has been applied to the percutaneous measurement of oil and moisture in farmed salmon carcasses. Spectra were recorded through the skin and scales by means of a fibre-optic probe. Six selected sites were used on the dorsal and ventral surfaces of each fish side; 294 sample sites were utilized. Reference chemical values for oil and moisture were determined on these sites after excision. Calibrations were developed and evaluated separately for dorsal and ventral sites. The best dorsal calibration produced a standard error of prediction (SEP) for oil and moisture of 2.0 and 1.45%, respectively; corresponding figures for the best ventral calibration were 2.4 and 1.9%, respectively.     

Relationships between the back-scatter of polarised light and the fibre-optic detection of connective tissue fluorescence in beef

The back-scatter of light (400–800 nm) from bovine m longissimus lumborum (n=47) was measured with a fibre-optic probe fitted with crossed polarisers to exclude Fresnel reflectance. Unlike normal fibre-optic spectra (which may be relatively flat), back-scatter was approximately proportional to wavelength, being low at 400 nm and high at 800 nm. The shape of the spectrum was modified by myoglobin absorbance, with a Soret minimum at 430 nm. Connective tissue fluorescence (365 nm excitation, 400–550 nm emission) was measured through a single optical fibre moving down the longitudinal axis of the muscle. Back-scatter at 430 nm was correlated positively with minimum fluorescence (r=0·73, P<0·001), the area under the fluorescence signal cm⁻¹ (r=0·81, P<0·001) and fluorescence peaks cm⁻¹ (r=0·46, P<0·005). Back-scatter at 800 nm was correlated weakly and negatively with minimum fluorescence (r=-0·28, P<0·05) and peaks cm⁻¹ (r=-0·26, P<0·05). Thus, in the probe detection of connective tissue fluorescence in meat, errors caused by differences in myoglobin concentration may exceed those caused by differences in pH-related light scattering. © 1997 SCI.     

Potential of near infrared spectroscopy for the analysis of volatile components in cheeses

Near Infrared Spectroscopy (NIRS) was used for the determination of volatile compounds in cheeses allowed to ripen for different times using a remote fibre-optic reflectance probe. To do so, cheeses with known and varying percentages of cow's, ewe's, and goat's milk were elaborated and used as reference material. The volatile compounds determined were: acetaldehyde, ethanol, 1-propanol, 2-butanol, 2-pentanol, 3-methyl-1-butanol, 2-butanone, 2-pentanone, 2-heptanone and 2-nonanone. The regression method employed was the modified partial least squares (MPLS). The calibration results using 67–72 samples of cheese had a correlation coefficients (RSQ) between 0.600 for the 3-methyl-1-butanol and 0.903 for the 2-nonanone. The robustness of the method was confirmed by applying it to twenty new samples of different compositions and ripening times which did not belong to the calibration group. Likewise, the correlations between the factors of influence studied and the volatile compounds were carried out. The results of the NIRS method are comparable with those of the purge-and-trap-gas chromatography-mass spectrometry.     

Post-mortem spectrophotometry of pork and beef using quartz optical fibres

A high intensity xenon illuminator, a diffraction grating monochromator and a photomultiplier were linked to pork or beef samples with a bifurcated light guide composed of quartz optical fibers in a random pattern. When muscle fibres and optical fibres were parallel and coaxial, absorbance was greater than when they were perpendicular. As judged by the coefficient of variation at different wavelengths, the effect of fat in the measuring field was not uniform at all wavelengths. For the study of optical changes in pork, from slaughter to 24 h, the fibre-optic probe was maintained in a stationary position. The changes detected were: (1) a slight transient increase in absorbance at all wavelengths in the first few hours post mortem, (2) an eventual decline in absorbance at all wavelengths to reach minimum values at 24 h and (3) a spectrally limited decrease in absorbance, peaking somewhere in the 390 to 450 nm range, which started immediately post mortem.     

Determination of phenolic compounds of grape skins during ripening by NIR spectroscopy

The potential of near infrared spectroscopy (NIRS) to determine the content of phenolic compounds in red grapes has been evaluated. The near infrared spectra of intact grapes and grape skins throughout maturity were recorded using a fibre-optic probe and a transport quartz cup, respectively. Reference values of phenolic compounds were obtained by HPLC-DAD-MS. Modified Partial Least Squares (MPLS) regression was used to develop the quantitative models for flavanols, flavonols, phenolic acids, anthocyanins and total phenolic compounds. The procedure reported here seems to have an excellent potential for fast and reasonable cost analysis. The results of this work show that the models developed using NIRS technology together with chemometric tools allow the quantification of total phenolic compounds and the families of main phenolic compounds in grape skins throughout maturation. The validation of these models showed the best results for the determination of flavonols (differences between HPLC and NIRS of 7.8% using grapes and 10.7% using grape skins) in the external validation procedure. Good results in the external validation were also obtained for the determination of total phenolic compounds (differences of 11.7% using grapes and 14.7% using grape skins). The best results were generally obtained recording the spectra directly in intact grapes.