2.9.38. 筛分法评估颗粒度大小分布(17)
PARTICLE-SIZE DISTRIBUTION ESTIMATION BY ANALYTICAL SIEVING(17)
筛分是对粉末和颗粒通过颗粒大小分布进行分级的最老的方法之一。当使用织物
筛布时，筛分基本上依据筛网的中间尺寸大小（即幅度或宽度）对颗粒进行分类。如果大部分的颗粒大于75微米左右，采用机筛法是最合适的。对于更小的颗粒，由于质量轻，在筛分过程中，它们不能克服表面凝聚力和粘附力，使颗粒相互粘
在一起或粘在筛网上，从而导致那些本该能通过筛孔的颗粒而未能通过。对于这
样的材料，其它的振动方式，如喷气筛分或声波筛分器筛分可能更为合适。然而，筛分有时可被用于一些中值颗粒尺寸小于75微米的粉末或颗粒，只要该方法经
过验证。在制药行业，对单一粉末或颗粒进行粗略等级分类时，筛分通常是被选
择的方法。这是一个尤其引人注目的方法，因为该方法仅依据粒径大小对粉末和
颗粒进行颗粒大小分级，在大多数情况下，干粉状态下即可进行检测。
Sieving is one of the oldest methods of classifying powders and granules by particle-size distribution. When using a woven sieve cloth, the sieving will essentially sort the particles by their intermediate size dimension (i.e. breadth or width). Mechanical sieving is most suitable where the majority of the particles are larger than about 75 µm. For smaller particles, their light weight provides insufficient force during sieving to overcome the surface forces of cohesion and adhesion that cause the particles to stick to each other and to the sieve, and thus cause particles that would be expected to pass through the sieve to be retained. For such materials other means of agitation such as air-jet sieving or sonic-sifter sieving may be more appropriate. Nevertheless, sieving can sometimes be used for some powders or granules having median particle sizes smaller than 75 µm where the method can be validated. In pharmaceutical terms, sieving is usually the method of choice for classification of the coarser grades of single powders or granules. It is a particularly attractive method in that powders and granules are classified only on the basis of particle size, and in most cases the analysis can be carried out in the dry state.
筛分方法的局限性包括：需要可观质量的样品（通常至少为25克，这取决于粉
末或颗粒的密度和试验筛的直径）；以及在筛分那些容易堵塞筛孔的油性或有粘
着力的粉末或颗粒时存在困难。该方法在本质上是一个对颗粒大小的两个维度的
估计，因为是否能通过筛孔，通常更多地取决于最大宽度和厚度，而非长度。Among the limitations of the sieving method are the need for an appreciable amount of sample (normally at least 25 g, depending on the density of the powder or granule, and the diameter of the test sieves) and the difficulty in sieving oily or other cohesive powders or granules that tend to clog the sieve openings. The method is essentially a two-dimensional estimate of size because passage through the sieve aperture is frequently more dependent on maximum width and thickness than on length.
此方法拟用于某个单一物质的总体粒度大小分布的估计。而不用于测定通过或保
留在1个或2个筛上颗粒的比例。
This method is intended for estimation of the total particle-size distribution of a
single material. It is not intended for determination of the proportion of particles passing or retained on 1 or 2 sieves.
按照干筛法中所述对颗粒度大小分布进行估计，除非个论中另有规定。可能遇到的困难是在过筛临近终点时（如材料不容易通过筛子），或当需要使用筛分范围（小于75µm）中偏细的筛子时，使用替代粒度分级方法时必须慎重。Estimate the particle-size distribution as described under Dry sieving method,
unless otherwise specified in the individual monograph. Where difficulty is experienced in reaching the endpoint (i.e. material does not readily pass through the sieves) or when it is necessary to use the finer end of the sieving range (below 75 µm), serious consideration must be given to the use of an alternative particle-sizing method.
筛分必须在不会造成测试样增加或失去水分的条件下进行。筛分环境中的相对湿度必须加以控制，以防止样品吸收水分或水分流失。在缺乏相反证据的情况下，进行筛分分析测试通常是在周围环境湿度中进行。适用于某个特殊材料的任何特殊条件必须在个论中详细描述。
Sieving is carried out under conditions that do not cause the test sample to gain or lose moisture. The relative humidity of the environment in which the sieving is carried out must be controlled to prevent moisture uptake or loss by the sample. In the absence of evidence to the contrary, analytical test sieving is normally carried out at ambient humidity. Any special conditions that apply to a particular material must be detailed in the individual monograph.
过筛检测原则。检测用试验筛：一个经过简单编织能够织成类似方孔的金属丝网，再连接到一个开口筒状容器的底部所构成。基本的检测方法包括：将筛子按照筛孔粗细程度从小到大的顺序逐一堆叠起来，然后将待测试的粉末置于顶层筛面上。套筛经受一个标准时间的摇动，然后每层筛上留有的待测试粉末
的质量就可以准确确定。这个测试方法可得出粉末在每个筛子孔径范围内的质量百分比。Principles of analytical sieving. Analytical test sieves are constructed from a woven-wire mesh, which is of simple weave that is assumed to give nearly square apertures and is joined to the base of an open cylindrical container. The basic analytical method involves stacking the sieves on top of one another in ascending degrees of coarseness, and then placing the test powder on the top sieve. The nest of sieves is subjected to a standardised period of agitation, and then the mass of material retained on each sieve is accurately determined. The test gives the mass percentage of powder in each sieve size range.
这种对单一的药物粉末进行颗粒尺寸分布估计的筛分过程通常用于至少有80％的颗粒大于75µm的粉末。使用分析过筛法测定颗粒大小分布过程中涉及的尺寸参数是指颗粒可通过的最小方孔的边长。
This sieving process for estimating the particle-size distribution of a single pharmaceutical powder is generally intended for use where at least 80 per cent of the particles are larger than 75 µm. The size parameter involved in determining particle-size distribution by analytical sieving is the length of the side of the minimum
reactive翻译
square aperture through which the particle will pass.
试验筛TEST SIEVES
适合药典测试的试验筛应符合ISO3310-1：试验筛-技术要求和检测- 第1部分：金属丝编织网试验筛（见表2.9.38.-1）现行版的要求。除非个论中另有规定，应使用表2.9.38.-1中列出的ISO筛主要尺寸，在个别地区推荐使用这些尺寸。Test sieves suitable for pharmacopoeial tests conform to the current edition of ISO 3310-1: Test sieves-Technical requirements and testing - Part 1: Test sieves of metal wire cloth (see Table 2.9.38.-1). Unless otherwise specified in the monograph, use those ISO sieves listed as principal sizes in Table 2.9.38.-1 that are recommended in the particular region.
表  2.9.38.-1
筛子选择时，应能涵盖测试样品中存在的所有颗粒大小的尺寸范围。建议套筛各
个筛网的筛孔面积按递增。套筛最上面安装最粗的筛网，底部安装最细的筛网。以微米或毫米表示试验筛筛孔大小。
Sieves are selected to cover the entire range of particle sizes present in the test
sample. A nest of sieves having a progression of the area of the sieve openings is recommended. The nest of sieves is assembled with the coarsest screen at the top and the finest at the bottom. Use micrometres or millimetres in denoting test sieve openings.
试验筛由不锈钢或其次情况下由黄铜或其它合适的非反应性金属丝制成。
Test sieves are made from stainless steel or, less preferably, from brass or another suitable non-reactive wire.
试验筛的校准和再校准应根据ISO3310-1现行版规定。在使用前应仔细检查筛网是否有严重变形和破裂，尤其是在网框接合处。可采用光学方法对筛网进行调校来估计筛孔的平均尺寸，以及筛孔开口目数
的变化。或者，可采用尺寸范围212-850µm的标准玻璃球对筛孔开口进行有效性评估。除非在个论中另有规定，筛分检测必须在受控的室温和周围环境中的相对湿度条件下进行。Calibration and recalibration of test sieves is in accordance with the current edition of ISO 3310-1. Sieves are carefully examined for gross distortions and fractures, especially at their screen frame joints, before use. Sieves may be calibrated optically to estimate the average opening size, and opening variability, of the sieve mesh. Alternatively, for the evaluation of the effective opening of test sieves in the size range of 212-850 µm, standard glass spheres are available. Unless otherwise specified in the individual monograph, perform the sieve analysis at controlled room temperature and at ambient relative humidity.
试验筛的清洁。理想的情况下，只能使用低压喷气或液体流对试验筛进行清洗。如果某些筛孔被测试粉末颗粒堵住了，万不得已的条件下，可小心轻轻擦拭。Cleaning test sieves. Ideally, test sieves are cleaned using only a low-pressure air jet or a liquid stream. If some apertures remain blocked by test particles, careful gentle brushing may be used as a last resort.
测试样/供试品. 如果在药典个论中没有给出某个具体材料所需供试样品的质量，对于直径200mm的试验筛，可使用25-100克的测试样品，具体量取决于该材料的堆积密度。对于直径76mm的筛子，所能容纳的测试样品质量大约是直径200mm试验筛所能容纳样品质量的1/7。通过精密称取不用质量的样品，如25克、50克和100克在同一机械振动筛上振动同样的时间来确定最适当的用于筛分检测的测试样质量，
（注：如果25克样品和50克样品的检测结果是相似的，但100克样品通过最细的筛子时却呈现出一个较低的比例，那100克的样品量就太多了）。如果只有10-25克可用样品，可用符合相同质量标准的金属丝网但直径更小的试验筛，但必须重新确定筛分终点。可能会需要使用更小质量的试验样品(如低至5g)。对于具有较低表观颗粒密度的检品，或者大部分是由直径高度接近

版权声明：本站内容均来自互联网，仅供演示用，请勿用于商业和其他非法用途。如果侵犯了您的权益请与我们联系QQ:729038198，我们将在24小时内删除。